ContentProvider使用示例

ContentProvider使用示例

1、MyContentProvider

public class MyContentProvider extends ContentProvider {

    private static final String TAG = "MyContentProvider";

    private Context context;

    private SQLiteDatabase sqLiteDatabase;

    public static final String AUTHORITY = "com.example.mycontentprovider.MyContentProvider";

    public static final int PROVIDER_CODE = 0;

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

    static {
        uriMatcher.addURI(AUTHORITY, MyDBHelper.TABLE_NAME, PROVIDER_CODE);
    }

    public MyContentProvider() {
    }

    /**
     * 通过uri匹配表名
     *
     * @param uri
     * @return
     */
    private String getTableName(Uri uri) {
        String tableName = null;
        switch (uriMatcher.match(uri)) {
            case PROVIDER_CODE:
                tableName = MyDBHelper.TABLE_NAME;
                break;
        }
        return tableName;
    }

    @Override
    public boolean onCreate() {
        init();
        return false;
    }

    private void init() {
        context = getContext();
        sqLiteDatabase = new MyDBHelper(context).getWritableDatabase();
    }

    @Nullable
    @Override
    public Cursor query(@NonNull Uri uri, @Nullable String[] projection, @Nullable String selection, @Nullable String[] selectionArgs, @Nullable String sortOrder) {
        String tableName = getTableName(uri);
        if (tableName == null) {
            Log.e(TAG, "query: 未匹配到uri");
            throw new IllegalArgumentException("Unsupported URI:" + uri);
        }
        return sqLiteDatabase.query(tableName, projection, selection, selectionArgs, null, null, sortOrder, null);
    }

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

    @Nullable
    @Override
    public Uri insert(@NonNull Uri uri, @Nullable ContentValues values) {
        String tableName = getTableName(uri);
        if (tableName == null) {
            Log.e(TAG, "insert: 未匹配到uri");
            throw new IllegalArgumentException("Unsupported URI:" + uri);
        }
        sqLiteDatabase.insert(tableName, null, values);
        context.getContentResolver().notifyChange(uri, null);
        Log.d(TAG, "insert: 添加成功");
        return uri;
    }

    @Override
    public int delete(@NonNull Uri uri, @Nullable String selection, @Nullable String[] selectionArgs) {
        String tableName = getTableName(uri);
        if (tableName == null) {
            Log.e(TAG, "delete: 未匹配到uri");
            throw new IllegalArgumentException("Unsupported URI:" + uri);
        }
        int count = sqLiteDatabase.delete(tableName, selection, selectionArgs);
        if (count > 0) {
            context.getContentResolver().notifyChange(uri, null);
        }
        Log.d(TAG, "delete: 删除成功");
        Log.d(TAG, "delete: count=" + count);
        return count;
    }

    @Override
    public int update(@NonNull Uri uri, @Nullable ContentValues values, @Nullable String selection, @Nullable String[] selectionArgs) {
        String tableName = getTableName(uri);
        if (tableName == null) {
            throw new IllegalArgumentException("Unsupported URI:" + uri);
        }
        int row = sqLiteDatabase.update(tableName, values, selection, selectionArgs);
        if (row > 0) {
            context.getContentResolver().notifyChange(uri, null);
        }
        return row;
    }
}

2、MyDBHelper

public class MyDBHelper extends SQLiteOpenHelper {
    /**
     * 库名
     */
    private static final String DBNAME = "provider.db";

    /**
     * 表明 测试用
     */
    public static final String TABLE_NAME = "provider_data";

    /**
     * 版本号
     */
    private static final int VERSION = 1;

    /**
     * 建表的sql语句
     */
    private static final String SQL = "create table " + TABLE_NAME + "(id integer primary key Autoincrement,name text)";

    private Context context;

    public MyDBHelper(Context context) {
        super(context, DBNAME, null, VERSION);
        this.context = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(SQL);
        Toast.makeText(context, "建表成功", Toast.LENGTH_SHORT).show();
        Log.d("MyContentProvider", "onCreate: 建表成功");
    }

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

    }
}

3、在MainActivity中使用

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private static final String TAG = "MyContentProvider";

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

    private void initView() {
        Button bt_init = findViewById(R.id.bt_init);
        bt_init.setOnClickListener(this);
        Button bt_add = findViewById(R.id.bt_add);
        bt_add.setOnClickListener(this);
        Button bt_delete = findViewById(R.id.bt_delete);
        bt_delete.setOnClickListener(this);
        Button bt_update = findViewById(R.id.bt_update);
        bt_update.setOnClickListener(this);
        Button bt_query = findViewById(R.id.bt_query);
        bt_query.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.bt_init:
                init();
                break;
            case R.id.bt_add:
                toAdd();
                break;
            case R.id.bt_delete:
                toDelete();
                break;
            case R.id.bt_update:
                toUpdate();
                break;
            case R.id.bt_query:
                toQuery();
                break;
        }
    }

    private void init() {
        getContentResolver().delete(nameUri, null, null);
    }

    private Uri nameUri = Uri.parse("content://com.example.mycontentprovider.MyContentProvider/provider_data");

    private void toAdd() {
        ContentValues contentValues = new ContentValues();
        contentValues.put("name", "水货");
        getContentResolver().insert(nameUri, contentValues);
    }

    private void toDelete() {
        getContentResolver().delete(nameUri, "name=?", new String[]{"水货"});
    }

    private void toUpdate() {
        ContentValues contentValues = new ContentValues();
        contentValues.put("name", "太阳");
        getContentResolver().update(nameUri, contentValues, "id=?", new String[]{"2"});
    }

    private void toQuery() {
        Cursor nameCursor = getContentResolver().query(nameUri, new String[]{"id", "name"}, null, null, null);
        if (nameCursor != null) {
            while (nameCursor.moveToNext()) {
                Log.e(TAG, "id:" + nameCursor.getInt(nameCursor.getColumnIndex("id"))
                        + " name:" + nameCursor.getString(nameCursor.getColumnIndex("name")));
            }
            Log.d(TAG, "toQuery: 查询成功");
            nameCursor.close();
        }
    }
}

activity_main.xml

4、manifest