java.util.concurrent包：
1.locks部分：顯式鎖（互斥鎖和速寫鎖）相關
2.atomic部分：原子變量類相關，是構建非阻塞算法的基礎
3.executor部分：線程池相關
4.collection部分：併發容器相關
5.tools部分：同步工具相關，如信號量、閉鎖、柵欄等功能
1.collection部分:
1.1 BlockingQueue
BlockingQueue爲接口，如果要用它，需要實現它的子類：
ArrayBlockingQueue
DelayQueue
LinkedBlockingQueue
SynchronousQueue
PriorityBlockingQueue
TransferQueue
/**- 在兩個獨立的線程中啓動一個Producer和一個Consumer
- Producer向一個共享的BlockingQueue注入字符串，而Comsumer從中拿出來
- @Author mufeng
-
@Date 2019-7-8 11:25
*/
public class BlockingQueueExample {
public static void main(String[] args) {
BlockingQueue blockingQueue=new ArrayBlockingQueue(1024);
Producer producer=new Producer(blockingQueue);
Consumer consumer=new Consumer(blockingQueue);
new Thread(producer).start();
new Thread(consumer).start();
try {
Thread.sleep(4000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
class Producer implements Runnable{
private BlockingQueue blockingQueue;
public Producer(BlockingQueue blockingQueue){br/>this.blockingQueue=blockingQueue;
}
@Override
public void run() {
try {
blockingQueue.put("1");
Thread.sleep(1000);
blockingQueue.put("2");
Thread.sleep(1000);
blockingQueue.put("3");
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
class Consumer implements Runnable{
private BlockingQueue blockingQueue;
public Consumer(BlockingQueue blockingQueue){
this.blockingQueue=blockingQueue;
}@Override
public void run() {
try {
System.out.println(blockingQueue.take());
System.out.println(blockingQueue.take());
System.out.println(blockingQueue.take());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
2.Tools部分
2.1 CountDownLatch用法
/**
- @Author mufeng
- @Date 2019-7-8 11:54
*/
public class TestCountDownLatch {
public static void main(String[] args) {
final CountDownLatch countDownLatch=new CountDownLatch(2);
new Thread(){
public void run(){
System.out.println(Thread.currentThread().getName()+"processing");
try {
Thread.sleep(3000);
System.out.println(Thread.currentThread().getName()+"ended");
countDownLatch.countDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}.start();
new Thread(){
public void run(){
System.out.println(Thread.currentThread().getName()+"processing");
try {
Thread.sleep(3000);
System.out.println(Thread.currentThread().getName()+"ended");
countDownLatch.countDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}.start();
try {
System.out.println("wait success...");
countDownLatch.await();//調用await（）方法的線程會被掛起，會等待直到count值爲0才繼續執行
System.out.println("2 end");
} catch (Exception e) {
e.printStackTrace();
}
}
}
/**
- 所有線程都停留在柵欄的位置，都結束，才繼續執行
- @Author mufeng
- @Date 2019-7-8 14:10
*/
public class TestCyclicBarrier {
public static void main(String[] args) {
int n=4;
CyclicBarrier cyclicBarrier=new CyclicBarrier(n);
for(int i=0;i<n;i++)
new Writer(cyclicBarrier).start();
}
}
class Writer extends Thread{
private CyclicBarrier cyclicBarrier;
public Writer(CyclicBarrier cyclicBarrier){
this.cyclicBarrier=cyclicBarrier;
}
public void run(){
try {
System.out.println("writer start");
Thread.sleep(5000);
System.out.println("writer end");
cyclicBarrier.await();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (BrokenBarrierException e) {
e.printStackTrace();
}
System.out.println("continue...");
}
}
/**
- Semaphore可以控制同時訪問的線程個數，通過acquire()獲取一個許可，如果沒有就等待，而release()釋放一個許可。
- @Author mufeng
- @Date 2019-7-8 14:32
*/
public class TestSemaphore {
public static void main(String[] args) {
int N=8;//工人數
Semaphore semaphore=new Semaphore(5);//機器數
for(int i=0;i<N;i++){
new Worker(i,semaphore).start();
}
}
}
class Worker extends Thread{
private int num;
private Semaphore semaphore;
public Worker(int num,Semaphore semaphore){
this.num=num;
this.semaphore=semaphore;
}
public void run(){
try {
semaphore.acquire();
System.out.println("工人"+this.num+"occupy a machine。。。");
Thread.sleep(2000);
semaphore.release();
System.out.println("工人"+this.num+"release a machine");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
/**
- Exchanger是在兩個任務之間交換對象的柵欄，當這些任務進入柵欄時，它們各自擁有一個對象，當它們離開時，它們都擁有之前由對象持有的對象
- @Author mufeng
- @Date 2019-7-8 14:54
*/
public class TestExchanger {
public static void main(String[] args) {
ExecutorService executor =Executors.newCachedThreadPool();
final Exchanger exchanger=new Exchanger();
executor.execute(new Runnable() {br/>@Override
public void run() {
String data1="li";
doExchangeWork(data1,exchanger);
}
});
executor.execute(new Runnable() {br/>@Override
public void run() {
String data1="zhang";
doExchangeWork(data1,exchanger);
}
});
executor.shutdown();
}
private static void doExchangeWork(String data1,Exchanger exchanger){
System.out.println(Thread.currentThread().getName()+"exchange:"+data1);
try {
String data2 = (String) exchanger.exchange(data1);
System.out.println(Thread.currentThread().getName()+"exchange to"+data2);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
3.Executor
四種線程池：newFixedThreadPool,newCachedThreadPool,newSingleThreadExecutor,newScheduledThreadPool
1.newFixedThreadPool創建一個可重用固定線程數的線程池，以共享的×××隊列方式來運行線程。
2.newCachedThreadPool創建一個可緩存線程池，如果線程池長度超過處理需要，可靈活回收空閒線程
3.newScheduledThreadPool創建一個定長線程池，支持定時及週期性任務執行
4.newSingleThreadExecutor創建一個單線程化的線程池，它只會用唯一的工作線程來執行任務，保證所有任務按照指定順序（FIFO,LIFO,優先級)執行
任務分兩類：一類是實現了Runnable接口的類，一類是實現了Callable接口的類， Callable的call（）方法只能通過ExecutorService的submit(Callable task)方法來執行，
並且返回一個Future.
4.lock
Synchronized缺點
1.無法中斷
2.無法設置超時
3.使用在方法上的synchronized其實是個語法糖
lock(),trylock(),tryLock(long time,TimeUnit unit)和lockInterruptibly()是用來獲取鎖的，unlock（）方法是用來釋放鎖的。
ReentrantLock 可重入鎖
5.atomic
標量類：AtomicBoolean,AtomicInteger,AtomicLong,AtomicReference
數組類：AtomicIntegerArray,AtomicLongArray,AtomicReferenceArray
更新器類：AtomicLongFieldUpdater,AtomicIntegerFieldUpdater,AtomicReferenceFieldUpdater
複合變量類：AtomicMarkableReference,AtomicStampedReference