java攻城狮之路(Android篇)--ListView与ContentProvider

一.ListView
1.三种Adapter构建ListView
ListView添加条目的时候, 可以使用setAdapter(ListAdapter)方法, 常用的ListAdapter有三种
BaseAdapter: 定义一个类继承BaseAdapter, 重写4个抽象方法, ListView的条目是由getView()方法构建出来的
SimpleAdapter: 创建SimpleAdapter对象时, 传入数据(List<Map<String, ?>>), 并指定数据的绑定关系
SimpleCursorAdapter: 创建SimpleCursorAdapter对象时, 传入一个Cursor, 指定数据的绑定关系

练习一：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context="com.shellway.sqlite.MainActivity"

    android:background="@color/abc_search_url_text_normal">

    <ListView

        android:id="@+id/id_LV"

        android:layout_width="fill_parent"

        android:layout_height="fill_parent"

         />

</RelativeLayout>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="horizontal"

    android:padding="10dp"

    >

    <TextView

        android:id="@+id/idTV"

        android:textSize="20sp"

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:layout_weight="1"

        android:gravity="center"

        android:text="1"

        />

    <TextView

        android:id="@+id/nameTV"

        android:textSize="20sp"

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:layout_weight="2"

        android:gravity="center"

        android:text="张三"

        />

    <TextView

        android:id="@+id/balanceTV"

        android:textSize="20sp"

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:layout_weight="2"

        android:gravity="center"

        android:text="10000"

        />

</LinearLayout>

item.xml

package com.shellway.sqlite;

import java.util.List;

import android.support.v7.app.ActionBarActivity;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseAdapter;

import android.widget.ListView;

import android.widget.TextView;

public class MainActivity extends ActionBarActivity {

    private ListView lv;

    private List<Person> persons;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        lv = (ListView) findViewById(R.id.id_LV); //获取ListView

        PersonDAO dao = new PersonDAO(this);

        persons = dao.findAll();

        //给ListView添加Adapter,按照Adapter中的方法对ListView添加条目

        lv.setAdapter(new myAdapter()); 

    }

    //定义Adapter，把每个Person对象生成一个条目，将所有条目装入ListView

    private class myAdapter extends BaseAdapter{

        @Override

        public int getCount() {  //返回ListView中要装入的条目的数量

            return persons.size();

        }

        @Override

        public Object getItem(int position) {//点哪个条目就返回哪个条目的对象

            return persons.get(position);

        }

        @Override

        public long getItemId(int position) {//返回条目的ID

            return position;

        }

        @Override

        //返回指定位置上的View,会被添加到ListView中（即一个Person构建成一个View,然后挂到ListView）

        public View getView(int position, View convertView, ViewGroup parent) {

            Person p = persons.get(position);

            //构建成一个条目(View)，第三个参数是要挂到谁身上，这里写null它会自动返回到LListView中

            View item = View.inflate(getApplicationContext(), R.layout.item, null);

            TextView idTV = (TextView) item.findViewById(R.id.idTV);

            TextView nameTV = (TextView) item.findViewById(R.id.nameTV);

            TextView balanceTV = (TextView) item.findViewById(R.id.balanceTV);

            idTV.setText(p.getId()+"");

            nameTV.setText(p.getName());

            balanceTV.setText(p.getBalance()+"");

            return item;

        }

    }

}

MainActivity

SimpleAdapter:

注意：若要修改成SimpleAdapter，不要忘记了修改AndroidManifest.xml中下面加粗位置部分。

        <activity

            android:name=".SimpleAdapterActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

package com.shellway.sqlite;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import android.support.v7.app.ActionBarActivity;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseAdapter;

import android.widget.ListView;

import android.widget.SimpleAdapter;

import android.widget.TextView;

public class SimpleAdapterActivity extends ActionBarActivity {

    private ListView lv;

    private List<Person> persons;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        lv = (ListView) findViewById(R.id.id_LV); //获取ListView

        PersonDAO dao = new PersonDAO(this);

        persons = dao.findAll();

        List<Map<String, Object>> data = new ArrayList<Map<String,Object>>();

        for (Person p : persons) {

            Map<String, Object> map = new HashMap<String, Object>();

            map.put("id", p.getId());

            map.put("name", p.getName());

            map.put("balance", p.getBalance());

            data.add(map);

        }

        lv.setAdapter(new SimpleAdapter(this, data , R.layout.item,

                new String[]{"id","name","balance"},

                new int[]{R.id.idTV,R.id.nameTV,R.id.balanceTV}));

        /**SimpleAdapter

         * 参数1：上下文环境

         * 参数2：数据，List<Map<String, Object>>每个Person装入一个Map，再将Map装入List

         * 参数3：布局文件的资源id

         * 参数4：Map中的Key,和参数5中的id对应，将指定key的value放入View中指定id对应和组件上

         * 参数5：View中的id

         */

    }

}

SimpleAdapter

SimpleCusorAdapter:

注意：使用SimpleCusorAdapter，在查询结果中要包含有“_id”这一列，这里我把id取别名为_id的方法解决。

    public Cursor queryAllCusor(){

        SQLiteDatabase db = helper.getReadableDatabase();

        //Cursor c = db.rawQuery("select id,name,balance from people", null);

        Cursor c = db.query("people", new String[]{"id as _id","name","balance"}, null, null, null, null, null, null);

        return c;

    }

package com.shellway.sqlite;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import android.support.v4.widget.SimpleCursorAdapter;

import android.support.v7.app.ActionBarActivity;

import android.database.Cursor;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseAdapter;

import android.widget.ListView;

import android.widget.SimpleAdapter;

import android.widget.TextView;

public class SimpleCusorAdapterActivity extends ActionBarActivity {

    private ListView lv;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        lv = (ListView) findViewById(R.id.id_LV); //获取ListView

        PersonDAO dao = new PersonDAO(this);

        Cursor c = dao.queryAllCusor();

        lv.setAdapter(new SimpleCursorAdapter(this, R.layout.item, c,

                new String[]{"_id","name","balance"},

                new int[]{R.id.idTV,R.id.nameTV,R.id.balanceTV}));

