（六）、集群Eureka构建

127.0.0.1 eureka7001.com
127.0.0.1 eureka7002.com

server:
  port: 7001
eureka:
  instance:
    hostname: eureka7001.com #eureka服务端的实例名称
  client:
    register-with-eureka: false     #false表示不向注册中心注册自己。
    fetch-registry: false     #false表示自己端就是注册中心，我的职责就是维护服务实例，并不需要去检索服务
    service-url:
      #集群指向其它eureka
      defaultZone: http://eureka7002.com:7002/eureka/
      #单机就是7001自己
      #defaultZone: http://eureka7001.com:7001/eureka/

server:
  port: 7002
eureka:
  instance:
    hostname: eureka7002.com #eureka服务端的实例名称
  client:
    register-with-eureka: false     #false表示不向注册中心注册自己。
    fetch-registry: false     #false表示自己端就是注册中心，我的职责就是维护服务实例，并不需要去检索服务
    service-url:
      #集群指向其它eureka
      defaultZone: http://eureka7001.com:7001/eureka/
      #单机就是7002自己
      #defaultZone: http://eureka7002.com:7002/eureka/

eureka:
  client:
    #表示是否将自己注册进Eurekaserver默认为true。
    register-with-eureka: true
    #是否从EurekaServer抓取已有的注册信息，默认为true。单节点无所谓，集群必须设置为true才能配合ribbon使用负载均衡
    fetchRegistry: true
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka, http://eureka7002.com:7002/eureka

@RestController
@Slf4j
public class PaymentController{
    @Value("${server.port}")
    private String serverPort;//添加serverPort
    @PostMapping(value = "/payment/create")
    public CommonResult create(@RequestBody Payment payment)
    {
        int result = paymentService.create(payment);
        log.info("*****插入结果：" + result);
        if(result > 0) {
            return new CommonResult(200,"插入数据库成功,serverPort: "+serverPort/*添加到此处*/, result);
        }else{
            return new CommonResult(444,"插入数据库失败",null);
        }
    }
}

@Slf4j
@RestController
public class OrderController {
    //public static final String PAYMENT_URL = "http://localhost:8001";
    public static final String PAYMENT_URL = "http://CLOUD-PAYMENT-SERVICE";
    ...
}

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 ApplicationContextConfig {
    @Bean
    @LoadBalanced//使用@LoadBalanced注解赋予RestTemplate负载均衡的能力
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }
}

There was an unexpected error (type=Internal Server Error, status=500).
500 : [{"timestamp":"2021-09-11T10:06:45.594+0000","status":500,"error":"Internal Server Error","message":"Invalid bound statement (not found): com.ylc.cloud.dao.PaymentDao.getPaymentById","trace":"org.apach... (6468 bytes)]
org.springframework.web.client.HttpServerErrorException$InternalServerError: 500 : [{"timestamp":"2021-09-11T10:06:45.594+0000","status":500,"error":"Internal Server Error","message":"Invalid bound statement (not found): com.ylc.cloud.dao.PaymentDao.getPaymentById","trace":"org.apach... (6468 bytes)]

eureka:
  ...
  instance:
    instance-id: payment8001 
    prefer-ip-address: true #添加此处
eureka:
  ...
  instance:
    instance-id: payment8002 
    prefer-ip-address: true #添加此处

import org.springframework.cloud.client.discovery.DiscoveryClient;
@Resource
private DiscoveryClient discoveryClient;
@GetMapping(value = "/payment/discovery")
    public Object discovery()
    {
        List<String> services = discoveryClient.getServices();
        for (String element : services) {
            log.info("*****element: "+element);
        }
        List<ServiceInstance> instances = discoveryClient.getInstances("CLOUD-PAYMENT-SERVICE");
        for (ServiceInstance instance : instances) {
            log.info(instance.getServiceId()+"\t"+instance.getHost()+"\t"+instance.getPort()+"\t"+instance.getUri());
        }
        return this.discoveryClient;
    }

@EnableDiscoveryClient//添加该注解

{"services":["cloud-payment-service"],"order":0}

*****element: cloud-payment-service