用Java语言简单实现MQ消息队列服务

大致的结构：

一个消息队列大致的结构：

消息处理中心 Broker

package com.tntxia;

import java.util.concurrent.ArrayBlockingQueue;

/**
 * 消息处理中心
 */
public class Broker {
    // 队列存储消息的最大数量
    private final static int MAX_SIZE = 3;

    // 保存消息数据的容器
    private static ArrayBlockingQueue<String> messageQueue = new ArrayBlockingQueue<String>(MAX_SIZE);

    // 生产消息
    public static void produce(String msg) {
        if (messageQueue.offer(msg)) {
            System.out.println("成功向消息处理中心投递消息：" + msg + "，当前暂存的消息数量是：" + messageQueue.size());
        } else {
            System.out.println("消息处理中心内暂存的消息达到最大负荷，不能继续放入消息！");
        }
        System.out.println("=======================");
    }

    // 消费消息
    public static String consume() {
        String msg = messageQueue.poll();
        if (msg != null) {
            // 消费条件满足情况，从消息容器中取出一条消息
            System.out.println("已经消费消息：" + msg + "，当前暂存的消息数量是：" + messageQueue.size());
        } else {
            System.out.println("消息处理中心内没有消息可供消费！");
        }
        System.out.println("=======================");

        return msg;
    }

}

消息处理中心服务 BrokerServer

package com.tntxia;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * 用于启动消息处理中心
 */
public class BrokerServer implements Runnable {

    public static int SERVICE_PORT = 9999;

    private final Socket socket;

    public BrokerServer(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        try (
                BufferedReader in = new BufferedReader(new InputStreamReader(
                        socket.getInputStream()));
                PrintWriter out = new PrintWriter(socket.getOutputStream())
        )
        {
            while (true) {
                String str = in.readLine();
                if (str == null) {
                    continue;
                }
                System.out.println("接收到原始数据：" + str);

                if (str.equals("CONSUME")) { //CONSUME 表示要消费一条消息
                    //从消息队列中消费一条消息
                    String message = Broker.consume();
                    out.println(message);
                    out.flush();
                } else if (str.contains("SEND:")){
                    //接受到的请求包含SEND:字符串 表示生产消息放到消息队列中
                    Broker.produce(str);
                }else {
                    System.out.println("原始数据:"+str+"没有遵循协议,不提供相关服务");
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws Exception {
        ServerSocket server = new ServerSocket(SERVICE_PORT);
        while (true) {
            BrokerServer brokerServer = new BrokerServer(server.accept());
            new Thread(brokerServer).start();
        }
    }
}

客户端：

package com.tntxia;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;

/**
 * 访问消息队列的客户端
 */
public class MqClient {

    //生产消息
    public static void produce(String message) throws Exception {
        //本地的的BrokerServer.SERVICE_PORT 创建SOCKET
        Socket socket = new Socket(InetAddress.getLocalHost(), BrokerServer.SERVICE_PORT);
        try (
                PrintWriter out = new PrintWriter(socket.getOutputStream())
        ) {
            out.println(message);
            out.flush();
        }
    }

    //消费消息
    public static String consume() throws Exception {
        Socket socket = new Socket(InetAddress.getLocalHost(), BrokerServer.SERVICE_PORT);
        try (
                BufferedReader in = new BufferedReader(new InputStreamReader(
                        socket.getInputStream()));
                PrintWriter out = new PrintWriter(socket.getOutputStream())
        ) {
            //先向消息队列发送命令
            out.println("CONSUME");
            out.flush();

            //再从消息队列获取一条消息
            String message = in.readLine();

            return message;
        }
    }

}

写两个测试的程序，测试生产和消费消息：

测试生产消息：

package com.tntxia;

public class ProduceClient {

    public static void main(String[] args) throws Exception {
        MqClient client = new MqClient();

        client.produce("SEND:Hello World");
    }

}

测试消费消息：

package com.tntxia;

public class ConsumeClient {

    public static void main(String[] args) throws Exception {
        MqClient client = new MqClient();
        String message = client.consume();

        System.out.println("获取的消息为：" + message);
    }
}