Hazelcast 简明教程

Hazelcast - First Application

Hazelcast 可以单独运行（单节点），也可以运行多个节点以形成一个集群。让我们先尝试启动一个实例。

Hazelcast can be run in isolation (single node) or multiple nodes can be run to form a cluster. Let us first try starting a single instance.

Single Instance

Example

现在，让我们尝试创建和使用 Hazelcast 集群的一个实例。为此，我们将创建 SingleInstanceHazelcastExample.java 文件。

Now, let us try creating and using a single instance of Hazelcast cluster. For that, we will create SingleInstanceHazelcastExample.java file.

package com.example.demo;

import java.util.Map;
import com.hazelcast.core.Hazelcast;
import com.hazelcast.core.HazelcastInstance;

public class SingleInstanceHazelcastExample {
   public static void main(String... args){
      //initialize hazelcast server/instance
      HazelcastInstance hazelcast = Hazelcast.newHazelcastInstance();
      System.out.println(“Hello world”);

      // perform a graceful shutdown
      hazelcast.shutdown();
   }
}

现在，让我们编译代码并执行它−

Now let’s compile the code and execute it −

mvn clean install
java -cp target/demo-0.0.1-SNAPSHOT.jar
com.example.demo.SingleInstanceHazelcastExample

Output

如果执行上述代码，输出将是−

If you execute above code, the output would be −

Hello World

然而，更重要的是，你还会注意到 Hazelcast 的日志行，它表示 Hazelcast 已启动。由于我们只运行此代码一次，即单个 JVM，我们的集群中只会有一个成员。

However, more importantly, you will also notice log lines from Hazelcast which signifies that Hazelcast has started. Since we are running this code only once, i.e., a single JVM, we would only have one member in our cluster.

Jan 30, 2021 10:26:51 AM com.hazelcast.config.XmlConfigLocator
INFO: Loading 'hazelcast-default.xml' from classpath.
Jan 30, 2021 10:26:51 AM com.hazelcast.instance.AddressPicker
INFO: [LOCAL] [dev] [3.12.12] Prefer IPv4 stack is true.
Jan 30, 2021 10:26:52 AM com.hazelcast.instance.AddressPicker
INFO: [LOCAL] [dev] [3.12.12] Picked [localhost]:5701, using socket
ServerSocket[addr=/0:0:0:0:0:0:0:0,localport=5701], bind any local is true
Jan 30, 2021 10:26:52 AM com.hazelcast.system
...

Members {size:1, ver:1} [
   Member [localhost]:5701 - 9b764311-9f74-40e5-8a0a-85193bce227b this
]

Jan 30, 2021 10:26:56 AM com.hazelcast.core.LifecycleService
INFO: [localhost]:5701 [dev] [3.12.12] [localhost]:5701 is STARTED
...

You will also notice log lines from Hazelcast at the end which signifies
Hazelcast was shutdown:
INFO: [localhost]:5701 [dev] [3.12.12] Hazelcast Shutdown is completed in 784 ms.
Jan 30, 2021 10:26:57 AM com.hazelcast.core.LifecycleService
INFO: [localhost]:5701 [dev] [3.12.12] [localhost]:5701 is SHUTDOWN

Cluster: Multi Instance

现在，让我们创建 MultiInstanceHazelcastExample.java 文件（如下所示），它将用于多实例集群。

Now, let’s create MultiInstanceHazelcastExample.java file (as below) which would be used for multi-instance cluster.

package com.example.demo;

import com.hazelcast.core.Hazelcast;
import com.hazelcast.core.HazelcastInstance;

public class MultiInstanceHazelcastExample {
   public static void main(String... args) throws InterruptedException{
      //initialize hazelcast server/instance
      HazelcastInstance hazelcast = Hazelcast.newHazelcastInstance();

      //print the socket address of this member and also the size of the cluster
      System.out.println(String.format("[%s]: No. of hazelcast members: %s",
         hazelcast.getCluster().getLocalMember().getSocketAddress(),
         hazelcast.getCluster().getMembers().size()));

      // wait for the member to join
      Thread.sleep(30000);

      //perform a graceful shutdown
      hazelcast.shutdown();
   }
}

让我们在 two different shells 上执行以下命令−

Let’s execute the following command on two different shells −

java -cp .\target\demo-0.0.1-SNAPSHOT.jar
com.example.demo.MultiInstanceHazelcastExample

你将在 1st shell 上注意到已启动 Hazelcast 实例，并且已分配了一个成员。请注意输出的最后一行，其中显示 single member using port 5701 。

You would notice on the 1st shell that a Hazelcast instance has been started and a member has been assigned. Note the last line of output which says that there is a single member using port 5701.

Jan 30, 2021 12:20:21 PM com.hazelcast.internal.cluster.ClusterService
INFO: [localhost]:5701 [dev] [3.12.12]
Members {size:1, ver:1} [
   Member [localhost]:5701 - b0d5607b-47ab-47a2-b0eb-6c17c031fc2f this
]
Jan 30, 2021 12:20:21 PM com.hazelcast.core.LifecycleService
INFO: [localhost]:5701 [dev] [3.12.12] [localhost]:5701 is STARTED
[/localhost:5701]: No. of hazelcast members: 1

你将在 2nd shell 上注意到 Hazelcast 实例已加入第一个实例。请注意输出的最后一行，其中显示现在有 two members using port 5702 。

You would notice on the 2nd shell that a Hazelcast instance has joined the 1st instance. Note the last line of the output which says that there are now two members using port 5702.

INFO: [localhost]:5702 [dev] [3.12.12]
Members {size:2, ver:2} [
   Member [localhost]:5701 - b0d5607b-47ab-47a2-b0eb-6c17c031fc2f
   Member [localhost]:5702 - 037b5fd9-1a1e-46f2-ae59-14c7b9724ec6 this
]
Jan 30, 2021 12:20:46 PM com.hazelcast.core.LifecycleService
INFO: [localhost]:5702 [dev] [3.12.12] [localhost]:5702 is STARTED
[/localhost:5702]: No. of hazelcast members: 2