springMVC文件上传下载

时间 2019-12-11

原文原文链接

springmvc为文件上传提供了直接的会吃，这种支持是用即插即用的MutipartResolver实现的。springmvc使用Apache Commons FileUpload技术实现了一个MutipartResolver的实现类，CommonMultipartResolver。所以，SpringMVC的文件上传还须要依赖Apache Common FileUpload的组件

依赖的jar包html

<dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>4.2.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>4.2.5.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-asl</artifactId>
            <version>1.9.13</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.3.3</version>
        </dependency>

实例代码
uploadForm.jspjava

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>文件上传</title>
</head>
<body>
    <h2>文件上传</h2>
    <form action="upload" enctype="multipart/form-data" method="post">
        <table>
            <tr>
                <td>文件描述:</td>
                <td><input type="text" name="description"></td>
            </tr>
            <tr>
                <td>请选择文件:</td>
                <td><input type="file" name="file"></td>
            </tr>
            <tr>
                <td><input type="submit" value="上传"></td>
            </tr>
        </table>
    </form>
</body>
</html>

负责上传文件的表单的编码类型必须是“Multipart/form-data”
FileUploadController.javaweb

package com.rookie.bigdata.controller;

import com.rookie.bigdata.domain.User;
import org.apache.commons.io.FileUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletRequest;
import java.io.File;

/**
 * Created by dell on 2019/6/16.
 */

@Controller
public class FileUploadController {

    @RequestMapping(value = "/{formName}")
    public String loginForm(@PathVariable String formName) {
        //动态条状页面
        return formName;
    }
    // 上传文件会自动绑定到MultipartFile中
    @RequestMapping(value="/upload",method= RequestMethod.POST)
    public String upload(HttpServletRequest request,
                         @RequestParam("description") String description,
                         @RequestParam("file") MultipartFile file) throws Exception {

        System.out.println("执行了该方法" + description);
        //判断文件是否为空
        if (!file.isEmpty()) {
            //获取文件的路径
            String path = request.getServletContext().getRealPath("content");
            //获取上传文件名
            String filename = file.getOriginalFilename();

            File filePath = new File(path, filename);
            //判断路径是否存在，不存在就建立一个
            if (!filePath.getParentFile().exists()) {
                filePath.getParentFile().mkdirs();
            }

            file.transferTo(new File(path + File.separator + filename));

            return "success";
        } else {
            return "error";
        }
    }
    @RequestMapping(value="/register")
    public String register(HttpServletRequest request,
                           @ModelAttribute User user,
                           Model model)throws Exception{
        System.out.println(user.getUsername());
        // 若是文件不为空，写入上传路径
        if(!user.getImage().isEmpty()){
            // 上传文件路径
            String path = request.getServletContext().getRealPath(
                    "/content/");
            // 上传文件名
            String filename = user.getImage().getOriginalFilename();
            File filepath = new File(path,filename);
            // 判断路径是否存在，若是不存在就建立一个
            if (!filepath.getParentFile().exists()) {
                filepath.getParentFile().mkdirs();
            }
            // 将上传文件保存到一个目标文件当中
            user.getImage().transferTo(new File(path+File.separator+ filename));
            // 将用户添加到model
            model.addAttribute("user", user);
            return "userInfo";
        }else{
            return "error";
        }
    }

    @RequestMapping(value="/download")
    public ResponseEntity<byte[]> download(HttpServletRequest request,
                                           @RequestParam("filename") String filename,
                                           Model model)throws Exception{
        // 下载文件路径
        String path = request.getServletContext().getRealPath(
                "/content/");
        File file = new File(path+File.separator+ filename);
        HttpHeaders headers = new HttpHeaders();
        // 下载显示的文件名，解决中文名称乱码问题
        String downloadFielName = new String(filename.getBytes("UTF-8"),"iso-8859-1");
        // 通知浏览器以attachment（下载方式）打开图片
        headers.setContentDispositionFormData("attachment", downloadFielName);
        // application/octet-stream ： 二进制流数据（最多见的文件下载）。
        headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        // 201 HttpStatus.CREATED
        return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),
                headers, HttpStatus.CREATED);
    }


}

springmvc会将上传的文件绑定到MultipartFile对象中，MultipartFile提供了获取上传文件内容，文件名等方法，经过transferTo()方法将文件存储到磁盘中
springmvc-config.xml文件spring

<?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:p="http://www.springframework.org/schema/p"
    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-4.2.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd     
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.2.xsd">
        
    <context:component-scan base-package="com.rookie.bigdata.controller"/>
    
    <!-- 视图解析器  -->
     <bean id="viewResolver"
          class="org.springframework.web.servlet.view.InternalResourceViewResolver"> 
        <!-- 前缀 -->
        <property name="prefix">
            <value>/WEB-INF/content/</value>
        </property>
        <!-- 后缀 -->
        <property name="suffix">
            <value>.jsp</value>
        </property>
    </bean>
    
   <bean id="multipartResolver"  
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver">  
        <!-- 上传文件大小上限，单位为字节（10MB） -->
        <property name="maxUploadSize">  
            <value>10485760</value>  
        </property>  
        <!-- 请求的编码格式，必须和jSP的pageEncoding属性一致，以便正确读取表单的内容，默认为ISO-8859-1 -->
        <property name="defaultEncoding">
            <value>UTF-8</value>
        </property>
    </bean>
    
</beans>

用户点击进行文件上传就能够了
apache

二、使用对象接受文件
registerForm.jspjson

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>用户注册</title>
</head>
<body>
    <h2>用户注册</h2>
    <form action="register" enctype="multipart/form-data" method="post">
        <table>
            <tr>
                <td>用户名:</td>
                <td><input type="text" name="username"></td>
            </tr>
            <tr>
                <td>请上传头像:</td>
                <td><input type="file" name="image"></td>
            </tr>
            <tr>
                <td><input type="submit" value="注册"></td>
            </tr>
        </table>
    </form>
</body>
</html>

User.javaapi

public class User implements Serializable {

    private String username;
    private MultipartFile image;

输入用户名并选择上传文件头像，点击注册按钮上传用户头像进入到下载页面
浏览器

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>文件下载</title>
</head>
<body>
<h3>文件下载</h3>
<a href="download?filename=${requestScope.user.image.originalFilename}">
${requestScope.user.image.originalFilename }
</a>
</body>
</html>

进入到下载页面点击下载便可spring-mvc