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This article mainly explains "how to solve the problem that Feign,@RequestBody cannot inherit in Spring Cloud". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's learn how to solve the problem of using Feign,@RequestBody in Spring Cloud.

directory

Using Feign in Spring Cloud,@RequestBody cannot inherit issues

cause analysis

solutions

Spring cloud problems with feign

1. Examples

2. First visit timeout problem

3. In the FeignClient interface, if you use @PathVariable, you must specify its value.

Using Feign in Spring Cloud,@RequestBody cannot inherit issues

According to the official website FeignClient example, write a simple updateUser interface, defined as follows

@RequestMapping("/user")public interface UserService { @RequestMapping(value = "/{userId}", method = RequestMethod.GET) UserDTO findUserById(@PathVariable("userId") Integer userId); @RequestMapping(value = "/update", method = RequestMethod.POST) boolean updateUser(@RequestBody UserDTO user);}

implementation class

@Override public boolean updateUser(UserDTO user) { LOGGER.info("===updateUser, id = " + user.getId() + " ,name= " + user.getUsername()); return false; }

Perform unit tests and find that expected input parameters are not captured

2018-09-07 15:35:38,558 [http-nio-8091-exec-5] INFO [com.springboot.user.controller.UserController] {} - ===updateUser, id = null ,name= null

cause analysis

SpringMVC uses RequestResponseBodyMethodProcessor class to parse incoming and outgoing parameters. The following method determines whether to convert the message body according to whether the parameter has the @RequestBody annotation.

@Override public boolean supportsParameter(MethodParameter parameter) { return parameter.hasParameterAnnotation(RequestBody.class); } Solutions

Since MVC uses RequestResponseBodyMethodProcessor for parameter parsing, you can implement a customized Processor to modify the supportParameter determination method.

@Override public boolean supportsParameter(MethodParameter parameter) { //springcloud interface input parameter does not write @RequestBody, and is a custom type object is also parsed as JSON if (AnnotatedElementUtils.hasAnnotation(parameter.getContainingClass(), FeignClient.class) && isCustomizedType(parameter.getParameterType())) { return true; } return super.supportsParameter(parameter); }

The decision logic here can be defined according to the actual framework, and the purpose is to determine the interface defined for Spring Cloud, and when it is a custom object, use the same content converter as @RequestBody.

After implementing the customized Processor, you also need to make the custom configuration take effect. There are two options:

Directly replace RequestResponseBodyMethodProcessor, custom RequestMappingHandlerAdapter is required under SpringBoot.

Implement the addArgumentResolvers interface in WebMvcConfigurator

The second, simpler approach is used here, where the message converter at initialization loads as needed:

public class XXXWebMvcConfig implements WebMvcConfigurer{@Override public void addArgumentResolvers(List resolvers) { StringHttpMessageConverter stringHttpMessageConverter = new StringHttpMessageConverter(); stringHttpMessageConverter.setWriteAcceptCharset(false); List

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