        /**SimpleAdapter

         * 参数1：上下文环境

         * 参数2：布局文件的资源id

         * 参数3：包含数据的游标

         * 参数4：游标中的列名

         * 参数5：条目中的组件的ID，游标中的数据就会放在对应的这些组件上

         */

    }

}

SimpleCusorAdapterActivity

运行结果：

2.监听ListView的点击
调用ListView.setOnItemClickListener(OnItemClickListener)方法注册一个监听器
在监听器的onItemClick()方法中使用 parent.getItemAtPosition(position) 方法可以获取指定条目上的数据
BaseAdapter: 返回的就是自定义的getItem()方法中返回的数据
SimpleAdapter: 返回的是一个Map, 就是创建SimpleAdapter时List中的一个Map
SimpleCursorAdapter: 返回的是一个Cursor, 这个Cursor就是创建时传入的Cursor, 但是已经通过moveToPosition()方法指定到点击的索引了

练习2：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context="com.shellway.sqlite.SimpleAdapterActivity"

    android:background="@color/abc_search_url_text_normal">

<LinearLayout

    android:id="@+id/ll"

    android:layout_width="match_parent"

    android:layout_height="wrap_content"

    android:orientation="horizontal"

    >

    <TextView

        android:textSize="20sp"

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:layout_weight="1"

        android:gravity="center"

        android:text="序号"

        />

    <TextView

        android:textSize="20sp"

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:layout_weight="2"

        android:gravity="center"

        android:text="姓名"

        />

    <TextView

        android:textSize="20sp"

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:layout_weight="2"

        android:gravity="center"

        android:text="余额"

        />

</LinearLayout>

    <ListView

        android:id="@+id/id_LV"

        android:layout_width="fill_parent"

        android:layout_height="fill_parent"

        android:layout_below="@id/ll"

    />

</RelativeLayout>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="horizontal"

    android:padding="10dp"

    >

    <TextView

        android:id="@+id/idTV"

        android:textSize="20sp"

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:layout_weight="1"

        android:gravity="center"

        android:text="1"

        />

    <TextView

        android:id="@+id/nameTV"

        android:textSize="20sp"

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:layout_weight="2"

        android:gravity="center"

        android:text="张三"

        />

    <TextView

        android:id="@+id/balanceTV"

        android:textSize="20sp"

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:layout_weight="2"

        android:gravity="center"

        android:text="10000"

        />

</LinearLayout>

item.xml

package com.shellway.sqlite;

import java.util.List;

import android.support.v4.widget.SearchViewCompat.OnCloseListenerCompat;

import android.support.v7.app.ActionBarActivity;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AdapterView;

import android.widget.AdapterView.OnItemClickListener;

import android.widget.BaseAdapter;

import android.widget.ListView;

import android.widget.TextView;

import android.widget.Toast;

public class BaseAdapterActivity extends ActionBarActivity {

    private ListView lv;

    private List<Person> persons;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        lv = (ListView) findViewById(R.id.id_LV); //获取ListView

        PersonDAO dao = new PersonDAO(this);

        persons = dao.findAll();

        //给ListView添加Adapter,按照Adapter中的方法对ListView添加条目

        lv.setAdapter(new myAdapter());

        //给ListView添加条目点击监听器

        lv.setOnItemClickListener(new myOnClickListener());

    }

    private class myOnClickListener implements OnItemClickListener{

        @Override

        public void onItemClick(AdapterView<?> parent, View view, int position,

                long id) {

            //获取点击的条目上的数据，其内部实际上是调用：myAdapter.getItem()

              Person p = (Person) parent.getItemAtPosition(position);

              Toast.makeText(getApplicationContext(), p.getBalance()+"", Toast.LENGTH_SHORT).show();

        }

    }

    //定义Adapter，把每个Person对象生成一个条目，将所有条目装入ListView

    private class myAdapter extends BaseAdapter{

        @Override

        public int getCount() {  //返回ListView中要装入的条目的数量

            return persons.size();

        }

        @Override

        public Object getItem(int position) {//点哪个条目就返回哪个条目的对象

            return persons.get(position);

        }

        @Override

        public long getItemId(int position) {//返回条目的ID

            return position;

        }

        @Override

        //返回指定位置上的View,会被添加到ListView中（即一个Person构建成一个View,然后挂到ListView）

        public View getView(int position, View convertView, ViewGroup parent) {

            Person p = persons.get(position);

            //构建成一个条目(View)，第三个参数是要挂到谁身上，这里写null它会自动返回到LListView中

            View item = View.inflate(getApplicationContext(), R.layout.item, null);

            TextView idTV = (TextView) item.findViewById(R.id.idTV);

            TextView nameTV = (TextView) item.findViewById(R.id.nameTV);

            TextView balanceTV = (TextView) item.findViewById(R.id.balanceTV);

            idTV.setText(p.getId()+"");

            nameTV.setText(p.getName());

            balanceTV.setText(p.getBalance()+"");

            return item;

        }

    }

}

BaseAdapterActivity添加ListView中条目点击监听事件

package com.shellway.sqlite;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import android.support.v7.app.ActionBarActivity;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AdapterView;

import android.widget.BaseAdapter;

import android.widget.ListView;

import android.widget.SimpleAdapter;

import android.widget.TextView;

import android.widget.Toast;

import android.widget.AdapterView.OnItemClickListener;

public class SimpleAdapterActivity extends ActionBarActivity {

    private ListView lv;

    private List<Person> persons;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        lv = (ListView) findViewById(R.id.id_LV); //获取ListView

        PersonDAO dao = new PersonDAO(this);

        persons = dao.findAll();

        List<Map<String, Object>> data = new ArrayList<Map<String,Object>>();

        for (Person p : persons) {

            Map<String, Object> map = new HashMap<String, Object>();

            map.put("id", p.getId());

            map.put("name", p.getName());

            map.put("balance", p.getBalance());

            data.add(map);

        }

        lv.setAdapter(new SimpleAdapter(this, data , R.layout.item,

                new String[]{"id","name","balance"},

                new int[]{R.id.idTV,R.id.nameTV,R.id.balanceTV}));

