Spring boot中feign使用GETPOST请求方式及@RequestParam，@RequestBody，@RequestPart的区别

Spring boot中feign使用GET/POST请求方式及@RequestParam，@RequestBody，@RequestPart的区别

使用@RequestPart，@RequestBody后，feign会使用post请求来访问远程客户端，并设置content-type为application/json，然后将@RequestPart/@RequestBody标识的参数以json格式放在body中，客户端接收需要使用@RequestBody进行接收，@RequestPart对应的 content-type为multipart/form-data或multipart/mixed stream

使用@RequestParam，无论是post还是get请求，@RequestParam标识的参数都会已queryString形式拼接在url后面，content-type为null，客户端接收需要使用@RequestParam进行接收

feign请求示例

	@RequestMapping(value = "/get_requestParam",method = RequestMethod.GET)
    Object get_requestParam(@RequestParam("accountId")String accountId);

    @RequestMapping(value = "/get_requestPart",method = RequestMethod.GET)
    Object get_requestPart(@RequestPart("accountId")String accountId);

    @RequestMapping(value = "/get_requestBody",method = RequestMethod.GET)
    Object get_requestBody(@RequestBody QueryAvailableTrialVoucherByUserParam param);

    @RequestMapping(value = "/post_requestParam",method = RequestMethod.POST)
    Object post_requestParam(@RequestParam("accountId") String accountId);

    @RequestMapping(value = "/post_requestPart",method = RequestMethod.POST)
    Object post_requestPart(@RequestPart("accountId") String accountId);

    @RequestMapping(value = "/post_requestBody",method = RequestMethod.POST)
    Object post_requestBody(@RequestBody QueryAvailableTrialVoucherByUserParam param);

客户端接口示例

	@GetMapping("/get_requestParam")
    public Object get_requestParam(@RequestParam("accountId") String accountId) {
        return "get_requestParam";
    }
	//requestPart 方式为post请求并需要使用@RequestBody接收
    @PostMapping("/get_requestPart")
    public Object get_requestPart(@RequestBody String accountId) {
        return "get_requestPart";
    }

    @PostMapping("/get_requestBody")
    public Object get_requestBody(@RequestBody QueryAvailableTrialVoucherByUserParam param) {
        return "get_requestBody";
    }

    @PostMapping("/post_requestParam")
    public Object post_requestParam(@RequestParam("accountId") String accountId) {
        return "post_requestParam";
    }
	//requestPart 需要使用@RequestBody接收
    @PostMapping("/post_requestPart")
    public Object post_requestPart(@RequestBody String accountId) {
        return "post_requestPart";
    }

    @PostMapping("/post_requestBody")
    public Object post_requestBody(@RequestBody QueryAvailableTrialVoucherByUserParam param) {
        return "post_requestBody";
    }

可能导致的问题

使用@RequestParam 发请求出现url长度过长问题

原因

无论是post还是get请求，@RequestParam标识的参数都会已queryString形式拼接在url后面，但是服务器对接收的url是有长度限制的，会截断后面的参数，致使请求失败

解决方法

修改 yml 或 properties 配置文件

server:
    port: 4450
    # 增加服务器请求头接受大小,URL 就是头部的一部分
    max-http-header-size: 10485760

把@RequestParam 的参数全部封装成一个对象，用@RequestBody 方式对该对象进行请求

使用@RequestBody 发请求出现 400 error `Illegal character ((CTRL-CHAR, code 31)): only regular white space (\r, \n, \t)`

原因

传输的请求体body过大，开启了gzip压缩来传输请求，提升效率，而客户端content-type为 application/json，使用JSON的格式接受但无法转换gzip压缩后的内容，导致报错

解决方法

修改feign配置，关闭请求压缩或者增大最小请求阈值长度

feign:
  compression:
  	# 请求是否开启gzip压缩
    request:
      enabled: false
      #最小请求阈值长度，超过该1024kb大小进行压缩
      min-request-size: 1024
    # 响应是否开启gzip压缩
    response:
      enabled: true
      # 响应解码
      useGzipDecoder: true

新增过滤器，专门处理Content-Encoding为gzip的请求

MyGzipRequestWrapper

public class MyGzipRequestWrapper extends HttpServletRequestWrapper {

    private HttpServletRequest request;

    public MyGzipRequestWrapper(HttpServletRequest request) {
        super(request);
        this.request = request;
    }
    
    @Override
    public ServletInputStream getInputStream() throws IOException {

        ServletInputStream inputStream = request.getInputStream();
        try {
            GZIPInputStream gzipInputStream = new GZIPInputStream(inputStream);
            ServletInputStream newStream = new ServletInputStream() {
                @Override
                public boolean isFinished() {
                    return false;
                }

                @Override
                public boolean isReady() {
                    return false;
                }

                @Override
                public void setReadListener(ReadListener readListener) {
                }

                @Override
                public int read() throws IOException {
                    return gzipInputStream.read();
                }
            };
            return newStream;
        } catch (Exception e) {
        }
        return inputStream;
    }
}

MyGzipFilter

public class MyGzipFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        String contentEncoding = request.getHeader("Content-Encoding");
        if (contentEncoding != null && !contentEncoding.isEmpty() && contentEncoding.contains("gzip")) {
            request = new MyGzipRequestWrapper(request);
        }
        System.out.println(request.getMethod());
        filterChain.doFilter(request, servletResponse);
    }
}

使用原生的http，构造body去请求客户端的api