Android 网页加载完成ProgressDialog运用

package gongzibai.co.cc;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;

public class WebView2Activity extends
  Activity {

 private ProgressDialog progressBar;
 WebView webview;
 AlertDialog alertDialog;

 /** Called when the activity is first created. */
 @Override
 public void onCreate(
   Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  webview = (WebView) findViewById(R.id.webview);
  progressBar = ProgressDialog
    .show(WebView2Activity.this,
      null,
      "正在进入网页，请稍后

…");
  webview.getSettings()
    .setJavaScriptEnabled(
      true);

  webview.loadUrl(" http://www.qq.com");

  AlertDialog alertDialog = new AlertDialog.Builder(
    this).create();

  // 设置视图客户端
  webview.setWebViewClient(new MyWebViewClient());

 }

 class MyWebViewClient extends
   WebViewClient {

  @Override
  public boolean shouldOverrideUrlLoading(
    WebView view, String url) {
   // TODO Auto-generated method stub

   view.loadUrl(url);
   return super
     .shouldOverrideUrlLoading(
       view, url);
  }

  public void onPageFinished(
    WebView view, String url) {
   // TODO Auto-generated method stub
   if (progressBar.isShowing()) {
    progressBar.dismiss();

   }
  }
 }
}