        /**SimpleAdapter

         * 参数1：上下文环境

         * 参数2：数据，List<Map<String, Object>>每个Person装入一个Map，再将Map装入List

         * 参数3：布局文件的资源id

         * 参数4：Map中的Key,和参数5中的id对应，将指定key的value放入View中指定id对应和组件上

         * 参数5：View中的id

         */

        lv.setOnItemClickListener(new myOnClickListener());

    }

    private class myOnClickListener implements OnItemClickListener{

        @Override

        public void onItemClick(AdapterView<?> parent, View view, int position,

                long id) {

            //SimpleAdapter返回的是一个map

              Map<String,Object> map =  (Map<String, Object>) parent.getItemAtPosition(position);

              Toast.makeText(getApplicationContext(), map.get("name").toString(), Toast.LENGTH_SHORT).show();

        }

    }

}

SimpleAdapterActivity添加ListView中条目点击监听事件

package com.shellway.sqlite;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import android.support.v4.widget.SimpleCursorAdapter;

import android.support.v7.app.ActionBarActivity;

import android.database.Cursor;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AdapterView;

import android.widget.BaseAdapter;

import android.widget.ListView;

import android.widget.SimpleAdapter;

import android.widget.TextView;

import android.widget.Toast;

import android.widget.AdapterView.OnItemClickListener;

public class SimpleCusorAdapterActivity extends ActionBarActivity {

    private ListView lv;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        lv = (ListView) findViewById(R.id.id_LV); //获取ListView

        PersonDAO dao = new PersonDAO(this);

        Cursor c = dao.queryAllCusor();

        lv.setAdapter(new SimpleCursorAdapter(this, R.layout.item, c,

                new String[]{"_id","name","balance"},

                new int[]{R.id.idTV,R.id.nameTV,R.id.balanceTV}));

        /**SimpleAdapter

         * 参数1：上下文环境

         * 参数2：布局文件的资源id

         * 参数3：包含数据的游标

         * 参数4：游标中的列名

         * 参数5：条目中的组件的ID，游标中的数据就会放在对应的这些组件上

         */

        lv.setOnItemClickListener(new myOnClickListener());

    }

    private class myOnClickListener implements OnItemClickListener{

        @Override

        public void onItemClick(AdapterView<?> parent, View view, int position,

                long id) {

            //SimpleCursorAdapter返回的是一个Cursor

              Cursor c = (Cursor) parent.getItemAtPosition(position);

              Toast.makeText(getApplicationContext(), c.getString(0), Toast.LENGTH_SHORT).show();

        }

    }

}

SimpleCusorAdapterActivity添加ListView中条目点击监听事件

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.shellway.sqlite"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="21" />

        <instrumentation

        android:targetPackage="com.shellway.sqlite"

        android:name="android.test.InstrumentationTestRunner" />

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

     <uses-library android:name="android.test.runner" />

        <activity

            android:name=".BaseAdapterActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

</manifest>

AndroidManifest.xml

辅助类：

package com.shellway.sqlite;

public class Person {

    private Integer id;

    private String name;

    private Integer balance;

    public Person() {

        super();

    }

    public Person(String name, Integer balance) {

        super();

        this.name = name;

        this.balance = balance;

    }

    public Person(Integer id, String name, Integer balance) {

        super();

        this.id = id;

        this.name = name;

        this.balance = balance;

    }

    public Integer getId() {

        return id;

    }

    public void setId(Integer id) {

        this.id = id;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public Integer getBalance() {

        return balance;

    }

    public void setBalance(Integer balance) {

        this.balance = balance;

    }

    @Override

    public String toString() {

        return "person [id=" + id + ", name=" + name + ", balance=" + balance

                + "]";

    }

}

Person.java

package com.shellway.sqlite;

import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

public class DBSQLiteHelper extends SQLiteOpenHelper {

    public DBSQLiteHelper(Context context){

        super(context,"data.db" , null, 4);

        /**

         * 由于弗雷没有无参的构造函数，必须显式调用有参的构造函数

         * 参数1：上下文环境，用来确定数据库文件存储的目录

         * 参数2：数据库文件的名字

         * 参数3：生成游标的工厂，填null就是使用默认的

         * 参数4：数据库的版本，从1开始

         */

    }

    @Override

    public void onCreate(SQLiteDatabase db) {

      System.out.println("onCreate");

      db.execSQL("CREATE TABLE people(id INTEGER PRIMARY KEY AUTOINCREMENT,name VACHAR(20))");

    }

    @Override

    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

     System.out.println("onUpgrade");

     db.execSQL("ALTER TABLE people ADD balance INTEGER");

    }

}

DBSQLiteHelper.java

package com.shellway.sqlite;

import java.util.ArrayList;

import java.util.List;

import android.content.ContentValues;

import android.content.Context;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

public class PersonDAO {

    private DBSQLiteHelper helper;

    public PersonDAO(Context context) {

        helper = new DBSQLiteHelper(context);

    }

    public long insert(Person p){

         SQLiteDatabase db = helper.getWritableDatabase();//获取数据库链接（可写的）

        //db.execSQL("INSERT INTO people(name,balance) VALUES(?,?)", new Object[]{p.getName(),p.getBalance()} );

         ContentValues values = new ContentValues();

         values.put("name", p.getName());

         values.put("balance", p.getBalance());

         /**

          * 这里的第二个参数 可以随便填表里的任意一个字段名，是为了防止插入的字段名为空时会出错，

          * 当你确定插入的值不会出错时候可以null

          * 返回值表示最新插入的记录的ID

          */

         long rows = db.insert("people", null, values);

         db.close();

         return rows;

    }

    public void delete(Integer id){

        SQLiteDatabase db = helper.getWritableDatabase();

        //db.execSQL("DELETE FROM people WHERE id = ?", new Object[]{id});

        db.delete("people", "id=?", new String[]{id+""});

        db.close();

    }

    public void update(Person p){

        SQLiteDatabase db = helper.getWritableDatabase();

        //db.execSQL("update people set name=?,balance=? where id=? ", new Object[]{p.getName(),p.getBalance(),p.getId()});

