Ribbon负载均衡以及Feign应用
结合我博文：https://blog.youkuaiyun.com/water_java/article/details/103897714观看
1、微服务调用Ribbon
简介
结合eureka集群的服务调用,使用ribbon
这里的话 就要用到Ribbon，结合eureka，来实现服务的调用；
Ribbon是Netflix发布的负载均衡器，它有助于控制HTTP和TCP的客户端的行为。为Ribbon配置服务提供者地址后，Ribbon就可基于某种负载均衡算法，自动地帮助服务消费者去请求。Ribbon默认为我们提供了很多负载均衡算法，例如轮询、随机等。当然，我们也可为Ribbon实现自定义的负载均衡算法。
在Spring Cloud中，当Ribbon与Eureka配合使用时，Ribbon可自动从Eureka Server获取服务提供者地址列表，并基于负载均衡算法，请求其中一个服务提供者实例。展示了Ribbon与Eureka配合使用时的架构。
Ribbon是客户端负载均衡，所以肯定集成再消费端，也就是consumer端
我们修改microservice-student-consumer-80
首先，引入依赖，pom.xml 加入 ribbon相关依赖
<!--ribbon相关依赖-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-ribbon</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-config</artifactId>
</dependency>
改变yml文件
ribbon结合eureka来调用服务提供者
server:
port: 80
context-path: /
eureka:
client:
service-url:
defaultZone: http://eureka2001.hsl.com:2001/eureka/,http://eureka2002.hsl.com:2002/eureka/,http://eureka2003.hsl.com:2003/eureka/
register-with-eureka: false
SpringCloudConfig要加个负载均衡配置 @LoadBalanced
因为和eureka整合，所以启动类StudentConsumerApplication_80 加个注解 @EnableEurekaClient
先在服务提供者microservice-student-provider-1001的application.yml加下配置，指定下应用名称：
application:
name: microservice-student
我微服务应用名称是 microservice-student
所以服务调用者这边的控制器里PRE_HOST改成 http://MICROSERVICE-STUDENT即可；
MICROSERVICE-STUDENT为Eureka注册中心的应用名称
测试：
访问成功！
2、Ribbon负载均衡
我上面的例子还不算是真正的Ribbon负载均衡，我下面建立三个服务提供者来实现Ribbon负载均衡，这三个服务提供者就像我之前建三个注册中心一样的做法
pom依赖
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.hsl</groupId>
<artifactId>t237microservice</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
<artifactId>microservice-student-provider</artifactId>
<properties>
<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.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
</dependency>
<!-- 修改后立即生效，热部署 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>springloaded</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
</dependency>
<dependency>
<groupId>com.hsl</groupId>
<artifactId>microservice-common</artifactId>
<version>1.0-SNAPSHOT</version>
<scope>compile</scope>
</dependency>
<!--添加注册中心Eureka相关配置-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-config</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
yml文件
---
server:
port: 1001
context-path: /
eureka:
instance:
hostname: localhost #eureka客户端主机实例名称
appname: microservice-student #客户端服务名
instance-id: microservice-student:1001 #客户端实例名称
prefer-ip-address: true #显示IP
client:
service-url:
defaultZone: http://eureka2001.hsl.com:2001/eureka/,http://eureka2002.hsl.com:2002/eureka/,http://eureka2003.hsl.com:2003/eureka/ #把服务注册到eureka注册中心
info:
groupId: com.hsl.testSpringcloud
artifactId: microservice-student-provider-1001
version: 1.0-SNAPSHOT
userName: http://hsl.com
phone: 123456
spring:
datasource:
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8
username: root
password: 1234
jpa:
hibernate:
ddl-auto: update
show-sql: true
application:
name: microservice-student
profiles: provider-1001
---
server:
port: 1002
context-path: /
eureka:
instance:
hostname: localhost #eureka客户端主机实例名称
appname: microservice-student #客户端服务名
instance-id: microservice-student:1002 #客户端实例名称
prefer-ip-address: true #显示IP
client:
service-url:
defaultZone: http://eureka2001.hsl.com:2001/eureka/,http://eureka2002.hsl.com:2002/eureka/,http://eureka2003.hsl.com:2003/eureka/ #把服务注册到eureka注册中心
info:
groupId: com.hsl.testSpringcloud
artifactId: microservice-student-provider-1002
version: 1.0-SNAPSHOT
userName: http://hsl.com
phone: 123456
spring:
datasource:
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8
username: root
password: 1234
jpa:
hibernate:
ddl-auto: update
show-sql: true
application:
name: microservice-student
