实现自己的DiscoveryClient

需要做的:

　　DiscoveryClient能提供那些服务的服务名列表

　　返回指定服务对于的ServiceInstance列表

　　返回DiscoveryClient的顺序

　　返回HealthIndicator里显示的描述

实现LoadBalanceClient

　　实现自己的ServiceList<T extends Server>

　　　　Ribbon提供了AbstractServerList<T extends Server>

　　提供一个配置类，声明ServerListBean 实例

pom引入

<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>


    <dependencyManagement>
        <dependencies>
            <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>

 bootstartp.properties

spring.application.name=name-service

application.yaml

server:
  port: 8080

#需要连接的服务
conns:
  services:
    - localhost:8088

DiscoveryClient服务列表

import lombok.Setter;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.cloud.client.DefaultServiceInstance;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;

import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

@ConfigurationProperties(prefix = "conns")
@Setter
@Slf4j
public class MyDiscoveryClient implements DiscoveryClient {

    public static final String SERVICE_ID = "conn-service";
    // waiter.services
    private List<String> services;

    @Override
    public String description() {
        return "DiscoveryClient that uses service.list from application.yml.";
    }

    @Override
    public List<ServiceInstance> getInstances(String serviceId) {
        if (!SERVICE_ID.equalsIgnoreCase(serviceId)) {
            return Collections.emptyList();
        }
        // 这里忽略了很多边界条件判断，认为就是 HOST:PORT 形式
        return services.stream()
                .map(s -> new DefaultServiceInstance(s,
                        SERVICE_ID,
                        s.split(":")[0],
                        Integer.parseInt(s.split(":")[1]),
                        false)).collect(Collectors.toList());
    }

    @Override
    public List<String> getServices() {
        return Collections.singletonList(SERVICE_ID);
    }
}

ServerList

import java.util.List;import java.util.stream.Collectors;public class MyServerList implements ServerList<Server> {    @Autowired    private  MyDiscoveryClient discoveryClient;    @Override    public List<Server> getInitialListOfServers() {        return getServers();    }    @Override    public List<Server> getUpdatedListOfServers() {        return getServers();    }    private List<Server>  getServers() {        return discoveryClient.getInstances(MyDiscoveryClient.SERVICE_ID).stream()                .map(i -> new Server(i.getHost(), i.getPort()))                .collect(Collectors.toList());    }}