spring cloud 为开发人员提供了快速构建分布式系统的一些工具,包括配置管理、服务发现、断路器、路由、微代理、事件总线、全局锁、决策竞选、分布式会话等等。
本篇文章源码地址case-01-start
一直下一步
创建完成之后的pom文件如下:
<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.1.RELEASE</version>
<relativePath/>
</parent>
<groupId>com.perfree</groupId>
<artifactId>spring-cloud-start</artifactId>
<version>1.0</version>
<packaging>jar</packaging>
<name>spring-cloud-start</name>
<description>spring-cloud-start</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.M3</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>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
</project>
在启动类添加@EnableEurekaServer注解,代表为一个服务注册组件
eureka是一个高可用的组件,在默认情况下erureka server也是一个eureka client ,必须要指定一个server,在application.properties配置如下:
#端口号
server.port=8881
#Eureka实例所在的主机名
eureka.instance.hostname=127.0.0.1
#是否在eureka服务器上注册自己的信息以供其他服务发现,server端不需要,所以写成false,默认true
eureka.client.register-with-eureka=false
#此客户端是否获取eureka服务器注册表上的注册信息,默认为true
eureka.client.fetch-registry=false
像普通springboot项目那样启动我们的服务,访问http://127.0.0.1:8881/
因为还没有服务来注册,所以是还没有服务被发现~
<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.perfree</groupId>
<artifactId>spring-cloud-client</artifactId>
<version>1.0</version>
<packaging>jar</packaging>
<name>spring-cloud-client</name>
<description>spring-cloud-client</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.M3</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>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
</project>
在启动类添加@EnableEurekaClient注解
#端口号
server.port=8882
#应用名称
spring.application.name=myClient
#服务中心地址
eureka.client.service-url.defaultZone=http://localhost:8881/eureka
当我们启动之后,再来观察http://127.0.0.1:8881/ 页面,如下
你会发现一个服务已经注册在服务中了,服务名为MYCLIENT,端口为8882
接下来,我们添加一个controller,提供一个hello的接口:
新建controller包,在里边新建HelloController类,如下:
package com.perfree.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HelloController {
@RequestMapping("/hello")
public String hello() {
return "Hello";
}
}
可以看到,该接口只返回了Hello字符串,接下来我们创建服务消费者进行调用
为了让我们更能够体会到Eureka所发挥的作用,我们下面来构建一个服务消费者,该服务消费者将调用spring-cloud-client所提供的服务。
勾选如下:
完整pom文件一览:
<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.1.RELEASE</version>
<relativePath/>
</parent>
<groupId>com.perfree</groupId>
<artifactId>spring-cloud-ribbon</artifactId>
<version>1.0</version>
<packaging>jar</packaging>
<name>spring-cloud-ribbon</name>
<description>spring-cloud-ribbon</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.M3</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</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>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
</project>
spring-cloud-starter-ribbon,该子项目提供客户端负载均衡功能,可以自动从Eureka服务器中获取服务提供者的地址列表,从而能够发起相应的调用
#端口号
server.port=8883
#应用名称
spring.application.name=myRibbon
#服务中心地址
eureka.client.service-url.defaultZone=http://localhost:8881/eureka
package com.perfree;
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;
@SpringBootApplication
@EnableDiscoveryClient
public class SpringCloudRibbonApplication {
public static void main(String[] args) {
SpringApplication.run(SpringCloudRibbonApplication.class, args);
}
//注入RestTemplate
@Bean
public RestTemplate restTemplate() {
return new RestTemplate();
}
}
package com.perfree.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
@RestController
public class HelloController {
@Autowired
private RestTemplate restTemplate;
@RequestMapping("/")
public String hello() {
return restTemplate.getForEntity("http://127.0.0.1:8882/hello", String.class).getBody()+" Spring Cloud";
}
}
启动成功之后可以看到注册中心:
我们接着访问http://127.0.0.1:8883/
已经调用成功~