Android中实现Webview顶部带进度条的方法

package com.droidyue.demo.webviewprogressbar;
import android.app.activity;
import android.os.bundle;
import android.view.menu;
import android.view.view;
import android.view.view.onclicklistener;
import android.webkit.webchromeclient;
import android.webkit.webview;
import android.widget.progressbar;

 

import com.droidyue.demo.webviewprogressbar.r;

public class mainactivity extends activity {

  @override
  protected void oncreate(bundle savedinstancestate) {
      super.oncreate(savedinstancestate);
      setcontentview(r.layout.activity_main);
      final progressbar bar = (progressbar)findviewbyid(r.id.myprogressbar);

      final webview webview = (webview)findviewbyid(r.id.mywebview);
      webview.setwebchromeclient(new webchromeclient() {

          @override
          public void onprogresschanged(webview view, int newprogress) {
              if (newprogress == 100) {
                  bar.setvisibility(view.invisible);
              } else {
                  if (view.invisible == bar.getvisibility()) {
                      bar.setvisibility(view.visible);
                  }
                  bar.setprogress(newprogress);
              }
              super.onprogresschanged(view, newprogress);
          }
         
      });
     
      findviewbyid(r.id.mybutton).setonclicklistener(new onclicklistener() {

          @override
          public void onclick(view arg0) {
              webview.reload();
          }
         
      });
      final string url = "http://jb51.net";
      webview.loadurl(url);
  }
 

  @override
  public boolean oncreateoptionsmenu(menu menu) {
      getmenuinflater().inflate(r.menu.main, menu);
      return true;
  }

}

<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingbottom="@dimen/activity_vertical_margin"
    android:paddingleft="@dimen/activity_horizontal_margin"
    android:paddingright="@dimen/activity_horizontal_margin"
    android:paddingtop="@dimen/activity_vertical_margin"
    tools:context=".mainactivity" >
 
    <button
        android:id="@+id/mybutton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="reload"
        />

 

    <progressbar
      style="?android:attr/progressbarstylehorizontal"
        android:id="@+id/myprogressbar"
        android:layout_below="@id/mybutton"
        android:layout_width="match_parent"
        android:layout_height="5px"
        />
  <webview
      android:id="@+id/mywebview"
      android:layout_below="@id/myprogressbar"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      />
</relativelayout>

<uses-permission android:name="android.permission.internet"/>