FileNotFoundException打开失败。在将图像文件保存到android的内部存储时，出现EPERM（操作不允许）。

Question

当我试图将图像保存到android的内部存储时，我面临着这个问题。

public static String setImage(Bitmap image) {
    if (image != null) {
        FileOutputStream outputStream = null;
        File dir = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/Caramel");
        dir.mkdir();
        String fileName = System.currentTimeMillis() + ".jpg";
        File file = new File(dir, fileName);
        try {
            outputStream = new FileOutputStream(file);
            image.compress(Bitmap.CompressFormat.JPEG, 100, outputStream);
            outputStream.flush();
            outputStream.close();
            return fileName;
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (outputStream != null) {
                    outputStream.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    return null;
}

一切都很顺利，我可以在调试模式下看到我的位图图像，但同样的，我得到了下一个错误。

    W/System.err: java.io.FileNotFoundException: /storage/emulated/0/Caramel/1587724428205.jpg: open failed: EPERM (Operation not permitted)
W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:495)
W/System.err:     at java.io.FileOutputStream.<init>(FileOutputStream.java:235)
W/System.err:     at java.io.FileOutputStream.<init>(FileOutputStream.java:186)
W/System.err:     at com.example.caramel.Position.setImage(Position.java:176)
W/System.err:     at com.example.caramel.PositionActivity.onActivityResult(PositionActivity.java:129)
W/System.err:     at android.app.Activity.dispatchActivityResult(Activity.java:8300)
W/System.err:     at android.app.ActivityThread.deliverResults(ActivityThread.java:4905)
W/System.err:     at android.app.ActivityThread.handleSendResult(ActivityThread.java:4953)
W/System.err:     at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51)
W/System.err:     at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
W/System.err:     at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
W/System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2043)
W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:106)
W/System.err:     at android.os.Looper.loop(Looper.java:216)
W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:7464)
W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
W/System.err:     at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:549)
W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:955)
W/System.err: Caused by: android.system.ErrnoException: open failed: EPERM (Operation not permitted)
W/System.err:     at libcore.io.Linux.open(Native Method)
W/System.err:     at libcore.io.ForwardingOs.open(ForwardingOs.java:166)
W/System.err:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:254)
W/System.err:     at libcore.io.ForwardingOs.open(ForwardingOs.java:166)
W/System.err:     at android.app.ActivityThread$AndroidOs.open(ActivityThread.java:7360)
W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:481)
W/System.err:   ... 17 more

看来，原因可能在我的Manifest.xml文件中，但我已经设置了这些权限。

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />

谢谢你的支持，伙计们。

Answer 1

android系统的权限系统是非常严格的，你必须考虑到这一点，当你向内部内存写东西的时候，可以试试这样的方法。

    public class MainActivity extends AppCompatActivity {
   Button save;
   Bitmap bitmap;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      Drawable drawable = getResources().getDrawable(R.drawable.mario);
      bitmap = ((BitmapDrawable) drawable).getBitmap();
      save = findViewById(R.id.save);
      save.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            ContextWrapper cw = new ContextWrapper(getApplicationContext());
            File directory = cw.getDir("imageDir", Context.MODE_PRIVATE);
            File file = new File(directory, "UniqueFileName" + ".jpg");
            if (!file.exists()) {
               Log.d("path", file.toString());
               FileOutputStream fos = null;
               try {
                  fos = new FileOutputStream(file);
                  bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
                  fos.flush();
                  fos.close();
               } catch (java.io.IOException e) {
                  e.printStackTrace();
               }
            }
         }
      });
   }
}