profiles: provider-1002
---
server:
port: 1003
context-path: /
eureka:
instance:
hostname: localhost #eureka客户端主机实例名称
appname: microservice-student #客户端服务名
instance-id: microservice-student:1003 #客户端实例名称
prefer-ip-address: true #显示IP
client:
service-url:
defaultZone: http://eureka2001.hsl.com:2001/eureka/,http://eureka2002.hsl.com:2002/eureka/,http://eureka2003.hsl.com:2003/eureka/ #把服务注册到eureka注册中心
info:
groupId: com.hsl.testSpringcloud
artifactId: microservice-student-provider-1003
version: 1.0-SNAPSHOT
userName: http://hsl.com
phone: 123456
spring:
datasource:
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8
username: root
password: 1234
jpa:
hibernate:
ddl-auto: update
show-sql: true
application:
name: microservice-student
profiles: provider-1003
启动类
package com.hsl.microservicestudentprovider;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@EntityScan("com.hsl.*.*")
@EnableEurekaClient
@SpringBootApplication
public class MicroserviceStudentProviderApplication {
public static void main(String[] args) {
SpringApplication.run(MicroserviceStudentProviderApplication.class, args);
}
}
StudentProviderController.java
StudentConsumerController.java
先启动注册中心，再启动三个服务提供者启动类，最后启动消费者
我测试了几遍，只有1001
轮询策略:
BestAvailableRule
public class BestAvailableRule extends
ClientConfigEnabledRoundRobinRule
选择一个最小的并发请求的server 逐个考察Server，如果Server被tripped了，则忽略，在选择其中ActiveRequestsCount最小的server
AvailabilityFilteringRule
public class AvailabilityFilteringRule extends PredicateBasedRule
过滤掉那些因为一直连接失败的被标记为circuit
tripped的后端server，并过滤掉那些高并发的的后端server（active connections
超过配置的阈值） 使用一个AvailabilityPredicate来包含过滤server的逻辑，其实就就是检查status里记录的各个server的运行状态
WeightedResponseTimeRule
public class WeightedResponseTimeRule extends RoundRobinRule
根据响应时间分配一个weight，响应时间越长，weight越小，被选中的可能性越低。 一个后台线程定期的从status里面读取评价响应时间，为每个server计算一个weight。Weight的计算也比较简单responsetime
减去每个server自己平均的responsetime是server的权重。当刚开始运行，没有形成status时，使用roubine策略选择server。
RetryRule
public class RetryRule extends AbstractLoadBalancerRule
对选定的负载均衡策略机上重试机制。 在一个配置时间段内当选择server不成功，则一直尝试使用subRule的方式选择一个可用的server
RoundRobinRule
public class RoundRobinRule extends AbstractLoadBalancerRule
roundRobin方式轮询选择server 轮询index，选择index对应位置的server
RandomRule
public class RandomRule extends
AbstractLoadBalancerRule 随机选择一个server 在index上随机，选择index对应位置的server
ZoneAvoidanceRule
public class ZoneAvoidanceRule extends PredicateBasedRule
复合判断server所在区域的性能和server的可用性选择server 使用ZoneAvoidancePredicate和AvailabilityPredicate来判断是否选择某个server，前一个判断判定一个zone的运行性能是否可用，剔除不可用的zone（的所有server），AvailabilityPredicate用于过滤掉连接数过多的Server。
默认7个策略，根据具体产品需求，我们选用；
RetryRule
SpringCloudConfig
package com.hsl.microservicestudentconsumer80.config;
import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RetryRule;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
@Configuration
public class SpringCloudConfig {
@LoadBalanced // 引入ribbon负载均衡
@Bean
public RestTemplate getRestTemplate(){
return new RestTemplate();
}
/**
* 自定义轮询算法
* @return
*/
@Bean
public IRule myRule(){
return new RetryRule();
}
}
测试：http://localhost/student/ribbon
测试发现共有三个服务可以提供使用，而且是随机的，但也引发了一个问题
若其中一个服务宕机了，那就执行到那个服务会报错
1001宕机
下面我会用Feign解决这个问题
3、Feign简介及应用
Feign简介
Feign是一个声明式的Web Service客户端，它使得编写Web Serivce客户端变得更加简单。我们只需要使用Feign来创建一个接口并用注解来配置它既可完成。它具备可插拔的注解支持，包括Feign注解和JAX-RS注解。Feign也支持可插拔的编码器和解码器。Spring Cloud为Feign增加了对Spring MVC注解的支持，还整合了Ribbon和Eureka来提供均衡负载的HTTP客户端实现。
前面Ribbon调用服务提供者，我们通过restTemplate调用，缺点是，多个地方调用，同一个请求要写多次，不方便统一维护，这时候Feign来了，就直接把请求统一搞一个service作为FeignClient，然后其他调用Controller需要用到的，直接注入service，直接调用service方法即可；同时Feign整合了Ribbon和Eureka，所以要配置负载均衡的话，直接配置Ribbon即可，无其他特殊地方；当然Fiegn也整合了服务容错保护，断路器Hystrix
应用
