线程池

由各个博客总结归纳而来。

1.线程池的基本思想：

线程池的基本思想还是一种对象池的思想，开辟一块内存空间，里面存放了众多(未死亡)的线程，池中线程执行调度由池管理器来处理。当有线程任务时，从池中取一个，执行完成后线程对象归池，这样可以避免反复创建线程对象所带来的性能开销，节省了系统的资源。

2.线程池的核心代码样式

 1 package BackStage;
 2 
 3 import java.util.concurrent.Executors;
 4 
 5 import java.util.concurrent.ExecutorService;
 6 
 7 public class JavaThreadPool {
 8 
 9     public static void main(String[] args) {
10 
11     // 创建一个可重用固定线程数的线程池
12 
13     ExecutorService pool = Executors.newFixedThreadPool(2);
14 
15     // 创建实现了Runnable接口对象，Thread对象当然也实现了Runnable接口
16 
17     Thread t1 = new MyThread();
18 
19     Thread t2 = new MyThread();
20 
21     Thread t3 = new MyThread();
22 
23     Thread t4 = new MyThread();
24 
25     Thread t5 = new MyThread();
26 
27     // 将线程放入池中进行执行
28 
29     pool.execute(t1);
30 
31     pool.execute(t2);
32 
33     pool.execute(t3);
34 
35     pool.execute(t4);
36 
37     pool.execute(t5);
38 
39     // 关闭线程池
40 
41     pool.shutdown();
42 
43     }
44 
45 }
46 
47 class MyThread extends Thread {
48 
49     @Override
50 
51     public void run() {
52 
53     System.out.println(Thread.currentThread().getName() + "正在执行。。。");
54 
55     }
56 
57 }

3.线程池的类型：

1.单任务线程池

ExecutorService pool = Executors.newSingleThreadExecutor();

2.固定大小的线程池

ExecutorService poo延迟连接池 = Executors.newFixedThreadPool(2);

3.可变尺寸的线程池

ExecutorService pool = Executors.newCachedThreadPool();

4.延迟连接池

ScheduledExecutorService pool = Executors.newScheduledThreadPool(2);

5.单任务延迟连接池

ScheduledExecutorService pool = Executors.newSingleThreadScheduledExecutor();

6.自定义线程池

ThreadPoolExecutor pool = new ThreadPoolExecutor(2,3,2,TimeUnit.MILLISECONDS,bqueue);

自定义线程池的详细资料见此链接 http://www.infoq.com/cn/articles/java-threadPool/