android - 如何从另一个 Activity 访问文件

Question

我尝试从相机拍摄照片，然后我尝试访问在我创建的 fileProvider() 方法的帮助下在另一个 Activity 中创建的这些两个文件已经写在下面，但对我不好的是，它总是在接收点显示我为空。有人可以帮助我如何访问在这里创建的不同 Activity 中的文件吗？

  public class FileGenerator extends Activity {
        File image1,image2,image3,image4;
        private String imagePath1,imagePath2,imagePath3,imagePath4;

        ....................
       .........................

    public void cameraShot() // This method would be called when the user clicks on a button on my activity to make a request of taking pic.
        {

                ContentValues values = new ContentValues();
                Intent intentPicture = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

                //startActivityForResult(intentPicture,ACTION_TAKE_PICTURE);

                Intent intent=new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);

                if(flipvalue == 0)
                {
                    intentPicture.putExtra(MediaStore.EXTRA_OUTPUT, firstCapturedImageURI);
                    values.put(MediaStore.Images.Media.TITLE, "testingimage1.jpg");
                    firstCapturedImageURI = getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);
                    startActivityForResult(intentPicture,CAMERA_DATA_FIRST);
                }

                if(flipvalue == 1)
                {
                    intentPicture.putExtra(MediaStore.EXTRA_OUTPUT, secondCapturedImageURI);
                    values.put(MediaStore.Images.Media.TITLE, "testingimage2.jpg");
                    secondCapturedImageURI = getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);
                    startActivityForResult(intentPicture,CAMERA_DATA_SECOND);


                }
    }

    protected void onActivityResult(int requestCode, int resultCode,Intent data)
        {
            super.onActivityResult(requestCode, resultCode, data);

            if(resultCode==RESULT_OK)
            {
                Bundle extras= data.getExtras();

                if(requestCode == 0)
                {
                    if(bitMap1 != null)
                    bitMap1.recycle();
                    bitMap1 = (Bitmap)extras.get("data");
                    imageView1.setImageBitmap(bitMap1);

                    selectedImagePath1 = getRealPathFromURI(firstCapturedImageURI);

                    imagePath1 = selectedImagePath1;
                    Log.d("Pic Path>>>", selectedImagePath1);

                    image1 = new File(selectedImagePath1);

                    flipvalue =1;

                }
                           if (requestCode == 1)
                {
                    if(bitMap2 != null)
                    bitMap2.recycle();
                    bitMap2 = (Bitmap)extras.get("data");
                    imageView2.setImageBitmap(bitMap2);

                    selectedImagePath2 = getRealPathFromURI(secondCapturedImageURI);

                    imagePath2 = selectedImagePath2;
                    Log.d("Pic Path>>>", selectedImagePath2);
                    image2 = new File(selectedImagePath2);

                    flipvalue =2;

                }
    }

protected File fileProvider(int i)
    {
        if(i==1)
        return image1;
        else
        return image2;


    }

public String getRealPathFromURI(Uri contentUri)
    {
        try
        {
            String[] proj = {MediaStore.Images.Media.DATA};
            Cursor cursor = getContentResolver().query(contentUri, proj, null, null, null);
            int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
            cursor.moveToFirst();
            return cursor.getString(column_index);
        }
        catch (Exception e)
        {
            return contentUri.getPath();
        }
    }
}

以下是我尝试接收这些文件的 Activity 。

public class FileReceiver extends Activity{
File receivedimage1, receivedimage2;
FileGenerator filegen = new FileGenerator();
               ..........................
                   ............................

           receivedimage1 = filegen.fileProvider(1);
            Log.d("File 1 ","file1 object"+receivedimage1);// always shows null

            receivedimage2 = filegen.fileProvider(2);
             Log.d("File 2 ","file2 object"+receivedimage2);// shows null

}

P.S. -- 在尝试此操作之前，我曾经将字符串(即 selectedImagePath1、selectedImagePath2)带到另一个 Activity 中，然后使用这些字符串创建文件。但不知道为什么这会以某种方式破坏我创建的图像文件。所以，我按照上面的代码方式，仍然没有运气。

Answer 1

您将需要使用 Intent 将文件路径发送到其他 Activity，如果您有两个以上的 Activity，则使用 SharedPreferences用于在 SharedPreferences 的其他 Activity 中存储文件路径和检索路径。您可以将 SharedPreferences 中的路径存储为:

 SharedPreferences pathPrefs = FileGenerator.this.getSharedPreferences(
                                             "filepathPrefs", MODE_WORLD_READABLE);
        SharedPreferences.Editor prefsEditor = pathPrefs.edit();
        prefsEditor.putString("image1",image1.getAbsolutePath().toString());
        prefsEditor.putString("image2",image2.getAbsolutePath().toString());
        prefsEditor.commit();

并且在其他 Activity 中从 SharedPreferences 获取文件路径为:

SharedPreferences pathPrefs = 
                   this.getSharedPreferences("filepathPrefs", MODE_WORLD_READABLE);
String image1 = pathPrefs.getString("image1", "defaultpath");
String image2 = pathPrefs.getString("image2", "defaultpath");
// now use both file path in your code..