SpringBoot实现注册时头像上传与下载

忘是亡心i 2023-10-17 22:21 11阅读 0赞

一、说明

1.为了能上传文件，必须将表单的method设置为POST,并将enctype设置为multipart/form-data。

2.SpringMVC为文件上传提供了直接的支持，这种支持是通过MultipartResolver实现的，SpringMVC使用Apache Commons FileUpload 技术实现了MultipartResolver实现类：CommonsMultipartResolver,因此SpringMVC的文件上传还需要依赖Commons FileUpload组件。

3.Spring Boot的spring-boot-starter-web已经集成了SpringMVC,所以使用SpringBoot完成文件上传更简单。

二、创建项目

1.创建一个Maven项目，命名为SpringBoot\_fileuploadtest,按照Maven项目的规范，src/main下新建一个resources的文件夹，再在此文件夹下新建static以及template两个文件夹。

2.修改pom.xml

主要是引入Apache Commons 依赖

由于不属于Spring Boot 所以要加上版本

代码：

<groupId>org.fkit</groupId>  
<artifactId>fileuploadtest</artifactId>  
<version>0.0.1-SNAPSHOT</version>  
<packaging>jar</packaging>

<name>fileuploadtest</name>  
<url>http://maven.apache.org</url>

<parent>  
<groupId>org.springframework.boot</groupId>  
<artifactId>spring-boot-starter-parent</artifactId>  
<version>2.0.0.RELEASE</version>  
<relativePath/>  
</parent>  
  
<properties>  
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>  
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>  
<java.version>1.8</java.version>  
</properties>

<dependencies>  
  
  
<dependency>  
<groupId>org.springframework.boot</groupId>  
<artifactId>spring-boot-starter-web</artifactId>  
</dependency>  
  
  
<dependency>  
<groupId>org.springframework.boot</groupId>  
<artifactId>spring-boot-starter-thymeleaf</artifactId>  
</dependency>  
  
  
<dependency>  
<groupId>commons-fileupload</groupId>  
<artifactId>commons-fileupload</artifactId>  
<version>1.3.3</version>  
</dependency>  
  
<dependency>  
<groupId>junit</groupId>  
<artifactId>junit</artifactId>  
<scope>test</scope>  
</dependency>  
</dependencies>  
</project>

三 、新建Index.html

<!DOCTYPE html>  
<html xmlns:th="[http://www.thymeleaf.org][http_www.thymeleaf.org]">  
<head>  
<meta charset="UTF-8"></meta>  
<title>文件上传下载示例</title>  
<link rel="stylesheet" th:href="@\{css/bootstrap.min.css\}" />  
<link rel="stylesheet" th:href="@\{css/bootstrap-theme.min.css\}"/>  
<script type="text/javascript" th:src="@\{js/jquery-1.11.0.min.js\}"></script>  
<script type="text/javascript" th:src="@\{js/bootstrap.min.js\}"></script>  
</head>  
<body>  
<div class="panel panel-primary">  
  
<div class="panel-heading">  
  
<h3 class="panel-title">文件上传下载示例：简单文件上传</h3>  
</div>  
</div>  
<div class="container">  
<div class="row">  
<div class="col-md-8">  
<form class="form-horizontal" action="upload" enctype="multipart/form-data" method="post">  
<div class="form-group">  
<div class="input-group col-md-4">  
<span class="input-group-addon"><i class="glyphicon glyphicon-pencil"></i></span>  
<input class="form-control" placeholder="文件描述" type="text" name="description" />  
</div>  
</div>  
<div class="form-group">  
<div class="input-group col-md-4">  
<span class="input-group-addon"><i class="glyphicon glyphicon-search"></i></span>  
<input class="form-control" placeholder="请选择文件" type="file" name="file"/>  
</div>  
</div>  
<div class="form-group">  
<div class="col-md-4">  
<div class="btn-group btn-group-justified" >  
<div class="btn-group" >  
<button type="submit" class="btn btn-success" id="submitbtn">  
<span class="glyphicon glyphicon-share"></span>&nbsp;文件上传</button>  
</div>  
</div>  
</div>  
</div>  
</form>  
</div>  
</div>  
</div>  
</body>  
</html>

