ActiveMQ

消息处理中心：

public class Broker {
    // 最大存储数
    private final static int MAX_SIZE = 3;

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

    // 生产消息
    public static void produce(String msg) {
        if (messageQueue.offer(msg)) {
            System.out.println("成功向消息中心发消息：" + msg + "，当前容量为：" + messageQueue.size());
        } else {
            System.out.println("消息中心超负荷");
        }
        System.out.println("-----------------");
    }

    // 消费消息
    public static String comsume() {
        String msg = messageQueue.poll();
        if (msg != null) {
            System.out.println("得到消息：" + msg + "，当前容量为：" + messageQueue.size());
        } else {
            System.out.println("消息中心没有消息");
        }
        System.out.println("-----------------");
        return msg;
    }
}

服务暴露：

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("收到消息为：" + str);
                if (str.equals("CONSUME")) {
                    // 消费消息
                    String message = Broker.comsume();
                    out.println(message);
                    out.flush();
                } else {
                    // 生产消息
                    Broker.produce(str);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

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

自定义客户端：

public class MyClient {
    // 生产消息
    public static void produce(String message) throws Exception {
        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())) {
            out.println("CONSUME");
            out.flush();

            String message = in.readLine();
            return message;
        }
    }
}

生产者客户端：

public class ProduceClient {
    public static void main(String[] args) throws Exception {
        MyClient client = new MyClient();
        client.produce("hello world");
    }
}

消费者客户端：

public class ConsumeClient {
    public static void main(String[] args) throws Exception {
        MyClient client = new MyClient();
        String message = client.consume();
        System.out.println("获取消息为：" + message);
    }
}