SpringCloud快速上手

注册中心Eureka:

每一个实例注册进Eureka后向他发送心跳,如果心跳超时,通常Eureka会删除该服务.

//启动类:
@SpringBootApplication
@EnableEurekaServer //关键
public class EurekaServerApplication {
    public static void main(String[] args) {
        SpringApplication.run( EurekaServerApplication.class, args );
    }
}

通过eureka.client.registerWithEureka：false和fetchRegistry：false来表明自己是一个eureka server,
不然启动会端口冲突报错,如果两台Eureka组成高可用的话,就不用配置为false.

//配置:
server:
  port: 8761
eureka:
  instance:
    hostname: localhost
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
spring:
  application:
    name: eureka-server

服务提供者:

启动两台服务提供者即可搭建服务集群,通过ribbon可实现负载均衡访问这两台服务提供者.

//启动类
@SpringBootApplication
@EnableEurekaClient //关键
@RestController
public class ServiceHiApplication {
 public static void main(String[] args) {
 	SpringApplication.run(ServiceHiApplication.class, args);
 }

 @Value("${server.port}") //注入配置文件字段
 String port;
 @RequestMapping("/client_hi")
 public String home(@RequestParam String name) {
 	return "hi "+name+",i am from port:" +port;
 }
}

//配置:
eureka:
client:
 serviceUrl:
   defaultZone: http://localhost:8761/eureka/ //声明注册中心地址
server:
port: 8762
spring:
application:
 name: service-client //声明服务名,将来使用这个服务时根据服务名调用

服务消费方

Spring cloud有两种服务调用方式，一种是ribbon+restTemplate，另一种是feign。

Feign默认集成了ribbon

先讲解下基于ribbon+rest

//启动类
@SpringBootApplication
@EnableDiscoveryClient //关键
public class ServiceRibbonApplication {
	public static void main(String[] args) {
		SpringApplication.run(ServiceRibbonApplication.class, args);
	}

	@Bean //向Spring仓库注入一个bean: restTemplate
	@LoadBalanced //表明这个restRemplate开启客户端负载均衡的功能
	RestTemplate restTemplate() {
		return new RestTemplate();
	}
}

//配置:
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/ //指定注册中心地址以发现服务
server:
  port: 8764
spring:
  application:
    name: service-ribbon //声明服务名

//应用代码
//service层
@Service
public class HelloService {

    @Autowired //注入启动类中的实例
    RestTemplate restTemplate;

    public String hiService(String name) {
        return restTemplate.getForObject("http://SERVICE-CLIENT/client_hi?name="+name,String.class);
    }
}
//controller层
@RestController
public class HelloControler {

    @Autowired
    HelloService helloService;
    
    @RequestMapping(value = "/hi")
    public String hi(@RequestParam String name){
        return helloService.hiService(name);
    }
}

访问http://localhost:8764/hi?name=forezp,返回hi forezp,i am from port:8762.调用成功

Feign:整合了Ribbon,默认开启负载均衡

//启动类
@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients //关键
public class ServiceFeignApplication {

	public static void main(String[] args) {
		SpringApplication.run(ServiceFeignApplication.class, args);
	}
}

//应用代码
@FeignClient("xc-service-manage-cms") //声明服务名以及调用服务的接口
public interface CmsPageClient extends CmsPageControllerApi {
}