四、新建FileUploadController

package com.ysh.fileuploadtest.controller;

import java.io.File;  
import java.net.URLEncoder;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.io.FileUtils;  
import org.springframework.http.MediaType;  
import org.springframework.http.ResponseEntity;  
import org.springframework.http.ResponseEntity.BodyBuilder;  
import org.springframework.stereotype.Controller;  
import org.springframework.ui.Model;  
import org.springframework.web.bind.annotation.ModelAttribute;  
import org.springframework.web.bind.annotation.PostMapping;  
import org.springframework.web.bind.annotation.RequestHeader;  
import org.springframework.web.bind.annotation.RequestMapping;  
import org.springframework.web.bind.annotation.RequestParam;  
import org.springframework.web.multipart.MultipartFile;

import com.ysh.fileuploadtest.domain.User;

@Controller  
public class FileUploadController \{

// 映射"/"请求  
@RequestMapping("/")  
public String index()\{  
// 根据Thymeleaf默认模板，将返回resources/templates/index.html  
return "index";  
\}

// 上传文件会自动绑定到MultipartFile中  
@PostMapping(value="/upload")  
public String upload(HttpServletRequest request,  
@RequestParam("description") String description,  
@RequestParam("file") MultipartFile file) throws Exception\{  
// 接收参数description  
System.out.println("description = " + description);  
// 如果文件不为空，写入上传路径  
if(!file.isEmpty())\{  
// 上传文件路径  
String path = request.getServletContext().getRealPath(  
"/upload/");  
System.out.println("path = " + path);  
// 上传文件名  
String filename = file.getOriginalFilename();  
File filepath = new File(path,filename);  
// 判断路径是否存在，如果不存在就创建一个  
if (!filepath.getParentFile().exists()) \{  
filepath.getParentFile().mkdirs();  
\}  
// 将上传文件保存到一个目标文件当中  
file.transferTo(new File(path+File.separator+ filename));  
return "success";  
\}else\{  
return "error";  
\}  
  
\}

附：

SpringMVC会将上传文件绑定到MultipartFile对象中，MultipartFile提供了获取上传文件的内容、文件名等方法，通过transferTo()方法还可以将文件存储到磁盘中

五、测试运行文件上传

启动App,输入：[http://localhost:8080/][http_localhost_8080]

文件上传页面

![70][]

选择文件后

![70 1][]

单击文件上传按钮，图片会被上传保存到项目的upload文件夹下，跳转到成功页面

![70 2][]

此时控制台会输出上传文件的描述信息和保存路径

![70 3][]

复制此路径，找到电脑上对应位置可以看到

![70 4][]

照片已经成功上传

六、使用对象方式接受上传文件

在实际项目中，很多时候上传的文件会作为对象的属性保存

registerForm.html:

<!DOCTYPE html>  
<html xmlns:th="[http://www.thymeleaf.org][http_www.thymeleaf.org]">  
<head>  
<meta charset="UTF-8"></meta>  
<title>文件上传下载示例</title>  
<link rel="stylesheet" th:href="@\{css/bootstrap.min.css\}" />  
<link rel="stylesheet" th:href="@\{css/bootstrap-theme.min.css\}"/>  
<script type="text/javascript" th:src="@\{js/jquery-1.11.0.min.js\}"></script>  
<script type="text/javascript" th:src="@\{js/bootstrap.min.js\}"></script>  
</head>  
<body>  
<div class="panel panel-primary">  
  
<div class="panel-heading">  
  
<h3 class="panel-title">文件上传下载示例：用户注册</h3>  
</div>  
</div>  
<div class="container">  
<div class="row">  
<div class="col-md-8">  
<form class="form-horizontal" action="register" enctype="multipart/form-data" method="post">  
<div class="form-group">  
<div class="input-group col-md-4">  
<span class="input-group-addon"><i class="glyphicon glyphicon-user"></i></span>  
<input class="form-control" placeholder="用户名" type="text" name="username" />  
</div>  
</div>  
<div class="form-group">  
<div class="input-group col-md-4">  
<span class="input-group-addon"><i class="glyphicon glyphicon-search"></i></span>  
<input class="form-control" placeholder="请选择头像" type="file" name="headPortrait"/>  
</div>  
</div>  
<div class="form-group">  
<div class="col-md-4">  
<div class="btn-group btn-group-justified" >  
<div class="btn-group" >  
<button type="submit" class="btn btn-success" id="submitbtn">  
<span class="glyphicon glyphicon-share"></span>&nbsp;注册</button>  
</div>  
</div>  
</div>  
</div>  
</form>  
</div>  
</div>  
</div>  
</body>  
</html>

