相关疑难解决方法(0)

我正在尝试通过以下代码保存位图图像：

File sdcard = Environment.getExternalStorageDirectory();
            String filename = "test";
            File folder = new File(sdcard, "/Download");
            Log.v("ImageStorage1", "EXiST?: " + folder.exists());
            folder.mkdirs();
            Log.v("ImageStorage2", "EXIST!: " + folder.exists());
            Log.v("ImageStorage", "Folder: " + folder);
            File file = new File(folder, filename + ".jpg");

            try {
                FileOutputStream out = new FileOutputStream(file.getAbsoluteFile());
                result.compress(Bitmap.CompressFormat.JPEG, 90, out);
                out.flush();
                out.close();
            } catch (Exception e) {
                e.printStackTrace();
            }

我还在清单文件中使用：

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

但我得到了这个：

V/ImageStorage1: EXiST?: true
V/ImageStorage2: EXIST!: true
W/System.err: java.io.FileNotFoundException: 
/storage/emulated/0/Download/test.jpg (Permission denied)
    W/System.err:     at java.io.FileOutputStream.open0(Native Method)
    W/System.err:     at java.io.FileOutputStream.open(FileOutputStream.java:287) …