如何解码保存到 SQLite 数据库并在 ImageView 中显示的图像文件路径

Question

这就是我目前正在努力解决的问题。我正在使用以下代码将相机拍摄的图像保存到我的 SQLite 数据库中：

数据库数据库：

@Override
public void onCreate(SQLiteDatabase db) {
    String sql =     "create table " + DATABASE_TABLE + " ( " +
            FIELD_ROW_ID + " integer primary key autoincrement , " +
            FIELD_LNG + " double , " +
            FIELD_LAT + " double , " +
            FIELD_ZOOM + " text , " +
            FIELD_IMG + " text " +
            " ) ";

    db.execSQL(sql);
}

然后在相机意图中（Main Activity）

StrictMode.VmPolicy.Builder builder = new StrictMode.VmPolicy.Builder();
            StrictMode.setVmPolicy(builder.build());
            Intent getCameraImage = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            File cameraFolder;
            if   (android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED))
                cameraFolder = new    File(android.os.Environment.getExternalStorageDirectory(),"MapImages/");
            else
                cameraFolder= context.getFilesDir();
            if(!cameraFolder.exists())
                cameraFolder.mkdirs();
            String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
            String imageFileName = "JPEG_" + timeStamp + "_";
            File photo = new File(cameraFolder, "MapImages/" + imageFileName + ".jpg");
            getCameraImage.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photo));
            Uri.fromFile(photo);
            startActivityForResult(getCameraImage, TAKE_PICTURE);

            drawMarker(point);
            ContentValues contentValues = new ContentValues();
            contentValues.put(LocationsDB.FIELD_LAT, point.latitude);
            contentValues.put(LocationsDB.FIELD_LNG, point.longitude);
            contentValues.put(LocationsDB.FIELD_ZOOM, mMap.getCameraPosition().zoom);
            contentValues.put(FIELD_IMG, String.valueOf(photo));
            LocationInsertTask insertTask = new LocationInsertTask();
            insertTask.execute(contentValues);

所以当我查看数据库时，它会将图像文件位置保存为：

/storage/emulated/0/MapImages/MapImages/JPEG_20211105_091000_.jpg

所以一切都很好！但是我现在如何检索该图像并将其显示在 ImageView 中？

我已经尝试过了（在 onloadFinished 中）

public void onLoadFinished(Loader<Cursor> arg0, Cursor arg1) {
    int locationCount = 0;
    double lat = 0;
    double lng = 0;
    float zoom = 0;
    double img = 0;

    locationCount = arg1.getCount();
    arg1.moveToFirst();

    for (int i = 0; i < locationCount; i++) {
        lat = arg1.getDouble(arg1.getColumnIndex(LocationsDB.FIELD_LAT));
        lng = arg1.getDouble(arg1.getColumnIndex(LocationsDB.FIELD_LNG));
        zoom = arg1.getFloat(arg1.getColumnIndex(LocationsDB.FIELD_ZOOM));
        img = arg1.getDouble(arg1.getColumnIndex(LocationsDB.FIELD_IMG));
        LatLng location = new LatLng(lat, lng);
        drawMarker(location);
        arg1.moveToNext();
    }

    if (locationCount > 0) {
        mMap.moveCamera(CameraUpdateFactory.newLatLng(new LatLng(lat, lng)));
        mMap.animateCamera(CameraUpdateFactory.zoomTo(zoom));
        Bitmap myBitmap = BitmapFactory.decodeFile(String.valueOf(img));
        ImageView myImage = (ImageView) findViewById(R.id.imageView);
        myImage.setImageBitmap(myBitmap);
        }
    }

但随后收到以下错误：

E/BitmapFactory: Unable to decode stream: java.io.FileNotFoundException: 0.0: open failed: ENOENT (No such file or directory)

我不想将图像保存为blob，因为这是不好的做法，因此我将文件路径保存到数据库

如果有人可以帮助指导我从数据库中检索文件并显示在我的ImageView

谢谢大家！

Answer 1

替换：

img = arg1.getDouble(arg1.getColumnIndex(LocationsDB.FIELD_IMG));

与：

img = arg1.getString(arg1.getColumnIndex(LocationsDB.FIELD_IMG));

这还需要您将img 声明为String。

文件系统路径是字符串，而不是浮点数。