Firebase Android：如何取消下载？

Question

如何从Firebase取消我的下载任务？

我想取消下载，只要我点击ProgressDialog以外的地方。

以下是我的下载活动ExamesActivity.java所在的部分。它看起来像：

//Download the File on Button(Download) click: 
     bDownload.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 

       //Initalizing teh Spinner-to-String functions: 
       Grade = spClasse.getSelectedItem().toString(); 
       Type = spEpoca.getSelectedItem().toString(); 
       Subject = spDisciplina.getSelectedItem().toString(); 
       Year = spAno.getSelectedItem().toString(); 

       //Download the File: 
       //First Check if ON the Spinner, everything is choosen. It should be. If not, show error Toast. 
       if (Grade.equals("...") | Type.equals("...") | Disciplina.equals("...") | Year.equals("..."){ 

        //Show the The Error Toast: 
        Toast.makeText(ExamesActivity.this, "everything shall be choosen", Toast.LENGTH_SHORT).show(); 

       } else {           //What the dir would look like: "Subject/Grade/Year-Type.extension" 
        pdfRef = mStorageRef.child(Subject + "/" + Grade + "/" + Year + "-" + Type + ".pdf"); 
        File root = android.os.Environment.getExternalStorageDirectory(); 
        File dir = new File(root.getAbsolutePath() + "/Exams-App/"); 

        //Show the ProgressDialog while downloading: 
        progressDialog.show(); 

        if (!dir.exists()) { 
         dir.mkdirs(); 
        } 

        localFile = new File(dir, Subject + "-" + Year + "-" + Grade + "-" + Type + ".pdf"); 


        pdfRef.getFile(localFile).addOnSuccessListener(new OnSuccessListener<FileDownloadTask.TaskSnapshot>() { 
         @Override 
         public void onSuccess(FileDownloadTask.TaskSnapshot taskSnapshot) { 
          // Local temp file has been created 
          progressDialog.dismiss(); 
          Toast.makeText(ExamesActivity.this, "Exam was successfully downloaded!️", Toast.LENGTH_SHORT).show(); 
         } 
        }).addOnFailureListener(new OnFailureListener() { 
         @Override 
         public void onFailure(@NonNull Exception exception) { 
          // Handle any errors 
          progressDialog.dismiss(); 
          Toast.makeText(ExamesActivity.this, "Exam not found on the server.", Toast.LENGTH_LONG).show(); 
         } 

        }).addOnProgressListener(new OnProgressListener<FileDownloadTask.TaskSnapshot>() { 
         @Override 
         public void onProgress(FileDownloadTask.TaskSnapshot taskSnapshot) { 
          //Some math to get the Percentage of the Download :) 
          double progressPercentage = (100.0 * taskSnapshot.getBytesTransferred())/taskSnapshot.getTotalByteCount(); 
          double size = (taskSnapshot.getTotalByteCount())/(1000000); 
          progressDialog.setMessage("PDF Size: " + (size) + " - " + ((int) progressPercentage) + "% - Click away to cancel the download."); 

         } 
        }); 
       } 
      } 
     }); 

Answer 1

pdfRef.[getFile][1](localFile)返回FileDownloadTask。该对象是CancellableTask的子类，它具有cancel()方法。您需要持有对此任务的参考，并调用其取消方法取消下载。