# 文件上传

其实，进度条不用后端实现，很多前端的组件可以加载进度条。

1. pom.xml 增加

   <!--添加文件上传支持-->
   <dependency>
       <groupId>commons-io</groupId>
       <artifactId>commons-io</artifactId>
       <version>2.4</version>
   </dependency>
   <dependency>
       <groupId>commons-fileupload</groupId>
       <artifactId>commons-fileupload</artifactId>
       <version>1.3.1</version>
   </dependency>
   

2. 新建进程类Progress

   @Data
   @Builder
   @NoArgsConstructor
   @AllArgsConstructor
   public class Progress {
       private long bytesRead; //已读取文件的比特数
       private long contentLength;//文件总比特数
       private long items; //正读的第几个文件
   }
   

3. 进程监听器FileUploadProgressListener

   @Component
   public class FileUploadProgressListener implements ProgressListener {
       private HttpSession session;
       public void setSession(HttpSession session){
           this.session=session;
           Progress status = new Progress();//保存上传状态
           session.setAttribute("status", status);
       }
       @Override
       public void update(long bytesRead, long contentLength, int items) {
           Progress status = (Progress) session.getAttribute("status");
           status.setBytesRead(bytesRead);
           status.setContentLength(contentLength);
           status.setItems(items);
       }
   }
   

4. 自定义文件解析器

   public class CustomMultipartResolver extends CommonsMultipartResolver {
       // 注入第二步写的FileUploadProgressListener
       @Autowired
       private FileUploadProgressListener progressListener;
   
       public void setFileUploadProgressListener(FileUploadProgressListener progressListener){
           this.progressListener = progressListener;
       }
   
       @Override
       public MultipartParsingResult parseRequest(HttpServletRequest request) throws MultipartException {
           String encoding = determineEncoding(request);
           FileUpload fileUpload = prepareFileUpload(encoding);
           //fileUpload.setFileSizeMax(1024 * 1024 * 500);// 单个文件最大500M
           //fileUpload.setSizeMax(1024 * 1024 * 500);// 一次提交总文件最大500M
           progressListener.setSession(request.getSession());// 问文件上传进度监听器设置session用于存储上传进度
           fileUpload.setProgressListener(progressListener);// 将文件上传进度监听器加入到 fileUpload 中
           try{
               List<FileItem> fileItems = ((ServletFileUpload) fileUpload).parseRequest(request);
               return parseFileItems(fileItems, encoding);
           } catch (FileUploadBase.SizeLimitExceededException ex) {
               throw new MaxUploadSizeExceededException(fileUpload.getSizeMax(), ex);
           } catch (FileUploadException ex){
               throw new MultipartException("Could not parse multipart servlet request", ex);
           }
       }
   }
   
   

5. 启动类排除加载配置MultipartAutoConfiguration，同时注入 MultipartResolver

   @SpringBootApplication(exclude = MultipartAutoConfiguration.class)
   @MapperScan("com.dao")
   @EnableAspectJAutoProxy(exposeProxy = true)
   public class SpringBootMybatisApplication {
   
       public static void main(String[] args) {
           SpringApplication.run(SpringBootMybatisApplication.class, args);
       }
   
       @Bean(name = "multipartResolver")
       public MultipartResolver multipartResolver() {
           return new CustomMultipartResolver();
       }
   }
   

6. yml 增加

   spring:    
     session:
       store-type: redis
       redis:
         flush-mode: immediate
   

   Apache Commons FileUpload 组件上传文件时总是返回 null

   Spring Boot中有默认的文件上传组件，在使用ServletFileUpload时需要关闭Spring Boot的默认配置 。

   spring.http.multipart.enabled=false // 1.x

   spring.servlet.multipart.enabled=false // 2.x

7. 控制器

       @PostMapping("/upload")
       public String upload(MultipartFile file) throws IOException {
           // 获取文件名
           String fileName = file.getOriginalFilename();// 文件上传后的路径
           String filePath = "D:/package_test/" + fileName;
           File saveFile = new File(filePath);
           if (!saveFile.getParentFile().exists()) {
               saveFile.getParentFile().mkdirs();
           }
   
           Path path = Paths.get(filePath);
           Files.copy(file.getInputStream(), Paths.get(filePath), new StandardCopyOption[]{StandardCopyOption.REPLACE_EXISTING});
   //        Files.write(path, file.getBytes(), StandardOpenOption.SPARSE);
           return filePath;
       }
   
   
       @GetMapping("getPercent")
       public Integer getUploadPercent(HttpServletRequest request) {
           HttpSession session = request.getSession();
           Progress status = (Progress) session.getAttribute("status");
           logger.info("{}", (int)(status.getBytesRead() * 100.0 / status.getContentLength()));
           int percent = status == null ? 0 : (int) (status.getBytesRead() * 100.0 / status.getContentLength());
           return percent;
       }
   
   
       /**
        * 重置上传进度 前端调用进度之前调用此接口
        *
        * @param request
        * @return void
        */
       @PostMapping("resetPercent")
       public Boolean resetPercent(HttpServletRequest request) {
           HttpSession session = request.getSession();
           session.removeAttribute("status");
           return true;
       }