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;
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持毛票票。