如何将捕获的图像文件保存到 data/data/<package.name>/cache ？

Question

我需要保护我正在拍摄的图像。来自安卓Android Training 我能够拍摄全尺寸图像。但这不是我的需要。 我需要将全尺寸图像保存到缓存目录（/data/data//cache），当用户离开我的应用程序时，我将删除这些缓存文件夹。

这是我的代码，该文件在缓存目录中成功创建。但文件大小为零，没有写入图像

static final int REQUEST_TAKE_PHOTO = 1;

private void dispatchTakePictureIntent() {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    // Ensure that there's a camera activity to handle the intent
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
        File file=null;
        try {
            String fileName = "506214";
            file = File.createTempFile(fileName, null, this.getCacheDir());
        } catch (IOException e) {
            // Error while creating file
        }
        photoURI = Uri.fromFile(file);
        Toast.makeText(this, photoURI.toString(), Toast.LENGTH_SHORT).show();
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT,photoURI);
            startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if(requestCode == REQUEST_TAKE_PHOTO && resultCode == RESULT_OK){
        camera_image.setImageURI(photoURI);
    }
    super.onActivityResult(requestCode, resultCode, data);
}

Answer 1

我的朋友试试这个

File imagesFolder = new File(Environment.getExternalStorageDirectory(), "MyImages");
    imagesFolder.mkdirs(); // <----
    File image = new File(imagesFolder, "image_001.jpg");
    Uri uriSavedImage = Uri.fromFile(image);
    imageIntent.putExtra(MediaStore.EXTRA_OUTPUT, uriSavedImage);

别忘了在清单文件中添加权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Answer 2

如果您在Activity 类中，请使用this.getCacheDir() 作为File 的第一个参数和第二个参数作为您的文件名以存储在缓存目录中。

   File f = new File(this.getCacheDir(), "capture_"+ imageNumber++);
   try {
      f.createNewFile();
   } catch (IOException e) {
      e.printStackTrace();
   }

以下是我在上传到 S3 之前捕获并保存在缓存中的方法（此代码在 onActivityResult() 中）：

    if (requestCode == CAMERA_REQUEST && resultCode == Activity.RESULT_OK) {
        Bitmap photo = (Bitmap) data.getExtras().get("data");
        //create a file to write bitmap data
        File f = new File(this.getCacheDir(), "capture_"+ imageNumber++);
        try {
            f.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }

        //Convert bitmap to byte array
        Bitmap bitmap = photo;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG, 0 /*ignored for PNG*/, bos);
        byte[] bitmapdata = bos.toByteArray();

        //write the bytes in file
        FileOutputStream fos;
        try {
            fos = new FileOutputStream(f);
            fos.write(bitmapdata);
            fos.flush();
            fos.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }