Android中使用Content Providers进行数据共享的实例[页8]

javaCopy codepublic class StudentProvider extends ContentProvider {
    // Content Provider授权码
    public static final String AUTHORITY = "com.example.provider.student";

    // 数据库表格名称
    public static final String TABLE_NAME = "students";

    // 数据库表格字段
    public static final String _ID = "_id";
    public static final String NAME = "name";
    public static final String AGE = "age";
    public static final String GENDER = "gender";

    // 数据库帮助类
    private DatabaseHelper mDatabaseHelper;

    @Override
    public boolean onCreate() {
        mDatabaseHelper = new DatabaseHelper(getContext());
        return true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
        SQLiteDatabase db = mDatabaseHelper.getReadableDatabase();
        Cursor cursor = db.query(TABLE_NAME, projection, selection, selectionArgs, null, null, sortOrder);
        cursor.setNotificationUri(getContext().getContentResolver(), uri);
        return cursor;
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        SQLiteDatabase db = mDatabaseHelper.getWritableDatabase();
        long id = db.insert(TABLE_NAME, null, values);
        getContext().getContentResolver().notifyChange(uri, null);
        return ContentUris.withAppendedId(uri, id);
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        SQLiteDatabase db = mDatabaseHelper.getWritableDatabase();
        int count = db.update(TABLE_NAME, values, selection, selectionArgs);
        getContext().getContentResolver().notifyChange(uri, null);
        return count;
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        SQLiteDatabase db = mDatabaseHelper.getWritableDatabase();
        int count = db.delete(TABLE_NAME, selection, selectionArgs);
        getContext().getContentResolver().notifyChange(uri,

除了系统预定义的Content Providers，开发者也可以自己创建自定义Content Provider来进行数据共享。下面以一个简单的实例来介绍如何创建自定义Content Provider。