        ContentValues values = new ContentValues();

        values.put("name", p.getName());

        values.put("balance", p.getBalance());

        db.update("people", values, "id=?", new String[]{p.getId()+""});

        db.close();

    }

    //根据id查询某条记录

    public Person query(Integer id){

        /**

         * 查询时候应该优先使用getReadableDatabase()而不是getWritableDatabase()，

         * 其实getReadableDatabase是先获取getWritableDatabase，若获取失败则采用getReadableDatabase

         */

        SQLiteDatabase db = helper.getReadableDatabase();

        //Cursor c = db.rawQuery("select name,balance from people where id=?",new String[]{id+""});

        Cursor c = db.query("people", new String[]{"id","name","balance"}, "id=?", new String[]{id+""}, null, null, null, null);

        Person p = null ;

        if (c.moveToNext()) {

            String name = c.getString(c.getColumnIndex("name"));

            int balance = c.getInt(2);//若直接用下标方式，则注意该字段的索引，游标的索引是从0开始的

            p = new Person(id,name,balance);

        }

        c.close();

        db.close();

        return p;

    }

    //查询全部记录

    public List<Person> findAll(){

        SQLiteDatabase db = helper.getReadableDatabase();

        //Cursor c = db.rawQuery("select id,name,balance from people", null);

        Cursor c = db.query("people", null, null, null, null, null, null, null);

        List<Person>  persons = new ArrayList<Person>();

        while (c.moveToNext()) {

            Person p = new Person(c.getInt(0),c.getString(1),c.getInt(2));

            persons.add(p);

        }

        c.close();

        db.close();

        return persons;

    }

    public Cursor queryAllCusor(){

        SQLiteDatabase db = helper.getReadableDatabase();

        //Cursor c = db.rawQuery("select id,name,balance from people", null);

        Cursor c = db.query("people", new String[]{"id as _id","name","balance"}, null, null, null, null, null, null);

        return c;

    }

    //查询记录总条数

    public int queryCount(){

        SQLiteDatabase db = helper.getReadableDatabase();

        //Cursor c = db.rawQuery("select count(*) from people", null);

        Cursor c = db.query("people", new String[]{"count(*)"}, null, null, null, null, null);

        c.moveToNext();

        int i = c.getInt(0);

        c.close();

        db.close();

        return i;

    }

    //分页查询

    public List<Person> queryPage(int pageNum,int capacity){

        String offset = (pageNum-1) * capacity +"";  //偏移量，即是第几页的页数

        String len = capacity + "";                  //一页中显示的个数

        SQLiteDatabase db = helper.getReadableDatabase();

        //Cursor c = db.rawQuery("select id,name,balance from people limit ?,?", new String[]{offset,len});

        Cursor c = db.query("people", new String[]{"id","name","balance"}, null, null, null, null, null, offset+","+len);

        List<Person>  persons = new ArrayList<Person>();

        while (c.moveToNext()) {

            Person p = new Person(c.getInt(0),c.getString(1),c.getInt(2));

            persons.add(p);

        }

        c.close();

        db.close();

        return persons;

    }

}

PersonDAO.java

package com.shellway.sqlite;

import java.util.ArrayList;

import java.util.List;

import java.util.Random;

import android.database.sqlite.SQLiteDatabase;

import android.provider.SyncStateContract.Helpers;

import android.test.AndroidTestCase;

public class TestSQLite extends AndroidTestCase {

     public void test1(){

         DBSQLiteHelper helper = new DBSQLiteHelper(getContext());

         SQLiteDatabase sql = helper.getWritableDatabase();

         /**

          * 获取可写的数据库连接

          * 数据库文件不存在时，会创建数据库文件，并且执行onCreate()方法

          * 数据库文件存在，且版本没有改变时，不执行任何方法

          * 数据库文件存在，版本提升，执行onUpdate方法

          */

     }

     public void testInsert(){

         PersonDAO personDAO = new PersonDAO(getContext());

         long rows = personDAO.insert(new Person("KKK",20000));

         System.out.println(rows);

     }

     public void testDelete(){

         PersonDAO personDAO = new PersonDAO(getContext());

         personDAO.delete(104);

     }

     public void testUpdate(){

         PersonDAO personDAO = new PersonDAO(getContext());

         personDAO.update(new Person(1,"www",30000));

     }

     public void testQuery(){

         PersonDAO personDAO = new PersonDAO(getContext());

         System.out.println(personDAO.query(5));

     }

     public void testFindAll(){

         PersonDAO personDAO = new PersonDAO(getContext());

         List<Person> persons = personDAO.findAll();

         for (Person p : persons) {

            System.out.println(p);

        }

     }

     public void testQueryCount(){

         PersonDAO personDAO = new PersonDAO(getContext());

         int count = personDAO.queryCount();

         System.out.println(count);

     }

     public void testQueryPage(){

         PersonDAO personDAO = new PersonDAO(getContext());

         List<Person> persons = personDAO.queryPage(3, 20);

         for (Person p : persons) {

            System.out.println(p);

        }

     }

}

TestSQLite.java测试类

运行结果：

二.内容提供者(ContentProvider)
1.什么是ContentProvider
ContentProvider可以用来把程序中的数据对外进行共享, 提供增删改查的方法
ContentProvider中可以注册观察者, 监听数据的变化
* 2.怎么创建？

步骤1：在清单文件AndroidManifest.xml中注册

步骤2：定义类继承ContentProvider

package com.shellway.sqlite.provider;

import android.content.ContentProvider;

import android.content.ContentValues;

import android.database.Cursor;

import android.net.Uri;

public class SQLiteProvider extends ContentProvider {

    @Override

    public boolean onCreate() {

        return false;

    }

    @Override

    public Cursor query(Uri uri, String[] projection, String selection,

            String[] selectionArgs, String sortOrder) {

        System.out.println("query");

        return null;

    }

    @Override

    public Uri insert(Uri uri, ContentValues values) {

        System.out.println("insert");

        return null;

    }

    @Override

    public int delete(Uri uri, String selection, String[] selectionArgs) {

        System.out.println("delete");

        return 0;

