Java文件上传实例并解决跨域问题

      Return the contents of the file as an array of bytes.

      Return the content type of the file.

      Return an InputStream to read the contents of the file from.

      Return the name of the parameter in the multipart form.

      Return the original filename in the client's filesystem.

      Return the size of the file in bytes.

      Return whether the uploaded file is empty, that is, either no file has been chosen in the multipart form or the chosen file has no content.

      Transfer the received file to the given destination file.

@Autowired
private UploadService uploadService;

@PostMapping("image")
public ResponseEntity<String> uploadImage(@RequestParam("file") MultipartFile file){
   String url= this.uploadService.uploadImage(file);
   if (StringUtils.isBlank(url)){
       return ResponseEntity.badRequest().build();
   }
    return ResponseEntity.status(HttpStatus.CREATED).body(url);
}

//用于判断文件的类型，暂时只判断了“image/gif","image/jpeg”
private static final List<String> CONTENT_TYPES= Arrays.asList("image/gif","image/jpeg");

private static final Logger LOGGER= LoggerFactory.getLogger(UploadService.class);

/**
 * 业务逻辑代码
 * @param file 文件的存储的url
 * @return
 */
public String uploadImage(MultipartFile file) {

    String originalFilename = file.getOriginalFilename();
    //校验文件类型
    //方法一:截取字符串
    String afterLast = StringUtils.substringAfterLast(".", originalFilename);
    //方法二：使用getContentType方法
    String contentType = file.getContentType();
    if (!CONTENT_TYPES.contains(contentType)){
        LOGGER.info("文件类型不合法："+originalFilename);
        return null;
    }
    //校验文件内容
    try {
        //获取文件流
        BufferedImage bufferedImage = ImageIO.read(file.getInputStream());
        if (bufferedImage==null){
            LOGGER.info("文件内容不合法：{}",originalFilename);
            return null;
        }
        //保存到服务器   E:\fgba\image
        //将接收到的文件传输到给定的目标文件。
        file.transferTo(new File("E:\\fgba\\Image\\"+originalFilename));
        
        //返回URL，进行回显
        //可以使用Nginx-图片服务器
        return "fgba"+originalFilename;
    } catch (Exception e) {
        LOGGER.info("服务器内部错误："+originalFilename);
        e.printStackTrace();
    }
    return null;
}

    listen       80;
    server_name  ;

    proxy_set_header X-Forwarded-Host $host;
    proxy_set_header X-Forwarded-Server $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    
    location / {
        root E:\\fgba\\image;
    }
}

//白名单：存放放行的URL
private List<String> allowPaths;


@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
   
    //获取请求的url路径
    String path = request.getURI().getPath();
    boolean flag=isAllowPath(path);
    if (flag) {
        log.info("请求在白名单中，fgba.filter: {}",path);
        //放行
        return chain.filter(exchange);
    } else {
      //写其他的业务逻辑
        ~~~~
        
    }
}

private boolean isAllowPath(String path) {
 
      //判断是否允许放行
     if (allowPaths.contains(path)){
         return true;
     }
     return  false;

server {
    listen       80;
    server_name  fgba;

    proxy_set_header X-Forwarded-Host $host;
    proxy_set_header X-Forwarded-Server $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    # 新增加的配置，用于文件上传
    location /api/upload {
        proxy_pass;
        proxy_connect_timeout 600;
        proxy_read_timeout 600;
        
        rewrite "^/api/(.*)$" /$1 break;
    }
    # 网关的配置
    location / {
        proxy_pass;
        proxy_connect_timeout 600;
        proxy_read_timeout 600;
    }
}

@Bean
public CorsFilter corsFilter(){
    //初始化配置对象
    CorsConfiguration configuration = new CorsConfiguration();
    //允许跨域访问的域名
    configuration.addAllowedOrigin("*");
   // configuration.setAllowCredentials(true);  //运行携带cookie
    configuration.addAllowedMethod("*"); //代表所有请求方法
    configuration.addAllowedHeader("*"); //允许携带任何头信息

    //初始化cors配置源对象
    UrlBasedCorsConfigurationSource configurationSource=new UrlBasedCorsConfigurationSource();
    configurationSource.registerCorsConfiguration("/**",configuration);

    //返回CorSfilter实例，参数
    return new CorsFilter(configurationSource);
}