springcould学习（二）之eureka

一、eureka介绍

Eureka是Netflix开发的服务发现组件，本身是一个基于REST的服务。Spring Cloud将它集成在其子项目spring-cloud-netflix中，以实现Spring Cloud的服务发现功能。目前Eureka 项目相当活跃，代码更新相当频繁，目前最新的版本是1.5.5。Eureka 2.0也在紧锣密鼓地开发中，2.0将会带来更强的功能和更好的扩展性，但是由于还没有Release，故而不作讨论

二、本节主要来使用eureka来做服务注册和发现

1、新建一个项目hjduan.spring.cloud.eureka继承自父工程，pom文件如下

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
    <parent>
        <groupId>com.hjduan.spring.cloudgroupId>
        <artifactId>hjduan.spring.cloudartifactId>
        <version>0.0.1-SNAPSHOTversion>
    parent>
    <artifactId>hjduan.spring.cloud.eurekaartifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-securityartifactId>
        dependency>

        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-eureka-serverartifactId>
        dependency>
    dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/resourcesdirectory>
                <includes>
                    <include>**/*.propertiesinclude>
                    <include>**/*.xmlinclude>
                    <include>**/*.ymlinclude>
                includes>
                <filtering>truefiltering>
            resource>
        resources>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-compiler-pluginartifactId>
            plugin>
        plugins>
    build>
project>

2、application.yml配置

server:
  port: 8761
eureka:
  instance:
    hostname: localhost
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://admin:admin@${eureka.instance.hostname}:${server.port}/eureka/
security:
  basic:
    enabled: true
  user:
    name: admin #登陆用户名
    password: admin#登陆密码

3、启动类

package com.hjduan.spring.cloud.eureka;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
/**
 * 启动一个服务注册中心
 */
@EnableEurekaServer
@SpringBootApplication
public class EurekaApplicationConfiguration {
    public  static void main (String[]args){
        new SpringApplication(EurekaApplicationConfiguration.class).run(args);
    }
}

二、修改上一节的两个项目

1、修改hjduan.spring.cloud.provider pom文件如下

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
    <parent>
        <groupId>com.hjduan.spring.cloudgroupId>
        <artifactId>hjduan.spring.cloudartifactId>
        <version>0.0.1-SNAPSHOTversion>
    parent>
    <artifactId>hjduan.spring.cloud.providerartifactId>
    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-eurekaartifactId>
        dependency>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
    dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/resourcesdirectory>
                <includes>
                    <include>**/*.propertiesinclude>
                    <include>**/*.xmlinclude>
                    <include>**/*.ymlinclude>
                includes>
                <filtering>truefiltering>
            resource>
        resources>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-compiler-pluginartifactId>
            plugin>
        plugins>
    build>
project>

2、application.yml配置

server:
  port: 8762
eureka:
  client:
    serviceUrl:
       defaultZone: http://admin:admin@localhost:8761/eureka/
  instance:
    prefer-ip-address: true
    instance-id: ${spring.application.name}:${spring.application.instance_id:${server.port}}
spring:
  application:
    name: hjduan-spring-cloud-provider

3、控制器

package com.hjduan.spring.cloud.provider;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import com.netflix.appinfo.InstanceInfo;
import com.netflix.discovery.EurekaClient;

@RestController
public class UserController {
    @Autowired
    private EurekaClient eurekaClient;
    @Autowired
    private DiscoveryClient discoveryClient;

    @GetMapping(value = "eureka-instance")
    public String serviceUrl() {
        InstanceInfo instance = eurekaClient.getNextServerFromEureka("HJDUAN-SPRING-CLOUD-CONSUMER", false);
        return instance.getHomePageUrl();
    }

    @SuppressWarnings("deprecation")
    @GetMapping(value = "instance-info")
    public ServiceInstance showInfo() {
        ServiceInstance localServiceInstance = this.discoveryClient.getLocalServiceInstance();
        return localServiceInstance;
    }

    /*@Autowired
    RestTemplate restTemplate;

    @GetMapping(value = "/hi/{name}")
    public String ribbonHelloWordService(@PathVariable String name) {
        return restTemplate.getForObject("http://HJDUAN-SPRING-CLOUD-CONSUMER/hi/{name}", String.class, name);
    }*/
}

4、启动类

package com.hjduan.spring.cloud.provider;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.client.RestTemplate;
/**
 * 注册提供者
 * 
 * 作者： 段浩杰 2017年7月25日
 */
@EnableEurekaClient
@SpringBootApplication
@Controller
public class ApplicationConfiguration {
    public static void main(String[] args) {
        new SpringApplication(ApplicationConfiguration.class).run(args);
    }

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

5、修改hjduan.spring.cloud.consumer pom如下

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0modelVersion>
  <parent>
    <groupId>com.hjduan.spring.cloudgroupId>
    <artifactId>hjduan.spring.cloudartifactId>
    <version>0.0.1-SNAPSHOTversion>
  parent>
  <artifactId>hjduan.spring.cloud.consumerartifactId>
  <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-eurekaartifactId>
        dependency>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
    dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/resourcesdirectory>
                <includes>
                    <include>**/*.propertiesinclude>
                    <include>**/*.xmlinclude>
                    <include>**/*.ymlinclude>
                includes>
                <filtering>truefiltering>
            resource>
        resources>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-compiler-pluginartifactId>
            plugin>
        plugins>
    build>
project>

6、application.yml配置

server:
  port: 8763
eureka:
  client:
    serviceUrl:
      defaultZone: http://admin:admin@localhost:8761/eureka/
  instance:
    prefer-ip-address: true
    instance-id: ${spring.application.name}:${spring.application.instance_id:${server.port}}
spring:
  application:
    name: hjduan-spring-cloud-consumer

7、控制器

package com.hjduan.spring.cloud.consumer;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

/**
 * 暴露的接口 
 * 作者： 段浩杰 2017年7月25日
 */
@RestController
public class UserController {

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

    @GetMapping(value = "/hi/{name}")
    public String showInfo(@PathVariable String name) {
        return "hi" + name+port;
    }
}

8、启动类

package com.hjduan.spring.cloud.consumer;

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

/**
 * 注册提供者 
 * 作者： 段浩杰 2017年7月25日
 */
@EnableEurekaClient
@SpringBootApplication
public class ApplicationConfiguration {
    public static void main(String[] args) {
        new SpringApplication(ApplicationConfiguration.class).run(args);
    }
}

9、然后分别启动hjduan.spring.cloud.eureka、hjduan.spring.cloud.provider、hjduan.spring.cloud.consumer这三个项目

10、访问http://localhost:8761,输入用户名密码，进入到eureka中心，来监控和管理服务。