Android 位图空对象引用

Question

这是我的例外：

   E/UploadBill: Error writing bitmap
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.graphics.Bitmap.compress(android.graphics.Bitmap$CompressFormat, int, java.io.OutputStream)' on a null object reference
    at kmsg.com.onetouch.activity.UploadDocumentActivity$UploadBill.doInBackground(UploadDocumentActivity.java:299)
    at kmsg.com.onetouch.activity.UploadDocumentActivity$UploadBill.doInBackground(UploadDocumentActivity.java:279)

这是我的代码：

  File imageFile;
  Bitmap photo;

这是我点击的按钮：

    public void getFile(View view) {
    if (ContextCompat.checkSelfPermission(UploadDocumentActivity.this, Manifest.permission.CAMERA)
            != PackageManager.PERMISSION_GRANTED){

        ActivityCompat.requestPermissions(UploadDocumentActivity.this,new String[]{Manifest.permission.CAMERA},
                MY_CAMERA_PERMISSION_CODE);
    } else {
        Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        File pictureDirectory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
        String pictureNm = getPictureName();
        imageFile = new File(pictureDirectory , pictureNm);
        Uri pictureUri = Uri.fromFile(imageFile);
        System.out.println("URI"+pictureUri);
        cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT,pictureUri);
        cameraIntent.putExtra(MediaStore.EXTRA_VIDEO_QUALITY,1);
        startActivityForResult(cameraIntent, CAMERA_REQUEST);

    }
}

这是 onActivityResult:

  @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    //super.onActivityResult(requestCode, resultCode, data);
    Bitmap myBitmap = BitmapFactory.decodeFile(imageFile.getAbsolutePath());
    mImgDocument.setImageBitmap(myBitmap);
}

我尝试压缩位图时出现错误：

   try {
            os = new FileOutputStream(imageFile.getAbsolutePath());
            photo.compress(Bitmap.CompressFormat.JPEG, 100, os);
            os.flush();
            os.close();

            } catch (Exception e) {
            Log.e(getClass().getSimpleName(), "Error writing bitmap", e);
            }
            partList.add(new FilePart("file", imageFile));
        } catch (FileNotFoundException e) {
        e.printStackTrace();
        }

我正在尝试像这样将图像发送到服务器，但我找不到我的代码出了什么问题。我想发送这个图像文件，但是当我看到我的日志时，它显示如下内容：

  I/System.out: partList:[file]

我想以正确的方式发送图片 only.Is Bitmap.compress 出了什么问题？？

Answer 1

在 onActivityResult() 中使用该文件而不是 'myBitmap' 存储到 'photo' 变量中。此处该文件可能存在也可能不存在，所以在抓图成功完成后执行此操作。

if (requestCode==CAMERA_REQUEST && resultCode==RESULT_OK){
     //load bitmap
}

Answer 2

您的 photo 变量未初始化。您需要在使用该变量之前对其进行初始化。

替换

Bitmap myBitmap = BitmapFactory.decodeFile(imageFile.getAbsolutePath()); // You never use myBitmap after creating and initializing it...
mImgDocument.setImageBitmap(myBitmap);

和

if (requestCode==CAMERA_REQUEST && resultCode==RESULT_OK){ // <- this ensures the user didn't cancel the Camera Intent
    photo= BitmapFactory.decodeFile(imageFile.getAbsolutePath()); // <- this initializes the variable so you can use it later.
    mImgDocument.setImageBitmap(photo);
}

Android 位图空对象引用

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