ANDROID_MARS学习笔记_S01原始版_010_ContentProvider

一、简介

一、代码
1.xml
(1)main.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical" android:layout_width="fill_parent"
     android:layout_height="fill_parent">
     <Button android:id="@+id/insertButton" android:layout_width="fill_parent"
         android:layout_height="wrap_content" android:text="insert" />
     <Button android:id="@+id/queryButton" android:layout_width="fill_parent"
         android:layout_height="wrap_content" android:text="query" />
 </LinearLayout>

(2)AndroidManifest.xml.xml

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.example.s01_original_e16_textcp"
     android:versionCode="1"
     android:versionName="1.0" >

     <uses-sdk
         android:minSdkVersion="8"
         android:targetSdkVersion="21" />

     <application
         android:allowBackup="true"
         android:icon="@drawable/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/AppTheme" >
         <activity
             android:name=".CPActivity"
             android:label="@string/app_name" >
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />

                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
         <provider android:name="com.example.s01_original_e16_textcp.FirstContentProvider"
             android:authorities="tony.cp.FirstContentProvider" />
     </application>

 </manifest>

2.java
(1)CPActivity.java

 package com.example.s01_original_e16_textcp;

 import android.app.Activity;
 import android.content.ContentValues;
 import android.database.Cursor;
 import android.net.Uri;
 import android.os.Bundle;
 import android.view.View;
 import android.widget.Button;

 import com.example.s01_original_e16_textcp.FirstProviderMetaData.UserTableMetaData;

 public class CPActivity extends Activity {
     /** Called when the activity is first created. */
     private Button insertButton = null;
     private Button queryButton = null;

     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);
         insertButton = (Button) findViewById(R.id.insertButton);
         insertButton.setOnClickListener(new View.OnClickListener() {

             @Override
             public void onClick(View v) {
                 ContentValues values = new ContentValues();
                 values.put(FirstProviderMetaData.UserTableMetaData.USER_NAME,
                         "zhangsan");
                 Uri uri = getContentResolver().insert(
                         FirstProviderMetaData.UserTableMetaData.CONTENT_URI,
                         values);
                 System.out.println("uri  ---> " + uri.toString());
             }
         });
         queryButton = (Button) findViewById(R.id.queryButton);
         queryButton.setOnClickListener(new View.OnClickListener() {

             @Override
             public void onClick(View v) {
                 Cursor c = getContentResolver().query(
                         FirstProviderMetaData.UserTableMetaData.CONTENT_URI,
                         null, null, null, null);
                 while (c.moveToNext()) {
                     System.out.println(c.getString(c
                             .getColumnIndex(UserTableMetaData.USER_NAME)));
                 }

             }
         });
     }
 }

(2)FirstContentProvider.java

 package com.example.s01_original_e16_textcp;

 import java.util.HashMap;

 import android.content.ContentProvider;
 import android.content.ContentUris;
 import android.content.ContentValues;
 import android.content.UriMatcher;
 import android.database.Cursor;
 import android.database.SQLException;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteQueryBuilder;
 import android.net.Uri;
 import android.text.TextUtils;

 import com.example.s01_original_e16_textcp.FirstProviderMetaData.UserTableMetaData;

 public class FirstContentProvider extends ContentProvider {

     // UriMatcher用来检查URI是否合法
     public static final UriMatcher uriMatcher;
     public static final int INCOMING_USER_COLLECTION = 1;
     public static final int INCOMING_USER_SINGLE = 2;

     private DatabaseHelper dh;

     static {
         uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
         uriMatcher.addURI(FirstProviderMetaData.AUTHORITY, "users",
                 INCOMING_USER_COLLECTION);
         uriMatcher.addURI(FirstProviderMetaData.AUTHORITY, "users/#",
                 INCOMING_USER_SINGLE);
     }

     //相当于给sql的列起别名
     public static HashMap<String, String> userProjectionMap;
     static {
         userProjectionMap = new HashMap<String, String>();
         userProjectionMap.put(UserTableMetaData._ID, UserTableMetaData._ID);
         userProjectionMap.put(UserTableMetaData.USER_NAME,
                 UserTableMetaData.USER_NAME);
     }

     @Override
     public int delete(Uri arg0, String arg1, String[] arg2) {
         // TODO Auto-generated method stub
         System.out.println("delete...");
         return 0;
     }

     // 根据传入的URI，返回该URI所表示的数据类型
     @Override
     public String getType(Uri uri) {
         System.out.println("getType...");
         switch (uriMatcher.match(uri)) {
         case INCOMING_USER_COLLECTION:
             return UserTableMetaData.CONTENT_TYPE;
         case INCOMING_USER_SINGLE:
             return UserTableMetaData.CONTENT_TYPE_ITEM;
         default:
             throw new IllegalArgumentException("Unknow URI " + uri);
         }
     }

