ContentProvider
是Android中提供的專門用于不同應用之間進行數據共享的方式
底層由Binder機制實現，由于系統對他做了封裝，使用起來比AIDL方便許多，無需關注底層細節即可輕松進行IPC
Provider的onCreate由Server端主線程調用，所以不要做耗時任務
CRUD操作由Binder線程調用，所以可以做并發操作，不會引起堵塞

Server

// 服務端數據庫
public class DbOpenHelper extends SQLiteOpenHelper {
    private static final String DB_NAME = "providers.db";
    private static final int DB_VERSION = 1;

    public static final String BOOK_TABLE_NAME = "book";
    public static final String USER_TABLE_NAME = "user";

    private static final String CREATE_BOOK_TABLE = "CREATE TABLE IF NOT EXISTS " + BOOK_TABLE_NAME + "(" +
            "_id    INTEGER PRIMARY KEY, " +
            "name   TEXT" +
            ")";

    private static final String CREATE_USER_TABLE = "CREATE TABLE IF NOT EXISTS " + USER_TABLE_NAME + "(" +
            "_id    INTEGER PRIMARY KEY, " +
            "name   TEXT," +
            "sex    INTEGER" +
            ")";


    public DbOpenHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }


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

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO: 2016/7/29 ignore
    }
}

// 實現內容提供者
public class CustomProvider extends ContentProvider {
    public static final String TAG = "CustomProvider";
    public static final String AUTHORITY = "com.rtfsc.auth.provider";

    public static final Uri BOOK_CONTENT_URI = Uri.parse("content://"
            + AUTHORITY + "/book");
    public static final Uri USER_CONTENT_URI = Uri.parse("content://"
            + AUTHORITY + "/user");

    public static final int BOOK_URI_CODE = 0;
    public static final int USER_URI_CODE = 1;

    private static final UriMatcher sUriMatcher = new UriMatcher(
            UriMatcher.NO_MATCH);

    private Context mContext;
    private SQLiteDatabase mDatabase;

    static {
        sUriMatcher.addURI(AUTHORITY, "book", BOOK_URI_CODE);
        sUriMatcher.addURI(AUTHORITY, "user", USER_URI_CODE);
    }

    private String getTableName(Uri uri) {
        String tableName = null;
        switch (sUriMatcher.match(uri)) {
            case BOOK_URI_CODE:
                tableName = DbOpenHelper.BOOK_TABLE_NAME;
                break;
            case USER_URI_CODE:
                tableName = DbOpenHelper.USER_TABLE_NAME;
                break;
            default:
                break;
        }
        return tableName;
    }

    @Override
    public boolean onCreate() {
        Log.d(TAG, "onCreate, current thread: " + Thread.currentThread().getName());
        mContext = getContext();
        mDatabase = new DbOpenHelper(mContext).getWritableDatabase();
        initData();
        return true;
    }

    private void initData() {
        mDatabase.execSQL("delete from " + DbOpenHelper.BOOK_TABLE_NAME);
        mDatabase.execSQL("delete from " + DbOpenHelper.USER_TABLE_NAME);

        mDatabase.execSQL("insert into " + DbOpenHelper.BOOK_TABLE_NAME + " values(1,'Android');");
        mDatabase.execSQL("insert into " + DbOpenHelper.BOOK_TABLE_NAME + " values(2,'iOS');");
        mDatabase.execSQL("insert into " + DbOpenHelper.BOOK_TABLE_NAME + " values(3,'Pytnon');");

        mDatabase.execSQL("insert into " + DbOpenHelper.USER_TABLE_NAME + " values(1,'Wong',1);");
        mDatabase.execSQL("insert into " + DbOpenHelper.USER_TABLE_NAME + " values(2,'Kim',1);");
        mDatabase.execSQL("insert into " + DbOpenHelper.USER_TABLE_NAME + " values(3,'Hung',1);");
    }

    @Nullable
    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
        Log.d(TAG, "query, current thread: " + Thread.currentThread().getName());
        String tableName = getTableName(uri);
        if (tableName.isEmpty()) {
            throw new IllegalArgumentException("Unsupport URI: " + uri);
        }
        return mDatabase.query(tableName, projection, selection, selectionArgs, null, null, null);
    }

    @Nullable
    @Override
    public String getType(Uri uri) {
        Log.d(TAG, "getType");
        return null;
    }

    @Nullable
    @Override
    public Uri insert(Uri uri, ContentValues values) {
        Log.d(TAG, "insert");
        String tableName = getTableName(uri);
        if (tableName.isEmpty()) {
            throw new IllegalArgumentException("Unsupport URI: " + uri);
        }
        mDatabase.insert(tableName, null, values);
        mContext.getContentResolver().notifyChange(uri, null);
        return uri;
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        Log.d(TAG, "delete");
        String tableName = getTableName(uri);
        if (tableName.isEmpty()) {
            throw new IllegalArgumentException("Unsupport URI: " + uri);
        }
        int count = mDatabase.delete(tableName, selection, selectionArgs);
        if (count > 0) {
            mContext.getContentResolver().notifyChange(uri, null);
        }
        return count;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        Log.d(TAG, "update");
        String tableName = getTableName(uri);
        if (tableName.isEmpty()) {
            throw new IllegalArgumentException("Unsupport URI: " + uri);
        }
        int row = mDatabase.update(tableName, values, selection, selectionArgs);
        if (row > 0) {
            mContext.getContentResolver().notifyChange(uri, null);
        }
        return row;
    }
}

//  注冊內容提供者
<provider
            android:name="com.rtfsc.CustomProvider"
            android:authorities="com.rtfsc.auth.provider"
            android:permission="com.rtfsc.provider"
            android:process=":provider"/>

Client

//  添加權限
<uses-permission android:name="com.rtfsc.provider"/>

public class MainActivity extends AppCompatActivity {

    public static final String PROVIDER_CONTENT_PREFIX = "content://com.rtfsc.auth.provider";

    private IOnChangeListener mListener = new IOnChangeListener.Stub() {
        @Override
        public void onChange(String aString) throws RemoteException {
            System.out.println(aString);
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Uri bookUri = Uri.parse(PROVIDER_CONTENT_PREFIX + "/book");
        Uri userUri = Uri.parse(PROVIDER_CONTENT_PREFIX + "/user");

        ContentValues contentValues = new ContentValues();
        contentValues.put("_id", 4);
        contentValues.put("name", "Effctive of java");

        getContentResolver().insert(bookUri, contentValues);

        Cursor cursor = getContentResolver().query(bookUri, new String[]{"_id", "name"}, null, null, null);
        if (cursor == null) {
            return;
        }
        while (cursor.moveToNext()) {
            String id = cursor.getString(cursor.getColumnIndex("_id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));
            System.out.println("id = " + id + " name = " + name);
        }
        cursor.close();
    }
}

//  log
07-29 09:28:34.885 1277-1277/com.rtfsc I/System.out: id = 1 name = Android
07-29 09:28:34.885 1277-1277/com.rtfsc I/System.out: id = 2 name = iOS
07-29 09:28:34.885 1277-1277/com.rtfsc I/System.out: id = 3 name = Pytnon
07-29 09:28:34.885 1277-1277/com.rtfsc I/System.out: id = 4 name = Effctive of java