SpringMVC学习总结(五)——SpringMVC文件上传例子

这是用的是SpringMVC-3.1.1、commons-fileupload-1.2.2和io-2.0.1

首先是web.xml

    <?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>

接下来是SpringMVC的配置文件upload-servlet.xml

    <?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/beans
                            http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
                            http://www.springframework.org/schema/mvc
                            http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd
                            http://www.springframework.org/schema/context
                            http://www.springframework.org/schema/context/spring-context-3.0.xsd">
        <context:component-scan base-package="com.jadyer"/>  

        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/jsp/"/>
            <property name="suffix" value=".jsp"/>
        </bean>  

        <!-- SpringMVC上传文件时，需要配置MultipartResolver处理器 -->
        <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
            <property name="defaultEncoding" value="UTF-8"/>
            <!-- 指定所上传文件的总大小不能超过200KB。注意maxUploadSize属性的限制不是针对单个文件，而是所有文件的容量之和 -->
            <property name="maxUploadSize" value="200000"/>
        </bean>  

        <!-- SpringMVC在超出上传文件限制时，会抛出org.springframework.web.multipart.MaxUploadSizeExceededException -->
        <!-- 该异常是SpringMVC在检查上传的文件信息时抛出来的，而且此时还没有进入到Controller方法中 -->
        <bean id="exceptionResolver" class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
            <property name="exceptionMappings">
                <props>
                    <!-- 遇到MaxUploadSizeExceededException异常时，自动跳转到/WEB-INF/jsp/error_fileupload.jsp页面 -->
                    <prop key="org.springframework.web.multipart.MaxUploadSizeExceededException">error_fileupload</prop>
                </props>
            </property>
        </bean>
    </beans>

下面是用于上传的表单页面//WEB-INF//jsp//user//add.jsp

    <%@ page language="java" pageEncoding="UTF-8"%>
    <form action="<%=request.getContextPath()%>/user/add" method="POST" enctype="multipart/form-data">
        username: <input type="text" name="username"/><br/>
        nickname: <input type="text" name="nickname"/><br/>
        password: <input type="password" name="password"/><br/>
        yourmail: <input type="text" name="email"/><br/>
        yourfile: <input type="file" name="myfiles"/><br/>
        yourfile: <input type="file" name="myfiles"/><br/>
        yourfile: <input type="file" name="myfiles"/><br/>
        <input type="submit" value="添加新用户"/>
    </form>

下面是上传成功后打印用户信息的页面//WEB-INF//jsp//user//list.jsp

    <%@ 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>

下面是上传文件内容过大时的提示页面//WEB-INF//jsp//error_fileupload.jsp

<%@ page language="java" pageEncoding="UTF-8"%>
<h1>文件过大，请重新选择</h1>

接下来是用到的实体类User.java

    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;
        }
    }

最后是核心的UserController.java

    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";
        }
    }

补充：记得建立这个目录，用于存放上传的文件，即//WEB-INF//upload//