SpringMVC中的文件上传

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
  xmlns="http://java.sun.com/xml/ns/javaee" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
  http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <servlet>
    <servlet-name>upload</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>upload</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
  <filter>
    <filter-name>SpringCharacterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>SpringCharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  <welcome-file-list>
    <welcome-file>/WEB-INF/jsp/user/add.jsp</welcome-file>
  </welcome-file-list>
</web-app>

<%@ page language="java" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<c:forEach items="${users}" var="user">
  ${user.value.username}----${user.value.nickname}----${user.value.password}----${user.value.email}
      <a href="<%=request.getContextPath()%>/user/${user.value.username}">查看</a>
      <a href="<%=request.getContextPath()%>/user/${user.value.username}/update">编辑</a>
      <a href="<%=request.getContextPath()%>/user/${user.value.username}/delete">删除</a>
  <br/>
</c:forEach>
<br/>
<a href="<%=request.getContextPath()%>/user/add">继续添加用户</a>

package com.jadyer.model;
/**
 * User
 * @author 宏宇
 * @create May 12, 2012 1:24:43 AM
 */
public class User {
  private String username;
  private String nickname;
  private String password;
  private String email;
  /*==四个属性的getter()、setter()略==*/
  public User() {}
  public User(String username, String nickname, String password, String email) {
    this.username = username;
    this.nickname = nickname;
    this.password = password;
    this.email = email;
  }
}

package com.jadyer.controller;
import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.io.FileUtils;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;
import com.jadyer.model.User;
/**
 * SpringMVC中的文件上传
 * @see 第一步：由于SpringMVC使用的是commons-fileupload实现，故将其组件引入项目中
 * @see       这里用到的是commons-fileupload-1.2.2.jar和commons-io-2.0.1.jar
 * @see 第二步：在####-servlet.xml中配置MultipartResolver处理器。可在此加入对上传文件的属性限制
 * @see 第三步：在Controller的方法中添加MultipartFile参数。该参数用于接收表单中file组件的内容
 * @see 第四步：编写前台表单。注意enctype="multipart/form-data"以及<input type="file" name="****"/>
 * @author 宏宇
 * @create May 12, 2012 1:26:21 AM
 */
@Controller
@RequestMapping("/user")
public class UserController {
  private final static Map<String,User> users = new HashMap<String,User>();
  //模拟数据源,构造初始数据
  public UserController(){
    users.put("张起灵", new User("张起灵", "闷油瓶", "02200059", "menyouping@yeah.net"));
    users.put("李寻欢", new User("李寻欢", "李探花", "08866659", "lixunhuan@gulong.cn"));
    users.put("拓拔野", new User("拓拔野", "搜神记", "05577759", "tuobaye@manhuang.cc"));
    users.put("孙悟空", new User("孙悟空", "美猴王", "03311159", "sunhouzi@xiyouji.zh"));
  }
  @RequestMapping("/list")
  public String list(Model model){
    model.addAttribute("users", users);
    return "user/list";
  }
  @RequestMapping(value="/add", method=RequestMethod.GET)
  public String addUser(){
    return "user/add";
  }
  @RequestMapping(value="/add", method=RequestMethod.POST)
  public String addUser(User user, @RequestParam MultipartFile[] myfiles, HttpServletRequest request) throws IOException{
    //如果只是上传一个文件，则只需要MultipartFile类型接收文件即可，而且无需显式指定@RequestParam注解
    //如果想上传多个文件，那么这里就要用MultipartFile[]类型来接收文件，并且还要指定@RequestParam注解
    //并且上传多个文件时，前台表单中的所有<input type="file"/>的name都应该是myfiles，否则参数里的myfiles无法获取到所有上传的文件
    for(MultipartFile myfile : myfiles){
      if(myfile.isEmpty()){
        System.out.println("文件未上传");
      }else{
        System.out.println("文件长度: " + myfile.getSize());
        System.out.println("文件类型: " + myfile.getContentType());
        System.out.println("文件名称: " + myfile.getName());
        System.out.println("文件原名: " + myfile.getOriginalFilename());
        System.out.println("========================================");
        //如果用的是Tomcat服务器，则文件会上传到\\%TOMCAT_HOME%\\webapps\\YourWebProject\\WEB-INF\\upload\\文件夹中
        String realPath = request.getSession().getServletContext().getRealPath("/WEB-INF/upload");
        //这里不必处理IO流关闭的问题，因为FileUtils.copyInputStreamToFile()方法内部会自动把用到的IO流关掉，我是看它的源码才知道的
        FileUtils.copyInputStreamToFile(myfile.getInputStream(), new File(realPath, myfile.getOriginalFilename()));
      }
    }
    users.put(user.getUsername(), user);
    return "redirect:/user/list";
  }
}