     /**
      * 该函数的返回值是一个Uri，这个Uri表示的是刚刚那使用这个函数所插入的数据
      * content://ycitss.cp.firstContentProivder/users/1
      */
     @Override
     public Uri insert(Uri uri, ContentValues values) {
         System.out.println("insert...");
         SQLiteDatabase db = dh.getWritableDatabase();
         long rowId = db.insert(UserTableMetaData.TABLE_NAME, null, values);
         if (rowId > 0) {
             Uri insertedUserUri = ContentUris.withAppendedId(
                     UserTableMetaData.CONTENT_URI, rowId);
             // 通知监听器，数据已经修改
             getContext().getContentResolver().notifyChange(insertedUserUri,
                     null);
             return insertedUserUri;
         }
         throw new SQLException("Failed to insert row into " + uri);
     }

     // 是一个回调方法，所以说在ContentProvider创建的时候执行
     @Override
     public boolean onCreate() {
         dh = new DatabaseHelper(getContext(),
                 FirstProviderMetaData.DATABASE_NAME);
         System.out.println("onCreate...");
         return true;
     }

     @Override
     public Cursor query(Uri uri, String[] projection, String selection,
             String[] selectionArgs, String sortOrder) {
         SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
         switch (uriMatcher.match(uri)) {
         case INCOMING_USER_COLLECTION:
             qb.setTables(UserTableMetaData.TABLE_NAME);
             qb.setProjectionMap(userProjectionMap);
             break;
         case INCOMING_USER_SINGLE:
             qb.setTables(UserTableMetaData.TABLE_NAME);
             qb.setProjectionMap(userProjectionMap);
             qb.appendWhere(UserTableMetaData._ID + "="
                     + uri.getPathSegments().get(1));
             break;
         }
         String orderBy;
         if (TextUtils.isEmpty(sortOrder)) {
             orderBy = UserTableMetaData.DEFAULT_SORT_ORDER;
         } else {
             orderBy = sortOrder;
         }
         SQLiteDatabase db = dh.getWritableDatabase();
         Cursor c = qb.query(db, projection, selection, selectionArgs, null,
                 null, orderBy);
         c.setNotificationUri(getContext().getContentResolver(), uri);
         System.out.println("query...");
         return c;
     }

     @Override
     public int update(Uri uri, ContentValues values, String selection,
             String[] selectionArgs) {
         System.out.println("update...");
         return 0;
     }

 }

(3)FirstProviderMetaData.java

 package com.example.s01_original_e16_textcp;

 import android.net.Uri;
 import android.provider.BaseColumns;

 public class FirstProviderMetaData {
     // 必需与AndroidManifest.xml中定义的android:authorities一致
     public static final String AUTHORITY = "tony.cp.FirstContentProvider";
     // 数据库名称
     public static final String DATABASE_NAME = "FirstProvider.db";
     // 数据库版本
     public static final int DATABASE_VERSION = 1;
     // 表名
     public static final String USERS_TABLE_NAME = "users";

     public static final class UserTableMetaData implements BaseColumns {
         // 表名
         public static final String TABLE_NAME = "users";
         // 访问该ContentProvider的URI
         public static final Uri CONTENT_URI = Uri.parse("content://"
                 + AUTHORITY + "/users");
         // 该contentProvider所返回的数据类型的定义
         public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.firstprovider.user";//访问整张表
         public static final String CONTENT_TYPE_ITEM = "vnd.android.cursor.item/vnd.firstprovider.user";//取一条数据
         // 列名
         public static final String USER_NAME = "name";
         // 默认的排序方法
         public static final String DEFAULT_SORT_ORDER = "_id desc";
     }
 }

(4)DatabaseHelper.java

 package com.example.s01_original_e16_textcp;

 import android.content.Context;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteDatabase.CursorFactory;
 import android.database.sqlite.SQLiteOpenHelper;

 public class DatabaseHelper extends SQLiteOpenHelper {
     private static final int VERSION = 1;

     public DatabaseHelper(Context context, String name, CursorFactory factory,
             int version) {
         super(context, name, factory, version);
         // TODO Auto-generated constructor stub
     }

     public DatabaseHelper(Context context, String name, int version) {
         this(context, name, null, version);
     }

     public DatabaseHelper(Context context, String name) {
         this(context, name, VERSION);
     }

     // 该函数是在第一次创建数据库的时候执行，实际上是在第一次得到SQLiteDAtabase对象的时候，才会调用这个方法
     @Override
     public void onCreate(SQLiteDatabase db) {
         System.out.println("cteate a Database");
         // execSQL函数用于执行SQL语句
         db.execSQL("create table " + FirstProviderMetaData.USERS_TABLE_NAME
                 + "(" + FirstProviderMetaData.UserTableMetaData._ID
                 + " INTEGER_PARIMARY_AUTOINCREMENT,"
                 + FirstProviderMetaData.UserTableMetaData.USER_NAME
                 + " varchar(20))");
     }

     @Override
     public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) {
         System.out.println("update a Database");
     }

 }