1. 類 Executors

此類中提供的一些方法有：
1.1 public
static ExecutorService newCachedThreadPool()

建立一個可根據需要建立新執行緒的執行緒池，但是在以前構造的執行緒可用時將重用它們。對於執行很多短期非同步任務的程式而言，這些執行緒池通常可提高程式效能。

 

1.2 public
static ExecutorService newFixedThreadPool(int nThreads)

建立一個可重用固定執行緒數的執行緒池，以共享的***佇列方式來執行這些執行緒。

 

1.3 public
static ExecutorService newSingleThreadExecutor()

建立一個使用單個 worker 執行緒的 Executor，以***佇列方式來執行該執行緒。

 

這三個方法都可以配合介面ThreadFactory的例項一起使用。並且返回一個ExecutorService介面的例項。
2. 介面 ThreadFactory

根據需要建立新執行緒的物件。使用執行緒工廠就無需再手工編寫對 new
Thread 的呼叫了，從而允許應用程式使用特殊的執行緒子類、屬性等等。
此介面最簡單的實現就是：
class SimpleThreadFactory implements
ThreadFactory {
  
public Thread newThread(Runnable r) {
    
return new Thread(r);
  
}
 }
3. 介面ExecutorService

該介面提供了管理終止的方法。
4.建立標準執行緒池啟動執行緒

4.1 提供一個簡單的實現Runnable介面的執行緒

MyThread.java

package com.zj.concurrency.executors;

 

public class MyThread implements Runnable {

    private int count = 1, number;

 

    public MyThread(int num) {

       number = num;

       System.out.println(“Create Thread-“ + number);

    }

 

    public void run() {

       while (true) {

           System.out.println(“Thread-“ + number + ” run “ + count+” time(s)”);

           if (++count == 3)

              return;

       }

    }

}
這個執行緒會列印出相應的建立和執行資訊。

 

4.2使用CachedThreadPool啟動執行緒

CachedThreadPool.java

package com.zj.concurrency.executors;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

 

public class CachedThreadPool {

    public static void main(String[] args) {

       ExecutorService exec = Executors.newCachedThreadPool();

       for (int i = 0; i < 5; i++)

           exec.execute(new MyThread(i));

       exec.shutdown();

    }

}
結果：
Create Thread-0

Create Thread-1

Create Thread-2

Create Thread-3

Thread-0 run 1 time(s)

Thread-0 run 2 time(s)

Thread-1 run 1 time(s)

Thread-1 run 2 time(s)

Thread-2 run 1 time(s)

Thread-2 run 2 time(s)

Create Thread-4

Thread-4 run 1 time(s)

Thread-4 run 2 time(s)

Thread-3 run 1 time(s)

Thread-3 run 2 time(s)

 

4.3 使用FixedThreadPool啟動執行緒

FixedThreadPool.java

package com.zj.concurrency.executors;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

 

public class FixedThreadPool {

    public static void main(String[] args) {

       ExecutorService exec = Executors.newFixedThreadPool(2);

       for (int i = 0; i < 5; i++)

           exec.execute(new MyThread(i));

       exec.shutdown();

    }

}
結果：
Create Thread-0

Create Thread-1

Create Thread-2

Create Thread-3

Create Thread-4

Thread-0 run 1 time(s)

Thread-0 run 2 time(s)

Thread-2 run 1 time(s)

Thread-2 run 2 time(s)

Thread-3 run 1 time(s)

Thread-3 run 2 time(s)

Thread-4 run 1 time(s)

Thread-4 run 2 time(s)

Thread-1 run 1 time(s)

Thread-1 run 2 time(s)

 

4.4 使用SingleThreadExecutor啟動執行緒

SingleThreadExecutor.java

package com.zj.concurrency.executors;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

 

public class SingleThreadExecutor {

    public static void main(String[] args) {

       ExecutorService exec = Executors.newSingleThreadExecutor();

       for (int i = 0; i < 5; i++)

           exec.execute(new MyThread(i));

       exec.shutdown();

    }

}
結果：
Create Thread-0

Create Thread-1

Create Thread-2

Create Thread-3

Create Thread-4

Thread-0 run 1 time(s)

Thread-0 run 2 time(s)

Thread-1 run 1 time(s)

Thread-1 run 2 time(s)

Thread-2 run 1 time(s)

Thread-2 run 2 time(s)

Thread-3 run 1 time(s)

Thread-3 run 2 time(s)

Thread-4 run 1 time(s)