    }

    @Override

    public int update(Uri uri, ContentValues values, String selection,

            String[] selectionArgs) {

        System.out.println("update");

        return 0;

    }

    @Override

    public String getType(Uri uri) {

        return null;

    }

}

定义类SQLiteProvider继承ContentProvider

步骤3：另创建一个工程访问内容提供者

package com.shellway.other;

import android.support.v7.app.ActionBarActivity;

import android.content.ContentProvider;

import android.content.ContentResolver;

import android.content.ContentValues;

import android.content.Context;

import android.net.Uri;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

public class MainActivity extends ActionBarActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        //获取解析器对象

        ContentResolver resolver = getContentResolver();

        //访问内容提供者

        ContentValues values = new ContentValues();

        Uri uri = Uri.parse("content://com.shellway.sqlite.provider");

        resolver.insert(uri, values);

        resolver.delete(uri, null, null);

        resolver.update(uri, values, null, null);

        resolver.query(uri, null, null, null, null);

    }

}

MainActivity

3.在手机上注册
将应用安装到手机上即可, 不用运行程序
* 4.怎么访问
获取解析器ContentResolver, 指定Uri
通过ContentResolver.insert(), delete(), update(), query()方法访问Uri关联的ContentProvider
5.Uri的处理
使用UriMatcher可以检查传入的Uri是否和指定的匹配
如果Uri带了id, 可以使用ContentUris获取id, 插入方法可以使用ContentUris给Uri加上id

练习：

package com.shellway.sqlite.provider;

import com.shellway.sqlite.dao.DBSQLiteHelper;

import android.content.ContentProvider;

import android.content.ContentUris;

import android.content.ContentValues;

import android.content.UriMatcher;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.net.Uri;

public class SQLiteProvider extends ContentProvider {

     private UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);

     private DBSQLiteHelper helper;

     private static final int PERSON = 1;

     private static final int PERSON_ID = 2;

    @Override

    public boolean onCreate() {

        helper = new DBSQLiteHelper(getContext());

        //设置一个Uri，如果匹配到person，则返回PERSON

        matcher.addURI("com.shellway.sqlite.provider", "person", PERSON);

        matcher.addURI("com.shellway.sqlite.provider", "person/#", PERSON_ID);

        return true;

    }

    @Override

    public Cursor query(Uri uri, String[] projection, String selection,

            String[] selectionArgs, String sortOrder) {

        SQLiteDatabase db = helper.getReadableDatabase();

        switch (matcher.match(uri)) {

        case PERSON_ID:

             long id = ContentUris.parseId(uri);

             selection = selection==null ? "id=" + id : selection + " AND id =" + id ;

        case PERSON:

            return db.query("people", projection, selection, selectionArgs, null, null, sortOrder);

        default:

            throw new RuntimeException("Uri不能试看识别。。。 ");

        }

    }

    @Override

    public Uri insert(Uri uri, ContentValues values) {

        SQLiteDatabase db = helper.getWritableDatabase();

        switch (matcher.match(uri)) {

        case PERSON:

            long id = db.insert("people", "id", values);

            return ContentUris.withAppendedId(uri, id);

        default:

            throw new RuntimeException("Uri不能试看识别。。。 ");

        }

    }

    @Override

    public int delete(Uri uri, String selection, String[] selectionArgs) {

        SQLiteDatabase db = helper.getWritableDatabase();

        switch (matcher.match(uri)) {

        case PERSON_ID:

             long id = ContentUris.parseId(uri);

             selection = selection==null ? "id=" + id : selection + " AND id =" + id ;

        case PERSON:

            return db.delete("people", selection, selectionArgs);

        default:

            throw new RuntimeException("Uri不能试看识别。。。 ");

        }

    }

    @Override

    public int update(Uri uri, ContentValues values, String selection,

            String[] selectionArgs) {

        SQLiteDatabase db = helper.getWritableDatabase();

        switch (matcher.match(uri)) {

        case PERSON_ID:

             long id = ContentUris.parseId(uri);

             selection = selection==null ? "id=" + id : selection + " AND id =" + id ;

        case PERSON:

            return db.update("people", values, selection, selectionArgs);

        default:

            throw new RuntimeException("Uri不能试看识别。。。 ");

        }

    }

    @Override

    public String getType(Uri uri) {

        return null;

    }

}

02.SQLlite工程中的内容提供者SQLiteProvider

package com.shellway.other;

import android.content.ContentResolver;

import android.content.ContentValues;

import android.database.Cursor;

import android.net.Uri;

import android.test.AndroidTestCase;

public class ProviderTest extends AndroidTestCase {

   public void test1(){

        //获取解析器对象

        ContentResolver resolver = getContext().getContentResolver();

        //访问内容提供者

        ContentValues values = new ContentValues();

        Uri uri = Uri.parse("content://com.shellway.sqlite.provider");

        resolver.insert(uri, values);

        resolver.delete(uri, null, null);

        resolver.update(uri, values, null, null);

        resolver.query(uri, null, null, null, null);

   }

   public void testQuery(){

       ContentResolver resolver = getContext().getContentResolver();

       Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person");

       Cursor c = resolver.query(uri, null, "balance>?", new String[]{8000+""}, "balance ASC");

       while (c.moveToNext()) {

          Person p = new Person(c.getInt(0),c.getString(1),c.getInt(2));

          System.out.println(p);

       }

   }

   public void testQuery2(){

       ContentResolver resolver = getContext().getContentResolver();

       Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person/10");

       Cursor c = resolver.query(uri, null, "balance>?", new String[]{8000+""}, "balance ASC");

       while (c.moveToNext()) {

          Person p = new Person(c.getInt(0),c.getString(1),c.getInt(2));

          System.out.println(p);

       }

   }

   public void testInsert(){

       ContentResolver resolver = getContext().getContentResolver();

       ContentValues values = new ContentValues();

       values.put("name", "Insert");

       values.put("balance", "54321");

       Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person");

       Uri count = resolver.insert(uri, values);

          System.out.println(count);

   }

   public void testUpdate(){

       ContentResolver resolver = getContext().getContentResolver();

