Java开发之文件下载，java文件下载, package

Java开发之文件下载，java文件下载, package

    package com.example.web;      import java.io.File;      import java.io.FileInputStream;      import java.io.IOException;      import java.io.InputStream;      import java.io.OutputStream;      import java.net.URLEncoder;      import javax.servlet.ServletException;      import javax.servlet.http.HttpServlet;      import javax.servlet.http.HttpServletRequest;      import javax.servlet.http.HttpServletResponse;      import org.apache.commons.io.IOUtils;      public class Download extends HttpServlet {          public void doGet(HttpServletRequest request, HttpServletResponse response)                  throws ServletException, IOException {              response.setContentType("text/html;charset=utf-8");              OutputStream out=response.getOutputStream();              //获取要下载的文件名              String fileName=request.getParameter("loadname");              fileName=new String(fileName.getBytes("ISO-8859-1"),"UTF-8");              //得到下载文件的路径              String storPath=getServletContext().getRealPath("WEB-INF/files");              //得到源文件名              String oldName=fileName.split("_")[1];              //进一步根据hashcode来确定子文件夹              String childPath=generateDir(storPath,fileName);              //判断要下载的文件是否还存在              File file=new File(storPath+File.separator+childPath+File.separator+fileName);              if(!file.exists()){                  out.write("你要下载的资源可能不存在".getBytes());              }else{                  //如果存在就进行下载操作                  InputStream is=new FileInputStream(file);                  //指明下载的响应头                  response.setHeader("Content-Disposition",                           "attachment;filename="+URLEncoder.encode(oldName,"UTF-8"));                  IOUtils.copy(is, out);                  is.close();              }          }          private String generateDir(String storePath, String fileName) {              int hashcode=fileName.hashCode();              int dir1=hashcode &  0xf;              int dir2=(hashcode & 0xf0)>>4;              String childPath=dir1+File.separator+dir2;              File file=new File(storePath,childPath);              if(!file.exists()){                  file.mkdirs();              }              return childPath;          }          public void doPost(HttpServletRequest request, HttpServletResponse response)                  throws ServletException, IOException {              this.doGet(request, response);          }      }