本文尝试在springboot下组建一个3节点的hazelcast集群。基础配置使用参考 Hazelcast4.2.2 在springboot下的使用

1.pom配置

需要导入的依赖jar包：

 <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</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-cache</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><!-- https://mvnrepository.com/artifact/com.hazelcast/hazelcast-all --><dependency><groupId>com.hazelcast</groupId><artifactId>hazelcast-all</artifactId><version>4.2.2</version></dependency><!-- lombok --><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></dependency>

2.yml配置

hazelcast.yaml 这个配置文件非常重要，hazelcast启动的时候会load这个文件，如果这个文件不存在，或者没有hazelcast相关的配置文件和@Bean,那么将不能启动hazelcast。相关的配置不能放置在application.yml中。目前没有springboot的starter.

hazelcast:cluster-name: hazelcast-clusternetwork:join:multicast:enabled: true

在这个配置文件中，需要指定要给cluster-name。

application.yml
在这个配置文件中需要配置启动tomcat的端口。
在下文中会分别定义三个节点的启动器。那么每次启动的时候都需要将这个文件中的端口修改为不同的端口。

server:port: 8080

3.java代码

CommandController：

package com.dhb.hazelcast.demo.controller;import com.dhb.hazelcast.demo.bean.CommandResponse;
import com.hazelcast.core.HazelcastInstance;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;import java.util.concurrent.ConcurrentMap;@RestController
public class CommandController {@Autowiredprivate HazelcastInstance hazelcastInstance;private ConcurrentMap<String,String> retrieveMap() {return hazelcastInstance.getMap("map");}@PostMapping("/put")public CommandResponse put(@RequestParam(value = "key") String key, @RequestParam(value = "value") String value) {retrieveMap().put(key, value);return new CommandResponse(value);}@GetMapping("/get")public CommandResponse get(@RequestParam(value = "key") String key) {String value = retrieveMap().get(key);return new CommandResponse(value);}@GetMapping("/getSize")public CommandResponse getSize() {int value = retrieveMap().size();return new CommandResponse(value + "");}}

CommandResponse:

package com.dhb.hazelcast.demo.bean;public class CommandResponse {private String value;public CommandResponse(String value) {this.value = value;}public String getValue() {return value;}public void setValue(String value) {this.value = value;}
}

HazelcastNode1Starter:

package com.dhb.hazelcast.demo;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;@EnableCaching
@SpringBootApplication
public class HazelcastNode1Starter {public static void main(String[] args) {SpringApplication.run(HazelcastNode1Starter.class, args);}}

HazelcastNode2Starter:

package com.dhb.hazelcast.demo;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;@EnableCaching
@SpringBootApplication
public class HazelcastNode2Starter {public static void main(String[] args) {SpringApplication.run(HazelcastNode2Starter.class, args);}}

HazelcastNode3Starter:

package com.dhb.hazelcast.demo;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;@EnableCaching
@SpringBootApplication
public class HazelcastNode3Starter {public static void main(String[] args) {SpringApplication.run(HazelcastNode3Starter.class, args);}}

4.启动测试

现在启动三个Node节点，需要注意的是，每个节点的port都需要配置为不同。
现在将port配置为8081，然后启动HazelcastNode1Starter:

2021-10-29 20:08:47.423  INFO 8664 --- [           main] c.h.internal.cluster.ClusterService      : [192.168.87.1]:5701 [hazelcast-cluster] [4.2.2] Members {size:1, ver:1} [Member [192.168.87.1]:5701 - 92936f5f-6e5d-486a-82a6-7db9d304cf76 this
]

可以看到，member中出现了一个成员。默认端口为5701。
然后修改port为8082，启动HazelcastNode2Starter：

2021-10-29 20:11:29.087  INFO 15176 --- [ration.thread-1] c.h.internal.cluster.ClusterService      : [192.168.87.1]:5702 [hazelcast-cluster] [4.2.2] Members {size:2, ver:4} [Member [192.168.87.1]:5701 - 92936f5f-6e5d-486a-82a6-7db9d304cf76Member [192.168.87.1]:5702 - 944879dd-1242-4ce5-96c7-efd080372836 this
]

可以看到，新加入了一个成员，端口为5702。
现在修改prot为8083，启动HazelcastNode3Starter：

2021-10-29 20:12:28.366  INFO 18400 --- [ration.thread-0] c.h.internal.cluster.ClusterService      : [192.168.87.1]:5703 [hazelcast-cluster] [4.2.2] Members {size:3, ver:5} [Member [192.168.87.1]:5701 - 92936f5f-6e5d-486a-82a6-7db9d304cf76Member [192.168.87.1]:5702 - 944879dd-1242-4ce5-96c7-efd080372836Member [192.168.87.1]:5703 - 9b75a1ce-c9a1-4ad5-87c9-19c17b3f0ca9 this
]

这样一个3节点的集群就启动了。

5.访问测试

通过调用post调用如下地址：

http://127.0.0.1:8081/put

post携带不同key和value数据，就能写入到对应的缓存中。

通过getSize方法可以查看map中的数据：

http://127.0.0.1:8081/getSize{"value": "4"
}

通过get方法可以拿到之前set进去的key。

http://127.0.0.1:8081/get?key=dff{"value": "44534"
}

6.客户端请求：

定义如下java客户端代码进行测试：

package com.dhb.hazelcast.demo.client;import com.hazelcast.client.HazelcastClient;
import com.hazelcast.client.config.ClientConfig;
import com.hazelcast.core.HazelcastInstance;
import lombok.extern.slf4j.Slf4j;import java.util.Map;@Slf4j
public class HazelcastGetStartClient {public static void main(String[] args) {ClientConfig clientConfig = new ClientConfig();clientConfig.setClusterName("hazelcast-cluster");HazelcastInstance instance = HazelcastClient.newHazelcastClient(clientConfig);Map<Integer, String> clusterMap = instance.getMap("map");
//		Queue<String> clusterQueue = instance.getQueue("MyQueue");log.info(instance.getConfig().toString());log.info("Map Value:" + clusterMap.toString());log.info("Map Size :" + clusterMap.size());instance.shutdown();}
}

这个代码中最关键的参数是需要设置之前定义的cluster-name “hazelcast-cluster”。
这样就实现了对hazelcast集群中map的调用。

上述过程中，如果关闭任意一个hazelcast节点，上述缓存中的数据都可用。很好的实现了分布式。
在后续文章中，我们将测试，写入100万条数据到hazelcast中，然后关闭某个节点，观察failover的过程。