webview

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://2014.qq.com/";
    private WebView webView;
    private ProgressDialog dialog;
    @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();
                         dialog=null;
                  }
            }

            private void openDialog(int newProgress) {
                // TODO Auto-generated method stub
                if(dialog==null)
                {
                    dialog=new ProgressDialog(MainActivity.this);
                    dialog.setTitle("正在加载");
                    dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                    dialog.setProgress(newProgress);
                    dialog.show();

                }
                else
                {
                    dialog.setProgress(newProgress);
                }


            }
        });



    }

    //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);
    }


}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.imooc.android_webview" android:versionCode="1" android:versionName="1.0" >

    <uses-sdk  android:minSdkVersion="16" android:targetSdkVersion="16" />
    <uses-permission android:name="android.permission.INTERNET"/>


    <application  android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" >
        <activity  android:name="com.imooc.android_webview.MainActivity" android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>