- Hystrix

Hystrix支持回退概念:当 断路器 打开或运行错误时,执行默认的代码,给@FeignClient定义一个fallback属性,设置它实现回退的,还需要将您的实现类声明为Spring Bean。

官方文档:http://cloud.spring.io/spring-cloud-static/Dalston.SR2/#spring-cloud-feign-hystrix-fallback

- 准备工作

1.启动Consul
2.创建 battcn-provider 和 battcn-consumer 如果看了上一章的,可以直接copy代码复用

- battcn-provider

- pom.xml

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<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-consul-discovery</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>

- ProviderApplication.java(有变化)

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@SpringBootApplication
@EnableDiscoveryClient
@RestController
public class ProviderApplication { @Value("${spring.application.name}")
String applicationName; public static void main(String[] args) {
SpringApplication.run(ProviderApplication.class, args);
} @GetMapping("/test1")
public String test1() {
return "My Name's :" + applicationName + " Email:[email protected]";
} @GetMapping("/test2")
public String test2() {
System.out.println(1/0);
return "hello error";
}
}

- bootstrap.yml

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server:
port: 8765 spring:
application:
name: battcn-provider
cloud:
consul:
host: localhost
port: 8500
enabled: true
discovery:
enabled: true
prefer-ip-address: true

- battcn-consumer

- pom.xml

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<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-consul-discovery</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>

- ConsumerApplication

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@SpringCloudApplication
@EnableFeignClients//开启 FeignClient支持
public class ConsumerApplication { @Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
} public static void main(String[] args) {
SpringApplication.run(ConsumerApplication.class, args);
} }

- HiClient

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package com.battcn.client;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.GetMapping; /**
* @author Levin
* @date 2017-08-07.
*/
@FeignClient(value = "battcn-provider",fallback = HiClient.HiClientFallback.class)
public interface HiClient { @GetMapping("/test1")
String test1(); @GetMapping("/test2")
String test2(); @Component
class HiClientFallback implements HiClient{
@Override
public String test1() {
return "fallback....";
} @Override
public String test2() {
return "fallback...";
}
}
}

- HiController

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package com.battcn.controller;

import com.battcn.client.HiClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController; @RestController
public class HiController {
@Autowired
HiClient hiClient;
@GetMapping("/h1")
public String hi() {
return hiClient.test1();
}
@GetMapping("/h2")
public String say() {
return hiClient.test2();
}
}

- bootstrap.yml

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server:
port: 8766 feign:
hystrix:
enabled: true #开启Feign Hystrix 支持 spring:
application:
name: battcn-consumer
cloud:
consul:
host: localhost
port: 8500
enabled: true
discovery:
enabled: true
prefer-ip-address: true

- 测试

启动:battcn-provider

启动:battcn-consumer

访问:http://localhost:8500/ 显示如下代表服务注册成功

断路器Hystrix(Feign)-LMLPHP查看注册中心

访问:http://localhost:8766/h1

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My Name's :battcn-provider Email:[email protected]	#正确情况

访问:http://localhost:8766/h2

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fallback...  	#错误情况,阻断输出fallback...

- 解锁新姿势

- 异常处理

画图工具:https://www.processon.com/

断路器Hystrix(Feign)-LMLPHP异常处理

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@ExceptionHandler(value = Exception.class)
@ResponseBody
public ErrorResponseEntity jsonErrorHandler(Exception e, HttpServletResponse rep) throws Exception {
if (e instanceof BattcnException) {
BattcnException exception = (BattcnException) e;
return exception.toErrorResponseEntity();
}
logger.error("服务器未知异常", e);
rep.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());
return new ErrorResponseEntity(HttpStatus.INTERNAL_SERVER_ERROR.value(), "服务器未知异常");
}
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@ExceptionHandler(value = Exception.class)
@ResponseBody
public ErrorResponseEntity jsonErrorHandler(Exception e, HttpServletResponse rep) throws Exception {
if (e instanceof HystrixBadRequestException) {
HystrixBadRequestException exception = (HystrixBadRequestException) e;
rep.setStatus(HttpStatus.BAD_REQUEST.value());
logger.info("[HystrixBadRequestException] - [" + exception.getMessage() + "]");
JSONObject obj = JSON.parseObject(exception.getMessage());
return new ErrorResponseEntity(obj.getInteger("customCode"), obj.getString("message"));
}
logger.error("服务器未知异常", e);
rep.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());
return new ErrorResponseEntity(HttpStatus.INTERNAL_SERVER_ERROR.value(), "服务器未知异常");
}

- FeignServiceErrorDecoder

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package com.battcn.config;

import com.netflix.hystrix.exception.HystrixBadRequestException;
import feign.Response;
import feign.Util;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import java.io.IOException; @Component
public class FeignServiceErrorDecoder implements feign.codec.ErrorDecoder {
static Logger LOGGER = LoggerFactory.getLogger(FeignServiceErrorDecoder.class);
@Override
public Exception decode(String methodKey, Response response) {
try {
if (response.status() >= 400 && response.status() <= 499) {
String error = Util.toString(response.body().asReader());
return new HystrixBadRequestException(error);
}
} catch (IOException e) {
LOGGER.error("[Feign解析异常] - [{}]", e);
}
return feign.FeignException.errorStatus(methodKey, response);
}
}

- 测试

访问:http://localhost:8766/h1

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My Name's :battcn-provider Email:[email protected]	#正确情况

访问:http://localhost:8766/h2

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{"customCode":400,"message":"请求错误"} 	#抛出异常,而不是进入阻断器

关闭battcn-provider:http://localhost:8766/h1

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fallback...  	#服务down机,阻断输出fallback...

- Request 参数传递

断路器Hystrix(Feign)-LMLPHP参数传递

- FeignRequest(consumer)

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package com.battcn.config;

import feign.RequestInterceptor;
import feign.RequestTemplate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import java.util.UUID; @Component
public class FeignRequest implements RequestInterceptor { final Logger LOGGER = LoggerFactory.getLogger(this.getClass().getSimpleName()); @Override
public void apply(RequestTemplate requestTemplate) {
//1.模拟获取request.header参数
String token = UUID.randomUUID().toString().replace("-","").toUpperCase();
LOGGER.info("传递的Token - [{}]",token);
requestTemplate.header("token",token);//模拟将Token放入在 feign.Request对象中 }
}

- HelloController(provider)

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@Value("${spring.application.name}")
String applicationName; @Autowired
HttpServletRequest request; @Override
@GetMapping("/test1")
public String test1() {
return "My Name's :" + applicationName + " Token:"+request.getHeader("token");
}

- 测试

断路器Hystrix(Feign)-LMLPHP日志结果

结果:My Name's :battcn-provider Token:5588551D64C8478BA681A35892A03437 代表我们Token(HttpServletRequest)传递成功…

05-11 17:43