使用getExternalFilesDir保存Android不一致的图片
在我的应用程序中，我正在尝试拍照，保存它，然后使用Android开发人员教程中提供的代码将其添加到ImageView
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"); } } } 有时，此代码按预期工作并拍摄图像，保存图像，将其加载回程序并将其添加到图像视图中。 但其他时候，它根本不起作用，似乎无法拍摄图像。
以下是成功捕获图像的logcat输出，其中图像显示在ImageView中
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
这里是失败的图像捕获的logcat输出，其中ImageView中没有图像
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
这似乎随机工作，80％的时间都失败了。 我正在使用getExternalFilesDir，因为我希望照片对应用程序是私有的。 我还为我的Manifest文件添加了WRITE_EXTERNAL_STORAGE权限。
我也明白我可以使用图像中的缩略图，但我希望拥有完整大小的图像，因为我稍后会将它添加到一个类中。
任何人都有任何关于什么出错的想法？
当您的应用在后台时，您的流程正在终止。 对于Android来说这是正常的，尽管你可能不会在这里期待它。 您需要在保存的实例状态Bundle保留EXTRA_OUTPUT 。
另请注意， 由于file: Uri值被禁止 ，您应该考虑切换到使用FileProvider 。
此示例应用程序演示了这两个方面。 不可否认，代码更复杂：
/*** 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 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(); } } } }
关于你的问题，我将输出位置保存在onSaveInstanceState()中的Bundle中，并在onCreate()再次使用它，如果我有一个正在恢复的Bundle 。