1.源码克隆：git clone https://github.com/spring-guides/gs-uploading-files.git
2.包含两个项目initial和complete，initial可以根据文档练习完善，complete是完整项目
3.功能描述：构建接受文件上传的应用程序，并且通过简单的 HTML 界面来测试文件上传下载

源码分析

1.POM依赖
<dependencies>
	<!--https://blog.csdn.net/tongxin_tongmeng/article/details/128396471-->
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-thymeleaf</artifactId>
	</dependency>
	<!--https://blog.csdn.net/tongxin_tongmeng/article/details/128397075-->
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-web</artifactId>
	</dependency>
	<!--https://blog.csdn.net/tongxin_tongmeng/article/details/128399703-->
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-test</artifactId>
		<scope>test</scope>
	</dependency>
</dependencies>

2.入口类
// https://blog.csdn.net/tongxin_tongmeng/article/details/128401278
@SpringBootApplication
// https://blog.csdn.net/tongxin_tongmeng/article/details/128401815
@EnableConfigurationProperties(StorageProperties.class)
public class UploadingFilesApplication {

	public static void main(String[] args) {
		SpringApplication.run(UploadingFilesApplication.class, args);
	}

    // https://blog.csdn.net/tongxin_tongmeng/article/details/128402169
	@Bean
	CommandLineRunner init(StorageService storageService) {
		return (args) -> {
			storageService.deleteAll();
			storageService.init();
		};
	}
}

3.控制器
@Controller
public class FileUploadController {

	private final StorageService storageService;

	// https://blog.csdn.net/tongxin_tongmeng/article/details/128402579
	@Autowired
	public FileUploadController(StorageService storageService) {
		this.storageService = storageService;
	}

	// https://blog.csdn.net/tongxin_tongmeng/article/details/128405403
	@GetMapping("/")
	public String listUploadedFiles(Model model) throws IOException {

		model.addAttribute("files", storageService.loadAll().map(
				path -> MvcUriComponentsBuilder.fromMethodName(FileUploadController.class,
						"serveFile", path.getFileName().toString()).build().toUri().toString())
				.collect(Collectors.toList()));

		return "uploadForm";
	}

	@GetMapping("/files/{filename:.+}")
	// https://blog.csdn.net/tongxin_tongmeng/article/details/128406009
	@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);
		// https://blog.csdn.net/tongxin_tongmeng/article/details/128406963
		redirectAttributes.addFlashAttribute("message",
				"You successfully uploaded " + file.getOriginalFilename() + "!");

		return "redirect:/";
	}

	// https://blog.csdn.net/tongxin_tongmeng/article/details/128406477
	@ExceptionHandler(StorageFileNotFoundException.class)
	public ResponseEntity<?> handleStorageFileNotFound(StorageFileNotFoundException exc) {
		return ResponseEntity.notFound().build();
	}

}