Android WebView实现文件下载功能
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(newMyWebViewDownLoadListener());
2、实现MyWebViewDownLoadListener这个类,具体可以如下这样:
privateclassMyWebViewDownLoadListenerimplementsDownloadListener{ @Override publicvoidonDownloadStart(Stringurl,StringuserAgent,StringcontentDisposition,Stringmimetype, longcontentLength){ Log.i("tag","url="+url); Log.i("tag","userAgent="+userAgent); Log.i("tag","contentDisposition="+contentDisposition); Log.i("tag","mimetype="+mimetype); Log.i("tag","contentLength="+contentLength); Uriuri=Uri.parse(url); Intentintent=newIntent(Intent.ACTION_VIEW,uri); startActivity(intent); } }
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。
WebViewwebview=(WebView)layout.findViewById(R.id.webview); webview.getSettings().setJavaScriptEnabled(true); webview.setWebChromeClient(newMyWebChromeClient()); 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(newMyWebViewClient()); webview.setDownloadListener(newMyWebViewDownLoadListener()); //内部类 publicclassMyWebViewClientextendsWebViewClient{ //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。 publicbooleanshouldOverviewUrlLoading(WebViewview,Stringurl){ L.i("shouldOverviewUrlLoading"); view.loadUrl(url); returntrue; } publicvoidonPageStarted(WebViewview,Stringurl,Bitmapfavicon){ L.i("onPageStarted"); showProgress(); } publicvoidonPageFinished(WebViewview,Stringurl){ L.i("onPageFinished"); closeProgress(); } publicvoidonReceivedError(WebViewview,interrorCode, Stringdescription,StringfailingUrl){ 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。 publicbooleanonKeyDown(intkeyCode,KeyEventevent){ //if((keyCode==KeyEvent.KEYCODE_BACK)&&webview.canGoBack()){ //webview.goBack(); //returntrue; //} returnfalse; }
第二步,起线程开始下载文件。
//内部类 privateclassMyWebViewDownLoadListenerimplementsDownloadListener{ @Override publicvoidonDownloadStart(Stringurl,StringuserAgent,StringcontentDisposition,Stringmimetype, longcontentLength){ if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){ Toastt=Toast.makeText(mContext,"需要SD卡。",Toast.LENGTH_LONG); t.setGravity(Gravity.CENTER,0,0); t.show(); return; } DownloaderTasktask=newDownloaderTask(); task.execute(url); } } //内部类 privateclassDownloaderTaskextendsAsyncTask{ publicDownloaderTask(){ } @Override protectedStringdoInBackground(String...params){ //TODOAuto-generatedmethodstub Stringurl=params[0]; //Log.i("tag","url="+url); StringfileName=url.substring(url.lastIndexOf("/")+1); fileName=URLDecoder.decode(fileName); Log.i("tag","fileName="+fileName); Filedirectory=Environment.getExternalStorageDirectory(); Filefile=newFile(directory,fileName); if(file.exists()){ Log.i("tag","Thefilehasalreadyexists."); returnfileName; } try{ HttpClientclient=newDefaultHttpClient(); //client.getParams().setIntParameter("http.socket.timeout",3000);//设置超时 HttpGetget=newHttpGet(url); HttpResponseresponse=client.execute(get); if(HttpStatus.SC_OK==response.getStatusLine().getStatusCode()){ HttpEntityentity=response.getEntity(); InputStreaminput=entity.getContent(); writeToSDCard(fileName,input); input.close(); //entity.consumeContent(); returnfileName; }else{ returnnull; } }catch(Exceptione){ e.printStackTrace(); returnnull; } } @Override protectedvoidonCancelled(){ //TODOAuto-generatedmethodstub super.onCancelled(); } @Override protectedvoidonPostExecute(Stringresult){ //TODOAuto-generatedmethodstub super.onPostExecute(result); closeProgressDialog(); if(result==null){ Toastt=Toast.makeText(mContext,"连接错误!请稍后再试!",Toast.LENGTH_LONG); t.setGravity(Gravity.CENTER,0,0); t.show(); return; } Toastt=Toast.makeText(mContext,"已保存到SD卡。",Toast.LENGTH_LONG); t.setGravity(Gravity.CENTER,0,0); t.show(); Filedirectory=Environment.getExternalStorageDirectory(); Filefile=newFile(directory,result); Log.i("tag","Path="+file.getAbsolutePath()); Intentintent=getFileIntent(file); startActivity(intent); } @Override protectedvoidonPreExecute(){ //TODOAuto-generatedmethodstub super.onPreExecute(); showProgressDialog(); } @Override protectedvoidonProgressUpdate(Void...values){ //TODOAuto-generatedmethodstub super.onProgressUpdate(values); } }
第三步,实现一些工具方法。
privateProgressDialogmDialog; privatevoidshowProgressDialog(){ if(mDialog==null){ mDialog=newProgressDialog(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(newOnDismissListener(){ @Override publicvoidonDismiss(DialogInterfacedialog){ //TODOAuto-generatedmethodstub mDialog=null; } }); mDialog.show(); } } privatevoidcloseProgressDialog(){ if(mDialog!=null){ mDialog.dismiss(); mDialog=null; } } publicIntentgetFileIntent(Filefile){ //Uriuri=Uri.parse("http://m.ql18.com.cn/hpf10/1.pdf"); Uriuri=Uri.fromFile(file); Stringtype=getMIMEType(file); Log.i("tag","type="+type); Intentintent=newIntent("android.intent.action.VIEW"); intent.addCategory("android.intent.category.DEFAULT"); intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); intent.setDataAndType(uri,type); returnintent; } publicvoidwriteToSDCard(StringfileName,InputStreaminput){ if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){ Filedirectory=Environment.getExternalStorageDirectory(); Filefile=newFile(directory,fileName); //if(file.exists()){ //Log.i("tag","Thefilehasalreadyexists."); //return; //} try{ FileOutputStreamfos=newFileOutputStream(file); byte[]b=newbyte[2048]; intj=0; while((j=input.read(b))!=-1){ fos.write(b,0,j); } fos.flush(); fos.close(); }catch(FileNotFoundExceptione){ //TODOAuto-generatedcatchblock e.printStackTrace(); }catch(IOExceptione){ //TODOAuto-generatedcatchblock e.printStackTrace(); } }else{ Log.i("tag","NOSDCard."); } } privateStringgetMIMEType(Filef){ Stringtype=""; StringfName=f.getName(); /*取得扩展名*/ Stringend=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";// } elseif(end.equals("m4a")||end.equals("mp3")||end.equals("mid")|| end.equals("xmf")||end.equals("ogg")||end.equals("wav")){ type="audio/*"; } elseif(end.equals("3gp")||end.equals("mp4")){ type="video/*"; } elseif(end.equals("jpg")||end.equals("gif")||end.equals("png")|| end.equals("jpeg")||end.equals("bmp")){ type="image/*"; } elseif(end.equals("apk")){ /*android.permission.INSTALL_PACKAGES*/ type="application/vnd.android.package-archive"; } //elseif(end.equals("pptx")||end.equals("ppt")){ //type="application/vnd.ms-powerpoint"; //}elseif(end.equals("docx")||end.equals("doc")){ //type="application/vnd.ms-word"; //}elseif(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="*/*"; } returntype; }
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