SQLite的使用案例

示例图 ：

activity_main.xml :

<TextView
     android:id="@+id/t1"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:textSize="20dp"
     android:layout_marginTop="10dp"
     android:layout_marginLeft="10dp"
     android:text="Name:"/>
 
 <EditText
     android:id="@+id/text_name"
     android:layout_width="200dp"
     android:layout_height="wrap_content"
     android:hint="Input Name"
     android:layout_toRightOf="@+id/t1"
     android:layout_marginLeft="100dp"
     android:layout_marginRight="10dp"
     />
 <TextView
     android:id="@+id/t2"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:text="Password:"
     android:layout_marginTop="20dp"
     android:layout_marginLeft="10dp"
     android:layout_below="@+id/t1"
     android:textSize="20dp"/>
 <EditText
     android:id="@+id/text_password"
     android:layout_width="200dp"
     android:layout_height="wrap_content"
     android:hint="Input Password"
     android:layout_below="@+id/text_name"
     android:layout_toRightOf="@id/t2"
     android:layout_marginLeft="65dp"
     android:layout_marginRight="10dp"
     />
 <Button
     android:id="@+id/btn_reg"
     android:layout_width="128dp"
     android:layout_height="wrap_content"
     android:layout_below="@+id/t2"
     android:layout_marginTop="30dp"
     android:text="注册"
 
     />
 
 <Button
     android:id="@+id/btn_del"
     android:layout_width="128dp"
     android:layout_height="wrap_content"
     android:layout_below="@+id/t2"
     android:layout_marginTop="30dp"
     android:layout_toRightOf="@+id/btn_reg"
     android:text="删除"
 
     />
 <Button
     android:id="@+id/btn_sel"
     android:layout_width="128dp"
     android:layout_height="wrap_content"
     android:layout_below="@+id/t2"
     android:layout_marginTop="30dp"
     android:layout_toRightOf="@id/btn_del"
     android:text="查询"
 
     />
 <LinearLayout
     android:id="@+id/layout"
     android:layout_below="@id/btn_sel"
     android:layout_height="match_parent"
     android:orientation="vertical"
     android:layout_width="match_parent"
     >
 </LinearLayout>
</RelativeLayout>
 
MainActivity.java :

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
    LinearLayout Layout ;
    EditText Name,Password;
    Button   bt_reg,bt_del,bt_sel;
    List<User> userList;
    private MyDatabaseHelper dbhelper;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }
    private void initView(){
        Layout=(LinearLayout) findViewById(R.id.layout);
        Name=(EditText)findViewById(R.id.text_name);
        Password=(EditText)findViewById(R.id.text_password);
        bt_reg=(Button)findViewById(R.id.btn_reg);
        bt_del=(Button)findViewById(R.id.btn_del);
        bt_sel=(Button)findViewById(R.id.btn_sel);
        bt_reg.setOnClickListener(this);
        bt_del.setOnClickListener(this);
        bt_sel.setOnClickListener(this);
        userList=new ArrayList<User>();
 
    }
    public void onClick(View view){
        switch (view.getId()) {
 
            case R.id.btn_reg:
                if (Name.getText().toString().matches("[a-zA-Z]*") && Name.getText().toString().length() > 5 && Name.getText().toString().length() < 13 && Password.getText().toString().matches("[0-9]*") && Password.getText().toString().length() > 2 && Password.getText().toString().length() < 7) {
                    dbhelper = new MyDatabaseHelper(this, "CREATE_USER.db", null, 1);
                    SQLiteDatabase db = dbhelper.getReadableDatabase();
                    db.execSQL("insert into user(name,password) values (?,?)", new String[]{Name.getText().toString(), Password.getText().toString()});
                    db.close();
                    Toast.makeText(MainActivity.this, "注册成功", Toast.LENGTH_SHORT).show();
 
                } else
                    Toast.makeText(MainActivity.this, "输入不合法", Toast.LENGTH_SHORT).show();
                break;
 
            case R.id.btn_del:
                if (Name.getText().toString().length() != 0 && Password.getText().toString().length() != 0) {
                    User user = null;
                    dbhelper = new MyDatabaseHelper(this, "CREATE_USER.db", null, 1);
                    SQLiteDatabase db = dbhelper.getReadableDatabase();
                    Cursor cursor = db.rawQuery("select * " + "from user where name=?", new String[]{Name.getText().toString()});
                    if (cursor.moveToFirst()) {
                        int id = cursor.getInt(cursor.getColumnIndex("id"));
                        String name = cursor.getString(cursor.getColumnIndex("name"));
                        String password = cursor.getString(cursor.getColumnIndex("password"));
                        user = new User(id, name, password);
                        cursor.close();
 
                        if (user.getPassword().equals(Password.getText().toString())) {
                            db.execSQL("delete from user where name=?", new String[]{Name.getText().toString()});
                            Toast.makeText(MainActivity.this, "删除成功", Toast.LENGTH_SHORT).show();
 
                        } else
                            Toast.makeText(MainActivity.this, "密码不正确", Toast.LENGTH_SHORT).show();
 
