学习SpringCloud02-Eureka

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文档

https://blog.csdn.net/forezp/article/details/70148833/

目的

搭建一个集群，包括服务注册、服务发现和负载均衡等。

大致步骤

  1. 创建一个注册中心eureka-server
  2. 创建两个服务提供者eureka-provider1、eureka-provider2
  3. 创建一个服务消费者eureka-consumer

注册中心

创建一个maven项目eureka-server。

pom.xml

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

<properties>
	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
	<java.version>1.8</java.version>
	<spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
</properties>

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

	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-test</artifactId>
		<scope>test</scope>
	</dependency>
</dependencies>

<dependencyManagement>
	<dependencies>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-dependencies</artifactId>
			<version>${spring-cloud.version}</version>
			<type>pom</type>
			<scope>import</scope>
		</dependency>
	</dependencies>
</dependencyManagement>

<build>
	<plugins>
		<plugin>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-maven-plugin</artifactId>
		</plugin>
	</plugins>
</build>

application.yml

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server:
  port: 8761

eureka:
  client:
    # registerWithEureka: false 和 fetchRegistry: false 表明自己是一个eureka server.
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://localhost:${server.port}/eureka/

Application.java

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package com.kangyonggan.sc;

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

@SpringBootApplication
@EnableEurekaServer
public class Application {

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

这就是一个简单的注册中心，启动后访问：http://localhost:8761/, 可以看到注册中心的界面。

服务提供者

创建一个maven项目eureka-provider1。

pom.xml

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

<properties>
	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
	<java.version>1.8</java.version>
	<spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
</properties>

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

	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-test</artifactId>
		<scope>test</scope>
	</dependency>
</dependencies>

<dependencyManagement>
	<dependencies>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-dependencies</artifactId>
			<version>${spring-cloud.version}</version>
			<type>pom</type>
			<scope>import</scope>
		</dependency>
	</dependencies>
</dependencyManagement>

<build>
	<plugins>
		<plugin>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-maven-plugin</artifactId>
		</plugin>
	</plugins>
</build>

application.yml

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eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
server:
  port: 8762
spring:
  application:
    name: service-hi

Application.java

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package com.kangyonggan.sc;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@EnableEurekaClient
@RestController
public class Application {

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

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

    @RequestMapping("hi")
    public String hi(@RequestParam String name) {
        return "hi "   name   ",i am from port:"   port;
    }
}

创建一个maven项目eureka-provider2。代码和eureka-provider1一样，只不过端口改为8763。

启动项目后再次访问:http://localhost:8761/，就可以看到Instances currently registered with Eureka下面已经有这两个服务了，由于这两个服务的Application Name一样，就形成了集群。

服务消费者

创建一个maven项目eureka-consumer。

pom.xml

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

<properties>
	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
	<java.version>1.8</java.version>
	<spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
</properties>

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

	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-test</artifactId>
		<scope>test</scope>
	</dependency>
</dependencies>

<dependencyManagement>
	<dependencies>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-dependencies</artifactId>
			<version>${spring-cloud.version}</version>
			<type>pom</type>
			<scope>import</scope>
		</dependency>
	</dependencies>
</dependencyManagement>

<build>
	<plugins>
		<plugin>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-maven-plugin</artifactId>
		</plugin>
	</plugins>
</build>

application.yml

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

Application.java

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package com.kangyonggan.sc;

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.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
public class Application {

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

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

HelloService.java

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package com.kangyonggan.sc;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

/**
 * @author kangyonggan
 * @since 6/20/18
 */
@Service
public class HelloService {

    @Autowired
    RestTemplate restTemplate;

    public String hiService(String name) {
        return restTemplate.getForObject("http://SERVICE-HI/hi?name="   name, String.class);
    }
}

HelloControler.java

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package com.kangyonggan.sc;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author kangyonggan
 * @since 6/20/18
 */
@RestController
public class HelloControler {

    @Autowired
    HelloService helloService;

    @RequestMapping("hi")
    public String hi(@RequestParam String name) {
        return helloService.hiService(name);
    }
}

启动后访问http://localhost:8764/hi?name=小新。不停的访问，界面会交替显示：

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hi 小新,i am from port:8762
hi 小新,i am from port:8763