在android中使用AsyncTask不显示进度条

Question

我刚刚写了一个代码，需要在与服务器交互时显示进度条。但是如果我在下面的代码中调用解除方法，它就不起作用了。

public class AsyncClass extends AsyncTask<String, String, String> {
    String result;
    public ProgressDialog progressbar;
    static Context context; 


    public AsyncClass(Context context,String result) {
        this.context = context;
        this.result = result;
    }

    @Override
    protected String doInBackground(String... params) {
        try {
            HttpClient httpclient = new DefaultHttpClient();
            URI u = new URI(params[0]);
            // url = Urls.SENDMOVIE_REQUEST_URL;
            HttpGet HG = new HttpGet(u);
            HttpResponse response = httpclient.execute(HG);
            //httpEntity = httpResponse.getEntity();
            result = EntityUtils.toString(response.getEntity());
            Log.d("result", result);
        } catch(Exception e) {
            e.printStackTrace();
        }

        return result;  
    }

    @Override
    protected void onPreExecute() {
        progressbar = new ProgressDialog(context);
        progressbar.setCancelable(true);
        progressbar.setMessage("loading....");
        progressbar.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        progressbar.setProgress(0);

        progressbar.show();
    }

    @Override
    protected void onPostExecute(String result) {
        progressbar.dismiss(); 
    }
}

Answer 1

我认为它没有显示是因为progressbar.setProgress(0);

只需删除它并尝试。

如果你想要progressUpdates，你需要这样做：

private class DownloadTask extends AsyncTask<String, String, String> {

    @Override 
    protected void onPreExecute() { 
        super.onPreExecute(); 
    } 

    @Override 
    protected String doInBackground(String... urls) {
        //Copy you logic to calculate progress and call 
        publishProgress("" + progress); 
    } 

    protected void onProgressUpdate(String... progress) {        
    mProgressDialog.setProgress(Integer.parseInt(progress[0]));
    } 

    @Override 
    protected void onPostExecute(String result) {           
        dismissDialog(DIALOG_DOWNLOAD_PROGRESS); 
    } 
} 

编辑伊克巴尔的回答

 private class ProgressTask extends AsyncTask<String, Void, Boolean> {
        private ProgressDialog dialog;

        public ProgressTask(){ 
           dialog = new ProgressDialog(HomeActivity.this);
           dialog.setCancelable(false);
        } 

        /** progress dialog to show user that the backup is processing. */  
        /** application context. */ 
          @Override 
         protected void onPreExecute() {  
               this.dialog.setMessage("Please wait"); 
                this.dialog.show(); 
          } 

          protected Boolean doInBackground(final String... args) {
                  /** * Write your code */  
           } 

          @Override 
           protected void onPostExecute(final Boolean success) { 
                if (dialog.isShowing()) { 
                      dialog.dismiss(); 
                }  
                if (success) { 
                    // display UI 
                 } 
           } 
     } 

Answer 2

使用下面的代码它会为你完成这项工作

private class ProgressTask extends AsyncTask<String, Void, Boolean> {
    private ProgressDialog dialog = new ProgressDialog(HomeActivity.this);
    /** progress dialog to show user that the backup is processing. */ 
    /** application context. */
      @Override
     protected void onPreExecute() { 
           this.dialog.setMessage("Please wait"); 
            this.dialog.show(); 
      }

      protected Boolean doInBackground(final String... args) {
              /** * Write your code */ 
       }

      @Override
       protected void onPostExecute(final Boolean success) { 
            if (dialog.isShowing()) { 
                  dialog.dismiss(); 
            } 
            if (success) { 
                // display UI
             }
       }
 }

编辑：

在构造函数中添加进度条的初始化为

public AsyncClass(Context context,String result) {
        this.context = context;
        this.result = result;
        progressbar = new ProgressDialog(context);
}

并将其从 internecine() 中删除。