1、基本概念
Java线程需要经过线程的创建，调用和销毁整个过程，频繁的创建和销毁会大大影响性能，所以引入的线程池：
好处：
提升性能：线程池能独立负责线程的创建、维护和分配
线程管理：每个Java线程池会保持一些基本的线程统计信息，对线程进行有效管理
2、JUC线程池架构
JUC指的是Java的并发工具包
1. Executor
Executor提供了execute()接口，用来执行已提交的Runnable目标实例，它只有1个方法：
void execute(Runnable command)
2. ExecutorService
继承于Executor.Java，异步目标任务的“执行者服务”接口，对外提供异步任务的接收服务
* @param task the task to submit * @param <T> the type of the task's result * @return a Future representing pending completion of the task * @throws RejectedExecutionException if the task cannot be * scheduled for execution * @throws NullPointerException if the task is null */ <T> Future<T> submit(Callable<T> task);//向线程池提交单个异步任务
//想线程池提交批量异步任务 <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) throws InterruptedException;
3. AbstractExecutorService
抽象类，实现了ExecutorService
4. ThreadPoolExecutor
线程池实现类，继承于AbstractExecutorService，JUC线程池的核心实现类
5. ScheduledExecutorService
继承于ExecutorService。它是一个可以完成“延时”和“周期性”任务的调度线程池接口
6. ScheduledThreadPoolExecutor
继承于ThreadPoolExecutor，实现了ExecutorService中延时执行和周期执行等抽象方法
7. Executors
静态工厂类，它通过静态工厂方法返回ExecutorService、ScheduledExecutorService等线程池示例对象
8. Executors创建线程的4种方法
newSingleThreadExecutor创建“单线程化线程池”
package threadpool; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.atomic.AtomicInteger; public class CreateThreadPollDemo { public static final int SLEEP_GAP=1000; static class TargetTask implements Runnable{ static AtomicInteger taskNo=new AtomicInteger(1); private String taskName; public TargetTask() { taskName="task-"+taskNo; taskNo.incrementAndGet(); } public void run() { System.out.println("task:"+taskName+" is doing..."); try { Thread.sleep(SLEEP_GAP); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("task:"+taskName+" end..."); } } public static void main(String[] args) { ExecutorService pool=Executors.newSingleThreadExecutor(); for(int i=0;i<3;i++) { pool.execute(new TargetTask()); pool.submit(new TargetTask()); } pool.shutdown(); } }
Java线程池（超详细）
