微服务框架——SpringCloud

1.SpringCloud微服务框架

　　a.概念：SpringCloud是基于SpringBoot的微服务框架

　　b.五大神兽：Eureka（服务发现）、Ribbon（客服端负载均衡）、Hystrix（断路器）、Zuul（服务网关）、Spring Cloud Config（分布式配置）

2.Eureka服务发现

　　a.组成：Eureka服务器和Eureka客户端

　　b.Eureka服务器（注册中心）

　　　　①新建springboot项目，依赖选择Eureka Server

　　　　②pom文件关键依赖

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

        ......

    </dependencies>

    ......

　　　　③application.yml文件

# 服务名称
spring:
  application:
    name: eureka-server
# 服务端口号
server:
  port: 8081

#Eureka 相关配置
eureka:
  instance:
    hostname: localhost
  client:
    service-url:
      defaultZone: http://localhost:${server.port}/eureka/
    # 是否从其他的服务中心同步服务列表
    fetch-registry: false
    # 是否把自己作为服务注册到其他服务注册中心
    register-with-eureka: false

　　　　④启动类添加注解@EnableEurekaServer

@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {

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

}

　　　　⑤启动后访问 localhost:8081 可进入管理员界面

　　c.Eureka客户端（生产者）

　　　　①新建springboot项目，依赖选择 Eureka Discovery 、Web

　　　　②pom文件关键依赖

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        ......

    </dependencies>

    ......

　　　　③application.yml文件

spring:
  application:
    name: eureka-client-producer
server:
  port: 8082

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8081/eureka/

　　　　④启动类添加注解@EnableEurekaClient

@SpringBootApplication
@EnableEurekaClient
public class EurekaClientProducerApplication {

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

}

　　　　⑤创建controller供外部调用

@RestController
public class CommonController {

    @Value("${server.port}")
    String port;

    @Value("${spring.application.name}")
    String name;

    @RequestMapping(value = "/printProducer")
    public String printProducer(String param){
        return "[" + name + "]请求参数：" + param + "，服务端口：" + port;
    }
}

3.Ribbon负载均衡

　　a.Eureka客户端(消费者) + Ribbon负载均衡

　　　　①新建springboot项目，依赖选择 Eureka Discovery 、Web 以及 Ribbon

　　　　②pom文件关键依赖

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

        ......

    </dependencies>

    ......

　　　　③application.yml文件

spring:
  application:
    name: eureka-client-consumer
server:
  port: 8085

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8081/eureka/

　　　　④启动类添加注解@EnableDiscoveryClient并且加入restTemplate

@SpringBootApplication
@EnableEurekaClient
public class EurekaClientConsumerApplication {

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

    @Bean
    @LoadBalanced
    RestTemplate restTemplate()
    {
        return new RestTemplate();
    }

}

　　　　⑤使用restTemplate调用服务

@RestController
public class CommonController {

    @Resource
    RestTemplate restTemplate;

    @RequestMapping(value = "/print")
    public String print(String param){
        String result = restTemplate.getForObject("http://EUREKA-CLIENT-PRODUCER/printProducer?param=" + param, String.class);
        return result;
    }

}

4.Hystrix断路器

　　a.消费者增加Hystrix依赖，pom中添加

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

　　b.启动类添加注解@EnableHystrix

@SpringBootApplication
@EnableEurekaClient
@EnableHystrix
public class EurekaClientConsumerApplication {

    ......

}

　　c.具体使用

@RestController
public class CommonController {

    @Resource
    RestTemplate restTemplate;

    /* 断路器配置，当无法调用如下方法时，就会调用自定的errorCallback方法。 */
    @HystrixCommand(fallbackMethod = "errorCallback")
    @RequestMapping(value = "/print")
    public String print(String param){
        String result = restTemplate.getForObject("http://EUREKA-CLIENT-PRODUCER/printProducer?param=" + param, String.class);
        return result;
    }

    public String errorCallback(String param){
        return "连接消费服务失败，请求参数：" + param;
    }

}