JSP的文件上传和下载

来源：互联网发布：2017年四川省大数据编辑：程序博客网时间：2024/06/05 08:37

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP '1.jsp' starting page</title>    <meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">-->  </head>    <body> <form enctype="multipart/form-data" action="<%=path %>/2.jsp" method="post">    文件名：<input  type="text" name="uname"/>   选择图片： <input  type="file"  name="myfile"/>   <input type="submit" value="提交"/>    </form>   <a href="Servlet?filename=/s.jpg ">下载文件</a>  ${errorResult}   </body></html>文件上传必须使用type="file"这个类型的

<%@page import="org.apache.commons.fileupload.FileItemFactory"%><%@page import="java.io.File"%><%@page import="org.apache.commons.fileupload.FileItem"%><%@page import="org.apache.commons.fileupload.disk.DiskFileItemFactory"%><%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@page import="org.apache.commons.fileupload.servlet.ServletFileUpload"%>
 <% 
   //解决乱码问题
   request.setCharacterEncoding("utf-8");
   //判断请求信息中的内容是否是"multipart/form-data"类型
   boolean flag=ServletFileUpload.isMultipartContent(request);
   if(flag){
   //找到一个解析器，解析请求中的各个项目
   //工厂参数是一个接口，用他的实现类
   FileItemFactory  factory=new DiskFileItemFactory();
   //如果要解析，必须借助工厂参数
   ServletFileUpload  upload=new  ServletFileUpload(factory);
   //使用parseRequest  返回一个类型为FileItem的list集合
   List<FileItem> list=upload.parseRequest(request);
   //每一个fileitem都代表一个表单元素
   //使用迭代器迭代
   Iterator<FileItem>  iter=list.iterator();
   //使用while循环进行逐项迭代
   //iter.hasNext()判断下一个有没有元素
   while(iter.hasNext()){
   //如果下一个不为空
      FileItem  item= iter.next();
      if(item!=null){
      //对当前item进行判断看是普通的还是上传用的
      boolean bool=item.isFormField();
      if(bool){//证明是普通表单
      //获取该表单的value
      String name=item.getFieldName();//返回表单元素的name值
      if(name.equals("uname")){
      out.print(item.getString("utf-8"));
      }
      }else{//是一个上传文件域
      String  fname=item.getName();//上传文件域的文件名
      //扔到服务器目录下
      String path="/upload/";//文件上传不能使用相对路径
      //转换为绝对路径
      path=this.getServletContext().getRealPath(path);
      //构建一个file对象,借助File对象的getname方法
      File file=new File(fname);
      //构建一个file对象  第一个参数父路径    第二个参数子路径  
      File ffile=new File(path,file.getName());
      item.write(ffile);
      out.print("上传成功");
      }
      }
   }
   }
   %>

这里是文件上传

下面是文件下载

package cn.happy;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.sun.corba.se.spi.orbutil.fsm.Input;public class Servlet extends HttpServlet {/**苏小白 */public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}/**苏小白 */public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {String path=getServletContext().getRealPath("/")+"/upload/";String filename=request.getParameter("filename");File file=new File(path+filename);if(file!=null){response.setContentType("application/x-msdownload");response.setHeader("Content-Disposition", "attachment;filefilename=\""+filename+"\"");InputStream inputStream=new FileInputStream(file);ServletOutputStream sops=response.getOutputStream();byte b[]=new byte[1024];int n;while((n=inputStream.read(b))!=-1){sops.write(b,0,n);}sops.close();inputStream.close();}else{request.setAttribute("errorResult", "文件不存在或加载失败");request.getRequestDispatcher("/1.jsp").forward(request, response);}}}

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