SpringBoot非官方教程 | 第十七篇：上传文件

谁借莪１个温暖的怀抱￠ 2022-06-16 00:23 194阅读 0赞

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> 本文出自[方志朋的博客][Link 1]

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这篇文章主要介绍，如何在springboot工程作为服务器，去接收通过http 上传的multi-file的文件。

## 构建工程 ##

为例创建一个springmvc工程你需要spring-boot-starter-thymeleaf和 spring-boot-starter-web的起步依赖。为例能够上传文件在服务器，你需要在web.xml中加入标签做相关的配置，但在sringboot 工程中，它已经为你自动做了，所以不需要你做任何的配置。

<dependencies>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-web</artifactId>
    		</dependency>
    
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-test</artifactId>
    			<scope>test</scope>
    		</dependency>
    
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-thymeleaf</artifactId>
    		</dependency>
    	</dependencies>

## 创建文件上传controller ##

直接贴代码：

@Controller
    public class FileUploadController {
    
        private final StorageService storageService;
    
        @Autowired
        public FileUploadController(StorageService storageService) {
            this.storageService = storageService;
        }
    
        @GetMapping("/")
        public String listUploadedFiles(Model model) throws IOException {
    
            model.addAttribute("files", storageService
                    .loadAll()
                    .map(path ->
                            MvcUriComponentsBuilder
                                    .fromMethodName(FileUploadController.class, "serveFile", path.getFileName().toString())
                                    .build().toString())
                    .collect(Collectors.toList()));
    
            return "uploadForm";
        }
    
        @GetMapping("/files/{filename:.+}")
        @ResponseBody
        public ResponseEntity<Resource> serveFile(@PathVariable String filename) {
    
            Resource file = storageService.loadAsResource(filename);
            return ResponseEntity
                    .ok()
                    .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\""+file.getFilename()+"\"")
                    .body(file);
        }
    
        @PostMapping("/")
        public String handleFileUpload(@RequestParam("file") MultipartFile file,
                                       RedirectAttributes redirectAttributes) {
    
            storageService.store(file);
            redirectAttributes.addFlashAttribute("message",
                    "You successfully uploaded " + file.getOriginalFilename() + "!");
    
            return "redirect:/";
        }
    
        @ExceptionHandler(StorageFileNotFoundException.class)
        public ResponseEntity handleStorageFileNotFound(StorageFileNotFoundException exc) {
            return ResponseEntity.notFound().build();
        }
    
    }

这个类通过@Controller注解，表明自己上一个Spring mvc的c。每个方法通过  
@GetMapping 或者@PostMapping注解表明自己的 http方法。

*  GET / 获取已经上传的文件列表
 *  GET /files/\{filename\} 下载已经存在于服务器的文件
 *  POST / 上传文件给服务器

## 创建一个简单的 html模板 ##

为了展示上传文件的过程，我们做一个界面：  
在src/main/resources/templates/uploadForm.html

<html xmlns:th="http://www.thymeleaf.org">
    <body>
    
    	<div th:if="${message}">
    		<h2 th:text="${message}"/>
    	</div>
    
    	<div>
    		<form method="POST" enctype="multipart/form-data" action="/">
    			<table>
    				<tr><td>File to upload:</td><td><input type="file" name="file" /></td></tr>
    				<tr><td></td><td><input type="submit" value="Upload" /></td></tr>
    			</table>
    		</form>
    	</div>
    
    	<div>
    		<ul>
    			<li th:each="file : ${files}">
    				<a th:href="${file}" th:text="${file}" />
    			</li>
    		</ul>
    	</div>
    
    </body>
    </html>

## 上传文件大小限制 ##

如果需要限制上传文件的大小也很简单，只需要在springboot 工程的src/main/resources/application.properties 加入以下：

spring.http.multipart.max-file-size=128KB
    spring.http.multipart.max-request-size=128KB

## 测试 ##

测试情况如图：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9mb3JlenAuYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70]

## 参考资料 ##

[https://spring.io/guides/gs/uploading-files/][https_spring.io_guides_gs_uploading-files]

## 源码下载 ##

[https://github.com/forezp/SpringBootLearning][https_github.com_forezp_SpringBootLearning]

### 更多阅读 ###

[史上最简单的 SpringCloud 教程汇总][SpringCloud]

[SpringBoot教程汇总][SpringBoot]

[Java面试题系列汇总][Java]

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[Link 1]: https://www.fangzhipeng.com/
[https_www.fangzhipeng.com_springboot_2017_05_17_sb17-upload.html]: https://www.fangzhipeng.com/springboot/2017/05/17/sb17-upload.html
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9mb3JlenAuYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70]: /images/20220616/5f8762fc6f794dcaad9afd00777616cc.png
[https_spring.io_guides_gs_uploading-files]: https://spring.io/guides/gs/uploading-files/
[https_github.com_forezp_SpringBootLearning]: https://github.com/forezp/SpringBootLearning
[SpringCloud]: https://blog.csdn.net/forezp/article/details/70148833
[SpringBoot]: https://blog.csdn.net/forezp/article/details/70341818
[Java]: https://blog.csdn.net/forezp/article/details/85163411
[SouthEast]: /images/20220616/08a21de7e0e2405ebc2f8425a8342620.png
[Link 2]: https://www.fangzhipeng.com