android：从意图中获取“ null”

Question

• 我正在开发一个应用程序，在该应用程序中我想从相机捕获图像并将其显示在图像视图中的另一个活动中，我的问题是在OnActivityResult中，数据中的数据为“空” ...我不知道为什么

这是我的代码PictureOptions.java

public void buttonCameraOpen(View view)
{
    // create Intent to take a picture and return control to the calling application
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

    fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE); // create a file to save the image
    intent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri); // set the image file name

    // start the image capture Intent
    startActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);
}

private static Uri getOutputMediaFileUri(int type){
      return Uri.fromFile(getOutputMediaFile(type));
}

/** Create a File for saving an image or video */
private static File getOutputMediaFile(int type){
    // To be safe, you should check that the SDCard is mounted
    // using Environment.getExternalStorageState() before doing this.

    File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
              Environment.DIRECTORY_PICTURES), "Easy Heal");
    // This location works best if you want the created images to be shared
    // between applications and persist after your app has been uninstalled.

    // Create the storage directory if it does not exist
    if (! mediaStorageDir.exists()){
        if (! mediaStorageDir.mkdirs()){
            Log.d("MyCameraApp", "failed to create directory");
            return null;
        }
    }

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

    return mediaFile;
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
     Bitmap selectedphoto   = null;

     super.onActivityResult(requestCode, resultCode, data);

     if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE  && resultCode == RESULT_OK && null!=data) {

            // Image captured and saved to fileUri specified in the Intent
            //selectedphoto = (Bitmap) data.getExtras().get("data");
            Uri selectedImage = data.getData();
             String [] filePathColumn = {MediaStore.Images.Media.DATA};
             Cursor cursor = getContentResolver().query(selectedImage, filePathColumn, null, null, null);
             cursor.moveToFirst();   
             int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
             String filePath = cursor.getString(columnIndex);
             File f =new File(filePath);
             String filename = f.getName();
             cursor.close();
             selectedphoto = BitmapFactory.decodeFile(filePath);

             Intent intent = new Intent(PictureOptions.this,ShowImage.class);
             //intent.putExtra("data", selectedphoto);
             intent.setData( selectedImage );
             startActivity(intent);
        } else if (resultCode == RESULT_CANCELED) {
            // User cancelled the image capture
        } else {
            // Image capture failed, advise user
       }

}

PictureOptions.xml

<Button
    android:id="@+id/buttonCameraOpen"
    android:layout_width="fill_parent"
    android:layout_height="72dp"
    android:layout_weight="0.35"
    android:onClick="buttonCameraOpen"
    android:text="@string/button_camera_open" />

ShowImage.java

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_show_image);
    ImageView imageview = (ImageView)findViewById(R.id.ImageShow);
    Uri imageUri = getIntent().getData();
    //Bitmap selectedphoto  =(Bitmap)this.getIntent().getParcelableExtra("data");
    imageview.setImageURI(imageUri);
}

ShowImage.xml

 <ImageView
    android:id="@+id/ImageShow"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" />

Answer 1

发生这种情况的原因是您忘记添加“写入外部存储”权限，或者您尝试保存图像的文件夹不存在，请首先创建文件夹。

请添加android.permission.WRITE_EXTERNAL_STORAGE

尝试保存其他位置

File mediaStorageDir = new File(Environment.getExternalStorageDirectory()+"/"+"Easy Heal");

Answer 2

如果未添加，请在您的活动中也使用此代码

@Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        // TODO Auto-generated method stub

        fileUri = savedInstanceState.getParcelable("file_uri");

        super.onRestoreInstanceState(savedInstanceState);
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        // TODO Auto-generated method stub

        outState.putParcelable("file_uri", fileUri);
        super.onSaveInstanceState(outState);
    }

Answer 3

通过捕获图像，您无需将此图像存储在文件中。 您可以使用以下方法直接获取位图。 这只是您在做一些额外的工作。

//Global variable
private static final int TAKE_IMAGE = 2;


//OnClick of your button or whereever you want to start camera
   @Override
        public void onClick(View v) {


            Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);  
            startActivityForResult(cameraIntent, TAKE_IMAGE); 
       }

//onActivityREsul portion of your code

@Override protected void onActivityResult（int requestCode，int resultCode，Intent data）{

    if(requestCode == TAKE_IMAGE ){
        try {

                bitmap = (Bitmap) data.getExtras().get("data");
           // bitmap = MediaStore.Images.Media.getBitmap( getApplicationContext().getContentResolver(),  capturedImageUri);


            YourImageViewObject.setImageBitmap(bitmap);
            } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            } 


    }


    super.onActivityResult(requestCode, resultCode, data);
}