这是一个用户注册页面，需要输入用户名和上传用户头像

User.java:

package com.ysh.fileuploadtest.domain;

import java.io.Serializable;  
import org.springframework.web.multipart.MultipartFile;

public class User implements Serializable\{  
  
private static final long serialVersionUID = 1L;  
  
private String username;  
// 对应上传的headPortrait，类型为MultipartFile，上传文件会自动绑定到image属性当中  
private MultipartFile headPortrait;  
  
public User() \{  
super();  
\}  
  
public String getUsername() \{  
return username;  
\}

public void setUsername(String username) \{  
this.username = username;  
\}

public MultipartFile getHeadPortrait() \{  
return headPortrait;  
\}  
public void setHeadPortrait(MultipartFile headPortrait) \{  
this.headPortrait = headPortrait;  
\}  
  
  
\}

User是对用户信息的封装，属性headPortrait对应页面html的file类型，类型为MultipartFile，上传文件会自动绑定到headPortrait属性中

FileUploadController中添加：

@RequestMapping("/registerForm")  
public String registerForm()\{  
return "registerForm";  
\}

@RequestMapping(value="/register")  
public String register(HttpServletRequest request,  
@ModelAttribute User user,  
Model model)throws Exception\{  
// 接收参数username  
System.out.println("username = " +user.getUsername());  
// 如果文件不为空，写入上传路径  
if(!user.getHeadPortrait().isEmpty())\{  
// 上传文件路径  
String path = request.getServletContext().getRealPath(  
"/upload/");  
System.out.println("path = " + path);  
// 上传文件名  
String filename = user.getHeadPortrait().getOriginalFilename();  
File filepath = new File(path,filename);  
// 判断路径是否存在，如果不存在就创建一个  
if (!filepath.getParentFile().exists()) \{  
filepath.getParentFile().mkdirs();  
\}  
// 将上传文件保存到一个目标文件当中  
user.getHeadPortrait().transferTo(new File(path+File.separator+ filename));  
// 将用户添加到model  
model.addAttribute("user", user);  
return "userInfo";  
\}else\{  
return "error";  
\}  
\}

register方法使用@ModelAttribute注解将表单参数绑定到User对象

html控件的username会保存到Use对象的username属性

html控件的headPortrait会保存到User对象的headPortrait属性，转换成MultipartFile类型

文件上传成功后将用户信息保存到model当中，跳转到userInfo.html

<!DOCTYPE html>  
<html xmlns:th="[http://www.thymeleaf.org][http_www.thymeleaf.org]">  
<head>  
<meta charset="UTF-8"></meta>  
<title>文件上传下载示例</title>  
<link rel="stylesheet" th:href="@\{css/bootstrap.min.css\}" />  
<link rel="stylesheet" th:href="@\{css/bootstrap-theme.min.css\}"/>  
<script type="text/javascript" th:src="@\{js/jquery-1.11.0.min.js\}"></script>  
<script type="text/javascript" th:src="@\{js/bootstrap.min.js\}"></script>  
</head>  
<body>  
<div class="panel panel-primary">  
  
<div class="panel-heading">  
  
<h3 class="panel-title">文件上传下载示例：文件下载</h3>  
</div>  
</div>  
<div class="container">  
<div class="panel panel-primary">  
  
