Eureka简介

Eureka是Netflix开发的服务发现框架,本身是一个基于REST的服务,主要用于定位运行在AWS域中的中间层服务,以达到负载均衡和中间层服务故障转移的目的。

Eureka包含两个组件：Eureka Server和Eureka Client：

• Eureka Server提供服务注册服务,各个节点启动后,会在Eureka Server中进行注册,这样EurekaServer中的服务注册表中将会存储所有可用服务节点的信息,服务节点的信息可以在界面中直观的看到。
• Eureka Client是一个java客户端,用于简化与Eureka Server的交互,客户端同时也就是一个内置的、使用轮询(round-robin)负载算法的负载均衡器。

在应用启动后,将会向Eureka Server发送心跳,默认周期为30秒,如果Eureka Server在多个心跳周期内没有接收到某个节点的心跳,Eureka Server将会从服务注册表中把这个服务节点移除(默认90秒)。

准备工作

• 第一步：
  在数据库whyorder创建表tb_order
  在数据库whyuser创建表tb_user

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

DROP TABLE IF EXISTS `tb_order`;
CREATE TABLE `tb_order`  (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '订单id',
  `user_id` bigint(20) NOT NULL COMMENT '用户id',
  `name` varchar(100) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '商品名称',
  `price` bigint(20) NOT NULL COMMENT '商品价格',
  `num` int(10) NULL DEFAULT 0 COMMENT '商品数量',
  PRIMARY KEY (`id`) USING BTREE,
  UNIQUE INDEX `username`(`name`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 109 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

INSERT INTO `tb_order` VALUES (101, 1, 'Apple 苹果 iPhone 12 ', 5999, 1);
INSERT INTO `tb_order` VALUES (102, 2, '雅迪 yadea 新国标电动车', 2099, 1);
INSERT INTO `tb_order` VALUES (103, 3, '骆驼（CAMEL）休闲运动鞋女', 439, 1);
INSERT INTO `tb_order` VALUES (104, 4, '小米10 双模5G 骁龙865', 3599, 1);
INSERT INTO `tb_order` VALUES (105, 5, 'OPPO Reno3 Pro 双模5G 视频双防抖', 2999, 1);
INSERT INTO `tb_order` VALUES (106, 6, '美的（Midea) 新能效 冷静星II ', 5449, 1);
INSERT INTO `tb_order` VALUES (107, 2, '西昊/SIHOO 人体工学电脑椅子', 799, 1);
INSERT INTO `tb_order` VALUES (108, 3, '梵班（FAMDBANN）休闲男鞋', 319, 1);

SET FOREIGN_KEY_CHECKS = 1;

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

DROP TABLE IF EXISTS `tb_user`;
CREATE TABLE `tb_user`  (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `username` varchar(100) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '收件人',
  `address` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '地址',
  PRIMARY KEY (`id`) USING BTREE,
  UNIQUE INDEX `username`(`username`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 109 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

INSERT INTO `tb_user` VALUES (1, '张三', '浙江省杭州市');
INSERT INTO `tb_user` VALUES (2, '李四', '浙江省宁波市');
INSERT INTO `tb_user` VALUES (3, '王五', '浙江省温州市');
INSERT INTO `tb_user` VALUES (4, '赵六', '浙江省台州市');
INSERT INTO `tb_user` VALUES (5, '田七', '浙江省金华市');
INSERT INTO `tb_user` VALUES (6, '赵八', '浙江省嘉兴市');

SET FOREIGN_KEY_CHECKS = 1;

• 第二步：
  快速创建两个springboot项目
  一个为privoder-server（服务提供者）
  一个为consumer-server（服务消费者）
  这里我用的是阿里云的镜像地址

• 第三步：引入相关依赖

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
</dependency>
<!-- mybatis -->
<dependency>
	<groupId>org.mybatis.spring.boot</groupId>
	<artifactId>mybatis-spring-boot-starter</artifactId>
	<version>2.2.0</version>
</dependency>
<!-- lombok -->
<dependency>
	<groupId>org.projectlombok</groupId>
	<artifactId>lombok</artifactId>
	<version>1.18.20</version>
</dependency>

• 第三步：
  快速创建实体类、Dao层、Service层和Controller

//实体类(两个项目的实体类一样)
//----------订单类----------
@Data
public class Order {
    private Long id;
    private Long price;
    private String name;
    private Integer num;
    private Long userId;
    private User user;
}
//----------用户类----------
@Data
public class User {
    private Long id;
    private String username;
    private String address;
}

