在访问之前确保 Cursor 被正确初始化

Question

我使用下一个代码来玩一个临时的 SQLite table:

public class DBHelperForTemp extends SQLiteOpenHelper {

private final static String DB_NAME = "tempdb";
private final static int DB_VERSION = 3;

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

@Override
public void onCreate(SQLiteDatabase db) {
    String createTable = "CREATE TABLE tbl ( ID INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, image BLOB )";
    db.execSQL(createTable);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS tbl");
    onCreate(db);
}

public boolean add_Temp_Values(String name, byte[] image) throws SQLiteException {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues contentValues = new ContentValues();
    contentValues.put("name", name);
    contentValues.put("image", image);

    long result = db.insert("tbl", null, contentValues);

    return result != -1;
}


public Cursor get_Data(){
    SQLiteDatabase db = this.getWritableDatabase();
    String query = "SELECT * FROM tbl";
    return db.rawQuery(query, null);
}


public void ClearData(){
    SQLiteDatabase db = this.getWritableDatabase();
    db.execSQL("delete from tbl");
}

}

将数据保存到临时文件：

private void  doTemp(){
    final Bitmap photo = ((BitmapDrawable) mPhotoImageView.getDrawable()).getBitmap();
    boolean insertData = mDBTemp.add_Temp_POI_Values(mNameEditText.getText().toString(),
           Utils.imageToByteArray(photo) );
    if (insertData){
        Toast.makeText(this, R.string.fb_success, Toast.LENGTH_SHORT).show();
    } else {
        Toast.makeText(this, R.string.fb_error, Toast.LENGTH_SHORT).show();
    }
    finish();
}

并尝试从临时读取并发送到 firebase：

private void onSubmit(){
    final DBHelperForTemp mDBTemp = new DBHelperForTemp(this);
    final Cursor data = mDBTemp.get_Data();
    if (data != null && data.getCount() != 0 && data.moveToFirst()){
        for (int i = 0; i < data.getCount(); i++) {
            final String name = data.getString(data.getColumnIndex("name"));
            final byte[] byteArray = data.getBlob(data.getColumnIndex("image"));
            final Bitmap photo = BitmapFactory.decodeByteArray(byteArray, 0 , byteArray.length);
.........

我在尝试使用它时收到下一个错误代码：

E/UncaughtException: java.lang.IllegalStateException: Couldn't read row 0, col 1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.
                                                                                         at android.database.CursorWindow.nativeGetString(Native Method)
                                                                                         at android.database.CursorWindow.getString(CursorWindow.java:451)
                                                                                         at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:51)
                                                                                         at com.test.test.activities.ActivityMain.onSubmit

有趣的是，如果我在临时 table 中没有图像，代码也能正常工作。如果有图像，应用程序会崩溃，但会尝试读取名称字符串而不是图像。

任何人都可以帮我检测问题吗？

data.getCount() return 1. data.getColumnIndex("name") return 0. data.getString(0) return 方法抛出 'java.lang.IllegalStateException' 异常。无法从 CursorWindow 读取第 0 行第 1 列。在从游标访问数据之前，确保游标已正确初始化。

Answer 1

可能是你存储的图片太大，CursorWindow每行最大尺寸为2048Kb

在访问之前确保 Cursor 被正确初始化

Make sure the Cursor is initialized correctly before accessing

database

sqlite

android

cursor