       ContentValues values = new ContentValues();

       values.put("name", "Update");

       values.put("balance", "12345");

       Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person/106");

       int i = resolver.update(uri, values, null, null);

          System.out.println(i);

   }

   public void testDelete(){

       ContentResolver resolver = getContext().getContentResolver();

       Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person/107");

       int i = resolver.delete(uri, null, null);

          System.out.println(i);

   }

}

03.Other测试工程中的测试内容提供者的类ProviderTest

细节补充：

    @Override

    public String getType(Uri uri) {

        switch (matcher.match(uri)) {

        case PERSON_ID:

             //一般返回的类型是：minetype? image/jpg  html/text css/text

             return "vnd.android.cursor.item/person"; //这里表示返回的是单条的person数据

        case PERSON:

            return "vnd.android.cursor.dir/person";//这里表示返回的是多条的person数据

        default:

            throw new RuntimeException("Uri不能试看识别。。。 ");

        }

    }

SQLiteProvider中的getType

   public void testType(){

       ContentResolver resolver = getContext().getContentResolver();

       String s1 = resolver.getType(Uri.parse("content://com.shellway.sqlite.provider/person/106"));

       String s2 = resolver.getType(Uri.parse("content://com.shellway.sqlite.provider/person"));

       System.out.println(s1);

       System.out.println(s2);

   }

ProviderTest中的测试getType方法：testType

注意1：ProviderTest类中的ContentResolver resolver = getContext().getContentResolver();这一行不能放到类的成员变量里边，因为：.class ->.dex ->.app ->安装 ->开启进程（开启主线程）->创建ProviderTest对象 ->setContext ->测试方法 ->getConTest。否则会出现空指针异常，因为还没有setContext就getContext.

注意2：SQLiteProvider中的onCreate() 方法是在第一次启动时执行，然后会长期驻留在后台，除非是被杀死，否则不会再执行。

6.注册观察者
在应用程序中可以对ContentProvider注册一个观察者(ContentObserver)
定义类继承ContentObserver, 重写onChange()方法
使用ContentResolver.registerContentObserver(Uri, boolean, ContentObServer)方法可以注册, 传入指定Uri, 是否监听子级路径, 和一个观察者对象
在收到数据改变通知之后, 会自动执行onChange()方法
7.通知观察者
注册观察者之后, 需要在ContentProvider中进行通知, 观察者才能收到, 使用ContentResolver.notifyChange()方法可以通知数据的改变

练习：

package com.shellway.sqlite.ui;

import java.util.List;

import com.shellway.sqlite.R;

import com.shellway.sqlite.dao.PersonDAO;

import com.shellway.sqlite.domain.Person;

import android.support.v4.widget.SearchViewCompat.OnCloseListenerCompat;

import android.support.v7.app.ActionBarActivity;

import android.content.ContentProvider;

import android.database.ContentObserver;

import android.net.Uri;

import android.os.Bundle;

import android.os.Handler;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AdapterView;

import android.widget.AdapterView.OnItemClickListener;

import android.widget.BaseAdapter;

import android.widget.ListView;

import android.widget.TextView;

import android.widget.Toast;

public class BaseAdapterActivity extends ActionBarActivity {

    private ListView lv;

    private List<Person> persons;

    private PersonDAO dao;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        lv = (ListView) findViewById(R.id.id_LV); //获取ListView

        dao = new PersonDAO(this);

        persons = dao.findAll();

        //给ListView添加Adapter,按照Adapter中的方法对ListView添加条目

        lv.setAdapter(new myAdapter());

        //给ListView添加条目点击监听器

        lv.setOnItemClickListener(new myOnClickListener());

        //注册一个内容观察者

        Uri uri = Uri.parse("content://com.shellway.sqlite.provider");

        //第二个参数表示监听上面uri子路径下所有的变化，若改为false则只监听uri本身的变化

        getContentResolver().registerContentObserver(uri , true, new MyContentObserver());

    }

    private class MyContentObserver extends ContentObserver{

        public MyContentObserver() {

            super(new Handler());//Handler()是一个处理器，目前没有用到

        }

        @Override

        public void onChange(boolean selfChange) {

            persons = dao.findAll();

            lv.setAdapter(new myAdapter());

        }

    }

    private class myOnClickListener implements OnItemClickListener{

        @Override

        public void onItemClick(AdapterView<?> parent, View view, int position,

                long id) {

            //获取点击的条目上的数据，其内部实际上是调用：myAdapter.getItem()

              Person p = (Person) parent.getItemAtPosition(position);

              Toast.makeText(getApplicationContext(), p.getBalance()+"", Toast.LENGTH_SHORT).show();

        }

    }

    //定义Adapter，把每个Person对象生成一个条目，将所有条目装入ListView

    private class myAdapter extends BaseAdapter{

        @Override

        public int getCount() {  //返回ListView中要装入的条目的数量

            return persons.size();

        }

        @Override

        public Object getItem(int position) {//点哪个条目就返回哪个条目的对象

            return persons.get(position);

        }

        @Override

        public long getItemId(int position) {//返回条目的ID

            return position;

        }

        @Override

        //返回指定位置上的View,会被添加到ListView中（即一个Person构建成一个View,然后挂到ListView）

        public View getView(int position, View convertView, ViewGroup parent) {

            Person p = persons.get(position);

            //构建成一个条目(View)，第三个参数是要挂到谁身上，这里写null它会自动返回到LListView中

            View item = View.inflate(getApplicationContext(), R.layout.item, null);

            TextView idTV = (TextView) item.findViewById(R.id.idTV);

            TextView nameTV = (TextView) item.findViewById(R.id.nameTV);

            TextView balanceTV = (TextView) item.findViewById(R.id.balanceTV);

            idTV.setText(p.getId()+"");

            nameTV.setText(p.getName());

            balanceTV.setText(p.getBalance()+"");

            return item;

        }

    }

}

02.SQLite工程中在BaseAdapterActivity里注册观察者观察一个Uri

package com.shellway.sqlite.provider;

import com.shellway.sqlite.dao.DBSQLiteHelper;

import android.content.ContentProvider;

import android.content.ContentUris;

import android.content.ContentValues;

import android.content.UriMatcher;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.net.Uri;

public class SQLiteProvider extends ContentProvider {

     private UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);

     private DBSQLiteHelper helper;

     private static final int PERSON = 1;

     private static final int PERSON_ID = 2;

