一、spring cloud简介
Spring Cloud为开发人员提供了快速构建分布式系统中一些常见模式的工具(例如配置管理,服务发现,断路器,智能路由,微代理,控制总线)。分布式系统的协调导致了样板模式, 使用Spring Cloud开发人员可以快速地支持实现这些模式的服务和应用程序。他们将在任何分布式环境中运行良好,包括开发人员自己的笔记本电脑,裸机数据中心,以及Cloud Foundry等托管平台。
特性
Spring Cloud专注于提供良好的开箱即用经验的典型用例和可扩展性机制覆盖。
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分布式/版本化配置
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服务注册和发现
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路由
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service - to - service调用
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负载均衡
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断路器
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分布式消息传递
二、 创建服务注册中心(eureka-server)
是采用Eureka作为服务注册与发现的组件
1 、首先创建一个maven主工程
首先创建一个主Maven工程,在其pom文件引入依赖,spring Boot版本为2.0.4.RELEASE,Spring Cloud版本为Finchley.RELEASE。
父pom.xml 文件:
<?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>
<groupId>com.example.demo</groupId>
<artifactId>springcloud-eureka</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<name>springcloud-eureka</name>
<description>Demo project for Spring Boot</description>
<modules>
<module>eureka-server</module>
<module>eureka-client</module>
</modules>
<parent>
<groupId>com.example</groupId>
<artifactId>springcloud-master</artifactId>
<version>0.0.1-SNAPSHOT</version>
</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.boot</groupId>
<artifactId>spring-boot-starter</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>
</project>
2 、创建两个model工程,分别为eureka-server和eureka-cient:
2.1、eureka-server的pom.xml文件:
<?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>
<groupId>com.example.demo.eureka</groupId>
<artifactId>eureka-server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>eureka-server</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>com.example.demo</groupId>
<artifactId>springcloud-eureka</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<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>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
2.2、注册中心启动类,添加注解@EnableEurekaServer,表明自己是一个eurekaserver.
package com.example.demo.eureka;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
2.3、eureka是没有后端缓存的,每一个实例注册之后需要向注册中心发送心跳,在默认情况下erureka server也是一个eureka client ,所以必须要指定一个 server。
eureka-server的配置文件appication.yml:
server:
port: 8081
eureka:
instance:
hostname: localhost
client:
fetch-registry: false
register-with-eureka: false
serviceUrl:
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
spring:
application:
name: eureka-server
注意:通过eureka.client.fetch-registry: false:false和eureka.client.fetch-registry:false来表明自己是一个eureka server.
2.4、 启动工程,打开浏览器访问,http://localhost:8081 ,界面如下:
No application available 没有服务被发现 ,因为没有注册服务。
三、创建一个服务提供者 (eureka-client)
创建过程同server类似,创建完pom.xml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>
<groupId>com.example.demo.erueka</groupId>
<artifactId>eureka-client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>eureka-client</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>com.example.demo</groupId>
<artifactId>springcloud-eureka</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<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>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
启动类添加注解@EnableEurekaClient 表明自己是一个eurekaclient.
package com.example.demo.erueka;
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.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@EnableEurekaClient
@RestController
public class EurekaClientApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaClientApplication.class, args);
}
@Value("${server.port}")
private String port;
@GetMapping("/test")
public String test(String name){
return name + "============="+port;
}
}
还需要在配置文件中注明自己的服务注册中心的地址,application.yml配置文件如下:
server:
port: 8082
spring:
application:
name: eureka-client
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8081/eureka/
# fetch-registry: false
# register-with-eureka: false
注意:需要指明spring.application.name,因为在以后的服务与服务之间相互调用一般都是根据这个name 。
启动工程,打开http://localhost:8082
这会你发现一个服务已经注册在服务中了,服务名为SERVICE-CLIENT ,端口为8082
打开 http://localhost:8082/test?name=张三,浏览器上看到 :
张三=============8082