//---------------Dao层代码（privider-serve）---------------
@Mapper
public interface UserMapper {
    @Select("select * from tb_user where id = #{id}")
    User selectById(Long id);
}
//---------------Service层代码（privider-serve）---------------
@Service
public class UserService {
    @Autowired
    private UserMapper userMapper;

    public User queryUserById(Long id){
        User user = userMapper.selectById(id);
        return user;
    }
}
//---------------Cintroller（privider-serve）---------------
@Controller
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;

    @RequestMapping("/{id}")
    @ResponseBody
    public User queryUser(@PathVariable("id") Long userId){
        User user = userService.queryUserById(userId);
        return user;
    }
}

//---------------Dao层代码（consumer-serve）---------------
@Mapper
public interface OrderMapper {
    @Select("select * from tb_order where id = #{id}")
    Order selectById(Long id);
}
//---------------Service层代码（consumer-serve）---------------
@Service
public class OrderService {
    @Autowired
    private OrderMapper orderMapper;

    public Order queryOrderById(Long id){
        Order order = orderMapper.selectById(id);
        return order;
    }
}
//---------------Controller（consumer-serve）---------------
@Controller
@RequestMapping("/order")
public class OerderController {
    @Autowired
    private OrderService orderService;

    @RequestMapping("/{id}")
    @ResponseBody
    public Object queryOrder(@PathVariable("id") Long orderId){
        Order order = orderService.queryOrderById(orderId);
        return order;
    }
}

• 第四步：配置springboot配置文件

#provider-server配置文件
server:
  port: 8081
spring:
  datasource:
  	#参数是关于时区和字符集的
    url: jdbc:mysql://127.0.0.1:3306/whyuser?serverTimezone=UTC&useUnicode=true&zeroDateTimeBehavior=convertToNull&autoReconnect=true&characterEncoding=utf-8
    username: root
    password: why0417
    driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
  type-aliases-package: com.why.pojo
  configuration:
    map-underscore-to-camel-case: true
logging:
  level:
    com.why: debug
  pattern:
    dateformat: MM-dd HH:mm:ss:SSS

#consumer-server配置文件
server:
  port: 8080
spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/whyorder?serverTimezone=UTC&useUnicode=true&zeroDateTimeBehavior=convertToNull&autoReconnect=true&characterEncoding=utf-8
    username: root
    password: why0417
    driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
  type-aliases-package: com.why.pojo
  configuration:
    map-underscore-to-camel-case: true
logging:
  level:
    com.why: debug
  pattern:
    dateformat: MM-dd HH:mm:ss:SSS

搭建Eureka注册中心

• 第一步：快速创建springboot项目

• 第二步：导入eureka依赖

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

• 第三步：添加@EnableEurekaServer注解

/*Eureka自动装配*/
@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {

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

第四步：配置springboot配置文件

server:
  port: 8088

spring:
  application:
    #eureka的服务名称
    name: eurekaserver

eureka:
  client:
    service-url:
      #eureka的地址信息
      defaultZone: http://localhost:8088/eureka

启动项目并访问Eureka

服务注册

• 第一步：在服务提供者项目中添加eureka-client依赖

<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
	<version>2.2.6.RELEASE</version>
</dependency>

• 第二步：在application.yml配置文件中配置eureka地址

spring:
  application:
  	#配置服务名称
    name: userservice

eureka:
  client:
    service-url:
      #eureka地址信息
      defaultZone: http://localhost:8088/eureka

• 第三步：将服务提供者启动多次来模拟多实例部署

修改端口避免端口冲突-Dserver.port=8082

服务发现

• 第一步：在服务消费者项目中添加eureka-client依赖

<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
	<version>2.2.6.RELEASE</version>
</dependency>

• 第二步：在application.yml配置文件中配置eureka地址

spring:
  application:
  	#配置服务名称
    name: userservice

eureka:
  client:
    service-url:
      #eureka地址信息
      defaultZone: http://localhost:8088/eureka

• 第三步：注册RestTemplate(Spring提供的发送http请求的工具)

//写在配置类中(或者启动类,因为@SpringBootApplication是复合注解它包括@SpringBootConfiguration注解)
//注入依赖
@Bean
@LoadBalanced //负载均衡
public RestTemplate restTemplate() {
	return new RestTemplate();
}

• 第四步：修改Service层代码

@Service
public class OrderService {
    @Autowired
    private OrderMapper orderMapper;
    @Autowired
    private RestTemplate restTemplate;

    public Order queryOrderById(Long id){
        Order order = orderMapper.selectById(id);
        //远程调用
        //String url = "http://localhost:8081/user/"+order.getUserId();
        //用服务名代替IP端口
        String url = "http://userservice/user/"+order.getUserId();
        //发送http请求
        User user = restTemplate.getForObject(url, User.class);
        order.setUser(user);
        return order;
    }
}

测试

启动所有服务

注册到eureka的实例

访问order