使用下面的工作代码::
public class Android_Activity extends Activity {
private Android_Activity _activity;
    @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);     
            getWindow().requestFeature(Window.FEATURE_PROGRESS);
            _activity = this;   
            setContentView(R.layout.main);
            mwebview=(WebView)view.findViewById(R.id.webview);
            mwebview.getSettings().setJavaScriptEnabled(true);
            mwebview.getSettings().setJavaScriptCanOpenWindowsAutomatically(true);
            if(checkInternetConnection(_activity)==true){
                if(savedInstanceState==null)
                    mwebview.loadUrl("http://abc.com");
                else
                    mwebview.restoreState(savedInstanceState);
            }
            else{
                AlertDialog.Builder builder = new AlertDialog.Builder(_activity);
                builder.setMessage("Please check your network connection.")
                       .setCancelable(false)
                       .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                           public void onClick(DialogInterface dialog, int id) {
                           }
                       });
                AlertDialog alert = builder.create();    
                alert.show();
            }
            mwebview.setWebChromeClient(new WebChromeClient() {
                @Override
                public void onProgressChanged(WebView view, int progress) { 
                    if(mwebview.getVisibility()==View.VISIBLE)
                    {
                        _activity.setProgress(progress * 100);
                    }
                }
            });
            mwebview.setWebViewClient(new HelloWebViewClient());
        }
        //HelloWebViewClient class for webview
        private class HelloWebViewClient extends WebViewClient {
            @Override
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                // TODO Auto-generated method stub
                super.onPageStarted(view, url, favicon);
            }
            @Override
            public void onReceivedError(WebView view, int errorCode,
                    String description, String failingUrl) {
                // TODO Auto-generated method stub
                super.onReceivedError(view, errorCode, description, failingUrl);
            }
            @Override
            public void onPageFinished(WebView view, String url) {
                // TODO Auto-generated method stub
                super.onPageFinished(view, url);
            }
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                // Otherwise, the link is not for a page on my site, so launch another Activity that handles URLs
                view.loadUrl(url);
                return true;
            }
        }   //HelloWebViewClient-class
        @Override
        public boolean onKeyDown(int keyCode, KeyEvent event) {
            // Check if the key event was the Back button and if there's history
            if ((keyCode == KeyEvent.KEYCODE_BACK) && mwebview.canGoBack() ){
                mwebview.goBack();
                return true;
            }
            // If it wasn't the Back key or there's no web page history, bubble up to the default
            // system behavior (probably exit the activity)
            return super.onKeyDown(keyCode, event);
        }
        //To check whether network connection is available on device or not
            public static boolean checkInternetConnection(Activity _activity) {
                ConnectivityManager conMgr = (ConnectivityManager) _activity.getSystemService(Context.CONNECTIVITY_SERVICE);
                if (conMgr.getActiveNetworkInfo() != null
                        && conMgr.getActiveNetworkInfo().isAvailable()
                        && conMgr.getActiveNetworkInfo().isConnected()) 
                    return true;
                else
                    return false;
            }//checkInternetConnection()
}
而且在你的 main.xml 布局中,你必须有一个 id 为 webview 的 webview