SpringCloud-Fegion的Hystrix支持

概述

Fegion的Hystrix支持

    如果Hystrix在类路径上，feign.hystrix.enable=true，Feign将用断路器包装所有方法。

    Hystrix支持回退的概念：当电路断开或出现错误时执行的默认代码路径。要为给定的@FeignClient启用回退，请将fallback属性设置为实现回退的类名。

  Fign已经自带断路器了，就像自带了ribbon的负载均衡,如果想关闭feign自带的断路器，application.properties中添加feign.hystrix.enabled=false；

创建工程

pom.xml

microservice-consumer-movie-feign-with-hystrix/pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<artifactId>microservice-consumer-movie-feign-with-hystrix</artifactId>
	<packaging>jar</packaging>

	<parent>
		<groupId>com.itmuch.cloud</groupId>
		<artifactId>microservice-spring-cloud</artifactId>
		<version>0.0.1-SNAPSHOT</version>
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-eureka</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-feign</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-hystrix</artifactId>
		</dependency>
	</dependencies>
</project>

说明：

    1）增加引用spring-cloud-starter-feign；

application.yml

spring:
  application:
    name: microservice-consumer-movie-feign-with-hystrix
server:
  port: 7901
eureka:
  client:
    healthcheck:
      enabled: true
    serviceUrl:
      defaultZone: http://user:password123@localhost:8761/eureka
  instance:
    prefer-ip-address: true

说明：

1）增加配置启用,开启Hystrix的断路器功能，配置文件加上

    eureka:
      client:
        healthcheck:
          enabled: true

User

com.itmuch.cloud.entity.User

package com.itmuch.cloud.entity;

import java.math.BigDecimal;

public class User {
  private Long id;

  private String username;

  private String name;

  private Short age;

  private BigDecimal balance;

  public Long getId() {
    return this.id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  public String getUsername() {
    return this.username;
  }

  public void setUsername(String username) {
    this.username = username;
  }

  public String getName() {
    return this.name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public Short getAge() {
    return this.age;
  }

  public void setAge(Short age) {
    this.age = age;
  }

  public BigDecimal getBalance() {
    return this.balance;
  }

  public void setBalance(BigDecimal balance) {
    this.balance = balance;
  }

}

UserFeignClient

com.itmuch.cloud.feign.UserFeignClient

package com.itmuch.cloud.feign;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.itmuch.cloud.entity.User;

@FeignClient(name = "microservice-provider-user", fallback = HystrixClientFallback.class)
public interface UserFeignClient {
  @RequestMapping(value = "/simple/{id}", method = RequestMethod.GET)
  public User findById(@PathVariable("id") Long id);
}

说明：

    1）Feign访问服务接口，方法定义；

    2）有支持降级回调处理的配置；

HystrixClientFallback

com.itmuch.cloud.feign.HystrixClientFallback

package com.itmuch.cloud.feign;

import org.springframework.stereotype.Component;

import com.itmuch.cloud.entity.User;

@Component
public class HystrixClientFallback implements UserFeignClient {

  @Override
  public User findById(Long id) {
    User user = new User();
    user.setId(0L);
    return user;
  }
}

说明：

    1）UserFeignClientHystrix 需要实现UserFeignClient；

    2）Feign降级处理具体方法的实现；

MovieController

com.itmuch.cloud.controller.MovieController

package com.itmuch.cloud.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import com.itmuch.cloud.entity.User;
import com.itmuch.cloud.feign.UserFeignClient;

@RestController
public class MovieController {

  @Autowired
  private UserFeignClient userFeignClient;

  @GetMapping("/movie/{id}")
  public User findById(@PathVariable Long id) {
    return this.userFeignClient.findById(id);
  }
}

说明：

    1）通过Feign的方式访问服务；

ConsumerMovieFeignApplication

com.itmuch.cloud.ConsumerMovieFeignApplication

package com.itmuch.cloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
@EnableCircuitBreaker
public class ConsumerMovieFeignApplication {
  public static void main(String[] args) {
    SpringApplication.run(ConsumerMovieFeignApplication.class, args);
  }
}

说明：

    1）启动类增加注解

    2）加上@EnableFeignClients和@EnableCircuitBreaker；

小结

    1）增加引用
    2）增加配置启用
    3）启动类增加注解
    4）增加UserFeignClient业务接口，并配置fallback
    5）增加HystrixClientFallback类

测试

http://localhost:7901/movie/1

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