【ZooKeeper】Spring Boot 整合 ZooKeeper

发表于2021-08-28更新于2022-02-22字数统计1.5k阅读时长14分阅读次数

ZooKeeper是一个分布式协调工具，可以实现注册中心功能，Spring Cloud中整合ZooKeeper时创建的服务节点是临时节点。ZooKeeper详细介绍参考文章 【ZooKeeper】ZooKeeper。

本文将给出 Spring Boot 整合 ZooKeeper 的案例。

支付服务

新建名为cloud-provider-payment8004的支付服务Maven工程，占用端口8004。

引入 Maven 依赖

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<!-- Spring Cloud整合zookeeper客户端 -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-zookeeper-discovery</artifactId>
    <!--先排除自带的zookeeper3.5.3 防止与3.4.9起冲突-->
    <exclusions>
        <exclusion>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<!--添加zookeeper3.4.9版本-->
<dependency>
    <groupId>org.apache.zookeeper</groupId>
    <artifactId>zookeeper</artifactId>
    <version>3.4.9</version>
</dependency>

需要注意，spring-cloud-starter-zookeeper-discovery场景启动器自带一个ZooKeeper依赖，其版本可能与自己的ZooKeeper版本不兼容，从而无法启动Spring Boot项目，因此在pom文件中首先排除掉spring-cloud-starter-zookeeper-discovery中的ZooKeeper依赖，再自己添加符合自己版本的ZooKeeper依赖。（也可能会出现log4j依赖的冲突，解决方案相同）

修改配置文件

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# 8004表示注册到zookeeper服务器的支付服务提供者端口号
server:
  port: 8004

# 服务别名----注册zookeeper到注册中心名称
spring:
  application:
    name: cloud-provider-payment
  cloud:
    zookeeper:
      connect-string: 127.0.0.1:2181 # 192.168.111.144:2181 #

创建主启动类

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import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient // 该注解用于向使用consul或者zookeeper作为注册中心时注册服务
public class PaymentMain8004 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain8004.class, args);
    }
}

创建 Controller

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import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.UUID;

@RestController
@Slf4j
public class PaymentController
{
    @Value("${server.port}")
    private String serverPort;

    @RequestMapping(value = "/payment/zk")
    public String paymentzk()
    {
        return "springcloud with zookeeper: " + serverPort + "\t" +  UUID.randomUUID().toString();
    }
}

测试

启动支付服务8004注册进ZooKeeper（要先启动zookeeper的server）

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[zk: localhost:2181(CONNECTED) 0] ls /
[services, zookeeper]
[zk: localhost:2181(CONNECTED) 1] ls /services/cloud-provider-payment
[a4567f50-6ad9-47a3-9fbb-7391f41a9f3d]
[zk: localhost:2181(CONNECTED) 2] get /services/cloud-provider-payment/a4567f50-6ad9-47a3-9fbb-7391f41a9f3d
{"name":"cloud-provider-payment","id":"a4567f50-6ad9-47a3-9fbb-7391f41a9f3d","address":"192.168.199.218","port":8004,"ss
lPort":null,"payload":{"@class":"org.springframework.cloud.zookeeper.discovery.ZookeeperInstance","id":"application-1","
name":"cloud-provider-payment","metadata":{}},"registrationTimeUTC":1612811116918,"serviceType":"DYNAMIC","uriSpec":{"pa
rts":[{"value":"scheme","variable":true},{"value":"://","variable":false},{"value":"address","variable":true},{"value":"
:","variable":false},{"value":"port","variable":true}]}}
[zk: localhost:2181(CONNECTED) 3]

json格式化get /services/cloud-provider-payment/a4567f50-6ad9-47a3-9fbb-7391f41a9f3d的结果：

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{
    "name": "cloud-provider-payment", 
    "id": "a4567f50-6ad9-47a3-9fbb-7391f41a9f3d", 
    "address": "192.168.199.218", 
    "port": 8004, 
    "sslPort": null, 
    "payload": {
        "@class": "org.springframework.cloud.zookeeper.discovery.ZookeeperInstance", 
        "id": "application-1", 
        "name": "cloud-provider-payment", 
        "metadata": { }
    }, 
    "registrationTimeUTC": 1612811116918, 
    "serviceType": "DYNAMIC", 
    "uriSpec": {
        "parts": [
            {
                "value": "scheme", 
                "variable": true
            }, 
            {
                "value": "://", 
                "variable": false
            }, 
            {
                "value": "address", 
                "variable": true
            }, 
            {
                "value": ":", 
                "variable": false
            }, 
            {
                "value": "port", 
                "variable": true
            }
        ]
    }
}

订单服务

新建名为cloud-consumerzk-order80的订单服务Maven工程，端口号为80。

引入 Maven 依赖

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<!-- Spring Cloud整合zookeeper客户端 -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-zookeeper-discovery</artifactId>
    <!--先排除自带的zookeeper3.5.3 防止与3.4.9起冲突-->
    <exclusions>
        <exclusion>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<!--添加zookeeper3.4.9版本-->
<dependency>
    <groupId>org.apache.zookeeper</groupId>
    <artifactId>zookeeper</artifactId>
    <version>3.4.9</version>
</dependency>

需要注意，spring-cloud-starter-zookeeper-discovery场景启动器自带一个ZooKeeper依赖，其版本可能与自己的ZooKeeper版本不兼容，从而无法启动Spring Boot项目，因此在pom文件中首先排除掉spring-cloud-starter-zookeeper-discovery中的ZooKeeper依赖，再自己添加符合自己版本的ZooKeeper依赖。（也可能会出现log4j依赖的冲突，解决方案相同）

修改配置文件

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server:
  port: 80

# 服务别名----注册zookeeper到注册中心名称
spring:
  application:
    name: cloud-consumer-order
  cloud:
    zookeeper:
      connect-string: 127.0.0.1:2181 # 192.168.111.144:2181 #

创建主启动类

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import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class OrderZKMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderZKMain80.class, args);
    }
}

业务类

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import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class ApplicationContextConfig
{
    @Bean
    @LoadBalanced // 负载均衡
    public RestTemplate getRestTemplate()
    {
        return new RestTemplate();
    }
}
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import javax.annotation.Resource;

@RestController
@Slf4j
public class OrderZKController
{
    public static final String INVOKE_URL = "http://cloud-provider-payment";

    @Resource
    private RestTemplate restTemplate;

    @GetMapping(value = "/consumer/payment/zk")
    public String paymentInfo()
    {
        String result = restTemplate.getForObject(INVOKE_URL+"/payment/zk",String.class);
        return result;
    }
}

测试

先后运行ZooKeeper服务端，cloud-consumerzk-order80，cloud-provider-payment8004。

打开ZooKeeper客户端：

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[zk: localhost:2181(CONNECTED) 0] ls /
[services, zookeeper]
[zk: localhost:2181(CONNECTED) 1] ls /services
[cloud-consumer-order, cloud-provider-payment]
[zk: localhost:2181(CONNECTED) 2]

访问测试地址：http://localhost/consumer/payment/zk

原理

80客户端将从ZooKeeper中订阅8004服务端的URL信息，从而利用RestTemplate对象调用该URL对应的Rest请求，从而实现远程调用的效果