Java文件上传之SpringMVC实例

2023-07-30 14:28:22

一、配置文件

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>

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>

二、后端代码如下：

实体类User.java

package com.jadyer.model;

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;
}
}

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="****"/>
*/
@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";
}
}

三、前端代码

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>

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