大家好，最近在巩固JUC并发包，突然想到如果自己的应用体量不大，但有需要消息队列来实现应用解耦和削峰来缓解服务器突增压力，比如抢票时，突然有比较用户同时抢票，就容易造成服务器同时连接数较多，拒绝其他用户的使用，就想着可以用消息队列来缓解，但是体量有不大，还没必要用MQ框架，那就直接自己写一个，这样，抢票请求来了就直接丢给队列处理器，然后再延迟查询处理结果，这样能减轻不少压力，老样子，先看下实现效果

：

然后看下测试代码：

public class TestOptional {
    @Test
    public void doTestOptional(){

        MxMQ<Message> mxMQ = MxMQ.getInstance();

        /**
         * 添加分区 无消息一直阻塞
         */
        mxMQ.addPartion("test", new MQHandler<Message>() {
            @Override
            public void hand(Message message) {
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
                System.out.println(message.getMessage());
            }
        });
        /**
         * 添加分区 无消息且等待时长超过20秒自动移除该分区
         */
        mxMQ.addPartionAutoRemove("test2", new MQHandler<Message>() {
            @Override
            public void hand(Message message) {
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
                System.out.println(message.getMessage());
            }
        });

        for(int index = 0;index < 20;index++){
            int finalIndex = index;
            Message message = new Message("test_" + finalIndex);
            Message message2 = new Message("test2_" + finalIndex);
            try {
                mxMQ.sendMessage("test",message);
                mxMQ.sendMessage("test2",message2);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }

        while (true){}

    }
}

还可以自定义不同分区不同的处理器，逻辑自由定义，下面看下几个关键类：
MxMQRunnable：

package com.mx.mxmq;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.TimeUnit;

public class MxMQRunnable<T> implements Runnable{

    boolean isRun = false;
    ArrayBlockingQueue<T> arrayBlockingQueue = null;
    MQHandler<T> mqHandler = null;
    int state = 0;

    MxMQ.QueueEmpty queueEmpty = null;

    public void setQueueEmpty(MxMQ.QueueEmpty queueEmpty) {
        this.queueEmpty = queueEmpty;
    }

    public MxMQRunnable(MQHandler<T> mqHandler){
        isRun = true;
        arrayBlockingQueue = new ArrayBlockingQueue(50);
        this.mqHandler = mqHandler;
        state = MxMQ.STATE_WAIT;
    }

    public MxMQRunnable(int number,MQHandler<T> mqHandler){
        arrayBlockingQueue = new ArrayBlockingQueue(number);
        this.mqHandler = mqHandler;
        state = MxMQ.STATE_WAIT;
    }

    public void setState(int state) {
        this.state = state;
    }

    @Override
    public void run() {
        while (isRun){
            try {
                T t = null;
                if(state == MxMQ.STATE_WAIT){
                   t = arrayBlockingQueue.take();
                } else {
                   t = arrayBlockingQueue.poll(20,TimeUnit.SECONDS);
                   if(t == null){
                       close();
                       queueEmpty.empty(this);
                       break;
                   }
                }
                if(mqHandler != null){
                    mqHandler.hand(t);
                }
            } catch (Exception e) {
                 e.printStackTrace();
            }
        }
    }

    public boolean sendMessage(T t) throws InterruptedException {
        return arrayBlockingQueue.offer(t,20, TimeUnit.SECONDS);
    }

    public boolean removeMessage(T t){
        return arrayBlockingQueue.remove(t);
    }

    public void close(){
        isRun = false;
    }

}

MxMQ：

package com.mx.mxmq;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MxMQ<T> {

    public static final int STATE_WAIT = 0;
    public static final int STATE_REMOVE = 1;

    private MxMQ(){
        executors = Executors.newCachedThreadPool();
        partionRunMap = new ConcurrentHashMap<>();
    }

    public static MxMQ getInstance() {
        if(instance == null){
            synchronized (MxMQ.class){
                if(instance == null){
                    instance = new MxMQ();
                }
            }
        }
        return instance;
    }

    private static volatile MxMQ instance = null;

    private ConcurrentHashMap<String,MxMQRunnable<T>> partionRunMap = null;

    private ExecutorService executors =  null;

    /**
     * 添加分区
     * @param partion 分区
     * @param mxHandler 处理器
     * @return
     */
    public boolean addPartion(String partion,MQHandler<T> mxHandler){
        if(partionRunMap.get(partion) == null){
            MxMQRunnable<T> curMxMQRunnable = new MxMQRunnable<T>(mxHandler);
            partionRunMap.put(partion,curMxMQRunnable);
            executors.execute(curMxMQRunnable);
            System.out.println(partion+"被添加");
            return true;
        }
        return false;
    }

    /**
     * 当分区里面没有任务超过20秒后就会自动移除分区
     * @param partion 分区
     * @param mxHandler 处理器
     * @return
     */
    public boolean addPartionAutoRemove(String partion,MQHandler<T> mxHandler){
        if(partionRunMap.get(partion) == null){
            MxMQRunnable<T> curMxMQRunnable = new MxMQRunnable<T>(mxHandler);
            curMxMQRunnable.setState(STATE_REMOVE);
            curMxMQRunnable.setQueueEmpty(new QueueEmpty() {
                @Override
                public void empty(MxMQRunnable mxMQRunnable) {
                    removePartion(partion);
                }
            });
            partionRunMap.put(partion,curMxMQRunnable);
            executors.execute(curMxMQRunnable);
            System.out.println(partion+"被添加");
            return true;
        }
        return false;
    }

    public boolean removePartion(String partion){
        if(partionRunMap.get(partion) != null){
            MxMQRunnable<T> remove = partionRunMap.remove(partion);
            remove.close();
            System.out.println(partion+"被移除");
            return true;
        }
        return false;
    }

    public boolean sendMessage(String partion,T t) throws InterruptedException {
        MxMQRunnable<T> tMxMQRunnable = partionRunMap.get(partion);
        if(tMxMQRunnable != null){
            tMxMQRunnable.sendMessage(t);
            return true;
        }
        return false;
    }

    public boolean removeMessage(String partion,T t){
        MxMQRunnable<T> tMxMQRunnable = partionRunMap.get(partion);
        if(tMxMQRunnable != null){
            return tMxMQRunnable.removeMessage(t);
        }
        return false;
    }

    interface QueueEmpty{
        void empty(MxMQRunnable mxMQRunnable);
    }

}

MQHandler：

package com.mx.mxmq;

public interface MQHandler<T> {
    void hand(T t);
}

Message：

package com.mx.mxmq;

public class Message {
    String message;

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public Message(String message){
        this.message = message;
    }
}

好了，收，大概就是这样子，主要应用场景为：需要轻量级的顺序队列消费 应用场景文章来源地址https://www.toymoban.com/news/detail-743357.html

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