import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
 
/**
    本例介紹一個(gè)特殊的隊(duì)列:BlockingQueue,如果BlockQueue是空的,從BlockingQueue取東西的操作將會(huì)被阻斷進(jìn)入等待狀態(tài),直到BlockingQueue進(jìn)了東西才會(huì)被喚醒.同樣,如果BlockingQueue是滿的,任何試圖往里存東西的操作也會(huì)被阻斷進(jìn)入等待狀態(tài),直到BlockingQueue里有空間才會(huì)被喚醒繼續(xù)操作.
    本例再次實(shí)現(xiàn)11.4線程----條件Condition中介紹的籃子程序,不過(guò)這個(gè)籃子中最多能放的蘋果數(shù)不是1,可以隨意指定.當(dāng)籃子滿時(shí),生產(chǎn)者進(jìn)入等待狀態(tài),當(dāng)籃子空時(shí),消費(fèi)者等待.
 */
/**
    使用BlockingQueue的關(guān)鍵技術(shù)點(diǎn)如下:
    1.BlockingQueue定義的常用方法如下:
        1)add(anObject):把a(bǔ)nObject加到BlockingQueue里,即如果BlockingQueue可以容納,則返回true,否則招聘異常
        2)offer(anObject):表示如果可能的話,將anObject加到BlockingQueue里,即如果BlockingQueue可以容納,則返回true,否則返回false.
        3)put(anObject):把a(bǔ)nObject加到BlockingQueue里,如果BlockQueue沒(méi)有空間,則調(diào)用此方法的線程被阻斷直到BlockingQueue里面有空間再繼續(xù).
        4)poll(time):取走BlockingQueue里排在首位的對(duì)象,若不能立即取出,則可以等time參數(shù)規(guī)定的時(shí)間,取不到時(shí)返回null
        5)take():取走BlockingQueue里排在首位的對(duì)象,若BlockingQueue為空,阻斷進(jìn)入等待狀態(tài)直到Blocking有新的對(duì)象被加入為止
    2.BlockingQueue有四個(gè)具體的實(shí)現(xiàn)類,根據(jù)不同需求,選擇不同的實(shí)現(xiàn)類
        1)ArrayBlockingQueue:規(guī)定大小的BlockingQueue,其構(gòu)造函數(shù)必須帶一個(gè)int參數(shù)來(lái)指明其大小.其所含的對(duì)象是以FIFO(先入先出)順序排序的.
        2)LinkedBlockingQueue:大小不定的BlockingQueue,若其構(gòu)造函數(shù)帶一個(gè)規(guī)定大小的參數(shù),生成的BlockingQueue有大小限制,若不帶大小參數(shù),所生成的BlockingQueue的大小由Integer.MAX_VALUE來(lái)決定.其所含的對(duì)象是以FIFO(先入先出)順序排序的
        3)PriorityBlockingQueue:類似于LinkedBlockQueue,但其所含對(duì)象的排序不是FIFO,而是依據(jù)對(duì)象的自然排序順序或者是構(gòu)造函數(shù)的Comparator決定的順序.
        4)SynchronousQueue:特殊的BlockingQueue,對(duì)其的操作必須是放和取交替完成的.
    3.LinkedBlockingQueue和ArrayBlockingQueue比較起來(lái),它們背后所用的數(shù)據(jù)結(jié)構(gòu)不一樣,導(dǎo)致LinkedBlockingQueue的數(shù)據(jù)吞吐量要大于ArrayBlockingQueue,但在線程數(shù)量很大時(shí)其性能的可預(yù)見性低于ArrayBlockingQueue.         
 */
public class BlockingQueueTest {
       /**定義裝蘋果的籃子*/
       public static class Basket{
              //籃子,能夠容納3個(gè)蘋果
              BlockingQueue<String> basket = new ArrayBlockingQueue<String>(3);
              //生產(chǎn)蘋果,放入籃子
              public void produce() throws InterruptedException{
                     //put方法放入一個(gè)蘋果,若basket滿了,等到basket有位置
                     basket.put("An apple");
              }
              //消費(fèi)蘋果,從籃子中取走
              public String consume() throws InterruptedException{
                     //take方法取出一個(gè)蘋果,若basket為空,等到basket有蘋果為止
                     return basket.take();
              }
       }
       //測(cè)試方法
       public static void testBasket(){
              final Basket basket = new Basket();//建立一個(gè)裝蘋果的籃子
              //定義蘋果生產(chǎn)者
              class Producer implements Runnable{
                     public void run(){
                            try{
                                   while(true){
                                          //生產(chǎn)蘋果
                                          System.out.println("生產(chǎn)者準(zhǔn)備生產(chǎn)蘋果: " + System.currentTimeMillis());
                                          basket.produce();
                                          System.out.println("生產(chǎn)者生產(chǎn)蘋果完畢: " + System.currentTimeMillis());
                                          //休眠300ms
                                          Thread.sleep(300);
                                   }
                            }catch(InterruptedException ex){
                            }
                     }
              }
              //定義蘋果消費(fèi)者
              class Consumer implements Runnable{
                     public void run(){
                            try{
                                   while(true){
                                          //消費(fèi)蘋果
                                          System.out.println("消費(fèi)者準(zhǔn)備消費(fèi)蘋果: " + System.currentTimeMillis());
                                          basket.consume();
                                          System.out.println("消費(fèi)者消費(fèi)蘋果完畢: " + System.currentTimeMillis());
                                          //休眠1000ms
                                          Thread.sleep(1000);
                                   }
                            }catch(InterruptedException ex){
                            }
                     }
              }
              ExecutorService service = Executors.newCachedThreadPool();
              Producer producer = new Producer();
              Consumer consumer = new Consumer();
              service.submit(producer);
              service.submit(consumer);
              //程序運(yùn)行5s后,所有任務(wù)停止
              try{
                     Thread.sleep(5000);
              }catch(InterruptedException ex){
              }
              service.shutdownNow();
       }
       public static void main(String[] args){
              BlockingQueueTest.testBasket();
       }
}