Spring Cloud基础之Load Balancing负载均衡

这一篇依赖前面的SpringCloud的服务发现的服务，因此首先需要在Discovery Service服务发现那一篇中的创建Discovery Server服务

一、第一种方式通过@LoadBalanced注册LoadBalancing

1.创建ribbin-time-service服务

导入包，实际是通过Spring Initializr导入的，Eureka Discovery,Spring Web

spring-boot-starter-web
spring-cloud-starter-netflix-eureka-client

2.配置ribbin-time-service启动类注解

@RestController
@EnableDiscoveryClient
@SpringBootApplication
public class RibbonTimeServiceApplication {
    @Value("${server.port}")
    private int port;
    public static void main(String[] args) {
        SpringApplication.run(RibbonTimeServiceApplication.class, args);
    }
    @GetMapping
    public String getTime(){
        return "The current time is "+ new Date().toString()
                + "(answered by service running on "+ port +")";
    }
}

3.ribbin-time-service配置文件

spring.application.name=time-service
eureka.client.service-url.defaultZone=http://localhost:8761/eureka

4.创建ribbin-time-app服务

导入包，实际是通过Spring Initializr导入的，Eureka Discovery,Spring Web,Ribbon

spring-boot-starter-web
spring-cloud-starter-netflix-eureka-client
spring-cloud-starter-netflix-ribbon

5.配置ribbin-time-app启动类注解

@RestController
@EnableDiscoveryClient
@SpringBootApplication
public class RibbonTimeAppApplication {
    @Autowired
    private RestTemplate restTemplate;
    public static void main(String[] args) {
        SpringApplication.run(RibbonTimeAppApplication.class, args);
    }
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
    @GetMapping
    public String getTime(){
        return restTemplate.getForEntity("http://time-service",String.class).getBody();
    }
}

6.ribbin-time-app配置文件默认空配置

7.ribbin-time-service分别配置两个spring-boot服务，server.port分别为4444和5555，分别启动

ribbon-time-app启动后
通过http://localhost:8080/访问

//输出：
The current time is Mon Apr 13 22:53:15 CST 2020(answered by service running on 5555)
//或者
The current time is Mon Apr 13 22:53:15 CST 2020(answered by service running on 4444)

二、另一种方式通过@RibbonClient配置

1.创建ribbin-time-service服务

//配置启动类注解
@RestController
@SpringBootApplication
public class RibbonTimeServiceApplication {
    @Value("${server.port}")
    private int port;
    public static void main(String[] args) {
        SpringApplication.run(RibbonTimeServiceApplication.class, args);
    }
    @GetMapping
    public String getTime(){
        return "The current time is "+ new Date().toString()
                + "(answered by service running on "+ port +")";
    }
}

2.ribbin-time-service服务配置文件

spring.application.name=time-service

3.创建ribbon-time-app服务

//配置启动类注解
@RestController
@RibbonClient(name = "time-service")
@SpringBootApplication
public class RibbonTimeAppApplication {
    @Autowired
    private RestTemplate restTemplate;
    public static void main(String[] args) {
        SpringApplication.run(RibbonTimeAppApplication.class, args);
    }
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
    @GetMapping
    public String getTime(){
        return restTemplate.getForEntity("http://time-service",String.class).getBody();
    }
}

4.ribbon-time-app配置文件

time-service.ribbon.eureka.enabled=false
time-service.ribbon.listOfServers=http://localhost:4444,http://localhost:5555

5.ribbon-time-service分别配置两个spring-boot服务，server.port分别为4444和5555，分别启动

ribbon-time-app启动后
通过http://localhost:8080/访问

输出：
The current time is Mon Apr 13 22:53:15 CST 2020(answered by service running on 5555)
或者
The current time is Mon Apr 13 22:53:15 CST 2020(answered by service running on 4444)

三、自定义ribbon的负载规则IRule

1.RoundRibbonRule，滚动的负载，第一次a，第二次b，第三次a，以此循环

ResponseTimeWeightedRule根据每个节点的相应时间负载
RandomRule随机负载
ZoneAvoidanceRule以根据AWS区域和可用性发送流量

@Configuration
public class RibbonTimeConfig {
    @Bean
    public IRule ribbonRule(){
        return new RandomRule();
    }
}

2.自定义ribbon的负载规则IPing

DummyPing不检查活动性或者可用性，将流量发送到所有实例
PingUrl通过HTTP访问获取与其响应并检查结果
NIWSDiscoveryPing，Eureka发现服务的自动配置检测

@Configuration
public class RibbonTimeConfig {
@Bean
public PingUrl ribbonPing(){
    PingUrl pingUrl = new PingUrl();
    pingUrl.setExpectedContent("true");//这个内容需要与服务器接口返回的内容一致才认为服务是正常的
    return pingUrl;
}
}
//启动类中配置
@RestController
@RibbonClient(name = "time-service",configuration = RibbonTimeConfig.class)
@SpringBootApplication
public class RibbonTimeAppApplication {
}