Java阻塞隊(duì)列這個(gè)，就是當(dāng)隊(duì)列中沒有數(shù)據(jù)的時(shí)候，線程讀取的話會(huì)等待。當(dāng)隊(duì)列中的數(shù)據(jù)滿的時(shí)候，線程添加數(shù)據(jù)的時(shí)候，也會(huì)等待。

有個(gè)例子很生動(dòng)形象，往盤子里面放雞蛋，只能放固定數(shù)目的。盤子里面沒有雞蛋，無(wú)法從中拿出來(lái)。當(dāng)盤子里滿了，也放不進(jìn)去。直到被拿出去才能在放。

代碼如下,這里設(shè)置的是一個(gè)盤子最多放10個(gè)雞蛋：

package com.thread.two;
import java.util.ArrayList;
import java.util.List;
public class Plate {
    List<Object> eggs=new ArrayList<Object>();public synchronized Object getEgg(){while(eggs.size()==0){
            try {
                wait();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        Object egg=null;
        for (int i = 0; i < 10; i++) {
            egg=eggs.get(i);
            System.out.println("拿到雞蛋.........");
        }
        //Object egg=eggs.get(0);
        eggs.clear();
        notify();
        //System.out.println("拿到雞蛋.........");
        return egg;
    }    
    public synchronized void putEgg(Object egg){
while(eggs.size()>9){
            try {
                wait();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        eggs.add(egg);
        notify();
        System.out.println("放入雞蛋.........");
    }    
    static class AddThread extends Thread{
        private Plate plate;
        private Object egg=new Object();
        public AddThread(Plate plate){
            this.plate=plate;
        }
        public void run(){
            for (int i = 0; i < 1000; i++) {
                plate.putEgg(egg);
            }
        }
    }    
    static class GetThread extends Thread{
        private Plate plate;
        public GetThread(Plate plate){
            this.plate=plate;
        }
        public void run(){
            for (int i = 0; i < 1000; i++) {
                plate.getEgg();
            }
        }
    }    
    public static void main(String[] args) throws InterruptedException {
        Plate plate=new Plate();
        Thread add=new Thread(new AddThread(plate));
        Thread get=new Thread(new GetThread(plate));
        add.start();
        get.start();
        add.join();
        get.join();
        System.out.println("測(cè)試結(jié)束");
    }    
}

這個(gè)例子很形象，用線程實(shí)現(xiàn)了上面所說的。

java現(xiàn)在有concurrent包，里面有很多現(xiàn)成的可以用的類，很多是線程安全的，這樣，像上面寫的put或者get，都不需要自己寫同步方法了，這些類已經(jīng)包裝好了。

這里有一個(gè)ArrayBlockingQueue的例子，和上面實(shí)現(xiàn)的差不多。

首先是兩個(gè)線程，分別是put和get。

ThreadPut：

package com.thread.three;
import java.util.concurrent.ArrayBlockingQueue;
public class ThreadPut implements Runnable{
    private ArrayBlockingQueue<String> abq=null;
    public ThreadPut(ArrayBlockingQueue<String> abq){
        this.abq=abq;
    }
    public void run() {
        // TODO Auto-generated method stub
        while(true){
            System.out.println("要向隊(duì)列中存數(shù)據(jù)了");
            try {
                Thread.sleep(1000);
                abq.put("hi");
                System.out.println("存入后，數(shù)據(jù)一共為："+abq.size());
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

ThreadGet：

package com.thread.three;
import java.util.concurrent.ArrayBlockingQueue;
public class ThreadGet extends Thread {
    ArrayBlockingQueue<String> abq=null;
    public ThreadGet(ArrayBlockingQueue<String> abq){
        this.abq=abq;
    }
    @Override
    public void run() {
        // TODO Auto-generated method stub
        while(true){
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            System.out.println("我要從隊(duì)列中取數(shù)據(jù)了");
            String msg=null;
            if (abq.size()>0) {
                msg=abq.remove();
            }
            System.out.println("隊(duì)列中取得的數(shù)據(jù)為:"+msg+",隊(duì)列中還有一共："+abq.size());
        }
    }
}

測(cè)試類：

public class ArrayBlockQueueApp {    
    public static void main(String[] args) {
        ExecutorService  es=Executors.newCachedThreadPool();
        ArrayBlockingQueue<String> abq=new ArrayBlockingQueue<String>(10);
        ThreadGet tGet=new ThreadGet(abq);
        Thread tPut=new Thread(new ThreadPut(abq));
        es.execute(tGet);
        es.execute(tPut);
    }
}

這些隊(duì)列放消息的話挺不錯(cuò)的。如果大家想了解更多相關(guān)知識(shí)，不妨來(lái)關(guān)注一下本站的Java隊(duì)列，里面還有更豐富的知識(shí)等著大家去學(xué)習(xí)，相信對(duì)大家一定會(huì)有所幫助的。