SpringCloud之LoadBalancer负载均衡器的简单使用
loadbalancer用于对提供服务的集群做一个节点的选取规则。
如图所示,load balancer集成在调用方
示例
- 创建loadbalance-base模块,并引入相关依赖
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-bootstrap</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>
</dependencies>
版本信息
<properties>
<spring-boot.version>2.4.2</spring-boot.version>
<spring-cloud-alibaba.version>2021.1</spring-cloud-alibaba.version>
<nacos.version>2021.1</nacos.version>
<spring-cloud.version>2020.0.1</spring-cloud.version>
<spring-cloud-bootstrap.version>3.0.3</spring-cloud-bootstrap.version>
<spring-cloud-loadbalancer.version>3.0.1</spring-cloud-loadbalancer.version>
</properties>
- 创建服务提供者模块loadbalancer-provider-service
- 主类
@EnableDiscoveryClient
@SpringBootApplication
public class LoadBalanceProviderApplication {
public static void main(String[] args) {
SpringApplication.run(LoadBalanceProviderApplication.class, args);
}
}
- 配置
spring:
application:
name: loadbalance-provider-service
cloud:
nacos:
config:
group: loadbalance-group
namespace: loadbalance
server-addr: 192.168.56.102:8848
file-extension: yml
prefix: ${spring.application.name}
discovery:
group: loadbalance-group
namespace: loadbalance
server-addr: 192.168.56.102:8848
weight: 5
server:
port: 8082
- 服务类
@RestController
public class TestController {
@Value("${server.port}")
private int port;
@GetMapping("/service")
public String test(){
return "provicer servvice: [from port]:" + port;
}
}
- 启动nacos,创建响应的命名空间,并开启多实例服务,分别开启
8081
,和8082
的两个loadbalance-provider-service服务实例
- 创建loadbalancer-consumer-service
- 主类
@SpringBootApplication
@EnableDiscoveryClient
public class LoadBalanceConsumerApplication {
public static void main(String[] args) {
SpringApplication.run(LoadBalanceConsumerApplication.class, args);
}
}
- restTemplate配置类,此处必须在restTemplate上加上
@LoadBalanced
注解
@Configuration
public class LoadConfiguration {
@Bean
@LoadBalanced
public RestTemplate restTemplate(){
return new RestTemplate();
}
}
- 服务类,restTemplate调用host:port改为服务提供者的名称
@RestController
public class TestController {
@Resource
private RestTemplate restTemplate;
@GetMapping("/service")
public String test(){
return restTemplate.getForObject("http://loadbalance-provider-service/service", String.class);
}
}
- 配置
spring:
application:
name: loadbalance-consumer-service
cloud:
nacos:
config:
group: loadbalance-group
namespace: loadbalance
server-addr: 192.168.56.102:8848
file-extension: yml
prefix: ${spring.application.name}
discovery:
group: loadbalance-group
namespace: loadbalance
server-addr: 192.168.56.102:8848
weight: 1
server:
port: 9091
- 启动loadbalacer-consumer-service服务
访问localhost:9091/service,并多次刷新,可以看到8081,和8082两个服务交替
provicer servvice: [from port]:8081
provicer servvice: [from port]:8082
provicer servvice: [from port]:8081
provicer servvice: [from port]:8082
provicer servvice: [from port]:8081
provicer servvice: [from port]:8082
....
Load Balancer提供的策略
- RoundRobin: 轮询策略,意思循环往复的的服务进行选取。
- Random: 随机策略,随机对服务选取一个节点
Load Balancer的默认负载策略
RoundRobin: 轮询策略,意思循环往复的的服务进行选取。
替换默认的负载策略,使用随机策略模式
- 新建RandomLoadBalanceConfiguration配置类,将随机策略配置进去
public class RandomLoadBalanceConfiguration {
@Bean
public ReactorLoadBalancer<ServiceInstance> randomLoadBalancer(Environment environment, LoadBalancerClientFactory loadBalancerClientFactory) {
String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
return new RandomLoadBalancer(loadBalancerClientFactory
.getLazyProvider(name, ServiceInstanceListSupplier.class), name);
}
}
按照官方说法配置类The classes you pass as @LoadBalancerClient
or @LoadBalancerClients
configuration arguments should either not be annotated with @Configuration
or be outside component scan scope.
配置类不能加@Configuation
注解或者要放在不被Spring容器扫描到的地方,意思要放在和主类平级的包下,不能放在主类的包或者子包。
- 在主类或者某个能被扫描到的配置类上加上
@LoadBalancerClients
- 配置全局策略
@LoadBalancerClients(defaultConfiguration = WeightLoadBalanceConfiguration.class)
- 针对服务配置策略
@LoadBalancerClients({
@LoadBalancerClient(name = "loadbalance-provider-service", configuration = RandomLoadBalanceConfiguration.class)
})