SpringCloud - Feign服务调用，熔断，降级处理

首先我们看一下这次服务调用，先看下项目结构：

我们从注册中心依次叙述到服务调用

yyc父项目模块中的pom文件

在父项目中分别定义了Eureka注册中心ycc-registry,模块yyc-test以及模块yyc-demo
这次使用中将yyc-test作为服务的提供者，yyc-demo作为服务的消费者

<?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>

    <groupId>com.zhaixingzu</groupId>
    <artifactId>yyc</artifactId>
    <version>1.1.0-SNAPSHOT</version>
    <packaging>pom</packaging>

    <name>yyc</name>
    <description>yyc-pom</description>

    <modules>
        <module>yyc-registry</module>
        <module>yyc-test</module>
        <module>yyc-demo</module>
    </modules>

    <!-- 集中定义版本号 -->
    <properties>
        <spring-boot.version>2.1.3.RELEASE</spring-boot.version>
        <spring-cloud.version>Greenwich.RELEASE</spring-cloud.version>
        <spring-boot-admin.version>2.1.3</spring-boot-admin.version>
    </properties>

    <dependencies>

        <!--eureka 客户端-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!--测试依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!--监控-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!--断路器依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
         </dependency>
        <!--监控客户端-->
        <dependency>
            <groupId>de.codecentric</groupId>
            <artifactId>spring-boot-admin-starter-client</artifactId>
            <version>${spring-boot-admin.version}</version>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

</project>

yyc-registry中的pom文件

<?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>
    <parent>
        <groupId>com.zhaixingzu</groupId>
        <artifactId>yyc</artifactId>
        <version>1.1.0-SNAPSHOT</version>
    </parent>
    <artifactId>yyc-register</artifactId>
    <packaging>jar</packaging>
    <name>yyc-register</name>
    <description>yyc 注册中心</description>

    <dependencies>
        <!--服务中心-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <!--security-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-security</artifactId>
        </dependency>
        <!--web 模块-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <!--排除tomcat依赖-->
                <exclusion>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                    <groupId>org.springframework.boot</groupId>
                </exclusion>
            </exclusions>
        </dependency>
        <!--undertow容器-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-undertow</artifactId>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

yyc-registry注册中心的配置信息

server:
  port: 9900

spring:
  application:
    name: yyc-registry
  security:
    user:
      name: admin
      password: admin
  cloud:
    config:
      enabled: false


eureka:
  instance:
    hostname: 127.0.0.1
    prefer-ip-address: true
  server:
    #是否开启自我保护（运行期间spring会统计信条失败的比例在15分钟之内是否低于85%，如果不低于85%，Eureka会将实例注册信息保护起来，让这些实例不会过期）
    enable-self-preservation: false
    eviction-interval-timer-in-ms: 3000      #3秒钟自动剔除失效的节点,清理无效的节点
    response-cache-update-interval-ms: 3000  #eureka server刷新readCacheMap的时间，注意，client读取的是readCacheMap，这个时间决定了多久会把readWriteCacheMap的缓存更新到readCacheMap上
    response-cache-auto-expiration-in-seconds: 180
    #eureka server缓存readWriteCacheMap失效时间，这个只有在这个时间过去后缓存才会失效，失效前不会更新，过期后从registry重新读取注册服务信息，registry是一个ConcurrentHashMap。
    #由于启用了evict其实就用不太上改这个配置了
    #默认180s
  client:
    register-with-eureka: false #不要向注册中心注册自己
    fetch-registry: false
    serviceUrl:
      defaultZone: http://${spring.security.user.name}:${spring.security.user.password}@${eureka.instance.hostname}:${server.port}/eureka/  #设置与eureka交互的地址


#如果要开启全部的监听端点，可以在yml文件中加入下面的配置信息
#/actuator/health和/actuator/info以及/actuator这三个就是actuator提供的端点，
#注意以前的版本是没有/actuator前缀的，2.0以后的版本都加了/actuator前缀。
#可以访问localhost:8800/actuator尝试看监听的都是一些什么内容
management:
  endpoints:
    web:
      exposure:
        include: "*"

Eureka认证安全配置：

package com.zhaixingzu.yyc.registry.security;

import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;


/**
 * @author Herbert
 * @date 2019/06/24
 */
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) {
        try {
            http.csrf().disable()
                .authorizeRequests()
                .antMatchers("/actuator/**").permitAll()
                .anyRequest()
                .authenticated().and().httpBasic();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

yyc-registry 注册中心启动类：

package com.zhaixingzu.yyc.registry;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

/**
 * 服务注册中心
 * @author Herbert
 * @date 2019年06月19日
 */
@EnableEurekaServer
@SpringBootApplication
public class RegistryApplication {

    public static void main(String[] args) {
        SpringApplication.run(RegistryApplication.class, args);
    }

}

上述已经完全配置好注册中心，详见：

Eureka服务治理

yyc-test中的pom

<?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>
    <parent>
        <groupId>com.zhaixingzu</groupId>
        <artifactId>yyc</artifactId>
        <version>1.1.0-SNAPSHOT</version>
    </parent>
    <artifactId>yyc-test</artifactId>
    <packaging>jar</packaging>
    <name>yyc-test</name>
    <description>test</description>

