SpringBoot项目改造Spring Cloud项目总结

记录一下项目改造过程中，遇到的一些问题

status 404 reading xxxFeign#xxx; content:

解决方法

1. 客户端的注解@FeignClient中加入path属性，跟服务提供者中配置的context-path属性保持一致

@FeignClient(name = InterfaceService.SERVICE_NAME, path = "/v2/private/user", fallback = HystrixUserClient.class)

2. 在服务端与客户端的启动类中加入@EnableFeignClients
3. 有可能是注册过程中，本地启动时eureka的client注册到server时默认是使用hostname而不是ip,这就导致client在多台机器时，服务间相互调用时也会使用hostname进行调用，从而调用失败。
   这时候就需要使用ip来服务到eureka-server上，需要在eureka的client端增加配置如下：

eureka:
 instance:
   prefer-ip-address: true
     instance-id: ${spring.cloud.client.ip-address}:${spring.application.name}:${server.port}

Feign调用Hystrix报错There is already ‘computeClientHystrix’ bean method mapped

使用Feign调用Hystrix进行断路器的学习，一直报错There is already ‘computeClientHystrix’ bean method mapped
相关类如下：
调用远程服务的接口类

@FeignClient(value="COMPUTE-SERVICE", fallback=ComputeClientHystrix.class)
@RequestMapping("computer")
public interface ComputerController {
   @RequestMapping(method = RequestMethod.GET, value = "/add")
   Integer add(@RequestParam(value = "a") Integer a, @RequestParam(value = "b") Integer b);
}

实现接口类的实现类：

@Component
public class ComputeClientHystrix implements ComputerController{
   @Override
   public Integer add(@RequestParam(value = "a") Integer a, @RequestParam(value = "b") Integer b) {
       return -9999;
   }
}

看了下日志，先map了实现类的add方法，然后又去map了接口中的add方法，因为两者的继承关系，所以add方法的url是相同的，所以spring认为两个方法重复了，就报错了

[           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/computer/add],methods=[GET]}" onto public java.lang.Integer com.zeng.learn.spring.cloud.consumer.server.ComputeClientHystrix.add(java.lang.Integer,java.lang.Integer)
2017-04-23 12:04:31.744  WARN 10320 --- [           main] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'requestMappingHandlerMapping' defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'com.zeng.learn.spring.cloud.consumer.ServerController.ComputerController' method 
public abstract java.lang.Integer com.zeng.learn.spring.cloud.consumer.ServerController.ComputerController.add(java.lang.Integer,java.lang.Integer)
to {[/computer/add],methods=[GET]}: There is already 'computeClientHystrix' bean method
public java.lang.Integer com.zeng.learn.spring.cloud.consumer.server.ComputeClientHystrix.add(java.lang.Integer,java.lang.Integer) mapped.

改成如下的形式就ok了，应该是把url映射放在接口中。
接口：

@FeignClient(value="COMPUTE-SERVICE", fallback=ComputeClientHystrix.class)
public interface ComputerController {
   @RequestMapping(method = RequestMethod.GET, value = "/computer/add")
   Integer add(@RequestParam(value = "a") Integer a, @RequestParam(value = "b") Integer b);
}

实现：

@Component
public class ComputeClientHystrix implements ComputerController{
   @Override
   public Integer add(@RequestParam(value = "a") Integer a, @RequestParam(value = "b") Integer b) {
       return -9999;
   }
}

可以注意到RequestMapping中的value是“/conputer/add”，一般我们在spring mvc中，前面一致的都会放在class上，但是如果把@RequestMapping(value = “/computer”)放在接口上的话，还是会报错。

进入FeignClient注解里看了下属性，有一个path属性，是用来表示接口内所有方法请求的前缀的，而不是像springmvc，在接口上配置前缀@RequestMapping

@FeignClient(value = "spring-cloud-producer-chidao",fallback = StudentRemoteHystrix.class,path = "/student")
//@RequestMapping(value = "/student")
public interface StudentRemoteService {
   @GetMapping(value = "/selectAll")
   public Result<List<Student>> selectAll();
   @GetMapping(value = "/findByName")
   public Result<Student> findByName(@RequestParam(value = "name", required = true) String name);

这样就可以了