WebView 简单使用一

package com.imooc.android_webview;

import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.app.ProgressDialog;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;
import android.os.Build;

public class MainActivity extends Activity {

    private String url = "http://www.baidu.com/";
    private WebView webView;
    private ProgressDialog dialog; //定义ProgressDialog
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.web);
        // Uri uri = Uri.parse(url); //url为你要链接的地址
        // Intent intent =new Intent(Intent.ACTION_VIEW, uri);
        // startActivity(intent);
        init();
    }

    private void init() {
        // TODO Auto-generated method stub
        webView = (WebView) findViewById(R.id.webView);
        // WebView加载本地资源
        // webView.loadUrl("file:///android_asset/example.html");
        // WebView加载web资源
        webView.loadUrl(url);
        // 覆盖WebView默认通过第三方或者是系统浏览器打开网页的行为，使得网页可以在WebVIew中打开
        webView.setWebViewClient(new WebViewClient(){
            
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                // TODO Auto-generated method stub
                //返回值是true的时候控制网页在WebView中去打开，如果为false调用系统浏览器或第三方浏览器去打开
                view.loadUrl(url);
                return true;
            }
            //WebViewClient帮助WebView去处理一些页面控制和请求通知
            
        });
        //启用支持JavaScript
        WebSettings settings = webView.getSettings();
        settings.setJavaScriptEnabled(true);


        //WebView加载页面优先使用缓存加载
        settings.setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
        webView.setWebChromeClient(new WebChromeClient(){
            
            @Override
            public void onProgressChanged(WebView view, int newProgress) {
                // TODO Auto-generated method stub
                //newProgress 1-100之间的整数
                if(newProgress==100)
                {
                    //网页加载完毕，关闭ProgressDialog
                    closeDialog();
                }
                else
                {
                    //网页正在加载,打开ProgressDialog
                    openDialog(newProgress);
                }
            }

            private void closeDialog() {
                // TODO Auto-generated method stub
                  if(dialog!=null&&dialog.isShowing())
                  {
                         dialog.dismiss(); //取消显示
                         dialog=null;
                  }
            }

            private void openDialog(int newProgress) {
                // TODO Auto-generated method stub
                if(dialog==null)
                {
                    dialog=new ProgressDialog(MainActivity.this);//创建ProgressDialog对象
                    dialog.setTitle("正在加载");
                    dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);//设置进度条颜色
                    dialog.setProgress(newProgress);
                    dialog.show();
                    
                }
                else
                {
                    dialog.setProgress(newProgress); //让的进度条刷新进度
                }
            
                
            }
        });
        
        
        
    }
    
    //改写物理按键——返回的逻辑
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        if(keyCode==KeyEvent.KEYCODE_BACK)
        {
            //Toast.makeText(this, webView.getUrl(), Toast.LENGTH_SHORT).show();
            if(webView.canGoBack())
            {
                webView.goBack();//返回上一页面
                return true;
            }
            else
            {
                System.exit(0);//退出程序
            }
        }
        return super.onKeyDown(keyCode, event);
    }
    
    
}