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编程知识 时间:2024-12-04 12:25:33
作者:文/会员上传
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ContentResolver和ContentProvider是Android中用于实现数据共享和访问的重要组件。ContentResolver:ContentResolver用于与ContentProvider进行通信,它提供了一组方法来查询
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ContentResolver和ContentProvider是Android中用于实现数据共享和访问的重要组件。
public class MyContentProvider extends ContentProvider {private DBHelper dbHelper; // 数据库帮助类@Overridepublic boolean onCreate() {dbHelper = new DBHelper(getContext());return true;}@Overridepublic Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {SQLiteDatabase db = dbHelper.getReadableDatabase();Cursor cursor = db.query("table_name", projection, selection, selectionArgs, null, null, sortOrder);cursor.setNotificationUri(getContext().getContentResolver(), uri);return cursor;}@Overridepublic Uri insert(Uri uri, ContentValues values) {SQLiteDatabase db = dbHelper.getWritableDatabase();long id = db.insert("table_name", null, values);getContext().getContentResolver().notifyChange(uri, null);return ContentUris.withAppendedId(uri, id);}@Overridepublic int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {SQLiteDatabase db = dbHelper.getWritableDatabase();int rows = db.update("table_name", values, selection, selectionArgs);getContext().getContentResolver().notifyChange(uri, null);return rows;}@Overridepublic int delete(Uri uri, String selection, String[] selectionArgs) {SQLiteDatabase db = dbHelper.getWritableDatabase();int rows = db.delete("table_name", selection, selectionArgs);getContext().getContentResolver().notifyChange(uri, null);return rows;}@Overridepublic String getType(Uri uri) {return null;}}
在使用ContentResolver和ContentProvider时,需要先注册ContentProvider并在AndroidManifest.xml中声明权限和uri。然后可以通过ContentResolver来操作数据,例如查询、插入、更新、删除等操作。
以上是ContentResolver和ContentProvider的基本使用方法,开发者可以根据具体的需求来进一步深入学习和使用。
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