java - 如何使屏幕变暗并在android中启动progressBar？

Question

我正在写一个 android 应用程序，我想当 httpclient.execute() 被执行时，屏幕变暗并出现一个进度条，直到这一行被执行，我该怎么办？我的代码是这样的:

ProgressBar x = (ProgressBar) findViewById("R.id.progress") ;
x.setVisibility(ProgressBar.VISIBLE) ;
httpclient.execute()
x.setVisibility(ProgressBar.GONE) ;

但是使用这段代码只会出现进度条，屏幕不会变暗。

Answer 1

首先，我建议您在异步类中完成所有网络。您可以使用以下模板将您的代码放入异步类中。将 ProgressDialog 作为类变量。

YouClass
{
ProgressDialog dialog;

 onCreate(....)
{
  //Execute the async task here.
  new myNetworkingTask().execute("");
}

private class myNetworkingTask extends AsyncTask<String, Void, String> {

  @Override
  protected String doInBackground(String... params) 
        {
            //In this method you will do the networking task
            httpclient.execute();
        }
        return "";
  }      

  @Override
  protected void onPostExecute(String result) { 
          //In this method you will hide the progress bar
         dialog.dismiss();
  }

  @Override
  protected void onPreExecute() {
         //In this method you will display the progress bar.
        dialog = ProgressDialog.show(MyActivity.this, "", 
                    "Loading. Please wait...", true); 
  }

  @Override
  protected void onProgressUpdate(Void... values) {
  }