【常用代码】文件下载(http方式)

package org.codepackage.fileimport java.io.BufferedReader;import java.io.File;import java.io.FileReader;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class for Servlet: Downfile * */ public class Downfile extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet { static final long serialVersionUID = 1L; /* (non-Java-doc) * @see javax.servlet.http.HttpServlet#HttpServlet() */public Downfile() {super();} /* (non-Java-doc) * @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubdoprocess(request,response);} /* (non-Java-doc) * @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubdoprocess(request,response);} private void doprocess(HttpServletRequest request, HttpServletResponse response) throws IOException{// 实现文件下载String aa=request.getParameter("file");String fileName=new String(aa.getBytes("ISO-8859-1"),"UTF-8");// 解决href传入参数中含有中文，乱码的问题File file=new File(fileName); PrintWriter out=response.getWriter();if(!file.exists()){ // 文件不存在fileName=response.encodeURL(new String(fileName.getBytes(),"ISO8859_1"));out.write("<mce:script type="text/javascript"><!--alert('"+fileName+" "+response.encodeURL(new String("不存在".getBytes(),"ISO8859_1"))+"');window.location.href='AllFiles.do';// --></mce:script>");}else{fileName=response.encodeURL(new String(fileName.getBytes(),"ISO8859_1"));//转码，解决文件名中有中文出现无法下载的情况response.setHeader("Content-Disposition", "attachment; filename=/""+fileName+"/""); response.setContentType("application/octet-stream"); response.setCharacterEncoding("utf-8"); FileReader fileReader = new FileReader(file); BufferedReader br=new BufferedReader(fileReader);String str=br.readLine();while(str!=null){out.write(str+"/n");str=br.readLine();}}out.flush();out.close();return;}}