Android进度对话框

Question

我的应用程序从互联网中获取一些html代码，完成后，将其显示在设备屏幕上。由于这需要大约3-4秒的时间，因此在这段时间屏幕保持黑屏，我想使用进度对话框。这是我的代码：

package com.nextlogic.golfnews; 



// ALL THE IMPORTS .... 

public class Activity1 extends Activity { 

    private ProgressDialog progressDialog; 
@Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main2); 

     progressDialog = ProgressDialog.show(Activity1.this, "", "Loading..."); 
     new Thread() 
     { 
      public void run() 
      { 

      try 
       { 
       sleep(2000); 

      // HERE I'VE PUT ALL THE FUNCTIONS THAT WORK FOR ME 
} 
    catch (Exception e) 
    { 
     Log.e("tag",e.getMessage()); 
    } 
// dismiss the progressdialog 
    progressDialog.dismiss(); 
} 
}.start(); 

该程序的工作原理，但它不再显示任何东西。我在logcat有一个错误：

Only the original thread that created a view hierarchy can touch its views. 

你能帮我吗？提前致谢。

Answer 1

该错误足够明确。要更新一个可视对象，您必须在主线程内运行更改。一个快速而脏的修复可能会调用runOnUiThread()内的更新代码。

但在你的情况下，我会使用AsyncTask来下载和更新进度条的进度。该任务具有在UI线程结束时运行的属性（因此您可以在其中更新视图，例如解除进度对话框）

Here是一个示例，说明如何使用AsyncTask显示下载进度对话框。

更新

＃2已经拥有了你所有的问题。 Here是一个AsyncTask的例子，用于下载一些内容并显示下载进度。正是你想要的。

更新2

确定这里是使用的AsyncTask代码：

public class Activity1 extends Activity 
{ 
    private ProgressDialog progressDialog; 

    @Override 
    public void onCreate(Bundle savedInstanceState) 
    { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     new AsyncTask<Integer, Integer, Boolean>() 
     { 
      ProgressDialog progressDialog; 

      @Override 
      protected void onPreExecute() 
      { 
       /* 
       * This is executed on UI thread before doInBackground(). It is 
       * the perfect place to show the progress dialog. 
       */ 
       progressDialog = ProgressDialog.show(Activity1.this, "", 
         "Loading..."); 
      } 

      @Override 
      protected Boolean doInBackground(Integer... params) 
      { 
       if (params == null) 
       { 
        return false; 
       } 
       try 
       { 
        /* 
        * This is run on a background thread, so we can sleep here 
        * or do whatever we want without blocking UI thread. A more 
        * advanced use would download chunks of fixed size and call 
        * publishProgress(); 
        */ 
        Thread.sleep(params[0]); 
        // HERE I'VE PUT ALL THE FUNCTIONS THAT WORK FOR ME 
       } 
       catch (Exception e) 
       { 
        Log.e("tag", e.getMessage()); 
        /* 
        * The task failed 
        */ 
        return false; 
       } 

       /* 
       * The task succeeded 
       */ 
       return true; 
      } 

      @Override 
      protected void onPostExecute(Boolean result) 
      { 
       progressDialog.dismiss(); 
       /* 
       * Update here your view objects with content from download. It 
       * is save to dismiss dialogs, update views, etc., since we are 
       * working on UI thread. 
       */ 
       AlertDialog.Builder b = new AlertDialog.Builder(Activity1.this); 
       b.setTitle(android.R.string.dialog_alert_title); 
       if (result) 
       { 
        b.setMessage("Download succeeded"); 
       } 
       else 
       { 
        b.setMessage("Download failed"); 
       } 
       b.setPositiveButton(getString(android.R.string.ok), 
         new DialogInterface.OnClickListener() 
         { 

          @Override 
          public void onClick(DialogInterface dlg, int arg1) 
          { 
           dlg.dismiss(); 
          } 
         }); 
       b.create().show(); 
      } 
     }.execute(2000); 

     new Thread() 
     { 
      @Override 
      public void run() 
      { 

       // dismiss the progressdialog 
       progressDialog.dismiss(); 
      } 
     }.start(); 
    } 
} 

Answer 2

完成网络操作

runOnUiThread(new Runnable() { 
      @Override 
      public void run() { 
      progressDialog.dismiss(); 

      } 
     }); 

Answer 3

后创建UI线程你需要做这样

runOnUiThread(new Runnable() { 
    public void run() { 
     // Do Your Stuff 
    }}); 

Answer 4

解散你的对话是这样的：

Handler handler = new Handler(); 
handler.post(new Runnable(){ 
    public void run(){ 
     progressDialog.dismiss(); 
    } 
}); 

Answer 5

顶端回答的伟大工程，所以这里是落实MonoDroid的一个的AsyncTask的例子（感谢格雷格Shackels）：http://mono-for-android.1047100.n5.nabble.com/AsyncTask-td4346647.html