<div class="panel-heading">  
  
<h3 class="panel-title">用户信息列表</h3>  
</div>  
<div class="panel-body">  
<div class="table table-responsive">  
<table class="table table-bordered table-hover" >  
<tbody class="text-center">  
<tr>  
<td><img th:src="@\{'upload/'+$\{user.headPortrait.originalFilename\}\}" height="30"/></td>  
<td th:text="$\{user.username\}">用户名</td>  
<td >  
<a th:href="@\{download(filename=$\{user.headPortrait.originalFilename \})\}">下载头像</a>  
</td>  
</tr>  
</tbody>  
</table>  
</div>  
</div>  
</div>  
</div>  
</body>  
</html>

userInfo显示用户信息。

七、再次运行APP的main方法

在浏览器输入：[http://localhost:8080/registerForm][http_localhost_8080_registerForm]

输入badao，选择头像后，单击注册，跳转到用户信息界面

![70 5][]

![70 6][]八、文件下载

单击上面的下载头像超链接，可以进入dowload控制器进行文件下载操作

文件下载，直接在页面上给出一个超链接，该链接的href属性等于要下载的文件名

SpringMVC提供了一个responseEntity类型，可以很方便地定义返回的HttpHeaders和HttpStatus。

FileUploadController中添加：

@RequestMapping(value="/download")  
public ResponseEntity<byte\[\]> download(HttpServletRequest request,  
@RequestParam("filename") String filename,  
@RequestHeader("User-Agent") String userAgent,  
Model model)throws Exception\{  
// 下载文件路径  
String path = request.getServletContext().getRealPath(  
"/upload/");  
// 构建File  
File file = new File(path+File.separator+ filename);  
// ok表示Http协议中的状态 200  
BodyBuilder builder = ResponseEntity.ok();  
// 内容长度  
builder.contentLength(file.length());  
// application/octet-stream ： 二进制流数据（最常见的文件下载）。  
builder.contentType(MediaType.APPLICATION\_OCTET\_STREAM);  
// 使用URLDecoder.decode对文件名进行解码  
filename = URLEncoder.encode(filename, "UTF-8");  
// 设置实际的响应文件名，告诉浏览器文件要用于【下载】、【保存】attachment 以附件形式  
// 不同的浏览器，处理方式不同，要根据浏览器版本进行区别判断  
if (userAgent.indexOf("MSIE") > 0) \{  
// 如果是IE，只需要用UTF-8字符集进行URL编码即可  
builder.header("Content-Disposition", "attachment; filename=" + filename);  
\} else \{  
// 而FireFox、Chrome等浏览器，则需要说明编码的字符集  
// 注意filename后面有个\*号，在UTF-8后面有两个单引号！  
builder.header("Content-Disposition", "attachment; filename\*=UTF-8''" + filename);  
\}  
return builder.body(FileUtils.readFileToByteArray(file));  
\}

使用ResponseEntity对象，可以很方便地定义返回的BodyBuilder、HttpHeaders、和HttpStatus。

BodyBuilder对象用来构建返回的Body;

HttpHeaders类型代表的是HTTP中的头信息；

HttpStatus代表的是HTTP中的状态

九、实现下载

单击下载页面的下载链接

![70 7][]

将其下载到桌面，此时在桌面上已经有这张图片了

![70 8][]

[http_maven.apache.org_POM_4.0.0]: http://maven.apache.org/POM/4.0.0
[http_www.w3.org_2001_XMLSchema-instance]: http://www.w3.org/2001/XMLSchema-instance
[http_maven.apache.org_xsd_maven-4.0.0.xsd]: http://maven.apache.org/xsd/maven-4.0.0.xsd
[http_www.thymeleaf.org]: http://www.thymeleaf.org/
[http_localhost_8080]: http://localhost:8080/
[70]: https://img-blog.csdn.net/20180711080230390?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 1]: https://img-blog.csdn.net/20180711080246785?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 2]: https://img-blog.csdn.net/20180711080324166?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 3]: https://img-blog.csdn.net/20180711080351241?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 4]: https://img-blog.csdn.net/2018071108041227?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[http_localhost_8080_registerForm]: http://localhost:8080/registerForm
[70 5]: https://img-blog.csdn.net/20180711080512905?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 6]: https://img-blog.csdn.net/2018071108053438?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 7]: https://img-blog.csdn.net/20180711080602726?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
[70 8]: https://img-blog.csdn.net/20180711080611724?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70