springcloud用feign消费服务记录

springcloud提供了两种消费服务的方式，feign和ribbon。实质上feign是集成了ribbon的，最终也是利用ribbon做了均衡负载发了http请求。ribbon的方式编码的时候更像是用到了http请求，feign编码的时候感觉上更像使用了一个接口。所有还是用了feign（用起来舒服一点）

1.在消费者的项目里面新建一个类：

@RestController
@SpringBootApplication
@EnableFeignClients//开启feign
public class Hello {
	@Autowired
	private HelloRemote helloRemote;//定义的接口，供feign使用
	@RequestMapping("/hello/{name}")
	public String index(@PathVariable("name") String name) {
		return helloRemote.hello(name);
		// return "hello " + name;
	}

	@RequestMapping("/sayIp/{name}")
	public String sayIp(@PathVariable("name") String name) {
		if (!"aaa".equals(name)) {
			name = null;
		}
		return helloRemote.sayIp(name);
	}
}

2.在 消费者的项目里面创建HelloRemote接口

@FeignClient(name = "PRODUCER", fallback = HelloRemoteFallback.class)

//PRODUCER是生产者的名字fallback是断路后降级执行的类

public interface HelloRemote {@RequestMapping(value = "/hello")//服务提供者的路由地址，这里不支持getMapping方法@ResponseBodypublic String hello(@RequestParam(value = "name") String name);@RequestMapping(value = "/getIp", method = RequestMethod.POST)//参数包含了对象后，最好用post，get方式只能传简单参数（参数的地方有坑，需要注意到用）@ResponseBodypublic String sayIp(@PathVariable(value = "name") String name);//参数是null的时候，会报错}

3.在生产者里面创建一个服务：

@RestController
public class SayWord {
	@Autowired
	private DiscoveryClient discoveryClient;

	@RequestMapping(value = "hello")//消费者寻找的路由
	public String index(@RequestParam String name) {
		ServiceInstance aa = discoveryClient.getLocalServiceInstance();
		System.out.println(aa);
		return "hello! " + name + "，this is my first messge!";
	}

	@RequestMapping(value = "getIp")
	public String getIp(@RequestParam String name) throws UnknownHostException {
		ServiceInstance aa = discoveryClient.getLocalServiceInstance();
		String addr = InetAddress.getLocalHost().getHostAddress();
		System.out.println(aa);
		return "hello! " + name + "，this is my second messge!,I will tell you what is my IP:" + addr;
	}

}

4.在消费者项目中创建降级处理的类：

@Component
public class HelloRemoteFallback implements HelloRemote {//要实现需要降级处理的接口

	@Override
	public String hello(String name) {
		return null;
	}

	@Override
	public String sayIp(String name) {
		return "sayIp 错了";
	}

}

5.在消费者项目中创建

/***
 *
做一个熔断的判断，在400期间的异常，不熔断服务（400 期间的异常很多是使用feign的参数传递错误造成的，不必让服务熔断）**
 * 
 * @author aa
 **/
@Configuration
public class BizExceptionFeignErrorDecoder implements feign.codec.ErrorDecoder {

//重写一下errorDecoder,把400-500区间的异常，用不做服务熔断的方式进行一下处理
	private static final Logger logger = LoggerFactory.getLogger(BizExceptionFeignErrorDecoder.class);


	@Override
	public Exception decode(String methodKey, Response response) {
		logger.debug("bizExceptionFeignErrorDecoder decode:" + methodKey + "/" + response);
		Exception exception = null;
		if (response.status() >= 400 && response.status() <= 499) {
			exception = new HystrixBadRequestException(String.valueOf(response.status()));// 不会被计数，也不会进入阻断器
			logger.debug(exception.getMessage());
		} else {
			exception = feign.FeignException.errorStatus(methodKey, response);
			logger.debug(exception.getMessage());
		}
		return exception;
	}


}