相机拍摄的图像是否打算用于其他活动？

Question

这是在StackOverflow上看到的非常普遍的问题，我已经尝试了几乎所有的SO解决方案。 我仍然在onAtivityResult- data得到了一个NullPointerExeption 。

我努力了：

• http://developer.android.com/training/camera/photobasics.html

• http://developer.android.com/guide/topics/media/camera.html

• 从相机捕获图像并在活动中显示

• 如何将捕获的/画廊图像传递给android中的下一个活动

• http://hmkcode.com/android-camera-taking-photos-camera/

• 相机返回的onActivityResult，意图为null

• android camera：onActivityResult（）意图为null，如果它具有其他功能

下面是我第四次尝试的最后一个代码：

在按钮上单击：

Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
                File file=getOutputMediaFile(1);
                picUri = Uri.fromFile(file); // create
                cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, picUri); // set the image file
                    startActivityForResult(cameraIntent, REQUEST_TAKE_PHOTO);

getOutputMediaFile（）

 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;
            }

        }
        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;
    }

onActivityResult（）

 protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
        super.onActivityResult(requestCode, resultCode, intent);
        if (resultCode == RESULT_OK && requestCode == REQUEST_TAKE_PHOTO && intent != null){


            Uri selectedImage = intent.getData();
            String[] filePathColumn = {MediaStore.Images.Media.DATA};

            Cursor cursor = getContentResolver().query(selectedImage, filePathColumn, null, null, null);
            cursor.moveToFirst();

            int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
            //file path of captured image
            imagepath = cursor.getString(columnIndex);
            //file path of captured image
            File f = new File(imagepath);
            String filename = f.getName();
            cursor.close();
            Bitmap imageData = BitmapFactory.decodeFile(filename);
//            Bitmap imageData = (Bitmap) data.getExtras().get("data");

            Intent i = new Intent(this, EditImageActivity.class);
            i.putExtra("path", imageData );
            startActivity(i);
        }
    }
}

请提出一些我上面已经提到的链接中未提及的更好的方法，因为这对我不起作用。

我使用的是带有API 10+的 Android Atudio。

崩溃日志：

10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime: FATAL EXCEPTION: main
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime: Process: com.example.dell.drawdemo, PID: 25060
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=null} to activity {com.example.dell.drawdemo/com.example.dell.drawdemo.MainActivity}: java.lang.NullPointerException
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.ActivityThread.deliverResults(ActivityThread.java:3593)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.ActivityThread.handleSendResult(ActivityThread.java:3636)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.ActivityThread.access$1300(ActivityThread.java:151)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1390)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:110)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:193)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5334)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:515)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:676)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:  Caused by: java.lang.NullPointerException
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at com.example.dell.drawdemo.MainActivity.onActivityResult(MainActivity.java:131)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.Activity.dispatchActivityResult(Activity.java:5546)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.ActivityThread.deliverResults(ActivityThread.java:3589)
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.ActivityThread.handleSendResult(ActivityThread.java:3636) 
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.ActivityThread.access$1300(ActivityThread.java:151) 
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1390) 
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:110) 
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:193) 
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5334) 
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method) 
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:515) 
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:676) 
10-12 17:48:49.934 25060-25060/com.example.dell.drawdemo E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method) 

Answer 1

您好，请尝试以下代码，希望对您有所帮助，

private final int CAMERA_CAPTURE_IMAGE_REQUEST_CODE = 100;
private final int MEDIA_TYPE_IMAGE = 1;

捕获图像的意图代码

Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
m_fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE);
intent.putExtra(MediaStore.EXTRA_OUTPUT, m_fileUri);
startActivityForResult(intent, CAMERA_CAPTURE_IMAGE_REQUEST_CODE);


public Uri getOutputMediaFileUri(int p_type)
{
    return Uri.fromFile(getOutputMediaFile(p_type));
}


private File getOutputMediaFile(int p_type)
{
    File m_mediaFile;
    if (p_type == MEDIA_TYPE_IMAGE)
    {

            m_buffer = new StringBuffer();

            m_buffer.append(Environment.getExternalStorageDirectory().getPath() + File.separator).append("Image");
            File m_imageStorageFile = new File(m_buffer.toString());

            // Create the storage directory if it does not exist
            if (!m_imageStorageFile.exists())
            {
                if (!m_imageStorageFile.mkdirs())
                {
                    return null;
                }
            }
            // Create a media file name
            String m_timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(new java.util.Date());
            m_buffer = new StringBuffer();
            m_buffer.append(m_imageStorageFile.getPath()).append(File.separator).append("IMG_").append(m_timeStamp).append(".jpg");
            m_mediaFile = new File(m_buffer.toString());

    }
    else
    {
        return null;
    }

    return m_mediaFile;
}

在onActivityResult中编写以下代码

protected void onActivityResult(int p_requestCode, int p_resultCode, Intent p_data)
{
        super.onActivityResult(p_requestCode, p_resultCode, p_data);
        if (p_resultCode == RESULT_OK)
        {
            switch (p_requestCode)
            {
                case CAMERA_CAPTURE_IMAGE_REQUEST_CODE:
                    m_selectedPath = m_fileUri.getPath();
                break;

            }
        }
}

Constant.MEDIA_DIRECTORY_PATH包含您的目录路径示例：-mnt / sdcard0 / android / com.example

Answer 2

之所以得到NullPointerException是因为当用户转到摄像机意图时，并且当他捕获图像时，当用户从摄像机意图返回时，托管摄像机意图的活动将被破坏或重新创建。 picUri（通过摄像机意图创建的图像的路径）返回的picUri返回null因为当前没有此类对象存储在内存中。

这样保存图像的路径：

@Override
protected void onSaveInstanceState(Bundle savedInstanceState) {

    if(mImageCaptureUri!=null)
        savedInstanceState.putString("camera_image", picUri.toString());

    super.onSaveInstanceState(savedInstanceState);
}

然后从中检索图像路径：

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {

    if (savedInstanceState != null) {
        if (savedInstanceState.containsKey("camera_image")) {
            picUri = Uri.parse(savedInstanceState.getString("camera_image"));
        }
    }

    super.onRestoreInstanceState(savedInstanceState);
}

参考已回答的问题 。