    <dependencies>
        <!--web 模块-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <!--排除tomcat依赖-->
                <exclusion>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                    <groupId>org.springframework.boot</groupId>
                </exclusion>
            </exclusions>
        </dependency>
        <!--undertow容器-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-undertow</artifactId>
        </dependency>
    </dependencies>

</project>

yyc-test中的配置信息

server:
  port: 8800

spring:
  application:
    name: yyc-test

eureka:
  client:
      serviceUrl:
            defaultZone: http://admin:[email protected]:9900/eureka/  #设置与eureka交互的地址

yyc-test中的启动类

package com.zhaixingzu.yyc.test;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

/**
 *
 * @author Herbert
 * @date 2019年06月19日
 */
@EnableEurekaClient
@SpringBootApplication
public class TestApplication {

    public static void main(String[] args) {
        SpringApplication.run(TestApplication.class, args);
    }

}

yyc-test中的服务提供Controller

package com.zhaixingzu.yyc.test.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Created by Herbert on 2019/6/24.
 */
@RestController
@RequestMapping("/test")
public class TestController {

    @GetMapping("/show")
    public String show(){
        return "hello";
    }

}

上述服务注册到注册中心已经完成，也就是服务提供者，其实他也可以去消费其他的服务

yyc-demo中的pom文件

<?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>
    <parent>
        <groupId>com.zhaixingzu</groupId>
        <artifactId>yyc</artifactId>
        <version>1.1.0-SNAPSHOT</version>
    </parent>
    <artifactId>yyc-demo</artifactId>
    <packaging>jar</packaging>
    <name>yyc-demo</name>
    <description>demo</description>

    <dependencies>
        <!--web 模块-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <!--排除tomcat依赖-->
                <exclusion>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                    <groupId>org.springframework.boot</groupId>
                </exclusion>
            </exclusions>
        </dependency>
        <!--undertow容器-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-undertow</artifactId>
        </dependency>
        <!--feign 依赖-->
        <dependency>
            <groupId>io.github.openfeign</groupId>
            <artifactId>feign-okhttp</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
    </dependencies>

</project>

yyc-demo中的配置信息

server:
  port: 8801

spring:
  application:
    name: yyc-demo

eureka:
  client:
      serviceUrl:
            defaultZone: http://admin:[email protected]:9900/eureka/  #设置与eureka交互的地址

feign:
  hystrix:
    enabled: true

yyc-demo中的启动类

package com.zhaixingzu.yyc.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

/**
 *
 * @author Herbert
 * @date 2019年06月20日
 */
@EnableEurekaClient
@SpringBootApplication
@EnableFeignClients
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

//    @Bean // 自动扫描
//    @LoadBalanced //这个注解的意思是在启动时先加载注册中心的域名列表
//    public RestTemplate restTemplate() //这个方法用来发http请求
//    {
//        RestTemplate restTemplate=new RestTemplate();
//        return restTemplate;
//    }
}

yyc-demo中的服务调用controler

package com.zhaixingzu.yyc.demo.controller;

import com.zhaixingzu.yyc.demo.feign.DemoServer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Created by Herbert on 2019/6/25.
 */
@RestController
@RequestMapping("/demo")
public class DemoController {

    @Autowired
    private DemoServer demoServer;
  //  private RestTemplate restTemplate;

    @GetMapping("/show")
    public String show(){
        return demoServer.show();
    }
}

下面看一下yyc-demo的结构图：

建立feign文件，这个可以随便命名，我们写一个DemoServer中去利用Feign调用

package com.zhaixingzu.yyc.demo.feign;

import com.zhaixingzu.yyc.demo.feign.factory.DemoFeignFallbackFactory;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

/**
 * Created by Herbert on 2019/6/25.
 */
@FeignClient(value = "yyc-test",fallbackFactory =DemoFeignFallbackFactory.class)
public interface DemoServer {
    @GetMapping("/test/show")
    String show();
}

定义DemoFeignFallbackFactory

package com.zhaixingzu.yyc.demo.feign.factory;


import com.zhaixingzu.yyc.demo.feign.DemoServer;
import com.zhaixingzu.yyc.demo.feign.fallback.DemoServerImpl;
import feign.hystrix.FallbackFactory;
import org.springframework.stereotype.Component;

/**
 * Created by Herbert on 2019/6/26.
 */
@Component
public class DemoFeignFallbackFactory implements FallbackFactory<DemoServer> {

    public DemoServer create(Throwable throwable) {

        return new DemoServer() {
            public String show() {
                return "服务异常";
            }
        };
    }
}

也可以使用fallback来进行降级处理

@FeignClient(value = "yyc-test",fallback=DemoServerImpl.class)
public interface DemoServer {
    @GetMapping("/test/show")
    String show();
}

fallback所对应的DemoServerImpl

package com.zhaixingzu.yyc.demo.feign.fallback;

import com.zhaixingzu.yyc.demo.feign.DemoServer;
import org.springframework.stereotype.Component;

/**
 * Created by Herbert on 2019/6/26.
 */
@Component
public class DemoServerImpl implements DemoServer{

    public String show() {
        return "服务异常";
    }
}

配置好了以后请求后得到正常的返回数据

关掉yyc-test的服务，再次请求接口，会请求到降级服务

关于Feign Hystrix回退，如果需要方位导致回退的原因，可以使用@FeignClient内的fallbackFactory属性，如果只是启用回退，可使用fallback

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SpringCloud - Feign服务调用，熔断，降级处理

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