1、文件上传

从浏览器向客户端上传的过程

1.1表单准备

<form th:action="@{/fileup}" method="post" enctype="multipart/form-data">文件上传：<input type="file" name="fileName"><br><input type="submit" value="上传">
</form>

1. POST请求
2. 必须设置 表单属性enctype=“multipart/form-data” 默认是application/x-www-form-urlencoded

web.xml中配置

Spring6需要进行此配置

<servlet><servlet-name>springmvc</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:springmvc.xml</param-value></init-param><load-on-startup>1</load-on-startup><multipart-config><!--设置单个支持最大文件的大小--><max-file-size>102400</max-file-size><!--设置整个表单所有文件上传的最大值--><max-request-size>1024000</max-request-size><!--设置最小上传文件大小--><file-size-threshold>0</file-size-threshold></multipart-config></servlet><servlet-mapping><servlet-name>springmvc</servlet-name><url-pattern>/</url-pattern></servlet-mapping>

1.2 控制器代码

  @PostMapping("/fileup")@ResponseBodypublic String fileUp(@RequestParam("fileName") MultipartFile multipartFile,HttpServletRequest request) throws IOException {String name = multipartFile.getName();  // 获取的是参数的名字 fileNameString originalFilename = multipartFile.getOriginalFilename();  // 获取的是文件真实的名字// 输入流InputStream in = multipartFile.getInputStream();    // 输入流，负责读客服端的文件BufferedInputStream bis = new BufferedInputStream(in);// 输出流ServletContext application = request.getServletContext();String realPath = application.getRealPath("/upload");File file = new File(realPath);System.out.println(realPath);if (!file.exists()){file.mkdirs();}File destFile = new File(file.getAbsolutePath() + "/" + UUID.randomUUID().toString() + originalFilename.substring(originalFilename.lastIndexOf(".")));BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(destFile));// 一边读一边写byte [] bytes = new byte[1024 * 10];int readCount = 0;while ((readCount = bis.read(bytes)) != -1){bos.write(bytes,0,readCount);}bos.flush();bos.close();bis.close();}

2. 文件下载

2.1 下载链接

<a th:href="@{/download}">文件下载</a>

2.1 对应控制器

@GetMapping("/download")
public ResponseEntity<byte[]> downloadFile(HttpServletResponse response, HttpServletRequest request) throws IOException {File file = new File(request.getServletContext().getRealPath("/upload") + "/avatar2.jpg");// 创建响应头对象HttpHeaders headers = new HttpHeaders();// 设置响应内容类型headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);// 设置下载文件的名称headers.setContentDispositionFormData("attachment", file.getName());// 下载文件ResponseEntity<byte[]> entity = new ResponseEntity<byte[]>(Files.readAllBytes(file.toPath()), headers, HttpStatus.OK);return entity;
}