                        db.close();
                    }
                }
                else if(Name.getText().toString().length() != 0 && Password.getText().toString().length() == 0){
                    User user = null;
                    dbhelper = new MyDatabaseHelper(this, "CREATE_USER.db", null, 1);
                    SQLiteDatabase db = dbhelper.getReadableDatabase();
                    Cursor cursor = db.rawQuery("select * " + "from user where name=?", new String[]{Name.getText().toString()});
                    if (cursor.moveToFirst()) {
                        int id = cursor.getInt(cursor.getColumnIndex("id"));
                        String name = cursor.getString(cursor.getColumnIndex("name"));
                        String password = cursor.getString(cursor.getColumnIndex("password"));
                        user = new User(id, name, password);
                        cursor.close();
                        if (user.getName().equals(Name.getText().toString())) {
                            db.execSQL("delete from user where name=?", new String[]{Name.getText().toString()});
                            Toast.makeText(MainActivity.this, "删除成功", Toast.LENGTH_SHORT).show();
 
                        } else
                            Toast.makeText(MainActivity.this, "用户不存在", Toast.LENGTH_SHORT).show();
 
                        db.close();
                    }
 
                }
                break;
 
            case R.id.btn_sel:
 
                Layout.removeAllViews();
 
                if (Name.getText().toString().length() == 0 && Password.getText().toString().length() == 0) {
                    dbhelper = new MyDatabaseHelper(this, "CREATE_USER.db", null, 1);
                    SQLiteDatabase db = dbhelper.getReadableDatabase();
                    Cursor cursor = db.rawQuery("select * from user", null);
 
                    if (cursor.moveToFirst()) {
                        do {
                            int id = cursor.getInt(cursor.getColumnIndex("id"));
                            String name = cursor.getString(cursor.getColumnIndex("name"));
                            String password = cursor.getString(cursor.getColumnIndex("password"));
                            User user = new User(id, name, password);
                            userList.add(user);
                        } while (cursor.moveToNext());
                    }
                    for (User user : userList) {
                        TextView tv = new TextView(this);
                        tv.setText(user.toString());
                        tv.setTextSize(20);
                        Layout.addView(tv);
                    }
                    userList.clear();
                    cursor.close();
                    db.close();
 
                } else if (Name.getText().toString().length() != 0 && Password.getText().toString().length() == 0) {
 
                    dbhelper = new MyDatabaseHelper(this, "CREATE_USER.db", null, 1);
                    SQLiteDatabase db = dbhelper.getReadableDatabase();
                    Cursor cursor = db.rawQuery("select * " + "from user where name=?", new String[]{Name.getText().toString()});
                    User user = null;
 
                    if (cursor.moveToFirst()) {
                        int id = cursor.getInt(cursor.getColumnIndex("id"));
                        String name = cursor.getString(cursor.getColumnIndex("name"));
                        String password = cursor.getString(cursor.getColumnIndex("password"));
                        user = new User(id, name, password);
                        cursor.close();
                        db.close();
 
                        TextView tv = new TextView(this);
                        tv.setText(user.toString());
                        tv.setTextSize(20);
                        Layout.addView(tv);
                    }
                }
 
                else if (Name.getText().toString().length()!=0){
                    dbhelper=new MyDatabaseHelper(this,"CREATE_USER.db" ,null,1);
                    SQLiteDatabase db=dbhelper.getReadableDatabase();
                   Cursor cursor=db.rawQuery("select * " + "from user where name=?",new String[]{Name.getText().toString()});
                    User user=null;
 
                    if(cursor.moveToFirst()){
                        int id = cursor.getInt(cursor.getColumnIndex("id"));
                        String name = cursor.getString(cursor.getColumnIndex("name"));
                        String password =cursor.getString(cursor.getColumnIndex("password"));
                        user=new User(id,name,password);
                        cursor.close();
                        db.close();
 
                        if(user.getPassword().equals(Password.getText().toString())) {
                            TextView tv = new TextView(this);
                            tv.setText(user.toString());
                            tv.setTextSize(20);
                            Layout.addView(tv);
                        }
                       else if (Password.getText().toString().length()==0){
                            Toast.makeText(MainActivity.this,"用户不存在",Toast.LENGTH_SHORT).show();
                       }
 
                        else
                            Toast.makeText(MainActivity.this,"密码不正确",Toast.LENGTH_SHORT).show();
                    }}
                break;
        }}}

MyDatabaseHelper.java

public class MyDatabaseHelper extends SQLiteOpenHelper {

    public static final String CREATE_USER = "create table User("
            +"id integer primary key autoincrement,"
            +"name text not null,"
            +"password integer not null)";
    private Context mContext;
    public MyDatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version){
        super(context , name ,factory,version);
        mContext = context;
    }
    @Override
    public void onCreate(SQLiteDatabase db){
        db.execSQL(CREATE_USER);
        Toast.makeText(mContext, "", Toast.LENGTH_SHORT).show();
    }
    @Override
    public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion){
        db.execSQL("drop table if exists User");
        onCreate(db);
    }
}

User.java

public class User {
    private String name;
    private String password;
    private int id;
 
    public User(int id,String name,String password){
        super();
        this.id = id;
        this.name = name;
        this.password = password;
    }
    public void setId(int id){
        this.id = id;
    }
    public void setName(String name){
        this.name = name;
    }
    public void setPassword(String password){
        this.password = password;
    }
    public int getId(){
        return id;
    }
    public String getName(){
        return name;
    }
    public String getPassword(){
        return password;
    }
    public String toString() {
        return "Id:"+this.id+"    姓名："+this.name+"    密码："+this.password;
    }
}