java - 保存图像时找不到文件

Question

我正在尝试在 Android 应用程序中保存相机拍摄的照片。我使用 AsyncTask 类来完成这项工作，但是在 onBackground 函数中抛出异常 - FileNotFoundException。即使我对 list 中的外部存储具有读取和写入权限，也会发生这种情况。

private class SaveImageTask extends AsyncTask<byte[], Void, String> {

    @Override
    protected String doInBackground(byte[]... data) {
        FileOutputStream outStream = null;
        String url = "example";
        try {       
            System.out.println("x");
            File dir = new File (Environment.getExternalStorageDirectory() + "/camtest/");
            System.out.println(dir);
            if(!dir.exists()) dir.mkdir();              
            Locale locale = new Locale("en");
            String fileName = String.format(locale, "%d.jpg", System.currentTimeMillis());          
            File outFile = new File(dir, fileName);
            System.out.println(outFile.getAbsolutePath());
            outStream = new FileOutputStream(outFile);              
            outStream.write(data[0]);
            outStream.flush();
            outStream.close();          
            System.out.println("x");
            refreshGallery(outFile);        
            Toast.makeText(getApplicationContext(), "try", Toast.LENGTH_LONG).show();
            url = outFile.getAbsolutePath();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
            System.out.println("File not found");
        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("IO exception");
        } finally {
        }
        return url;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        locationToSave.setPhotoURL(result);
        Toast.makeText(getApplicationContext(), result, Toast.LENGTH_LONG).show();

    }
}

我的输出日志如下:

01-02 16:53:12.692: I/System.out(16460): x
01-02 16:53:12.692: I/System.out(16460): /mnt/sdcard/camtest
01-02 16:53:12.692: I/System.out(16460): /mnt/sdcard/camtest/1420213992701.jpg
01-02 16:53:12.722: I/System.out(16460): File not found

很明显，当尝试写入文件时，它会跳转到 catch block 。在我看来，这条路看起来也不错。

有什么想法吗？

编辑:堆栈跟踪

01-02 17:18:48.300: W/System.err(18516): java.io.FileNotFoundException:     /mnt/sdcard/camtest/1420215528309.jpg: open failed: EACCES (Permission denied)
01-02 17:18:48.300: W/System.err(18516):    at libcore.io.IoBridge.open(IoBridge.java:406)
01-02 17:18:48.300: W/System.err(18516):    at java.io.FileOutputStream.<init>(FileOutputStream.java:88)
01-02 17:18:48.300: W/System.err(18516):    at java.io.FileOutputStream.<init>(FileOutputStream.java:73)
01-02 17:18:48.300: W/System.err(18516):    at     michal.myapp.activities.CameraActivity$SaveImageTask.doInBackground(CameraActivity.java:244)
01-02 17:18:48.300: W/System.err(18516):    at michal.myapp.activities.CameraActivity$SaveImageTask.doInBackground(CameraActivity.java:1)
01-02 17:18:48.300: W/System.err(18516):    at android.os.AsyncTask$2.call(AsyncTask.java:264)
01-02 17:18:48.300: W/System.err(18516):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
01-02 17:18:48.300: W/System.err(18516):    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
01-02 17:18:48.300: W/System.err(18516):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
01-02 17:18:48.300: W/System.err(18516):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
01-02 17:18:48.300: W/System.err(18516):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
01-02 17:18:48.300: W/System.err(18516):    at java.lang.Thread.run(Thread.java:864)
01-02 17:18:48.300: W/System.err(18516): Caused by: libcore.io.ErrnoException: open failed: EACCES (Permission denied)
01-02 17:18:48.310: W/System.err(18516):    at libcore.io.Posix.open(Native Method)
01-02 17:18:48.310: W/System.err(18516):    at libcore.io.BlockGuardOs.open(BlockGuardOs.java:110)
01-02 17:18:48.310: W/System.err(18516):    at libcore.io.IoBridge.open(IoBridge.java:390)
01-02 17:18:48.310: W/System.err(18516):    ... 11 more

Answer 1

权限:

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

应在 Android Manifest 中的应用程序标记之外声明。就像这个线程一样:

Exception 'open failed: EACCES (Permission denied)' on Android