1. Eureka集群

1.1 集群架構

1.2 實作Eureka集群

1.2.1 修改服務器專案

ServerApp:

package org.crazyit.cloud;

import java.util.Scanner;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@SpringBootApplication
@EnableEurekaServer
public class ServerApp {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String profiles = scan.nextLine();
        new SpringApplicationBuilder(ServerApp.class).profiles(profiles).run(args);
    }
}

application.yml：

server:
  port: 8761
spring:
  application:
    name: cloud-114
  profiles: slave1
eureka:
  client: 
    serviceUrl:
      defaultZone: http://slave2:8762/eureka
---
server:
  port: 8762
spring:
  application:
    name: cloud-114
  profiles: slave2
eureka:
  client: 
    serviceUrl:
      defaultZone: http://slave1:8761/eureka

這樣我們就可以使用控制臺輸入想要打開的服務器，

運行程式：

輸入slave1，回車，即可啟動slave1服務器，

這時候會報錯，因為我們slave2服務器沒有啟動，不需要理會，直接再運行一遍程式，在控制臺輸入slave2：

1.2.2 修改服務提供者專案

PoliceServer：

package org.crazyit.cloud;

import java.util.Scanner;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient
public class PoliceServer {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        // 讀取控制臺的埠輸入
        String port = scan.nextLine();
        new SpringApplicationBuilder(PoliceServer.class).properties("server.port=" + port).run(args);
    }

}

PoliceController：

package org.crazyit.cloud;

import javax.servlet.http.HttpServletRequest;

import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class PoliceController {

    @RequestMapping(value = "/call/{id}", method = RequestMethod.GET, 
            produces = MediaType.APPLICATION_JSON_VALUE)
    public Police call(@PathVariable Integer id, HttpServletRequest request) {
        Police p = new Police();
        p.setId(id);
        p.setName("angus");
        p.setMessage(request.getRequestURL().toString());
        return p;
    }
}

application.yml：

spring:
  application:
    name: cloud-police
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/, http://localhost:8762/eureka/

運行專案：

然后再弄個8082，

1.2.3 修改服務呼叫者專案

application.yml：

server:
  port: 9000
spring:
  application:
    name: cloud-person
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/, http://localhost:8762/eureka/

TestController：

package org.crazyit.cloud;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.client.RestTemplate;

@Controller
@Configuration
public class TestController {
    
    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }

    @GetMapping("/router")
    @ResponseBody
    public String router() {
        RestTemplate tpl = getRestTemplate();
        String json = tpl.getForObject("http://cloud-police/call/1", String.class);
        return json;
    }

}

運行程式：

重繪網站可以看到切換了服務器：

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