    @Override

    public boolean onCreate() {

        helper = new DBSQLiteHelper(getContext());

        //设置一个Uri，如果匹配到person，则返回PERSON

        matcher.addURI("com.shellway.sqlite.provider", "person", PERSON);

        matcher.addURI("com.shellway.sqlite.provider", "person/#", PERSON_ID);

        return true;

    }

    @Override

    public Cursor query(Uri uri, String[] projection, String selection,

            String[] selectionArgs, String sortOrder) {

        SQLiteDatabase db = helper.getReadableDatabase();

        switch (matcher.match(uri)) {

        case PERSON_ID:

             long id = ContentUris.parseId(uri);

             selection = selection==null ? "id=" + id : selection + " AND id =" + id ;

        case PERSON:

            return db.query("people", projection, selection, selectionArgs, null, null, sortOrder);

        default:

            throw new RuntimeException("Uri不能试看识别。。。 ");

        }

    }

    @Override

    public Uri insert(Uri uri, ContentValues values) {

        SQLiteDatabase db = helper.getWritableDatabase();

        switch (matcher.match(uri)) {

        case PERSON:

            long id = db.insert("people", "id", values);

            getContext().getContentResolver().notifyChange(uri, null);

            return ContentUris.withAppendedId(uri, id);

        default:

            throw new RuntimeException("Uri不能试看识别。。。 ");

        }

    }

    @Override

    public int delete(Uri uri, String selection, String[] selectionArgs) {

        SQLiteDatabase db = helper.getWritableDatabase();

        switch (matcher.match(uri)) {

        case PERSON_ID:

             long id = ContentUris.parseId(uri);

             selection = selection==null ? "id=" + id : selection + " AND id =" + id ;

        case PERSON:

            int count = db.delete("people", selection, selectionArgs);

            getContext().getContentResolver().notifyChange(uri, null);

            return count;

        default:

            throw new RuntimeException("Uri不能试看识别。。。 ");

        }

    }

    @Override

    public int update(Uri uri, ContentValues values, String selection,

            String[] selectionArgs) {

        SQLiteDatabase db = helper.getWritableDatabase();

        switch (matcher.match(uri)) {

        case PERSON_ID:

             long id = ContentUris.parseId(uri);

             selection = selection==null ? "id=" + id : selection + " AND id =" + id ;

        case PERSON:

            int count = db.update("people", values, selection, selectionArgs);

            getContext().getContentResolver().notifyChange(uri, null);

            return count;

        default:

            throw new RuntimeException("Uri不能试看识别。。。 ");

        }

    }

    @Override

    public String getType(Uri uri) {

        switch (matcher.match(uri)) {

        case PERSON_ID:

             //一般返回的类型是：minetype? image/jpg  html/text css/text

             return "vnd.android.cursor.item/person"; //这里表示返回的是单条的person数据

        case PERSON:

            return "vnd.android.cursor.dir/person";//这里表示返回的是多条的person数据

        default:

            throw new RuntimeException("Uri不能试看识别。。。 ");

        }

    }

}

02.SQLite工程中在SQLiteProvider内容提供者里编写内容变更通知语句

package com.shellway.other;

import android.content.ContentResolver;

import android.content.ContentValues;

import android.database.Cursor;

import android.net.Uri;

import android.test.AndroidTestCase;

public class ProviderTest extends AndroidTestCase {

   public void test1(){

        //获取解析器对象

        ContentResolver resolver = getContext().getContentResolver();

        //访问内容提供者

        ContentValues values = new ContentValues();

        Uri uri = Uri.parse("content://com.shellway.sqlite.provider");

        resolver.insert(uri, values);

        resolver.delete(uri, null, null);

        resolver.update(uri, values, null, null);

        resolver.query(uri, null, null, null, null);

   }

   public void testQuery(){

       ContentResolver resolver = getContext().getContentResolver();

       Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person");

       Cursor c = resolver.query(uri, null, "balance>?", new String[]{8000+""}, "balance ASC");

       while (c.moveToNext()) {

          Person p = new Person(c.getInt(0),c.getString(1),c.getInt(2));

          System.out.println(p);

       }

   }

   public void testQuery2(){

       ContentResolver resolver = getContext().getContentResolver();

       Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person/10");

       Cursor c = resolver.query(uri, null, "balance>?", new String[]{8000+""}, "balance ASC");

       while (c.moveToNext()) {

          Person p = new Person(c.getInt(0),c.getString(1),c.getInt(2));

          System.out.println(p);

       }

   }

   public void testInsert(){

       ContentResolver resolver = getContext().getContentResolver();

       ContentValues values = new ContentValues();

       values.put("name", "Test5");

       values.put("balance", "12345");

       Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person");

       Uri count = resolver.insert(uri, values);

   }

   public void testUpdate(){

       ContentResolver resolver = getContext().getContentResolver();

       ContentValues values = new ContentValues();

       values.put("name", "shellway");

       values.put("balance", "10000");

       Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person/116");

       int i = resolver.update(uri, values, null, null);

   }

   public void testDelete(){

       ContentResolver resolver = getContext().getContentResolver();

       Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person/122");

       int i = resolver.delete(uri, null, null);

   }

   public void testType(){

       ContentResolver resolver = getContext().getContentResolver();

       String s1 = resolver.getType(Uri.parse("content://com.shellway.sqlite.provider/person/106"));

       String s2 = resolver.getType(Uri.parse("content://com.shellway.sqlite.provider/person"));

       System.out.println(s1);

       System.out.println(s2);

   }

}

在A应用(03.Other)中使用内容提供者，使得数据发生改变

package com.shellway.contentobserver;

import android.support.v7.app.ActionBarActivity;

import android.database.ContentObserver;

import android.database.Cursor;

import android.net.Uri;

import android.os.Bundle;

import android.os.Handler;

import android.view.Menu;

import android.view.MenuItem;

import android.widget.Toast;

public class MainActivity extends ActionBarActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        Uri uri = Uri.parse("content://com.shellway.sqlite.provider");

        getContentResolver().registerContentObserver(uri , true, new MyContentOberver());

