WebView浅谈

课程Demo

public class MainActivity extends Activity {
   private String url = "http://baidu.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);
      //监控当前网站的加载进度
      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;  //为了消耗当前页面
         }
         else
         {
            System.exit(0);//退出程序
         }
      }
      return super.onKeyDown(keyCode, event);
   }
}