springcloud内容知识点

一、eureka：服务注册
    1、服务端（先启动）
        1、pom.xml
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
            </dependency>
        2、application.yml
            server:
              port: 8081
            spring:
              application:
                name: EurekaServer
            eureka:
              client:
                register-with-eureka: false #Eureka服务本身无需注册
                fetch-registry: false #Eureka服务本身无需获取注册信息
                service-url:
                  defaultZone: http://127.0.0.1:${server.port}/eureka/
        3、启动类
            @SpringBootApplication
            @EnableEurekaServer
            public class MyEurekaServer {
                public static void main(String[] args) {
                    SpringApplication.run(MyEurekaServer.class);
                }
            }
    2、客户端
        1、pom.xml
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
        2、application.yml
            server:
              port: 8082
            spring:
              application:
                name: EurekaClient
            eureka:
              client:
                service-url:
                  defaultZone: http://127.0.0.1:8081/eureka/
              instance:
                prefer-ip-address: true #跨域
        3、启动类
            @SpringBootApplication
            @EnableEurekaClient
            public class MyEurekaClient {
                public static void main(String[] args) {
                    SpringApplication.run(MyEurekaClient.class);
                }
            }
二、feign：服务间调用，有负载均衡功能
    1、被调用方不用动代码（@ResponseBody返回值不能是Object）
    2、调用方
        1、pom.xml
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
            </dependency>
        2、feign接口（调用方直接调接口的方法，即可实现服务间调用）
            @FeignClient("EurekaClientA")
            public interface AFeign {
                @RequestMapping(value = "/a/amethod/{id}")
                Msg ametohd(@PathVariable("id") Integer id);
            }
        3、启动类
            @SpringBootApplication
            @EnableEurekaClient
            @EnableDiscoveryClient
            @EnableFeignClients
            public class MyEurekaClientB {
                public static void main(String[] args) {
                    SpringApplication.run(MyEurekaClientB.class);
                }
            }
三、hystrix：熔断器
    1、被调用方不用动代码
    2、调用方
        1、application.yml
            feign:
              hystrix:
                enabled: true
        2、feign接口
            @FeignClient(value = "EurekaClientA", fallback = AFeignImpl.class)
            public interface AFeign {
                @RequestMapping(value = "/a/amethod/{id}")
                Msg ametohd(@PathVariable("id") Integer id);
            }
        3、实现feign接口（被调用方停止服务，即会调用熔断器方法，被调用方重新提供服务，即会重新调用所提供的的服务）
            @Component
            public class AFeignImpl implements AFeign {
                @Override
                public Msg ametohd(Integer id) {
                    return Msg.fail().add("branch", "熔断器触发");
                }
            }