试图保存图像时，mediastore.images.media.InsertImage返回null

Question

我使用一个自定义的视图，在我使用画布，用户可以绘制任何东西，之后，我想保存在sd卡的图像，英国电信是不能做到这一点。不知道是怎么回事。

else if(view.getId()==R.id.save_btn){
            //save drawing
            AlertDialog.Builder saveDialog = new AlertDialog.Builder(this);
            saveDialog.setTitle("Save drawing");
            saveDialog.setMessage("Save drawing to device Gallery?");
            saveDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener(){
                private FileOutputStream fOut;

                public void onClick(DialogInterface dialog, int which){
                    //save drawing
                    drawView.setDrawingCacheEnabled(true);

                    //attempt to save
                    String imgSaved = MediaStore.Images.Media.insertImage(
                            getContentResolver(), drawView.getDrawingCache(),
                            UUID.randomUUID().toString()+".png", "drawing");
                    //feedback
                    if(imgSaved!=null){
                        Toast savedToast = Toast.makeText(getApplicationContext(), 
                                "Drawing saved to Gallery!", Toast.LENGTH_SHORT);
                        savedToast.show();
                    }
                    else{
                        Toast unsavedToast = Toast.makeText(getApplicationContext(), 
                                "Oops! Image could not be saved.", Toast.LENGTH_SHORT);
                        unsavedToast.show();
                    }
                    drawView.destroyDrawingCache();
                }
            });
            saveDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener(){
                public void onClick(DialogInterface dialog, int which){
                    dialog.cancel();
                }
            });
            saveDialog.show();
        }

04-14 11:24:28.700: E/MediaStore(6866): Failed to insert image
04-14 11:24:28.700: E/MediaStore(6866): java.io.FileNotFoundException: No such file or directory
04-14 11:24:28.700: E/MediaStore(6866):     at android.database.DatabaseUtils.readExceptionWithFileNotFoundExceptionFromParcel(DatabaseUtils.java:146)
04-14 11:24:28.700: E/MediaStore(6866):     at android.content.ContentProviderProxy.openAssetFile(ContentProviderNative.java:577)
04-14 11:24:28.700: E/MediaStore(6866):     at android.content.ContentResolver.openAssetFileDescriptor(ContentResolver.java:673)
04-14 11:24:28.700: E/MediaStore(6866):     at android.content.ContentResolver.openOutputStream(ContentResolver.java:537)
04-14 11:24:28.700: E/MediaStore(6866):     at android.content.ContentResolver.openOutputStream(ContentResolver.java:513)
04-14 11:24:28.700: E/MediaStore(6866):     at android.provider.MediaStore$Images$Media.insertImage(MediaStore.java:891)
04-14 11:24:28.700: E/MediaStore(6866):     at com.example.clent.MainActivity$9.onClick(MainActivity.java:238)
04-14 11:24:28.700: E/MediaStore(6866):     at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
04-14 11:24:28.700: E/MediaStore(6866):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-14 11:24:28.700: E/MediaStore(6866):     at android.os.Looper.loop(Looper.java:137)
04-14 11:24:28.700: E/MediaStore(6866):     at android.app.ActivityThread.main(ActivityThread.java:5103)
04-14 11:24:28.700: E/MediaStore(6866):     at java.lang.reflect.Method.invokeNative(Native Method)
04-14 11:24:28.700: E/MediaStore(6866):     at java.lang.reflect.Method.invoke(Method.java:525)
04-14 11:24:28.700: E/MediaStore(6866):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
04-14 11:24:28.700: E/MediaStore(6866):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
04-14 11:24:28.700: E/MediaStore(6866):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

我在模拟器(Android4.4)中遇到了这个问题，结果发现这是由于Android的一个bug，当用户以前没有在设备上拍摄照片时（即gallery是空的，并且没有初始化）。解决办法是手动初始化照片目录：

void fixMediaDir() {
    File sdcard = Environment.getExternalStorageDirectory();
    if (sdcard != null) {
        File mediaDir = new File(sdcard, "DCIM/Camera");
        if (!mediaDir.exists()) {
            mediaDir.mkdirs();
        }
    }
}

不确定这是否在Android的后续版本中得到修复。