Question

我正在创建一个应用程序，此时需要从sqlite数据库获取文件名，获取具有该文件名的图像并将其插入ImageView，我现在已经创建了此代码，但我想我我在这里做错了什么......

Database db = new Database(getApplicationContext());
SQLiteDatabase readableDatabase = db.getReadableDatabase();
final Cursor curFileName = readableDatabase.rawQuery("select filename from data order by id asc", null);
image = (ImageView) findViewById(R.id.image);
int filename = curFileName.getColumnIndex("filename");
String filenameString = curFileName.getString(filename);
d = Drawable.createFromPath(Environment.getExternalStorageDirectory().toString()+filenameString);
Toast.makeText(getApplicationContext(), filenameString, Toast.LENGTH_SHORT).show();
handleDrawable(d);

对不起，这是例外：

04-09 13:48:16.950: E/AndroidRuntime(30802): FATAL EXCEPTION: main
04-09 13:48:16.950: E/AndroidRuntime(30802): java.lang.RuntimeException: Unable to start activity ComponentInfo{g.d.filer/g.d.filer.Favorites}: android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 33

Answer 1

您必须先定位光标才能阅读

 int filename = curFileName.getColumnIndex("filename");
 if (cur.moveToFirst()) { // position cursor to first item. false: empty resultset
     String filenameString = curFileName.getString(filename);
     d = Drawable.createFromPath(Environment.getExternalStorageDirectory().toString()+filenameString);
     Toast.makeText(getApplicationContext(), filenameString, Toast.LENGTH_SHORT).show();
     handleDrawable(d);
     ...
 }

Answer 2

我编辑了我的答案。我希望这会对你有所帮助。：d

if (cursor.moveToFirst()){
   do{
      String data = cursor.getString(cursor.getColumnIndex("filename"));
      // here you have to generate Image view and add bitmap to imageview
   }while(cursor.moveToNext());
}
cursor.close()

Answer 3

你添加了

吗？

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

或

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

清单文件中的

。因为，从Android 4.4开始，如果您只读取或写入应用程序专用的文件，则不需要这些权限。有关更多信息，请参阅

http://developer.android.com/guide/topics/data/data-storage.html#filesExternal

从数据库中获取文件名并使用它来填充ImageView

3 个答案: