webview下载文件

WebView控制调用相应的WEB页面进行展示。当碰到页面有下载链接的时候，点击上去是一点反应都没有的。原来是因为WebView默认没有开启文件下载的功能，如果要实现文件下载的功能，需要设置WebView的DownloadListener，通过实现自己的DownloadListener来实现文件的下载。具体操作如下： 

1、设置WebView的DownloadListener： 
    webView.setDownloadListener(new MyWebViewDownLoadListener()); 

2、实现MyWebViewDownLoadListener这个类，具体可以如下这样：  

  这只是调用系统中已经内置的浏览器进行下载，还没有WebView本身进行的文件下载，不过，这也基本上满足我们的应用场景了。 

我在项目中的运用 
项目要求这样： 
1，需要使用WebView加载一个网页； 
2，网页中有文件下载的链接，点击后需要下载文件到SDcard； 
3，然后自动打开文件； 
下面是具体解决办法 
第一步，对WebView进行一系列设置。 

WebView webview=(WebView)layout.findViewById(R.id.webview);webview.getSettings().setJavaScriptEnabled(true);webview.setWebChromeClient(new MyWebChromeClient());webview.requestFocus();//webview.loadUrl("file:///android_asset/risktest.html");webview.loadUrl(jcrs_sub.get(position).addr);// 设置web视图客户端webview.setWebViewClient(new MyWebViewClient());webview.setDownloadListener(new MyWebViewDownLoadListener());//内部类public class MyWebViewClient extends WebViewClient {// 如果页面中链接，如果希望点击链接继续在当前browser中响应，// 而不是新开Android的系统browser中响应该链接，必须覆盖 webview的WebViewClient对象。public boolean shouldOverviewUrlLoading(WebView view, String url) {L.i("shouldOverviewUrlLoading");view.loadUrl(url);return true;}public void onPageStarted(WebView view, String url, Bitmap favicon) {L.i("onPageStarted");showProgress();}public void onPageFinished(WebView view, String url) {L.i("onPageFinished");closeProgress();}public void onReceivedError(WebView view, int errorCode,String description, String failingUrl) {L.i("onReceivedError");closeProgress();}}// 如果不做任何处理，浏览网页，点击系统“Back”键，整个Browser会调用finish()而结束自身，// 如果希望浏览的网 页回退而不是推出浏览器，需要在当前Activity中处理并消费掉该Back事件。public boolean onKeyDown(int keyCode, KeyEvent event) {// if((keyCode==KeyEvent.KEYCODE_BACK)&&webview.canGoBack()){// webview.goBack();// return true;// }return false;}

第二步，起线程开始下载文件。 

//内部类private class MyWebViewDownLoadListener implements DownloadListener {        @Override        public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype,                                    long contentLength) {        if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){        Toast t=Toast.makeText(mContext, "需要SD卡。", Toast.LENGTH_LONG);t.setGravity(Gravity.CENTER, 0, 0);t.show();return;        }DownloaderTask task=new DownloaderTask();task.execute(url);        }    }//内部类private class DownloaderTask extends AsyncTask<String, Void, String> {     public DownloaderTask() {     }@Overrideprotected String doInBackground(String... params) {// TODO Auto-generated method stubString url=params[0];//Log.i("tag", "url="+url);String fileName=url.substring(url.lastIndexOf("/")+1);fileName=URLDecoder.decode(fileName);Log.i("tag", "fileName="+fileName);File directory=Environment.getExternalStorageDirectory();File file=new File(directory,fileName);if(file.exists()){Log.i("tag", "The file has already exists.");return fileName;}try {                  HttpClient client = new DefaultHttpClient();  //                client.getParams().setIntParameter("http.socket.timeout",3000);//设置超时                HttpGet get = new HttpGet(url);                  HttpResponse response = client.execute(get);                if(HttpStatus.SC_OK==response.getStatusLine().getStatusCode()){HttpEntity entity = response.getEntity();InputStream input = entity.getContent();writeToSDCard(fileName,input);input.close();//entity.consumeContent();return fileName;                  }else{                return null;                }            } catch (Exception e) {                  e.printStackTrace();                return null;            }}@Overrideprotected void onCancelled() {// TODO Auto-generated method stubsuper.onCancelled();}@Overrideprotected void onPostExecute(String result) {// TODO Auto-generated method stubsuper.onPostExecute(result);closeProgressDialog();if(result==null){Toast t=Toast.makeText(mContext, "连接错误！请稍后再试！", Toast.LENGTH_LONG);t.setGravity(Gravity.CENTER, 0, 0);t.show();return;}Toast t=Toast.makeText(mContext, "已保存到SD卡。", Toast.LENGTH_LONG);t.setGravity(Gravity.CENTER, 0, 0);t.show();File directory=Environment.getExternalStorageDirectory();File file=new File(directory,result);Log.i("tag", "Path="+file.getAbsolutePath());Intent intent = getFileIntent(file);startActivity(intent);}@Overrideprotected void onPreExecute() {// TODO Auto-generated method stubsuper.onPreExecute();showProgressDialog();}@Overrideprotected void onProgressUpdate(Void... values) {// TODO Auto-generated method stubsuper.onProgressUpdate(values);} } 