1、在common项目里建一个service（实际项目肯定是多个service）作为Feign客户端，用Feign客户端来调用服务器提供者，当然可以配置负载均衡；Feign客户端定义的目的，就是为了方便给其他项目调用；
修改 microservice-common
pom.xml引入Feign依赖：
<!--引入Feign依赖-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
新建一个Feign消费者项目；
参考microservice-student-consumer-80建一个microservice-student-consumer-feign-80
代码都复制一份，包括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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.hsl</groupId>
<artifactId>t237microservice</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
<artifactId>microservice-student-consumer-feign-80</artifactId>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>com.hsl</groupId>
<artifactId>microservice-common</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</dependency>
<!-- 修改后立即生效，热部署 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>springloaded</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
</dependency>
<dependency>
<groupId>com.hsl</groupId>
<artifactId>microservice-common</artifactId>
<version>1.0-SNAPSHOT</version>
<scope>compile</scope>
</dependency>
<!--ribbon相关依赖-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-ribbon</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-config</artifactId>
</dependency>
<!--引入Feign依赖-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
SpringCloudConfig
package com.hsl.microservicestudentconsumerfeign80.config;
import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RetryRule;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;
@Configuration
public class SpringCloudConfig {
@LoadBalanced // 引入ribbon负载均衡
@Bean
public RestTemplate getRestTemplate(){
return new RestTemplate();
}
/**
* 自定义轮询算法
* @return
*/
@Bean
public IRule myRule(){
return new RetryRule();
}
}
MicroserviceStudentConsumerFeign80Application
package com.hsl.microservicestudentconsumerfeign80;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;
@EnableEurekaClient
@EnableFeignClients(value = "com.hsl.*.*")
@SpringBootApplication(exclude={DataSourceAutoConfiguration.class, HibernateJpaAutoConfiguration.class})
public class MicroserviceStudentConsumerFeign80Application {
public static void main(String[] args) {
SpringApplication.run(MicroserviceStudentConsumerFeign80Application.class, args);
}
}
yml文件
server:
port: 80
context-path: /
eureka:
client:
service-url:
defaultZone: http://eureka2001.hsl.com:2001/eureka/,http://eureka2002.hsl.com:2002/eureka/,http://eureka2003.hsl.com:2003/eureka/
register-with-eureka: false
StudentConsumerController
package com.hsl.microservicestudentconsumerfeign80.controller;
import com.hsl.microservicecommon.entity.Student;
import com.hsl.microservicecommon.service.StudentClientService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;
import java.util.List;
@RestController
@RequestMapping("/student")
public class StudentConsumerController {
@Autowired
private StudentClientService studentClientService;
@Autowired
private RestTemplate restTemplate;
@PostMapping(value = "/save")
private boolean save(Student student) {
return studentClientService.save(student);
}
@GetMapping(value = "/list")
public List<Student> list() {
return studentClientService.list();
}
@GetMapping(value = "/get/{id}")
public Student get(@PathVariable("id") Integer id) {
return studentClientService.get(id);
}
@GetMapping(value = "/delete/{id}")
public boolean delete(@PathVariable("id") Integer id) {
try {
studentClientService.delete(id);
return true;
} catch (Exception e) {
return false;
}
}
@RequestMapping("/ribbon")
public String ribbon(){
return studentClientService.ribbon();
}
}
测试：
和之前测试结果一样，我就不展示了，不过其中有一个服务宕机了，就不会再访问这一个了，不会报错，然后再把宕机的服务启动，又会有这个服务的访问，这样就解决了上面的问题
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