自定义一个简单ContentProvider

在开始之前我们先要创建一个数据库创建类

DBOpenHelper.java

public class DBOpenHelper extends SQLiteOpenHelper {

    final String CREATE_SQL = "CREATE TABLE test(_id INTEGER PRIMARY KEY AUTOINCREMENT,name)";
    
    public DBOpenHelper(Context context, String name, CursorFactory factory,
            int version) {
        super(context, name, null, 1);
    }

    
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_SQL);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

    }

}

下面我们自定义ContentProvider类，实现onCreate()，getType()，根据需求重写对应的增删改查方法：

NameContentProvider.java

public class NameContentProvider extends ContentProvider {

    //初始化一些常量
     private static UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);        
     private DBOpenHelper dbOpenHelper;
    
    //为了方便直接使用UriMatcher,这里addURI,下面再调用Matcher进行匹配
     
     static{  
         matcher.addURI("com.jay.example.providers.myprovider", "test", 1);
     }  
     
    @Override
    public boolean onCreate() {
        dbOpenHelper = new DBOpenHelper(this.getContext(), "test.db", null, 1);
        return true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection,
            String[] selectionArgs, String sortOrder) {
        return null;
    }

    @Override
    public String getType(Uri uri) {
        return null;
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        
        switch(matcher.match(uri))
        {
        //把数据库打开放到里面是想证明uri匹配完成
        case 1:
            SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
            long rowId = db.insert("test", null, values);
            if(rowId > 0)
            {
                //在前面已有的Uri后面追加ID
                Uri nameUri = ContentUris.withAppendedId(uri, rowId);
                //通知数据已经发生改变
                getContext().getContentResolver().notifyChange(nameUri, null);
                return nameUri;
            }
        }
        return null;
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        return 0;
    }

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

}

AndroidManifest.xml中为ContentProvider进行注册

接下来，创建一个新的项目，我们来实现ContentResolver的部分，我们直接通过按钮点击插入一条数据：

MainActivity.java

public class MainActivity extends Activity {

    private Button btninsert;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        btninsert = (Button) findViewById(R.id.btninsert);
        
        //读取contentprovider 数据  
        final ContentResolver resolver = this.getContentResolver();
        
        
        btninsert.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                 ContentValues values = new ContentValues();
                 values.put("name", "测试");
                 Uri uri = Uri.parse("content://com.jay.example.providers.myprovider/test");
                resolver.insert(uri, values);
                Toast.makeText(getApplicationContext(), "数据插入成功", Toast.LENGTH_SHORT).show();
                
            }
        });
       
    }
}

就这样