第三步，实现一些工具方法。 

private ProgressDialog mDialog;private void showProgressDialog(){if(mDialog==null){mDialog = new ProgressDialog(mContext);  mDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);//设置风格为圆形进度条  mDialog.setMessage("正在加载 ，请等待...");  mDialog.setIndeterminate(false);//设置进度条是否为不明确  mDialog.setCancelable(true);//设置进度条是否可以按退回键取消  mDialog.setCanceledOnTouchOutside(false);mDialog.setOnDismissListener(new OnDismissListener() {@Overridepublic void onDismiss(DialogInterface dialog) {// TODO Auto-generated method stubmDialog=null;}});mDialog.show();}}private void closeProgressDialog(){if(mDialog!=null){mDialog.dismiss();mDialog=null;}} public Intent getFileIntent(File file){// Uri uri = Uri.parse("http://m.ql18.com.cn/hpf10/1.pdf");Uri uri = Uri.fromFile(file);String type = getMIMEType(file);Log.i("tag", "type="+type);    Intent intent = new Intent("android.intent.action.VIEW");    intent.addCategory("android.intent.category.DEFAULT");    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);    intent.setDataAndType(uri, type);    return intent;  } public void writeToSDCard(String fileName,InputStream input){if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){File directory=Environment.getExternalStorageDirectory();File file=new File(directory,fileName);//if(file.exists()){//Log.i("tag", "The file has already exists.");//return;//}try {FileOutputStream fos = new FileOutputStream(file);byte[] b = new byte[2048];int j = 0;while ((j = input.read(b)) != -1) {fos.write(b, 0, j);}fos.flush();fos.close();} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}else{Log.i("tag", "NO SDCard.");}}private String getMIMEType(File f){         String type="";        String fName=f.getName();        /* 取得扩展名 */        String end=fName.substring(fName.lastIndexOf(".")+1,fName.length()).toLowerCase();            /* 依扩展名的类型决定MimeType */      if(end.equals("pdf")){      type = "application/pdf";//      }      else if(end.equals("m4a")||end.equals("mp3")||end.equals("mid")||        end.equals("xmf")||end.equals("ogg")||end.equals("wav")){          type = "audio/*";         }        else if(end.equals("3gp")||end.equals("mp4")){          type = "video/*";        }        else if(end.equals("jpg")||end.equals("gif")||end.equals("png")||        end.equals("jpeg")||end.equals("bmp")){          type = "image/*";        }        else if(end.equals("apk")){           /* android.permission.INSTALL_PACKAGES */           type = "application/vnd.android.package-archive";       }//      else if(end.equals("pptx")||end.equals("ppt")){//      type = "application/vnd.ms-powerpoint"; //      }else if(end.equals("docx")||end.equals("doc")){//      type = "application/vnd.ms-word";//      }else if(end.equals("xlsx")||end.equals("xls")){//      type = "application/vnd.ms-excel";//      }      else{//      /*如果无法直接打开，就跳出软件列表给用户选择 */          type="*/*";      }      return type;    }