来源:Eureka配置:http://www.ityouknow.com/springcloud/2017/05/10/springcloud-eureka.html
Eureka使用:http://www.ityouknow.com/springcloud/2017/05/12/eureka-provider-constomer.html
学习的时候遇到了几个问题,记下来:
记录的时间为:2019年11月12日10:33:16,后续可能会有更新
0. Eureka server 的配置:
0.0 依赖
新建一个springboot项目
<?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 https://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>2.2.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.jack</groupId>
<artifactId>SpringCloudEurekaServer</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>SpringCloudEurekaServer</name>
<description>demo</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Hoxton.RC1</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</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-devtools</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
</repository>
</repositories>
</project>
注意:
(0)关注各种版本号的不同,每次更新后的写法可能会有变化
(1)最主要是引入了eureka-server
0.1 yml文件配置
server:
port: 8000
spring:
application:
name: spring-cloud-eureka-server
eureka:
client:
register-with-eureka: false
fetch-registry: false
serviceUrl:
defaultZone: http://localhost:${server.port}/eureka/
说明:
(0)server.port 为内置tomcat服务器启动的端口,一般为8080,可修改
(1) name 指定的是当前服务的名称,后续可能会使用到
(2)register-with-eureka 默认为true,表示是否将本服务注册到eureka的server端,若为true,则会在进入eureka的控制界面的时候会出现本服务名,即上面的name
(3)fetch-registry:是否从远端获取注册列表,这里只有单注册中心,所以不用获取
(4)defaultZone:eureka server端的地址,在客户端中比较重要。前面的serviceUrl写为service-url也是可以识别的
0.2 启动类
package com.jack.SpringCloudDemo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@SpringBootApplication
@EnableEurekaServer
public class SpringCloudEurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(SpringCloudEurekaServerApplication.class, args);
}
}
说明:
(0)添加了EnableEurekaServer这个注解,用来启动EurekaServer相关的服务
然后启动项目,地址栏输入:http://localhost:8000/ 就可以跳转到eureka的控制台界面,可以看到当前注册到这个服务中的服务
红色圈出部分为已经注册的服务(我这里已经有启动的另外的服务,正常情况下这里应该是空的)。
1. eureka的服务提供端 producer1项目
服务中心建立以后,需要有其他的服务注册到服务中心来提供相应的服务,可以理解为生产者,还需要相对应的消费者,我们这里先写生产者
1.0 依赖
新建一个springboot项目,引入如下依赖
<?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 https://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>2.2.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.jack</groupId>
<artifactId>SpringCloudEurekaProducer1</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>SpringCloudEurekaProducer1</name>
<description>demo</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Hoxton.RC1</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</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>
</repository>
</repositories>
</project>
说明:
(0)注意版本
(1)主要是引入了eureka client
()devtools是为了热加载,更新代码以后自动重启项目
1.1 yml配置
server:
port: 9000
spring:
application:
name: spring-cloud-eureka-producer1
eureka:
client:
service-url:
defaultZone: http://localhost:8000/eureka
说明:
(0)port的端口和刚刚不能一样,两个服务不能使用同一个端口
(1)name:这个服务的名称,项目启动以后这个名称就会出现在Eureka控制台界面的Application一列(就是上面截图中红圈那一块)
(2)defaultZone:本项目为eureka的客户端,上面那个项目是服务端项目,所以这里填写的是服务端的地址
1.2 启动类
package com.jack.SpringCloudDemo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
@SpringBootApplication
@EnableDiscoveryClient
public class SpringCloudEurekaProducer1Application {
public static void main(String[] args) {
SpringApplication.run(SpringCloudEurekaProducer1Application.class, args);
}
}
说明:
(0)添加了@EnableDiscoveryClient注解,这里有@EnableDiscoveryClient与@EnableEurekaClient两种注解写法,可以自行搜索体会
1.3 controller
/**
*
*/
package com.jack.SpringCloudDemo.controllers;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class Producer1Controller {
@RequestMapping("/hello")
public String hello(String name) {
System.out.println("----------------" + name);
return "hello " + name +", this is producer1!";
}
}
说明:
(0)很普通的一个controller
2. eureka 消费者
我们再开一个新的springboot项目
请求过程
请求-》消费者-》生产者
2.0 依赖
<?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 https://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>2.2.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.jack</groupId>
<artifactId>SpringCloudEurekaConsumer1</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>SpringCloudEurekaConsumer1</name>
<description>demo</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Hoxton.RC1</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
