网站制作知识/怎样开自己的网站
阻塞队列 BlockingQueue
| 方式 | 抛出异常 | 有返回值 | 阻塞等待 | 超时等待 |
|---|---|---|---|---|
| 添加 | add | offer | put | offer(,) |
| 移除 | remove | poll | take | poll(,) |
| 判断队列首 | elment |
- 抛出异常 出现异常直接抛出
public static void test1(){//初始化是写入最大容量ArrayBlockingQueue arrayBlockingQueue = new ArrayBlockingQueue(3);System.out.println(arrayBlockingQueue.add("a"));System.out.println(arrayBlockingQueue.add("b"));System.out.println(arrayBlockingQueue.add("c"));//System.out.println(arrayBlockingQueue.add("d"));System.out.println(arrayBlockingQueue.remove());System.out.println(arrayBlockingQueue.remove());System.out.println(arrayBlockingQueue.remove());}
- 有返回值 不会抛出异常
public static void test2(){//初始化是写入最大容量ArrayBlockingQueue arrayBlockingQueue = new ArrayBlockingQueue(3);System.out.println(arrayBlockingQueue.offer("a"));System.out.println(arrayBlockingQueue.offer("b"));System.out.println(arrayBlockingQueue.offer("c"));//System.out.println(arrayBlockingQueue.add("d"));System.out.println(arrayBlockingQueue.poll());System.out.println(arrayBlockingQueue.poll());System.out.println(arrayBlockingQueue.poll());System.out.println(arrayBlockingQueue.poll());}
- 阻塞等待
public static void test3() throws InterruptedException {//初始化是写入最大容量ArrayBlockingQueue arrayBlockingQueue = new ArrayBlockingQueue(3);arrayBlockingQueue.put("a");arrayBlockingQueue.put("b");arrayBlockingQueue.put("c");//System.out.println(arrayBlockingQueue.add("d"));System.out.println(arrayBlockingQueue.take());System.out.println(arrayBlockingQueue.take());System.out.println(arrayBlockingQueue.take());System.out.println(arrayBlockingQueue.take());}
- 超时等待 超过设置的时间就会取消等待
public static void test4() throws InterruptedException {//初始化是写入最大容量ArrayBlockingQueue arrayBlockingQueue = new ArrayBlockingQueue(3);System.out.println(arrayBlockingQueue.offer("a"));System.out.println(arrayBlockingQueue.offer("b"));System.out.println(arrayBlockingQueue.offer("c"));//System.out.println(arrayBlockingQueue.add("d"));System.out.println(arrayBlockingQueue.poll());System.out.println(arrayBlockingQueue.poll());System.out.println(arrayBlockingQueue.poll());System.out.println(arrayBlockingQueue.poll(2, TimeUnit.SECONDS));}
同步队列 SynchronousQueue
- 没有容量 只能放进去一个元素取出后才可以放入
public static void main(String[] args) {SynchronousQueue<String> synchronousQueue = new SynchronousQueue<>();new Thread(()->{try {System.out.println("1111put");synchronousQueue.put("11");System.out.println("2222put");synchronousQueue.put("22");System.out.println("3333put");synchronousQueue.put("33");} catch (InterruptedException e) {e.printStackTrace();}},"1111").start();new Thread(()->{try {TimeUnit.SECONDS.sleep(2);synchronousQueue.take();System.out.println(111);TimeUnit.SECONDS.sleep(2);synchronousQueue.take();System.out.println(222);TimeUnit.SECONDS.sleep(2);synchronousQueue.take();System.out.println(333);} catch (InterruptedException e) {e.printStackTrace();}}).start();}
线程池
-
降低资源的消耗 提高响应的速度（不用新建和销毁）
-
方便管理
public ThreadPoolExecutor(int corePoolSize,//核心线程数int maximumPoolSize,//最大核心线程数long keepAliveTime,//超时时间TimeUnit unit,//超时时间单位BlockingQueue<Runnable> workQueue,//阻塞队列ThreadFactory threadFactory,//线程工厂，创建线程的RejectedExecutionHandler handler//拒绝策略) {if (corePoolSize < 0 ||maximumPoolSize <= 0 ||maximumPoolSize < corePoolSize ||keepAliveTime < 0)throw new IllegalArgumentException();if (workQueue == null || threadFactory == null || handler == null)throw new NullPointerException();this.corePoolSize = corePoolSize;this.maximumPoolSize = maximumPoolSize;this.workQueue = workQueue;this.keepAliveTime = unit.toNanos(keepAliveTime);this.threadFactory = threadFactory;this.handler = handler;}
线程池的创建
public static void main(String[] args) {ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(2,5,3, TimeUnit.SECONDS,new LinkedBlockingDeque<>(3),Executors.defaultThreadFactory(),new ThreadPoolExecutor.AbortPolicy());}
线程池的四种拒绝策略
最大线程如何定义
- CPU密集型
- 几核CPU就定义为几可以保持CPU的效率最高
//获取CPU的核数
Runtime.getRuntime().availableProcessors();
- IO密集型
- 判断程序中十分消耗IO的线程