上一篇中我们讲了 断路器Hystrix&＃xff08;Ribbon&＃xff09; 本章讲解Feign&＃43;Hystrix已经Request请求传递&＃xff0c;各种奇淫技巧….
- Hystrix
Hystrix支持回退概念&＃xff1a;当 断路器 打开或运行错误时&＃xff0c;执行默认的代码&＃xff0c;给&＃64;FeignClient定义一个fallback属性&＃xff0c;设置它实现回退的&＃xff0c;还需要将您的实现类声明为Spring Bean。
官方文档&＃xff1a;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&＃xff0c;可以直接copy代码复用
- battcn-provider
- pom.xml
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| <dependencies>
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-starter-consul-discoveryartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-actuatorartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-testartifactId>
<scope>testscope>
dependency>
dependencies>
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- ProviderApplication.java&＃xff08;有变化&＃xff09;
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&＃64;SpringBootApplication
&＃64;EnableDiscoveryClient
&＃64;RestController
public class ProviderApplication {
&＃64;Value("${spring.application.name}")
String applicationName;
public static void main(String[] args) {
SpringApplication.run(ProviderApplication.class, args);
}
&＃64;GetMapping("/test1")
public String test1() {
return "My Name&＃39;s :" &＃43; applicationName &＃43; " Email:1837307557&＃64;qq.com";
}
&＃64;GetMapping("/test2")
public String test2() {
System.out.println(1/0);
return "hello error";
}
}
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- 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.cloudgroupId>
<artifactId>spring-cloud-starter-feignartifactId>
dependency>
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-starter-hystrixartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-actuatorartifactId>
dependency>
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-starter-consul-discoveryartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-testartifactId>
<scope>testscope>
dependency>
dependencies>
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- ConsumerApplication
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| &＃64;SpringCloudApplication
&＃64;EnableFeignClients |
- 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;
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- 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;
&＃64;RestController
public class HiController {
&＃64;Autowired
HiClient hiClient;
&＃64;GetMapping("/h1")
public String hi() {
return hiClient.test1();
}
&＃64;GetMapping("/h2")
public String say() {
return hiClient.test2();
}
}
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- bootstrap.yml
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| server:
port: 8766
feign:
hystrix:
enabled: true |
- 测试
启动&＃xff1a;battcn-provider
启动&＃xff1a;battcn-consumer
访问&＃xff1a;http://localhost:8500/ 显示如下代表服务注册成功
查看注册中心
访问&＃xff1a;http://localhost:8766/h1
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| My Name&＃39;s :battcn-provider Email:1837307557&＃64;qq.com #正确情况
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访问&＃xff1a;http://localhost:8766/h2
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| fallback... #错误情况&＃xff0c;阻断输出fallback...
|
- 解锁新姿势
- 异常处理
画图工具&＃xff1a;https://www.processon.com/
异常处理
如果我们FeignClient服务都是内部的&＃xff0c;在客户端抛出异常直接往最外层抛出&＃xff0c;就不需要在消费者通过硬编码处理了&＃xff0c;关键代码&＃xff08;完整代码看GIT&＃xff09;…
battcn-provider 中异常处理
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| &＃64;ExceptionHandler(value &＃61; Exception.class)
&＃64;ResponseBody
public ErrorResponseEntity jsonErrorHandler(Exception e, HttpServletResponse rep) throws Exception {
if (e instanceof BattcnException) {
BattcnException exception &＃61; (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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battcn-consumer 中异常处理
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| &＃64;ExceptionHandler(value &＃61; Exception.class)
&＃64;ResponseBody
public ErrorResponseEntity jsonErrorHandler(Exception e, HttpServletResponse rep) throws Exception {
if (e instanceof HystrixBadRequestException) {
HystrixBadRequestException exception &＃61; (HystrixBadRequestException) e;
rep.setStatus(HttpStatus.BAD_REQUEST.value());
logger.info("[HystrixBadRequestException] - [" &＃43; exception.getMessage() &＃43; "]");
JSONObject obj &＃61; 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");
}
|
在Hystrix中只有&＃xff0c;HystrixBadRequestException 是不会被计数&＃xff0c;也不会进入阻断器&＃xff0c;所以我们定义一个自己的错误解码器
- 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;
&＃64;Component
public class FeignServiceErrorDecoder implements feign.codec.ErrorDecoder {
static Logger LOGGER &＃61; LoggerFactory.getLogger(FeignServiceErrorDecoder.class);
&＃64;Override
public Exception decode(String methodKey, Response response) {
try {
if (response.status() >&＃61; 400 && response.status() <&＃61; 499) {
String error &＃61; 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);
}
}
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- 测试
访问&＃xff1a;http://localhost:8766/h1
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| My Name&＃39;s :battcn-provider Email:1837307557&＃64;qq.com #正确情况
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访问&＃xff1a;http://localhost:8766/h2
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| {"customCode":400,"message":"请求错误"} #抛出异常&＃xff0c;而不是进入阻断器
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关闭battcn-provider&＃xff1a;http://localhost:8766/h1
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| fallback... #服务down机&＃xff0c;阻断输出fallback...
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- Request 参数传递
在开发中难免会有 服务之间 请求头传递比如Token&＃xff0c;ID&＃xff0c;因为我们使用的是FeignClient 的方式&＃xff0c;那么我们无法获得HttpServletRequest的上下文&＃xff0c;这个时候怎么办呢&＃xff1f;通过硬编码是比较low的一种&＃xff0c;接下来为各位看官带来简单粗暴的&＃xff08;也就知道这种&＃xff0c;还有其它简单的方式欢迎交流….&＃xff09;
参数传递
- FeignRequest&＃xff08;consumer&＃xff09;
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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;
&＃64;Component
public class FeignRequest implements RequestInterceptor {
final Logger LOGGER &＃61; LoggerFactory.getLogger(this.getClass().getSimpleName());
&＃64;Override
public void apply(RequestTemplate requestTemplate) {
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- HelloController&＃xff08;provider&＃xff09;
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| &＃64;Value("${spring.application.name}")
String applicationName;
&＃64;Autowired
HttpServletRequest request;
&＃64;Override
&＃64;GetMapping("/test1")
public String test1() {
return "My Name&＃39;s :" &＃43; applicationName &＃43; " Token:"&＃43;request.getHeader("token");
}
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- 测试
日志结果
结果&＃xff1a;My Name&＃39;s :battcn-provider Token:5588551D64C8478BA681A35892A03437 代表我们Token&＃xff08;HttpServletRequest&＃xff09;传递成功…
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