SpringCloud-03-Zookeeper
在前面介绍SpringCloud Eureka已经停止更新，如果担心Eureka技术过时，可以选用 Zookeeper 作为注册中心，作为服务注册与发现。其实了解Dubbo的朋友应该知道。在Dubbo中，也是推荐使用Zookeeper作为注册中心，Dubbo是一门RPC框架，用于远程过程调用，在这里就不对Dubbo进行介绍。
ZooKeeper 是一个开放源代码的分布式协调服务，在之前，我已经写过几篇关于Zookeeper的文章，在系列文章中讲解了Zookeeper的作用，原理，安装和简单使用。不了解Zookeeper的工作原理的朋友，需要先去翻翻前面我写的Zookeeper相关的文章。
接下来就演示如何使用 Zookeeper 作为注册中心，实现服务注册与发现。
业务场景：用户服务UserService通过Zookeeper注册中心，获取微信服务WechatService的服务列表，然后发送http请求，获取用户的微信用户信息。
整个过程如图所示：
1 搭建Zookeeper集群
1.1 配置和启动 192.168.43.51上的Zookeeper服务
上传 zookeeper安装包并解压，复制 zoo_sample.cfg 为配置文件 zoo.cfg。
[tag@localhost ~]$ ll apache-zookeeper-3.6.1-bin.tar.gz
-rw-r--r--. 1 tag tag 12436328 8月 10 2020 apache-zookeeper-3.6.1-bin.tar.gz
[tag@localhost ~]$ tar -zxvf apache-zookeeper-3.6.1-bin.tar.gz
[tag@localhost ~]$ mv apache-zookeeper-3.6.1-bin zk-3.6.1
[tag@localhost ~]$ cd zk-3.6.1/conf
[tag@localhost conf]$ cp zoo_sample.cfg zoo.cfg
[tag@localhost conf]$
修改配置文件 zoo.cfg
[tag@localhost conf]$ vim zoo.cfg
# The number of milliseconds of each tick
tickTime=2000
# The number of ticks that the initial
# synchronization phase can take
initLimit=10
# The number of ticks that can pass between
# sending a request and getting an acknowledgement
syncLimit=5
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just
# example sakes.
#配置 ZooKeeper 服务器存储快照文件的目录
dataDir=/home/tag/zk-3.6.1/data
# the port at which the clients will connect
clientPort=2181
# the maximum number of client connections.
# increase this if you need to handle more clients
#maxClientCnxns=60
#
# Be sure to read the maintenance section of the
# administrator guide before turning on autopurge.
#
# http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance
#
# The number of snapshots to retain in dataDir
#autopurge.snapRetainCount=3
# Purge task interval in hours
# Set to "0" to disable auto purge feature
#autopurge.purgeInterval=1
server.1=192.168.43.51:2888:3888
server.2=192.168.43.52:2888:3888
server.3=192.168.43.53:2888:3888
新增 myid 文件
[tag@localhost conf]$ mkdir /home/tag/zk-3.6.1/data
[tag@localhost conf]$ cd /home/tag/zk-3.6.1/data
[tag@localhost data]$ vi myid
1
~
启动zookeeper服务，可以看到 2181 端口已启动成功
[tag@localhost data]$ /home/tag/zk-3.6.1/bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /home/tag/zk-3.6.1/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
[tag@localhost data]$ ss -nultp | grep 2181
tcp LISTEN 0 50 :::2181 :::* users:(("java",pid=31393,fd=56))
1.2 配置和启动 192.168.43.52 和 192.168.43.53上 的Zookeeper服务
根据192.168.43.51机器上的zookeeper服务安装步骤，搭建zookeeper。
**注意：**在192.168.43.52上修改数据目录/home/tag/zk-3.6.1/data下面的myid文件内容为2，而192.168.43.53中的myid文件内容为3。
修改好了myid文件后，分别启动zookeeper服务。
查看集群状态
192.168.43.51
[tag@localhost ~]$ /home/tag/zk-3.6.1/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /home/tag/zk-3.6.1/bin/../conf/zoo.cfg
Client port found: 2181. Client address: localhost.
Mode: follower
192.168.43.52
[tag@localhost ~]$ /home/tag/zk-3.6.1/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /home/tag/zk-3.6.1/bin/../conf/zoo.cfg
Client port found: 2181. Client address: localhost.
