Question

我正在尝试通过Android模拟器捕获并保存图像，正在捕获图像，但正在保存的文件已损坏。

可能导致这种情况的原因是什么？任何人都可以帮我识别可能的错误点吗？

以下是我的代码：

**public void onCreate**(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    **Intent** intent = new **Intent**("android.media.action.IMAGE_CAPTURE");
    try {
        fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE);
    } 

    catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    intent.putExtra(**MediaStore**.EXTRA_OUTPUT, fileUri);
    startActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);
}

@Override
**protected void onActivityResult**(int requestCode, int resultCode, Intent data) {
    if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
        if (resultCode == RESULT_OK) {
            StoreImage(this, data.getData(),
            mediaFile);
            finish();
        } 

        else if (resultCode == RESULT_CANCELED) {
            // User cancelled the image capture
        } 

        else {
            finish();
            try {
            } 

            catch (Exception e) {
               e.printStackTrace();
            }
        }
    }

}

堆栈跟踪低于::

04-05 23:55:40.369: E/AndroidRuntime(534): FATAL EXCEPTION: main
04-05 23:55:40.369: E/AndroidRuntime(534): java.lang.RuntimeException: Unable to start activity ComponentInfo{camera.android/camera.android.CameraActivity}: java.lang.NullPointerException: file
04-05 23:55:40.369: E/AndroidRuntime(534):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)

04-05 23:55:40.369: E/AndroidRuntime(534): Caused by: java.lang.NullPointerException: file
04-05 23:55:40.369: E/AndroidRuntime(534):  at android.net.Uri.fromFile(Uri.java:441)
04-05 23:55:40.369: E/AndroidRuntime(534):  at camera.android.CameraActivity.getOutputMediaFileUri(CameraActivity.java:72)
04-05 23:55:40.369: E/AndroidRuntime(534):  at camera.android.CameraActivity.onCreate(CameraActivity.java:34)
04-05 23:55:40.369: E/AndroidRuntime(534):  at android.app.Activity.performCreate(Activity.java:4465)
04-05 23:55:40.369: E/AndroidRuntime(534):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
04-05 23:55:40.369: E/AndroidRuntime(534):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)

Answer 1

交换这一行，

if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
                if (resultCode == RESULT_OK) {

到

 if (resultCode == RESULT_OK) {
                    if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {

首先检查子活动是否成功完成其工作。

Answer 2

检查您是否在清单文件::

中添加了以下权限

<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.CAMERA" />

也在

fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE);

我认为你必须附上你想要保存的文件名，只给出路径是不够的....

Answer 3

“@ Agarwal：关于调用onActivityResult”

@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
            if (resultCode == RESULT_OK) {
                StoreImage(this, data.getData(), mediaFile);
                finish();

            } else if (resultCode == RESULT_CANCELED) {
                // User cancelled the image capture
            } else {
                finish();
                try {

                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

        }

    }

“如果结果成功，则来自实习生的数据存储在n文件中，该文件被创建并保存为jpeg格式”

public static void StoreImage(Context mContext, Uri imageLoc, File imageDir) {
        Bitmap bm = null;
        try {
            bm = Media.getBitmap(mContext.getContentResolver(), imageLoc);
            FileOutputStream out = new FileOutputStream(imageDir);
            bm.compress(Bitmap.CompressFormat.JPEG, 100, out);
            bm.recycle();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

Answer 4

尝试以下代码，

Intent i = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);

    File file=getOutputMediaFile(1);
    picUri = Uri.fromFile(file); // create
    i.putExtra(MediaStore.EXTRA_OUTPUT,picUri); // set the image file

    startActivityForResult(i, CAPTURE_IMAGE);

getOutputMediaFile（int）将在哪里，

/** Create a File for saving an image */
private  File getOutputMediaFile(int type){
    File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
              Environment.DIRECTORY_PICTURES), "MyApplication");

    /**Create the storage directory if it does not exist*/
    if (! mediaStorageDir.exists()){
        if (! mediaStorageDir.mkdirs()){
            return null;
        }
    }

    /**Create a media file name*/
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    File mediaFile;
    if (type == 1){
        mediaFile = new File(mediaStorageDir.getPath() + File.separator +
        "IMG_"+ timeStamp + ".png");
    } else {
        return null;
    }

    return mediaFile;
}

最后，

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (resultCode == Activity.RESULT_OK) {
        Intent i;
        switch (requestCode) {
        case CAPTURE_IMAGE:
            //THIS IS YOUR Uri
            Uri uri=picUri; 
            break;
        }
    }   
}

欢呼....：）

使用android模拟器捕获并保存图像时获取Null指针异常

4 个答案: