(安卓)相机捕获未保存，无法加载图像的位图

Question

我正在尝试编写启动相机应用程序、保存图像，然后显示捕获图像的位图的代码。

这是相关代码，改编自 https://guides.codepath.com/android/Accessing-the-Camera-and-Stored-Media：

public static final int PICTURE_REQUEST_CODE = 1034;
public static final String FILE_BEGIN = "note";
private int note_id = 4;
public static final String FILE_END = ".jpg";
private static final String APP_TAG = "School_App";
private void takePicture() {
Intent i = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
i.putExtra(MediaStore.EXTRA_OUTPUT, getPhotoFileUri(FILE_BEGIN + note_id + FILE_END));
if (i.resolveActivity(getPackageManager()) != null){
startActivityForResult(i, PICTURE_REQUEST_CODE);
}
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == PICTURE_REQUEST_CODE) {
if (resultCode == RESULT_OK) {
Uri takenPhotoUri = getPhotoFileUri(FILE_BEGIN + note_id + FILE_END);
Log.d("NotesDetail", takenPhotoUri.toString());
// by this point we have the camera photo on disk
Bitmap takenImage = BitmapFactory.decodeFile(takenPhotoUri.getPath());
// RESIZE BITMAP, see section below
// Load the taken image into a preview
ImageView ivPreview = (ImageView) findViewById(R.id.iv_notes_picture);
ivPreview.setImageBitmap(takenImage);
} else { // Result was a failure
Toast.makeText(this, "Picture wasn't taken!", Toast.LENGTH_SHORT).show();
}
}
}
private Uri getPhotoFileUri(String fileName) {
if(isSpaceAvailable()){
File mediaStorageDir = new File(getExternalFilesDir(Environment.DIRECTORY_PICTURES), APP_TAG);
if (!mediaStorageDir.exists() && !mediaStorageDir.mkdirs()){
Log.d(APP_TAG, "Failed to make directory");
}
File file = new File(mediaStorageDir.getPath() + File.separator + fileName);
Uri uri = FileProvider.getUriForFile(NotesDetail.this, "com.kfode.schoolapp.fileprovider", file);
Log.d("getPhotoFileUri", uri.toString());
return uri;
}
return null;
}
private boolean isSpaceAvailable() {
String state = Environment.getExternalStorageState();
return state.equals(Environment.MEDIA_MOUNTED);
}

我还设置了以下权限：

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

在清单的应用程序标记中...

<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="com.kfode.schoolapp.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/file_paths"
/>
</provider>

在file_paths.xml之内

<paths xmlns:android="http://schemas.android.com/apk/res/android">
<external-files-path name="images"
path="Pictures"/>

当我运行该应用程序时，我收到以下日志消息和异常：

D/getPhotoFileUri: content://com.kfode.schoolapp.fileprovider/images/School_App/note4.jpg
D/NotesDetail: content://com.kfode.schoolapp.fileprovider/images/School_App/note4.jpg
E/BitmapFactory: Unable to decode stream: java.io.FileNotFoundException: /images/School_App/note4.jpg: open failed: ENOENT (No such file or directory)

不知道这里发生了什么。请帮忙？

Answer 1

Bitmap takenImage = BitmapFactory.decodeFile(takenPhotoUri.getPath());

这是行不通的。Uri不是File.

将getPhotoFileUri()重构为两种方法：

• 产生FilegetPhotoFile()
• 获得该FileFileProviderUri的getPhotoFileUri()

然后，使用图像加载库(Glide、Picasso 等(从getPhotoFile()返回的文件中填充ImageView。这不仅会为你处理所有BitmapFactory的东西，而且还会在后台线程上完成这项工作，所以你不会像在当前代码中那样冻结你的 UI。