如何從另一個活動訪問文件

Question

我嘗試從相機拍攝照片，然後我嘗試通過fileProvider()方法在下面編寫的方法訪問在另一個活動中創建的這些two files，但對我來說很糟糕在接受點總是顯示我爲空。有人可以幫助我如何訪問在這裏創建的不同活動中的文件嗎？

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(); 
     } 
    } 
} 

以下是我嘗試接收這些文件的活動。

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. - （即，selectedImagePath1, selectedImagePath2）之前嘗試此，我常帶串到另一個活動，然後使用這些字符串創建文件。但不知道爲什麼這會破壞我創建的圖像文件。所以，我遵循上面的代碼方式，仍然沒有運氣。

Answer 1

您需要使用Intent將文件路徑發送到其他活動，如果您有多於兩個活動，則使用SharedPreferences來從SharedPreferences中對其他活動中的文件路徑和回溯路徑進行存檔。

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(); 

和其他活動獲取文件路徑從SharedPreferences如：你可以在SharedPreferences作爲存儲路徑

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..