SpringMVC中的文件上傳

這是用的是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>

接下來是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上傳文件時，需要配置MultipartResolver處理器 -->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="UTF-8"/>
        <!-- 指定所上傳文件的總大小不能超過200KB。注意maxUploadSize屬性的限制不是針對單個文件，而是所有文件的容量之和 -->
        <property name="maxUploadSize" value="200000"/>
    </bean>

    <!-- SpringMVC在超出上傳文件限制時，會拋出org.springframework.web.multipart.MaxUploadSizeExceededException -->
    <!-- 該異常是SpringMVC在檢查上傳的文件信息時拋出來的，而且此時還沒有進入到Controller方法中 -->
    <bean id="exceptionResolver" class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
        <property name="exceptionMappings">
            <props>
                <!-- 遇到MaxUploadSizeExceededException異常時，自動跳轉到/WEB-INF/jsp/error_fileupload.jsp頁面 -->
                <prop key="org.springframework.web.multipart.MaxUploadSizeExceededException">error_fileupload</prop>
            </props>
        </property>
    </bean>
</beans>

下面是用於上傳的表單頁面//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="添加新用戶"/>
</form>

下面是上傳成功後打印用戶信息的頁面//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">編輯</a>
        <a href="<%=request.getContextPath()%>/user/${user.value.username}/delete">刪除</a>
    <br/>
</c:forEach>
<br/>
<a href="<%=request.getContextPath()%>/user/add">繼續添加用戶</a>

下面是上傳文件內容過大時的提示頁面//WEB-INF//jsp//error_fileupload.jsp

<%@ page language="java" pageEncoding="UTF-8"%>
<h1>文件過大，請重新選擇</h1>

接下來是用到的實體類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;
    /*==四個屬性的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;
    }
}

最後是核心的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中的文件上傳
 * @see 第一步：由於SpringMVC使用的是commons-fileupload實現，故將其組件引入項目中
 * @see       這裏用到的是commons-fileupload-1.2.2.jar和commons-io-2.0.1.jar
 * @see 第二步：在####-servlet.xml中配置MultipartResolver處理器。可在此加入對上傳文件的屬性限制
 * @see 第三步：在Controller的方法中添加MultipartFile參數。該參數用於接收表單中file組件的內容
 * @see 第四步：編寫前臺表單。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>();

    //模擬數據源,構造初始數據
    public UserController(){
        users.put("張起靈", new User("張起靈", "悶油瓶", "02200059", "[email protected]"));
        users.put("李尋歡", new User("李尋歡", "李探花", "08866659", "[email protected]"));
        users.put("拓拔野", new User("拓拔野", "搜神記", "05577759", "[email protected]"));
        users.put("孫悟空", new User("孫悟空", "美猴王", "03311159", "[email protected]"));
    }

    @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{
        //如果只是上傳一個文件，則只需要MultipartFile類型接收文件即可，而且無需顯式指定@RequestParam註解
        //如果想上傳多個文件，那麼這裏就要用MultipartFile[]類型來接收文件，並且還要指定@RequestParam註解
        //並且上傳多個文件時，前臺表單中的所有<input type="file"/>的name都應該是myfiles，否則參數裏的myfiles無法獲取到所有上傳的文件
        for(MultipartFile myfile : myfiles){
            if(myfile.isEmpty()){
                System.out.println("文件未上傳");
            }else{
                System.out.println("文件長度: " + myfile.getSize());
                System.out.println("文件類型: " + myfile.getContentType());
                System.out.println("文件名稱: " + myfile.getName());
                System.out.println("文件原名: " + myfile.getOriginalFilename());
                System.out.println("========================================");
                //如果用的是Tomcat服務器，則文件會上傳到\\%TOMCAT_HOME%\\webapps\\YourWebProject\\WEB-INF\\upload\\文件夾中
                String realPath = request.getSession().getServletContext().getRealPath("/WEB-INF/upload");
                //這裏不必處理IO流關閉的問題，因爲FileUtils.copyInputStreamToFile()方法內部會自動把用到的IO流關掉，我是看它的源碼才知道的
                FileUtils.copyInputStreamToFile(myfile.getInputStream(), new File(realPath, myfile.getOriginalFilename()));
            }
        }
        users.put(user.getUsername(), user);
        return "redirect:/user/list";
    }
}

補充：記得建立這個目錄，用於存放上傳的文件，即//WEB-INF//upload//