Mode: leader
192.168.43.53
[tag@localhost ~]$ /home/tag/zk-3.6.1/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /home/tag/zk-3.6.1/bin/../conf/zoo.cfg
Client port found: 2181. Client address: localhost.
Mode: follower
可以看到 192.168.43.52 为leader节点，而192.168.43.51和192.168.43.53分别为follower节点
2. 搭建服务提供者 provider-zk-wechat9101
搭建 wechatService 的第一个服务实例 9101。
pom.xml
006SpringCloud
com.xander
1.0-SNAPSHOT
4.0.0
provider-zk-wechat9101
org.springframework.cloud
spring-cloud-starter-zookeeper-discovery
org.springframework.boot
spring-boot-starter-web
com.xander
common-api
1.0-SNAPSHOT
application.yml
server:
port: 9101
spring:
application:
# 微服务名称
name: wechatService
cloud:
zookeeper:
#Zookeeper服务连接地址，如果是集群，使用逗号分隔
connect-string: 192.168.43.51:2181,192.168.43.51:2181,192.168.43.51:2181
discovery:
# 服务实例注册进zookeeper的host
instance-host: 127.0.0.1
服务启动类 ProviderZkWechat9101.java，添加 @EnableDiscoveryClient 注解
@SpringBootApplication
@EnableDiscoveryClient
public class ProviderZkWechat9101 {
public static void main(String[] args) {
SpringApplication.run(ProviderZkWechat9101.class, args);
}
}
新建实体类 WechatInfo
/**
* Description: 模拟微信用户信息
*
* @author Xander
* datetime: 2021-05-14 16:24
*/
public class WechatInfo {
private String userName;
private String openId;
public static WechatInfo newInstance() {
WechatInfo instance = new WechatInfo();
return instance;
}
public String getUserName() {
return userName;
}
public WechatInfo setUserName(String userName) {
this.userName = userName;
return this;
}
public String getOpenId() {
return openId;
}
public WechatInfo setOpenId(String openId) {
this.openId = openId;
return this;
}
}
WechatController
@RestController
@RequestMapping("/wechat")
public class WechatController {
@Value("${server.port}")
private String serverPort;
@GetMapping(value = "/getByUserId/{userId}")
public CommonResult getWechatInfo(@PathVariable("userId") Long userId) {
WechatInfo wechatInfo = WechatInfo.newInstance().setOpenId(userId + "-openId").setUserName(userId + "-name");
return CommonResult.newInstance().setCode(200).setMessage("查询成功,serverPort：" + serverPort).setData(wechatInfo);
}
}
3. 搭建服务提供者 provider-zk-wechat9102
搭建 wechatService 的第二个服务实例 9102。
pom.xml
006SpringCloud
com.xander
1.0-SNAPSHOT
4.0.0
provider-zk-wechat9102
org.springframework.cloud
spring-cloud-starter-zookeeper-discovery
org.springframework.boot
spring-boot-starter-web
com.xander
common-api
1.0-SNAPSHOT
application.yml
server:
port: 9102
spring:
application:
# 微服务名称
name: wechatService
cloud:
zookeeper:
#Zookeeper服务连接地址，如果是集群，使用逗号分隔
connect-string: 192.168.43.51:2181,192.168.43.51:2181,192.168.43.51:2181
discovery:
# 服务实例注册进zookeeper的host
instance-host: 127.0.0.1
服务启动类 ProviderZkWechat9102.java，添加 @EnableDiscoveryClient 注解
@SpringBootApplication
@EnableDiscoveryClient
public class ProviderZkWechat9102 {
public static void main(String[] args) {
SpringApplication.run(ProviderZkWechat9102.class, args);
}
}
WechatController
@RestController
@RequestMapping("/wechat")
public class WechatController {
@Value("${server.port}")
private String serverPort;
@GetMapping(value = "/getByUserId/{userId}")
public CommonResult getByUserId(@PathVariable("userId") Long userId) {
WechatInfo wechatInfo = WechatInfo.newInstance().setOpenId(userId + "-openId").setUserName(userId + "-name");
return CommonResult.newInstance().setCode(200).setMessage("查询成功,serverPort：" + serverPort).setData(wechatInfo);
}
}
4. 搭建服务提供者 consumer-zk-user8101
