springcloud project created

1. Create a maven simple web project in idea.
2. Create a module in the simple maven project.
   1. The moudle name is eureka,it's a discovery and register services.
   2. 
   4. 

   5. server:
        port: 8761
      
      eureka:
        instance:
          hostname: localhost
        client:
          registerWithEureka: false
          fetchRegistry: false
          serviceUrl:
            defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
      

      　　yml 配置文件，没有yml后缀的，直接添加一个文件即可

   6.  在application中加入注解@EnableEurekaServer，申明此处为服务注册中心。

      package com.bcd.cloud.pf.eureka;
      
      import org.springframework.boot.SpringApplication;
      import org.springframework.boot.autoconfigure.SpringBootApplication;
      import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
      
      /**
       * EurekaApplication class
       *
       * @EnableEurekaServer was created by myself
       *
       * @author myself
       * @date 2019/12/05
       */
      @SpringBootApplication
      @EnableEurekaServer
      public class EurekaApplication {
      
      	public static void main(String[] args) {
      		SpringApplication.run(EurekaApplication.class, args);
      	}
      
      }
      

      　　Start this project，and view in the web explorer.http://localhost:8761/

   7. You will see this view.
3. create productor.
   1. This project is a web, created project type is 

      EnableEurekaClient

   2. eureka:
        client:
          serviceUrl:
            defaultZone: http://localhost:8761/eureka/
      server:
        port: 8763
      spring:
        application:
          name: productor
      

      　　productor was set eureka client，it will discovery by 8761，but its port is 8763.

   3. package com.bcd.cloud.pf.productor;
      
      import org.springframework.boot.SpringApplication;
      import org.springframework.boot.autoconfigure.SpringBootApplication;
      import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
      
      /**
       * ProductorApplication class
       *
       * @EnableEurekaClient was created by myself
       *
       * @author myself
       * @date 2019/12/05
       */
      @SpringBootApplication
      @EnableEurekaClient
      public class ProductorApplication {
      
      	public static void main(String[] args) {
      		SpringApplication.run(ProductorApplication.class, args);
      	}
      
      }
      

      　　

   4. The APPController was added by myself.

      package com.bcd.cloud.pf.productor.rest;
      
      import org.springframework.beans.factory.annotation.Value;
      import org.springframework.web.bind.annotation.RequestMapping;
      import org.springframework.web.bind.annotation.RequestParam;
      import org.springframework.web.bind.annotation.RestController;
      
      /**
       * Demo class
       *
       * @author keriezhang
       * @date 2016/10/31
       */
      @RestController
      public class AppController {
      
          @Value("${server.port}")
          String port;
      
          @RequestMapping("/hi")
          public String home(@RequestParam String name)
          {
              return "hi " + name + ",i am from port:" + port;
          }
      }
      

      　　

   5. Run this application,you will see this view.

   6. 

4. create consume. invoke above project that productor.
   1. 　　The project name is ribbon.瑞本；丝带、条状物，这里用来做断路由使用；他调用上面的productor 生产者。

      <dependencies>
      		<dependency>
      			<groupId>org.springframework.cloud</groupId>
      			<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
      		</dependency>
      		<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>
      		<!--断路器-->
      		<dependency>
      			<groupId>org.springframework.cloud</groupId>
      			<artifactId>spring-cloud-starter-hystrix</artifactId>
      			<version>1.4.4.RELEASE</version>
      		</dependency>
      		<dependency>
      			<groupId>org.springframework.boot</groupId>
      			<artifactId>spring-boot-starter-test</artifactId>
      			<scope>test</scope>
      			<exclusions>
      				<exclusion>
      					<groupId>org.junit.vintage</groupId>
      					<artifactId>junit-vintage-engine</artifactId>
      				</exclusion>
      			</exclusions>
      		</dependency>
      	</dependencies>
      

      　　this is its pom.xml  ,add some dependency.

   2. yml file like this:

      eureka:
        client:
          serviceUrl:
            defaultZone: http://localhost:8761/eureka/
      server:
        port: 8764
      spring:
        application:
          name: ribbon
      

      　　This project's port is 8764.

   3. Infact this project is a web project also.
      1. 　　

         package com.bcd.cloud.pf.ribbon.service;
         
         import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
         import org.springframework.beans.factory.annotation.Autowired;
         import org.springframework.http.ResponseEntity;
         import org.springframework.stereotype.Service;
         import org.springframework.web.client.RestTemplate;
         
         @Service
         public class HelloService {
         
             @Autowired
             RestTemplate restTemplate;
         
             // 断路器配置，当无法调用如下方法时，就会调用自定的hiError方法。
             @HystrixCommand(fallbackMethod = "hiError")
             public String hiService(String name)
             {
                 ResponseEntity<Object> forEntity=restTemplate.getForEntity("http://PRODUCTOR/hi?name=" + name, Object.class);
                 Object forObject=restTemplate.getForObject("http://PRODUCTOR/hi?name=" + name, Object.class);
                 return restTemplate.getForObject("http://PRODUCTOR/hi?name=" + name, String.class);
             }
         
         
             public String hiError(String name) {
                 return "hi,"+name+",This has error in that page.";
             }
         }
         

         hiService invoke the 8763 method hi,you could see this url:

         "http://PRODUCTOR/hi?name=" 

         　　run this application you will see this view:

      2. The above methd is view that the 8763 server is running,if you stop the 8763 project,you will see this view:
      3. 

      4. The reason is that :

   4. The ribbon config code like this:

      package com.bcd.cloud.pf.ribbon;
      
      import org.springframework.boot.SpringApplication;
      import org.springframework.boot.autoconfigure.SpringBootApplication;
      import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
      import org.springframework.cloud.client.loadbalancer.LoadBalanced;
      import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
      import org.springframework.cloud.netflix.hystrix.EnableHystrix;
      import org.springframework.context.annotation.Bean;
      import org.springframework.web.client.RestTemplate;
      
      
      /**
       * RibbonApplication class
       *
       * @EnableEurekaClient was created by myself
       * @EnableHystrix was created by myself ,断路由
       *
       * @author myself
       * @date 2019/12/05
       */
      @SpringBootApplication
      //@EnableEurekaClient
      @EnableDiscoveryClient
      @EnableHystrix
      public class RibbonApplication {
      
      	public static void main(String[] args) {
      		SpringApplication.run(RibbonApplication.class, args);
      	}
      
      	/**
      	  *  加入restTemplate以消费相关的服务。
      	* */
      	@Bean
      	@LoadBalanced
      	RestTemplate restTemplate()
      	{
      		return new RestTemplate();
      	}
      
      }