Springcloud学习(一)——Eureka

一、搭建项目

　　父工程

　　pom

<?xml version="1.0" encoding="UTF-8"?>
<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>4.0.0</modelVersion>

    <packaging>pom</packaging>

    <groupId>com.badcat</groupId>
    <artifactId>springCloud-demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.SR1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-parent</artifactId>
                <version>2.1.5.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.8</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.6.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

　　1、注册中心模块

　　pom

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>springCloud-demo</artifactId>
        <groupId>com.badcat</groupId>
        <version>1.0-SNAPSHOT</version>
        <relativePath>../../pom.xml</relativePath>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <packaging>jar</packaging>

    <artifactId>euraka-server</artifactId>

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

　　application.properties

spring.application.name=eureka-server
server.port=20000

eureka.instance.hostname=localhost
####是否向注册中心注册，因为是单节点注册中心，所以false
eureka.client.register-with-eureka=false
####拉取注册中心表，不拉取
eureka.client.fetch-registry=false

　　启动类（注意@EnableEurekaServer）

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

/**
 * @author badcat
 * @date 2020-03-01 10:46
 */
@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {

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

}

　　启动注册中心，访问http://localhost:20000/

　　2、搭建服务提供方模块

　　　　pom

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>springCloud-demo</artifactId>
        <groupId>com.badcat</groupId>
        <version>1.0-SNAPSHOT</version>
        <relativePath>../../pom.xml</relativePath>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <packaging>jar</packaging>
    <artifactId>eureka-client</artifactId>
    <name>eureka-client</name>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
</project>

　　application.properties

spring.application.name=eureka-client
server.port=30000

eureka.client.serviceUrl.defaultZone=http://localhost:20000/eureka/

　　启动类（注意@EnableDiscoveryClient）

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

/**
 * @author badcat
 * @date 2020-03-01 11:25
 */
@SpringBootApplication
@EnableDiscoveryClient
public class EurekaClientApplication {

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

　　controller

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author badcat
 * @date 2020-03-01 11:27
 */
@RestController
@Slf4j
public class Controller {

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

    @GetMapping("/sayHi")
    public String sayHi(){
        return "this is " + port;
    }

    @PostMapping("/sayHi")
    public Friend sayHiPost(
            @RequestBody Friend friend){

        log.error("you are " + friend.getName());

        friend.setPort(port);
        return friend;
    }
}

　　启动该模块，刷新刚才注册中心的页面，出现这个

　　调用接口试一下，两个接口都能调通

　　3、搭建服务消费者模块（目的是为了调用上一步骤的服务）

　　pom

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>springCloud-demo</artifactId>
        <groupId>com.badcat</groupId>
        <version>1.0-SNAPSHOT</version>
        <relativePath>../../pom.xml</relativePath>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>eureka-consumer</artifactId>
    <name>eureka-consume</name>
    <packaging>jar</packaging>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-actuator</artifactId>
        </dependency>

    </dependencies>
</project>

　　application.properties

spring.application.name=eureka-consumer
server.port=31000

eureka.client.serviceUrl.defaultZone=http://localhost:20000/eureka/

　　启动类（注意@EnableDiscoveryClient、RestTemplate ）

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

/**
 * @author badcat
 * @date 2020-03-01 15:42
 */
@SpringBootApplication
@EnableDiscoveryClient
public class EurekaConsumerApplication {

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

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

}

　　controller

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

/**
 * @author badcat
 * @date 2020-03-01 15:43
 */
@RestController
@Slf4j
public class Controller {

    @Autowired
    private LoadBalancerClient client;
    @Autowired
    private RestTemplate restTemplate;

    @GetMapping("/hello")
    public String hello(){
        //获取注册中心已注册的服务
        ServiceInstance instance = client.choose("eureka-client");

        if (instance == null){
            return "no available instances";
        }

        String format = String.format("http://%s:%s/sayHi", instance.getHost(), instance.getPort());

        log.error("url is {}", format);

        return restTemplate.getForObject(format, String.class);
    }

    @PostMapping("/hello")
    public Friend helloPost(){
        ServiceInstance instance = client.choose("eureka-client");

        if (instance == null){
            return null;
        }

        String format = String.format("http://%s:%s/sayHi", instance.getHost(), instance.getPort());

        log.error("url is {}", format);

        Friend friend = new Friend();
        friend.setName("eureka consumer");

        return restTemplate.postForObject(format, friend, Friend.class);
    }
}

　　启动该模块，刷新注册中心页面

　　调用接口试一下

　　4、服务续约与剔除

　　服务注册方（以eureka-client模块为例）

　　application.properties中添加如下配置

# 每隔5秒钟，向服务注册中心发送一条续约指令
eureka.instance.lease-renewal-interval-in-seconds=5

# 如果30秒依然没有收到续约请求，判定服务过期
eureka.instance.lease-expiration-duration-in-seconds=30

　　注册中心

　　application.properties中添加如下配置(关闭自保机制，每10秒提出一次过期的服务)

# 强制关闭自保（自动开关不起作用）
eureka.server.enable-self-preservation=false

# 每隔多久触发一次剔除（10秒）
eureka.server.eviction-interval-timer-in-ms=10000

　　测试剔除功能，将eureka-client的判定过期时间由30秒改为5秒、发送续约间隔由5秒改为60秒，也就是说改服务一定会过期

　　重启一下注册中心和eureka-client，不停刷新注册中心的那个页面，你会发现一开始eureka-client是注册成功的，几秒之后消失了。查看注册中心的控制台，发现剔除日志：

　　5、注册中心高可用

　　　　重新搭建两个注册中心

　　　　只贴出application.properties(注意eureka.client.service-url.defaultZone)

spring.application.name=eureka-server-peer1
server.port=20001

eureka.instance.hostname=peer1
eureka.client.service-url.defaultZone=http://peer2:40001/eureka

spring.application.name=eureka-server-peer2
server.port=40001

eureka.instance.hostname=peer2
eureka.client.service-url.defaultZone=http://peer1:20001/eureka

　　启动这两个注册中心，访问http://localhost:40001/，出现这个，说明成功

　　我们将之前的eureka-client只注册到peer1上，看看peer2上能不能也拿到eureka-client的信息

　　eureka-client的application.properties(注意eureka.client.serviceUrl.defaultZone是配置的20001端口，也就是peer1)

spring.application.name=eureka-client
server.port=30000

eureka.client.serviceUrl.defaultZone=http://peer1:20001/eureka/

　　启动eureka-client，刷新http://localhost:20001/和http://localhost:40001/，两个页面都会发现eureka-client信息，说明两个peer1和peer2是相互通信的

　　一般来说，我们应该将eureka-client同时配置两个注册中心，所以eureka-client的application.properties应该是这个样，但是这不是同时注册到两个注册中心，而是注册到第一个可用的注册中心，然后再由注册中心来传递eureka-client的信息

spring.application.name=eureka-client
server.port=30000

eureka.client.serviceUrl.defaultZone=http://peer1:20001/eureka/,http://peer2:40001/eureka/

Springcloud学习(一)——Eureka

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