Android 如何将图像从Gallery显示到ImageView？

我想在imageview中显示从图库中拍摄的图像。但这并没有发生。我不明白为什么。我可以很好地使用照相机功能，在照相机的imageview中看到图像，但不能看到从画廊中拍摄的图像。你们能帮帮我吗

这是我的密码

protected Button mFromCamera;
protected Button mFromGallery;
protected ImageView mImageView;

private static final int CAMERA_REQUEST = 1888;
private static final int SELECT_PHOTO = 100;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    //Initialize ImageView
    mImageView = (ImageView) findViewById(R.id.ImgPrev);
    //Initialize Camera
    mFromCamera = (Button) findViewById(R.id.FromCamera);

    //use camera
    mFromCamera.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
            startActivityForResult(cameraIntent, CAMERA_REQUEST);
        } //use camera end

    });

    //initialize button
    mFromGallery = (Button) findViewById(R.id.FromGallery);

    //pick a photo
    mFromGallery.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {
            Intent photoPickerIntent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
            photoPickerIntent.setType("image/*");
            startActivityForResult(photoPickerIntent, SELECT_PHOTO);
        }
    });//pick a photo end
}



//previewing Image
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    switch (requestCode) {
        //from the gallery
        case SELECT_PHOTO:
            if (requestCode == SELECT_PHOTO && resultCode == RESULT_OK && null!= 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 picturePath = cursor.getString(columnIndex);
                cursor.close();

                mImageView.setImageBitmap(BitmapFactory.decodeFile(picturePath));
            }
            break;
        //from the camera
        case CAMERA_REQUEST:
            if (requestCode == CAMERA_REQUEST && resultCode == RESULT_OK) {
                Bitmap photo = (Bitmap) data.getExtras().get("data");
                mImageView.setImageBitmap(photo);
            }
            break;
    }
}//Preview Image End

---

唯一的问题是，从库中选择的图像不会显示在ImageView中。我试着像对待“相机请求”一样对待“选择照片”的案例。它也不起作用。

可能

BitmapFactory.decodeFile（picturePath）

返回空值。检查一下。并检查是否在AndroidManifest.xml中添加了权限：

android.permission.WRITE_EXTERNAL_STORAGE
android.permission.READ_EXTERNAL_STORAGE

文档中的BitmapFactory.decodeFile（字符串文件路径）：

返回： 生成的解码位图，如果路径为空或无法解码，则为null