Android使用getExternalFilesDir保存图片不一致

Question

In my app, I am trying to take a picture, save it, and add it to an ImageView with this code I got from the Android Developers tutorial

private static final int REQUEST_IMAGE_CAPTURE = 1;
private String lastImagePath;

//Create temporary image file using getExternalFilesDir()
private File createImageFile() throws IOException{
    String timestamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = "JPEG_" + timestamp + "_";
    File storageDir = getActivity().getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(imageFileName, ".jpg", storageDir);
    lastImagePath = image.getAbsolutePath();
    return image;
}

//Start picture intent and save to file
private void takePicture(){
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    File photoFile = null;
    if(takePictureIntent.resolveActivity(getActivity().getPackageManager())!= null){
        try{
            photoFile = createImageFile();
        }catch (IOException e){
            Log.e(TAG, "Error Creating image file");
            e.printStackTrace();
        }
        if (photoFile !=null){
            Log.e(TAG, photoFile.getAbsolutePath());
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photoFile));
            startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
        }
    }
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data){
    super.onActivityResult(requestCode, resultCode, data);
    if(requestCode == REQUEST_IMAGE_CAPTURE && resultCode == Activity.RESULT_OK){

        //Ensure the path has been set
        if(lastImagePath !=null){
            Log.e(TAG, "LastImagePath: " + lastImagePath);

            //DEBUG:see if it actually created the file
            File file = new File(lastImagePath);
            if(file.exists()){
                Log.e(TAG, "File exists");
            }

            //Decode file
            Bitmap image = BitmapFactory.decodeFile(lastImagePath);

            //DEBUG: see if image is null
            if(image == null){
                Log.e(TAG, "Image is null");
            }else{
                Log.e(TAG, "Image is not null");
            }

            //convert full sized image to thumbnail and add it to imageView
            Bitmap thumbnail = ThumbnailUtils.extractThumbnail(image, 200, 200);
            image1.setImageBitmap(thumbnail);
        }else{
            Log.e(TAG, "lastImagePath is null");
        }
    }
}

Sometimes this code works as expected and takes an image, saves it, loads it back into the program and adds it to the image view. But other times, it doesn't work at all and seems to fail to take the image.

Here is the logcat output for a successful image capture where the image appears in the ImageView

05-04 17:27:49.218 4964-4964/com.noah.stickynotes_clientside E/SUBMIT_FRAGMENT: /storage/emulated/0/Android/data/com.noah.stickynotes_clientside/files/Pictures/JPEG_20160504_172748_-1847663626.jpg
05-04 17:28:03.886 4964-4964/com.noah.stickynotes_clientside E/SUBMIT_FRAGMENT: LastImagePath: /storage/emulated/0/Android/data/com.noah.stickynotes_clientside/files/Pictures/JPEG_20160504_172748_-1847663626.jpg
05-04 17:28:04.359 4964-4964/com.noah.stickynotes_clientside E/SUBMIT_FRAGMENT: File exists
05-04 17:28:04.825 4964-4964/com.noah.stickynotes_clientside E/SUBMIT_FRAGMENT: Image is not null

And here is the logcat output for a failed image capture where there is no image in the ImageView

05-04 17:29:00.070 4964-4964/com.noah.stickynotes_clientside E/SUBMIT_FRAGMENT: /storage/emulated/0/Android/data/com.noah.stickynotes_clientside/files/Pictures/JPEG_20160504_172900_-1359930406.jpg
05-04 17:29:06.581 4964-4964/com.noah.stickynotes_clientside E/SUBMIT_FRAGMENT: LastImagePath: /storage/emulated/0/Android/data/com.noah.stickynotes_clientside/files/Pictures/JPEG_20160504_172900_-1359930406.jpg
05-04 17:29:06.583 4964-4964/com.noah.stickynotes_clientside E/SUBMIT_FRAGMENT: File exists
05-04 17:29:06.583 4964-4964/com.noah.stickynotes_clientside E/SUBMIT_FRAGMENT: Image is null

This seems to work randomly and fails 80% of the time. I'm using getExternalFilesDir because I want the photos to be private to the application. I also added the WRITE_EXTERNAL_STORAGE permission to my Manifest file.

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

I also understand that I could use the thumbnail from the image but I want to have the full sized image because I will be adding it to a class later on.

Anyone have any ideas on whats going wrong?

Answer 1

Your process is being terminated while your app is in the background. This is normal for Android, though you may not be expecting it here. You need to hold onto your EXTRA_OUTPUT in the saved instance state Bundle .

Also note that since file: Uri values are being banned , you should consider switching to using FileProvider .

This sample app demonstrates both of those things. Admittedly, the code is more complicated:

/***
 Copyright (c) 2008-2016 CommonsWare, LLC
 Licensed under the Apache License, Version 2.0 (the "License"); you may not
 use this file except in compliance with the License. You may obtain a copy
 of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required
 by applicable law or agreed to in writing, software distributed under the
 License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
 OF ANY KIND, either express or implied. See the License for the specific
 language governing permissions and limitations under the License.

 From _The Busy Coder's Guide to Android Development_
 https://commonsware.com/Android
 */

package com.commonsware.android.camcon;

import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.provider.MediaStore;
import android.support.v4.content.FileProvider;
import java.io.File;
import java.util.List;

public class CameraContentDemoActivity extends Activity {
  private static final String EXTRA_FILENAME=
    "com.commonsware.android.camcon.EXTRA_FILENAME";
  private static final String FILENAME="CameraContentDemo.jpeg";
  private static final int CONTENT_REQUEST=1337;
  private static final String AUTHORITY=
    BuildConfig.APPLICATION_ID+".provider";
  private static final String PHOTOS="photos";
  private File output=null;
  private Uri outputUri=null;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Intent i=new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

    if (savedInstanceState==null) {
      output=new File(new File(getFilesDir(), PHOTOS), FILENAME);

      if (output.exists()) {
        output.delete();
      }
      else {
        output.getParentFile().mkdirs();
      }
    }
    else {
      output=(File)savedInstanceState.getSerializable(EXTRA_FILENAME);
    }

    outputUri=FileProvider.getUriForFile(this, AUTHORITY, output);

    if (savedInstanceState==null) {
      i.putExtra(MediaStore.EXTRA_OUTPUT, outputUri);

      if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.LOLLIPOP) {
        i.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
      }
      else {
        List<ResolveInfo> resInfoList=
          getPackageManager()
            .queryIntentActivities(i, PackageManager.MATCH_DEFAULT_ONLY);

        for (ResolveInfo resolveInfo : resInfoList) {
          String packageName = resolveInfo.activityInfo.packageName;
          grantUriPermission(packageName, outputUri,
            Intent.FLAG_GRANT_WRITE_URI_PERMISSION |
              Intent.FLAG_GRANT_READ_URI_PERMISSION);
        }
      }

      startActivityForResult(i, CONTENT_REQUEST);
    }
  }

  @Override
  protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);

    outState.putSerializable(EXTRA_FILENAME, output);
  }

  @Override
  protected void onActivityResult(int requestCode, int resultCode,
                                  Intent data) {
    if (requestCode == CONTENT_REQUEST) {
      if (resultCode == RESULT_OK) {
        Intent i=new Intent(Intent.ACTION_VIEW);

        i.setDataAndType(outputUri, "image/jpeg");
        i.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
        startActivity(i);
        finish();
      }
    }
  }
}

With respect to your problem, I am saving my output location in the Bundle in onSaveInstanceState() and using it again in onCreate() if I have a Bundle that is being restored.