doesn't show picture in android 6 and above

问题

I am trying to learn how to use the camera in an app and this is what I reached , the idea is having a button that opens the camera and that the picture will instantly show on the screen after we take the picture, the second button is from an earlier version that couldn't show the picture immediately and had to be clicked in order to show it.

Anyways my problem is that this code doesn't show the picture at android 6.. on my android 5 device it works fine.. the picture is saved in the "sdcard/camera_app/cam_image.jpg" path either way and the button doesn't work as well so I'm thinking something about the imageview has changed from android 5 to 6? the question is pretty much how to make this work for android 6 phones

public class Add_Comment_Picture extends AppCompatActivity {
    static final int CAM_REQUEST = 1;
    ImageView imageView;
    Button button;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add__comment__picture);
        button = (Button) findViewById(R.id.button);
        imageView = (ImageView) findViewById(R.id.imageView);
        Button button2 = (Button) findViewById(R.id.button3);
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Intent camera_intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
                File file = getFile();
                camera_intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(file));
                startActivityForResult(camera_intent , CAM_REQUEST);
            }
        });
        button2.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                String path = "sdcard/camera_app/cam_image.jpg";
                imageView.setImageDrawable(Drawable.createFromPath(path));

            }
        });




    }

    private File getFile()
    {
        File folder = new File("sdcard/camera_app");
        if (!folder.exists())
        {
            folder.mkdir();
        }
        File image_file = new File(folder,"cam_image.jpg");
        return image_file;
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        String path = "sdcard/camera_app/cam_image.jpg";
        imageView.setImageDrawable(Drawable.createFromPath(path));
        super.onActivityResult(requestCode, resultCode, data);
    }

}

回答1:

You need to give READ_EXTERNAL_STORAGE and WRITE_EXTERNAL STORANGE permissions programmatically.

MANIFEST PERMISSIONS WON'T WORK on Android 6

With marshmallow(newest version of Android). We have got some restrictions in Using Sensitive permissions like : Storage,Contacts access, etc..In edition to give these permissions in manifest, We need to request them from users at Runtime.

For more details refer this : Android M permissions

For coding reference please refer this SO question : Android marshmallow request permission?

Add this code in your activity :

@Override
protected void onStart() {
    super.onStart();

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {

        int hasWritePermission = checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE);
        int hasReadPermission = checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE);
        int hasCameraPermission = checkSelfPermission(Manifest.permission.CAMERA);

        List<String> permissions = new ArrayList<String>();
        if (hasWritePermission != PackageManager.PERMISSION_GRANTED) {
            permissions.add(Manifest.permission.WRITE_EXTERNAL_STORAGE);

        } 

        if (hasReadPermission != PackageManager.PERMISSION_GRANTED) {
            permissions.add(Manifest.permission.READ_EXTERNAL_STORAGE);

        } 

        if (hasCameraPermission != PackageManager.PERMISSION_GRANTED) {
            permissions.add(Manifest.permission.CAMERA);

        } 
        if (!permissions.isEmpty()) {
            requestPermissions(permissions.toArray(new String[permissions.size()]), 111);
        }
    }


}

Add this after onActivityResult :

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    switch (requestCode) {
        case 111: {
            for (int i = 0; i < permissions.length; i++) {
                if (grantResults[i] == PackageManager.PERMISSION_GRANTED) {
                    System.out.println("Permissions --> " + "Permission Granted: " + permissions[i]);


                } else if (grantResults[i] == PackageManager.PERMISSION_DENIED) {
                    System.out.println("Permissions --> " + "Permission Denied: " + permissions[i]);

                }
            }
        }
        break;
        default: {
            super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        }
    }
}

回答2:

After android 6.0 permission structure has changed. You must check permission on run-time. For example you will select a picture from image gallery, User give permission for gallery access before entering gallery.

You can look this document for this newness.

https://developer.android.com/training/permissions/requesting.html

Sample code for your issue

if (checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
            == PackageManager.PERMISSION_GRANTED) {
        Log.v(TAG,"Permission is granted");
        return true;
  }

If not, you need to ask the user to grant your app a permission:

ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE);

Good luck :)

来源：https://stackoverflow.com/questions/37269199/doesnt-show-picture-in-android-6-and-above