Thread-4 run 2 time(s)
5.配合ThreadFactory介面的使用

我們試圖給執行緒加入daemon和priority的屬性設定。
5.1設定後臺執行緒屬性

DaemonThreadFactory.java

package com.zj.concurrency.executors.factory;

import java.util.concurrent.ThreadFactory;

 

public class DaemonThreadFactory implements ThreadFactory {

    public Thread newThread(Runnable r)
{

       Thread t = new Thread(r);

       t.setDaemon(true);

       return t;

    }

}

 

5.2 設定優先順序屬性

最高優先順序MaxPriorityThreadFactory.java

package com.zj.concurrency.executors.factory;

import java.util.concurrent.ThreadFactory;

 

public class MaxPriorityThreadFactory implements ThreadFactory {

    public Thread newThread(Runnable r)
{

       Thread t = new Thread(r);

       t.setPriority(Thread.MAX_PRIORITY);

       return t;

    }

}
最低優先順序MinPriorityThreadFactory.java

package com.zj.concurrency.executors.factory;

import java.util.concurrent.ThreadFactory;

 

public class MinPriorityThreadFactory implements ThreadFactory {

    public Thread newThread(Runnable r)
{

       Thread t = new Thread(r);

       t.setPriority(Thread.MIN_PRIORITY);

       return t;

    }

}

 

5.3啟動帶有屬性設定的執行緒

ExecFromFactory.java

package com.zj.concurrency.executors;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import
com.zj.concurrency.executors.factory.DaemonThreadFactory;

import
com.zj.concurrency.executors.factory.MaxPriorityThreadFactory;

import
com.zj.concurrency.executors.factory.MinPriorityThreadFactory;

 

public class ExecFromFactory {

    public static void main(String[] args) throws Exception
{

       ExecutorService defaultExec =
Executors.newCachedThreadPool();

       ExecutorService daemonExec = Executors

              .newCachedThreadPool(new
DaemonThreadFactory());

       ExecutorService maxPriorityExec =
Executors

              .newCachedThreadPool(new
MaxPriorityThreadFactory());

       ExecutorService minPriorityExec =
Executors

              .newCachedThreadPool(new MinPriorityThreadFactory());

       for (int i = 0; i < 10; i++)

           daemonExec.execute(new MyThread(i));

       for (int i = 10; i < 20; i++)

           if (i == 10)

              maxPriorityExec.execute(new MyThread(i));

           else if (i == 11)

              minPriorityExec.execute(new MyThread(i));

           else

              defaultExec.execute(new MyThread(i));

    }

}
結果：
Create Thread-0

Create Thread-1

Create Thread-2

Create Thread-3

Thread-0 run 1 time(s)

Thread-0 run 2 time(s)

Thread-1 run 1 time(s)

Thread-1 run 2 time(s)

Thread-2 run 1 time(s)

Thread-2 run 2 time(s)

Create Thread-4

Thread-4 run 1 time(s)

Thread-4 run 2 time(s)

Create Thread-5

Thread-5 run 1 time(s)

Thread-5 run 2 time(s)

Create Thread-6

Create Thread-7

Thread-7 run 1 time(s)

Thread-7 run 2 time(s)

Create Thread-8

Thread-8 run 1 time(s)

Thread-8 run 2 time(s)

Create Thread-9

Create Thread-10

Thread-10 run 1 time(s)

Thread-10 run 2 time(s)

Create Thread-11

Thread-9 run 1 time(s)

Thread-9 run 2 time(s)

Thread-6 run 1 time(s)

Thread-6 run 2 time(s)

Thread-3 run 1 time(s)

Thread-3 run 2 time(s)

Create Thread-12

Create Thread-13

Create Thread-14

Thread-12 run 1 time(s)

Thread-12 run 2 time(s)

Thread-13 run 1 time(s)

Thread-13 run 2 time(s)

Create Thread-15

Thread-15 run 1 time(s)

Thread-15 run 2 time(s)

Create Thread-16

Thread-16 run 1 time(s)

Thread-16 run 2 time(s)

Create Thread-17

Create Thread-18

Create Thread-19

Thread-14 run 1 time(s)

Thread-14 run 2 time(s)

Thread-17 run 1 time(s)

Thread-17 run 2 time(s)

Thread-18 run 1 time(s)

Thread-18 run 2 time(s)

Thread-19 run 1 time(s)

Thread-19 run 2 time(s)

Thread-11 run 1 time(s)

Thread-11 run 2 time(s)