setContentView(R.layout.web);
web = (WebView)findViewById(R.id.web);
web.setWebViewClient(new DownLoadWebViewClient(this));
WebSettings s = web.getSettings();
s.setSaveFormData(false);
s.setSavePassword(false);
s.setUseWideViewPort(true);
s.setJavaScriptEnabled(true);
s.setLightTouchEnabled(true);
web.setWebChromeClient(new WebChromeClient() {public void onProgressChanged(WebView view, int progress) {//Activity和Webview根据加载程度决定进度条的进度大小//当加载到100%的时候 进度条自动消失context.setProgress(progress * 100);}
});
web.loadUrl("http://www.top100.cn/");

public class DownLoadWebViewClient extends WebViewClient {private Context context;public DownLoadWebViewClient(Context context){this.context = context;}@Overridepublic boolean shouldOverrideUrlLoading(WebView view, String url) {Log.i("info", "open an url");String urlStr = "";                                 //存放解码后的url//如果是utf8编码if (isUtf8Url(url)){urlStr = Utf8URLdecode(url);//如果不是utf8编码} else {urlStr = URLDecoder.decode(url);}//如果链接是下载top100.cn中的mp3文件if (url.substring(url.length()-4).equals(".mp3")&&url.substring(7,10).equals("221")){Log.i("info", "mp3 file");String ss[] = urlStr.split("/");String musicName = ss[ss.length-1];                //得到音乐文件的全名（包括后缀）Log.i("info", "musicfile: " + musicName);//将下载链接和文件名传递给下载模块Intent intent = new Intent(context,DownLoadService.class);intent.putExtra("url", url);intent.putExtra("musicName", musicName);context.startService(intent);}return super.shouldOverrideUrlLoading(view, url);}

public class DownLoadService extends Service implements Runnable{  //实现Runable接口private String URL_str;                        //网络歌曲的路径private File download_file;                    //下载的文件private int total_read = 0;                 //已经下载文件的长度（以字节为单位）private int readLength = 0;                   //一次性下载的长度（以字节为单位）private int music_length = 0;                  //音乐文件的长度（以字节为单位）private boolean flag = false;                   //是否停止下载，停止下载为trueprivate Thread downThread;                 //下载线程private String musicName;                 //下载的文件名@Overridepublic IBinder onBind(Intent intent) {return null;}@Overridepublic void onCreate() {downThread = new Thread(this);          //初始化下载线程downThread.start();}@Overridepublic void onStart(Intent intent, int startId) {URL_str = intent.getExtras().getString("url");       //获取下载链接的urlmusicName = intent.getExtras().getString("musicName");//获取下载的文件名}@Overridepublic void onDestroy() {flag = true;                                //停止下载}//实现Run方法，进行歌曲的下载@Overridepublic void run() {                                                            FileOutputStream fos = null;               //文件输出流FileInputStream fis = null;             //文件输出流InputStream is = null;                  //网络文件输入流URL url = null;try {url = new URL(URL_str);              //网络歌曲的urlHttpURLConnection httpConnection = null;httpConnection = (HttpURLConnection)url.openConnection();               //打开网络连接download_file = new File(Environment.  //在sdcard根目录建立一个与要下载的文件的名字相同的文件getExternalStorageDirectory()+ "/" + musicName);fos = new FileOutputStream(download_file, true);        //初始化文件输出流fis = new FileInputStream(download_file);                //初始化文件输入流total_read = fis.available();                        //初始化“已下载部分”的长度，此处应为0music_length = httpConnection.getContentLength();      //要下载的文件的总长度if (is == null) {                             //如果下载失败则打印日志，并返回Log.i("info", "donload failed...");return;}byte buf[] = new byte[1024];                    　　//定义下载缓冲区readLength = 0;                         　　//一次性下载的长度Log.i("info", "download start...");                     //向前台发送开始下载广播Intent startIntent = new Intent();startIntent.setAction("com.alex.downloadstart");sendBroadcast(startIntent);//如果读取网络文件的数据流成功，且用户没有选择停止下载，则开始下载文件while (readLength != -1  && !flag) {                    if((readLength = is.read(buf))>0){fos.write(buf, 0, readLength);total_read += readLength;         //已下载文件的长度增加}   if (total_read == music_length) {         //当已下载的长度等于网络文件的长度，则下载完成flag = false;Log.i("info", "download complete...");//向前台发送下载完成广播Intent completeIntent = new Intent();completeIntent.setAction("com.alex.downloadcompleted");sendBroadcast(completeIntent);//关闭输入输出流fos.close();is.close();fis.close();}Thread.sleep(50);                         //当前现在休眠50毫秒Log.i("info", "download process : "                 //打印下载进度+ ((total_read+0.0)/music_length*100+"").substring(0, 4)+"%");}} catch (Exception e) {Intent errorIntent = new Intent();errorIntent.setAction("com.alex.downloaderror");sendBroadcast(errorIntent);e.printStackTrace();}}}