jsp如何实现下载文件的功能.doc

jsp如何实现下载文件的功能
第一步：创建Servlet
第二步：写代码‍
publicclassFielDownLoadextendsHttpServlet{
/***Constructoroftheobject.*/publicFielDownLoad(){super();}
/***Destructionoftheservlet.<br>*/publicvoiddestroy(){super.destroy();//Justputs"destroy"stringinlog//Putyourcodehere}
/***ThedoGetmethodoftheservlet.<br>**Thismethodiscalledwhenaformhasitstagvaluemethodequalstoget.**@paramrequesttherequestsendbytheclienttotheserver*@paramresponsetheresponsesendbytheservertotheclient*@throwsServletExceptionifanerroroccurred*@throwsIOExceptionifanerroroccurred*/publicvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
doPost(request,response);}
/***ThedoPostmethodoftheservlet.<br>**Thismethodiscalledwhenaformhasitstagvaluemethodequalstopost.**@paramrequesttherequestsendbytheclienttotheserver*@paramresponsetheresponsesendbytheservertotheclient*@throwsServletExceptionifanerroroccurred*@throwsIOExceptionifanerroroccurred*/publicvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
Stringfilename=request.getParameter("file_name");if(filename==null)filename="";filename=filename.trim();
InputStreaminStream=null;Stringattchname="";
byte[]b=newbyte[100];intlen=0;try{attchname=getAttachName(filename);//取得附件的名称filename=getRealName(request,filename);//取得附件的全路径if(filename==null){response.setContentType("text/html;charset=GBK");response.getWriter().print("<spanstyle='color:red'>文件不存在,或者禁止下载!</span>");return;}attchname=toUtf8String(attchname);//将文件转码UTF-8inStream=newFileInputStream(filename);response.reset();//必须reset，否则会出现文件不完整SmartUploadsu=newSmartUpload();//新建一个SmartUpload对象su.initialize(this.getServletConfig(),request,response);//初始化//设定contentDisposition为null以禁止浏览器自动打开文件，//保证点击链接后是下载文件。若不设定，则下载的文件扩展名为//doc时，浏览器将自动用word打开它。扩展名为pdf时，//浏览器将用acrobat打开。su.setContentDisposition(null);su.downloadFile(filename);//下载文件//循环取出流中的数据while((len=inStream.read(b))>0){response.getOutputStream().write(b,0,len);}inStream.close();