spring mvc 文件上传

jsp页面：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@taglib prefix="sf" uri="http://www.springframework.org/tags/form"%>
<%
    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 'add.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">

</head>

<body>
    <sf:form method="post" modelAttribute="user"
        enctype="multipart/form-data">
        
        file:<input type="file" name="files" />
        <br />
        file:<input type="file" name="files" />
        <br />
        file:<input type="file" name="files" />
        <br />
        <input type="submit" />
    </sf:form>
</body>
</html>

springmvc.xml配置：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc
     http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd
        http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans-4.1.xsd
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context-4.1.xsd">
    ...

    <!-- 文件上传配置 -->
    <bean id="multipartResolver"
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="maxUploadSize" value="50000000" />
    </bean>
    ...

</beans>

controller：

package com.stone.controller;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

import javax.servlet.http.HttpServletRequest;
import javax.validation.Valid;

import org.apache.commons.io.FileUtils;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.PathVariable;
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.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.SessionAttributes;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

import com.stone.model.User;

@Controller
@RequestMapping("/user")
@SessionAttributes("loginUser")
public class UserController {

    private final static Map<String, User> users = new HashMap<String, User>();

    public UserController() {
        users.put("ldh", new User("ldh", "刘德华", "123", "123@123.com"));
        users.put("zxy", new User("zxy", "张学友", "123", "123@123.com"));
        users.put("gfc", new User("gfc", "郭富城", "123", "123@123.com"));
        users.put("lm", new User("lm", "黎明", "123", "123@123.com"));
    }

    @RequestMapping("/users")
    public String list(Model model) {
        model.addAttribute("users", users);
        return "user/list";
    }

    @RequestMapping(value = "/add", method = RequestMethod.GET)
    public String add(Model model) {
        model.addAttribute(new User());
        return "user/add";
    }

    @RequestMapping(value = "/add", method = RequestMethod.POST)
    public String add(@RequestParam(required = false) MultipartFile[] files,
            HttpServletRequest req) throws IOException {
        
        for (MultipartFile file : files) {
            System.out.println(file.getContentType() + "," + file.getName()
                    + "," + file.getOriginalFilename());
            String realpath = req.getSession().getServletContext()
                    .getRealPath("/resources/upload/");
            System.out.println(realpath);
            if (!file.isEmpty()) {
                FileUtils.copyInputStreamToFile(
                        file.getInputStream(),
                        new File(realpath + File.separator
                                + new Random().nextInt()));
            }
        }

         
        return InternalResourceViewResolver.REDIRECT_URL_PREFIX + "/user/users";
    }

//如果是一个文件的话，使用这样的方式 
@RequestMapping(value = "/add", method = RequestMethod.POST)
    public String add( MultipartFile files,
            HttpServletRequest req) throws IOException {
            System.out.println(file.getContentType() + "," + file.getName()
                    + "," + file.getOriginalFilename());
            String realpath = req.getSession().getServletContext()
                    .getRealPath("/resources/upload/");
            System.out.println(realpath);
            if (!file.isEmpty()) {
                FileUtils.copyInputStreamToFile(
                        file.getInputStream(),
                        new File(realpath + File.separator
                                + new Random().nextInt()));
            }
     

         
        return InternalResourceViewResolver.REDIRECT_URL_PREFIX + "/user/users";
    }