4.1 Eureka-client 和 zookeeper-discovery 都已内置Ribbon
在SpringCloud 的服务发现组件中，都已经内置了 Ribbon 组件，可直接配置客户端的负载均衡策略。
Eureka-client内置了Ribbon
zookeeper-discovery内置了Ribbon
4.2 新建module consumer-zk-user8101
pom.xml
006SpringCloud
com.xander
1.0-SNAPSHOT
4.0.0
consumer-zk-user8101
org.springframework.cloud
spring-cloud-starter-zookeeper-discovery
org.springframework.boot
spring-boot-starter-web
com.xander
common-api
1.0-SNAPSHOT
application.yml
server:
port: 8101
spring:
application:
# 微服务名称
name: userService
cloud:
zookeeper:
#Zookeeper服务连接地址，如果是集群，使用逗号分隔
connect-string: 192.168.43.51:2181,192.168.43.51:2181,192.168.43.51:2181
discovery:
# 服务实例注册进zookeeper的host
instance-host: 127.0.0.1
服务启动类 ConsumerZkUser8101.java，添加 @EnableDiscoveryClient 注解
@SpringBootApplication
@EnableDiscoveryClient
public class ConsumerZkUser8101 {
public static void main(String[] args) {
SpringApplication.run(ConsumerZkUser8101.class, args);
}
}
应用配置类AppConfig，配置Ribbon策略
/**
* Description: 应用配置类
*
* @author Xander
* datetime: 2021-05-11 18:18
*/
@Configuration
public class AppConfig {
/**
* 配置应用的负载均衡规则为轮询策略 RoundRobinRule
*
* @return
*/
@Bean
public IRule rule() {
return new RoundRobinRule();
}
@Bean
@LoadBalanced //开启 Ribbon 功能
public RestTemplate restTemplate(){
return new RestTemplate();
}
}
UserController
@RestController
@RequestMapping("/user")
public class UserController {
private Logger logger = LoggerFactory.getLogger(this.getClass());
public static final String WECHAT_SERVICE = "wechatService";
@Autowired
private DiscoveryClient discoveryClient;
@Autowired
private RestTemplate restTemplate;
@GetMapping(value = "/wechatInfo/{userId}")
public CommonResult wechatInfo(@PathVariable("userId") Long userId) {
List instances = this.discoveryClient.getInstances(WECHAT_SERVICE);
// 打印服务实例信息
for (ServiceInstance instance : instances) {
this.logger.info("serviceId: " + instance.getServiceId() + "\t" + "host: " + instance.getHost() + "\t"
+ "port: " + instance.getPort() + "\t" + "uri: " + instance.getUri());
}
return this.restTemplate.getForObject("http://" + WECHAT_SERVICE + "/wechat/getByUserId/" + userId, CommonResult.class);
}
}
5. 分别启动2个wechatServcie和userServcie
启动后，在zookeeper中的任意一台机器上查看服务注册信息，可以看到userService, wechatService都已经成功注册进zookeeper注册中心，其中userService包含一个服务实例，而wechatService有两个服务实例。
[tag@localhost ~]$ zk-3.6.1/bin/zkCli.sh
[zk: localhost:2181(CONNECTED) 1] ls /
[services, zookeeper]
[zk: localhost:2181(CONNECTED) 2] ls /services
[userService, wechatService]
[zk: localhost:2181(CONNECTED) 3] ls /services/wechatService
[77ff5bfc-4779-47ed-9b81-621b558326e5, ca38ab47-8e0f-4723-b9dc-77bf50a59aca]
[zk: localhost:2181(CONNECTED) 4] ls /services/userService
[38f6bcfa-1a77-4948-b077-b3155ee81142]
[zk: localhost:2181(CONNECTED) 5]
6. 服务调用
在浏览器上调用两次 http://localhost:8101/user/wechatInfo/1，响应成功并且我们配置的ribbon轮询策略起作用了，端口本别调用 9101、9102。
再来看看我们在 consumer-zk-user8101 中打印的服务信息，可以看到在 userService 中可以通过zookeeper注册中心拉取到 wechatService 的两个服务信息。
2021-05-14 17:54:43.326 INFO 3204 --- [nio-8101-exec-1] c.xander.user.controller.UserController : serviceId: wechatService host: 127.0.0.1 port: 9101 uri: http://127.0.0.1:9101
2021-05-14 17:54:43.326 INFO 3204 --- [nio-8101-exec-1] c.xander.user.controller.UserController : serviceId: wechatService host: 127.0.0.1 port: 9102 uri: http://127.0.0.1:9102
代码：
https://github.com/wengxingxia/006SpringCloud.git
[慕课手记同步： SpringCloud-03-Zookeeper] https://www.imooc.com/article/317541
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