Spring Cloud应用中可以支持多种的服务治理框架，比如Eureka、Consul、Zookeeper等，现在我们用的是consul,本文以SpringCloud Dalston.SR5版本介绍Eureka的使用：
- 创建服务注册中心
- 创建服务提供者
- 创建服务消费者
- 服务消费
- 踩的坑
一、创建服务注册中心
1.创建一个基础SpringBoot工程，命名为eureka-server
2.修改pom.xml
(1)修改一：SpringCloud版本管理
<!-- 使用dependencyManagement进行版本管理 -->
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.SR5</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
(2)修改二：添加Eureka Server 起步依赖
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka-server</artifactId>
</dependency>
(3)完整pom.xml
<?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>1.5.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.zrk</groupId>
<artifactId>eureka-server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>eureka-server</name>
<description>Eureka Server</description> <!-- 使用dependencyManagement进行版本管理 -->
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.SR5</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement> <properties>
<java.version>1.8</java.version>
</properties> <dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-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>
3.修改主启动类
只需在主启动类上添加@EnableEurekaServer注解就可以启动一个服务注册中心：
@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
官方文档截图：
4.修改配置
修改配置文件，如application.properties，也可用application.yml(官方文档使用)等：
spring.application.name=eureka-server
server.port=8761 eureka.instance.hostname=localhost
#不把自己注册到注册中心
eureka.client.register-with-eureka=false
#不去发现服务
eureka.client.fetch-registry=false
#服务注册中心url
eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${server.port}/eureka
启动工程，访问http://localhost:8761
可以看到Eureka管理页面，看到No instances available，表示还没有实例注册到注册中心。
注：后续就会发现SpringCloud整合其他框架时都是先导入对应起步依赖，再添加对应注解，再修改配置。
更多详细配置可以参考EurekaInstanceConfigBean.java and EurekaClientConfigBean.java。
二、创建服务提供者
1.创建一个基础SpringBoot工程，命名为eureka-provider-user
2.修改pom.xml
(1)修改一：SpringCloud版本管理
<!-- 使用dependencyManagement进行版本管理 -->
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.SR5</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
(2)修改二：添加Eureka起步依赖
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
(3)完整pom.xml
<?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>1.5.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.zrk</groupId>
<artifactId>eureka-provider-user</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>eureka-provider-user</name>
<description>Eureka Client</description> <!-- 使用dependencyManagement进行版本管理 -->
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.SR5</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement> <properties>
<java.version>1.8</java.version>
</properties> <dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</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>
3.修改主启动类
只需在主启动类上添加@EnableEurekaClient注解,也可使用@EnableDiscoveryClient注解，两个注解都能激活Eureka中的DiscoveryClient实现，只是前者仅限于使用Eureka的情况下使用。
@SpringBootApplication
//@EnableEurekaClient
@EnableDiscoveryClient
public class EurekaProviderUserApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaProviderUserApplication.class, args);
}
}
4.修改配置
spring.application.name=provider-user
server.port=8081
#设置服务注册中心的URL
eureka.client.serviceUrl.defaultZone=http://localhost:8761/eureka/
启动该工程，访问http://localhost:8761
可以看到provider-user服务已经注册成功！
5.添加业务逻辑
(1)UserController.java
@RestController
@RequestMapping("user")
public class UserController
{
@RequestMapping(value = "getUserById/{id}")
public User getUser(@PathVariable Integer id){
User user = new User();
user.setId(id);
user.setName("张三");
user.setPassword("123");
return user;
}
}
(2)User.java
public class User {
private Integer id;
private String name;
private String password;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
三、创建服务消费者
1.创建一个基础SpringBoot工程，命名为eureka-consumer-basketball
2.修改pom.xml
(1)修改同eureka-provider-user，只是多了web相关依赖：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
(2)完整pom.xml
<?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>1.5.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.zrk</groupId>
<artifactId>eureka-consumer-basketball</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>eureka-consumer-basketball</name>
<description>Eureka Client</description> <properties>
<java.version>1.8</java.version>
</properties> <!-- 使用dependencyManagement进行版本管理 -->
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.SR5</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement> <dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</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>
3.修改主启动类
在主启动类上添加@EnableDiscoveryClient注解，并添加RestTemplate组件
@SpringBootApplication
@EnableDiscoveryClient
public class EurekaConsumerBasketballApplication { @Bean(name = "restTemplate")
RestTemplate restTemplate() {
return new RestTemplate();
} public static void main(String[] args) {
SpringApplication.run(EurekaConsumerBasketballApplication.class, args);
} }
4.修改配置
spring.application.name=consumer-basketball
server.port=8082
eureka.client.serviceUrl.defaultZone=http://localhost:8761/eureka/
5.添加业务逻辑
(1)BasketballController.java
@RestController
public class BasketballController { @Resource
private RestTemplate restTemplate; @RequestMapping(value = "getUser/{id}")
public User getUserById(@PathVariable Integer id){
return this.restTemplate.getForObject("http://provider-user/user/getUserById/" + id,User.class);
}
}
(2)User.java
public class User {
private Integer id;
private String name;
private String password;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
启动该工程，访问http://localhost:8761
可以看到consumer-basketball服务已经注册成功！
四、服务消费
浏览器访问http://localhost:8082/getUser/1
报了 java.net.UnknownHostException: provider-user异常，发现通过provider-user服务名直接访问不可以，查询后需要加@loadBalance注解才能用服务名访问，调整如下：
(1)修改一：添加ribbon依赖
<!-- ribbon ，实现客户端负载均衡-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-ribbon</artifactId>
</dependency>
(2)修改二：加@loadBalance
重启工程，再次访问http://localhost:8082/getUser/1
访问成功！
五、踩的坑
1、网速慢下载maven很慢
在网速慢的情况下下载maven依赖特别慢，可以通过修改setting.xml解决
参考链接：https://www.cnblogs.com/zrk3/p/maven_speed_up.html
2、版本兼容问题
SpringCloud跟SpringBoot存在版本兼容问题，导致启动报错java.lang.NoSuchMethodError: org.springframework.boot.builder.SpringApplicationBuilder
参考链接：https://www.cnblogs.com/zrk3/p/10405989.html
3、服务名访问问题
消费者通过生产者服务的服务名进行访问时报 java.net.UnknownHostException异常。
参考链接：https://blog.csdn.net/qq_18416057/article/details/79432504