<version>1.4.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</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>
</repository>
</repositories>
</project>
说明:
(0)和上一个项目引入的依赖是一样的
2.1 yml配置
server:
port: 10001
spring:
application:
name: spring-cloud-eureka-consumer1
eureka:
client:
service-url:
defaultZone: http://localhost:8000/eureka/
说明:
(0)换了一个10001的端口
(1)name:名字和上两个也不一样
(2)将项目注册到最初的注册中心
2.2 启动类
package com.jack.SpringCloudDemo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class SpringCloudEurekaConsumer1Application {
public static void main(String[] args) {
SpringApplication.run(SpringCloudEurekaConsumer1Application.class, args);
}
}
说明:
(0)添加了@EnableDiscoveryClient 和 @EnableFeignClients 两个注解
(1)@EnableDiscoveryClient:这个注解是启用服务发现功能
(2)@EnableFeignClients : 启用feign进行远程调用,就是可以利用他来调用别的controller
2.3 写一个调用远程方法的接口
/**
*
*/
package com.jack.SpringCloudDemo.remoteInterface;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
@FeignClient(name = "spring-cloud-eureka-producer1")
public interface HelloRemote {
@RequestMapping("/hello")
public String hello(@RequestParam(value = "name")String name);
}
说明:
(0)最上面的name是指我们将要调用的服务的名称
(1)下面的方法和远程的方法需要方法名和参数都一致
(2)在这个方法中,我们携带了一个参数name。
(3)这里可以这样理解,将这里的hello方法理解为就是远程方法,那么忽略interface这个单词,这里看上去就像是一个controller类
(4)这里使用了@RequestParam这个注解,是用来从请求中获取参数的。我以前在接口方法中是不写这些参数的,直接通过参数名来对应,本来这个也没有这个注解,但是会是的producer1(生产者)中的hello方法接受到的参数为null,查了一些其他人的写法,也大都这么写的。
2.4 项目自己的controller
/**
*
*/
package com.jack.SpringCloudDemo.controllers;
import javax.websocket.server.PathParam;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.jack.SpringCloudDemo.remoteInterface.HelloRemote;
@RestController
public class Consumer1Controller {
@Autowired
HelloRemote helloRemote;
@RequestMapping("/hello/{name}")
public String hello(@PathVariable String name) {
System.out.println("-------------------" + name);
return helloRemote.hello(name);
}
}
说明:
(0)这里是我们从客户端请求第一个访问的controller
(1)注入了刚才写的接口
(2)注意这里的hello方法,@PathVariable注解是为了从请求的url中获取数据,然后将参数传到接口中的hello方法,而这个hello方法正是对应生产者的controller中的方法
3.启动项目
(0)依次启动上面0,1,2三个项目,地址栏输入http://localhost:8000/就可以看到刚刚注册的生产者和消费者两个项目,如下:
(1)在地址栏输入http://localhost:10001/hello/hello-world,结果如下:
4.使用默认的负载均衡
使用微服务的一个好处就是可以简单的做到负载均衡
保持上面的三个项目不动,我们在创建一个producer2项目,来实现两个producer之间的负载均衡。
4.0 新建一个新的springboot项目,配置与上述步骤1的producer1的配置相同,但是有几个地方需要修改
4.1 依赖是一毛一样的
<?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 https://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>2.2.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.jack</groupId>
<artifactId>SpringCloudEurekaProducer2</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>SpringCloudEurekaProducer2</name>
<description>demo</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Hoxton.RC1</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</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>
</repository>
</repositories>
</project>
4.2 yml配置
server:
port: 9001
spring:
application:
name: spring-cloud-eureka-producer1
eureka:
client:
service-url:
defaultZone: http://localhost:8000/eureka
说明:
(0)将端口从9000改到9001
(1)name不变,表示他们是同一个服务,spring cloud就是通过这个name来获取不同的服务的,name相同则表示是同一个服务,在有多个相同的服务的情况下,可以实现负载均衡
(2)同样注册到服务中心
4.3 启动类相同,同样只是添加了一个注解
package com.jack.SpringCloudDemo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
@SpringBootApplication
@EnableDiscoveryClient
public class SpringCloudEurekaProducer2Application {
public static void main(String[] args) {
SpringApplication.run(SpringCloudEurekaProducer2Application.class, args);
}
}
4.4 controller,这里有一点点不一样
/**
*
*/
package com.jack.SpringCloudDemo.controllers;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class Producer2Controller {
@RequestMapping("/hello")
public String hello(String name) {
System.out.println("----------------" + name);
return "hello " + name +", this is producer2!";
}
}
说明:
(0) 将打印的文字稍作修改,说明此时请求了producer2
4.5启动此项目,此时有四个项目在同时运行
5.运行情况
5.0 查看服务中心
地址栏输入http://localhost:8000/,如下:
说明:
(0)还是注册了两个服务,一个是consumer1,一个是producer1,这里两个字符串对应的是yml中的application name
(1)可以看到,producer2一行中,后面有两个端口在运行服务,其中就有我们刚刚创建producer2项目
5.1 在地址栏输入http://localhost:10001/hello/hello-world,并不停刷新界面,可以看到显示的文字是交替出现的,如下:
有这里可以看出,这里使用的负载均衡的策略为轮询,当然可以配置其他的策略,大家可以自行尝试,有问题可以在下方评论区交流。