    }

    private class MyContentOberver extends ContentObserver{

        public MyContentOberver() {

            super(new Handler());

        }

        @Override

        public void onChange(boolean selfChange) {

            Uri uri = Uri.parse("content://com.shellway.sqlite.provider/person");

            Cursor c = getContentResolver().query(uri, null, null, null, "id desc limit 1");

            while (c.moveToNext()) {

                Toast.makeText(getApplicationContext(), c.getString(1), Toast.LENGTH_SHORT).show();

            }

        }

    }

}

在B应用(04.ContentObserver)中也注册一个观察者观察相同的Uri,若该Uri上的数据发生改变,我会收到通知然后执行我的onChange方法

结果：一旦在A应用中通过内容提供者改变数据，则注册在该Uri上的观察者都会收到数据发生改变的通知，因为事先在内容提供者里都已经放了一个“通知者”，这里的通知者即是：getContext().getContentResolver().notifyChange(uri, null);所以，SQLite工程和B应用中的观察者都会接收到通知，从而执行自己的onChange()方法。

四.监听短信
1.获取源码
安装GIT工具:
在网站上下载com.android.providers.telephony源码:https://github.com/android
通过清单文件可以查找到Uri
2.监听改变
对指定Uri添加ContentOberver
在onChange方法中查询最新的记录, 收发短信时都会收到修改通知, 这样就能获取刚刚收发的短信了

package com.shellway.smsobserver;

import java.text.SimpleDateFormat;

import java.util.Date;

import android.support.v7.app.ActionBarActivity;

import android.content.ContentResolver;

import android.database.ContentObserver;

import android.database.Cursor;

import android.net.Uri;

import android.os.Bundle;

import android.os.Handler;

public class MainActivity extends ActionBarActivity {

    private Uri uri;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        //注册短信观察者

        uri = Uri.parse("content://sms");

        getContentResolver().registerContentObserver(uri , true, new MyObserver());

    }

    private class MyObserver extends ContentObserver{

        private long flag;

        public MyObserver() {

            super(new Handler());

        }

        @Override

        public void onChange(boolean selfChange) {

            ContentResolver resolver = getContentResolver();

            //查询最新的一条短信信息，因为收发短信，信息都会先往数据库存然后才显示在手机屏幕

            Cursor c = resolver.query(uri, null, null, null, "_id desc limit 1");

            while(c.moveToNext()){

                String addr = c.getString(c.getColumnIndex("address"));

                String body = c.getString(c.getColumnIndex("body"));

                int type = c.getInt(c.getColumnIndex("type"));

                Long date = c.getLong(c.getColumnIndex("date"));

                SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH：mm:ss");

                Date d = new Date(date);

                String dd = sdf.format(d);

                if(flag!=date){ //因为回短信时会打印出三条重复的信息，这里利用时间来控制打印结果只为一条信息

                System.out.println(dd +" " + (type == 1 ? "收":"发") + addr +" "+ body);

                flag = date;

                }

            }

        }

    }

}

监听短信信息变化：MainActivity.java

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.shellway.smsobserver"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="21" />

    <uses-permission  android:name="android.permission.READ_SMS"/>

    <uses-permission  android:name="android.permission.WRITE_SMS"/>

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name=".MainActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

</manifest>

AndroidManifest.xml

结果：

五.读写联系人
1.获取原码
和监听短信相同, 获取com.android.providers.contacts源码
2.读取联系人
先读raw_contacts表中的id, 在根据id查找data表
3.写出联系人
先向raw_contacts表中写出一个id(自动生成)
在向data表写出3条对应数据, raw_contact_id一列使用刚刚插入的id

练习：(读联系人)

1.新建一个工程：

2.分析：

3.编写程序：

package com.shellway.contacts;

import android.content.ContentResolver;

import android.database.Cursor;

import android.net.Uri;

import android.test.AndroidTestCase;

public class ContactsTest extends AndroidTestCase {

    public void testContexts(){

     Uri idUri = Uri.parse("content://com.android.contacts/raw_contacts");

     Uri dataUri = Uri.parse("content://com.android.contacts/data");

     ContentResolver resolver = getContext().getContentResolver();

     Cursor c = resolver.query(idUri, new String[]{"_id"}, null, null, null);

    /* String[] arr = c.getColumnNames();//打印raw_contacts表中的所有列名

     for (String s : arr) {

        System.out.println(s);

      }*/

     while(c.moveToNext()){

         int idRaw = c.getInt(0);

         Cursor datac = resolver.query(dataUri, new String[]{"mimetype","data1","data2","data3"}

                               , "raw_contact_id=?"

                               , new String[]{idRaw+""}

                               , null);

         while(datac.moveToNext()){

             if(datac.getString(0).equals("vnd.android.cursor.item/name")){

                 System.out.println("姓名： "+ datac.getString(datac.getColumnIndex("data1")));

             }else if(datac.getString(0).equals("vnd.android.cursor.item/phone_v2")){

                 System.out.println("电话： "+ datac.getString(datac.getColumnIndex("data1")));

             }else if(datac.getString(0).equals("vnd.android.cursor.item/email_v2")){

                 System.out.println("邮箱： "+ datac.getString(datac.getColumnIndex("data1")));

             }

         }

     }

  /*   Cursor datac = resolver.query(dataUri, null, null, null, null);//打印data表中的所有列名

     String[] s = datac.getColumnNames();

     for (String st : s) {

        System.out.println(st);

    }*/

   }

}

ContactsTest.java

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.shellway.contacts"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="21" />

        <instrumentation

        android:targetPackage="com.shellway.contacts"

        android:name="android.test.InstrumentationTestRunner" />

    <uses-permission android:name="android.permission.READ_CONTACTS"/>

    <uses-permission android:name="android.permission.WRITE_CONTACTS"/>

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

     <uses-library android:name="android.test.runner" />

    </application>

</manifest>

AndroidManifest.xml

结果：

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