工厂模式是最常用的模式之一,它可以把对象创建工作集中化,好处大家都知道:改变对象的创建方式将会变得很容易,而且可以控制创建对象的数量。
线程工厂(ThreadFactory接口)
在创建线程的时候,我们当然也能使用工厂模式来生产线程,ThreadFactory是用来实现创建线程的工厂接口,其实它只有一个方法Thread newThread(Runnable r),所以这个接口没多大用,可以自己编写新接口。
使用ThreadFactory工厂能替代默认的new Thread,而且在自定义工厂里面,我们能创建自定义化的Thread,并且计数,或则限制创建Thread的数量,给每个Thread设置对应的好听的名字,或则其他的很多很多事情。
ThreadFactory在并发中的使用
- 在Java中使用ThreadFactory最多应该就是Executor框架和Fork/Join框架了,使用ThreadFactory创建各种线程池中的线程。在Executor框架中,使用Executors创建线程池执行器的时候,也可以传入ThreadFactory对象,执行器将会使用该ThreadFactory对象来创建线程。
如:newCachedThreadPool(ThreadFactory threadFactory)
- 在Java中使用ThreadFactory最多应该就是Executor框架和Fork/Join框架了,使用ThreadFactory创建各种线程池中的线程。在Executor框架中,使用Executors创建线程池执行器的时候,也可以传入ThreadFactory对象,执行器将会使用该ThreadFactory对象来创建线程。
使用实例
下面的例子来自《Java并发编程实战》,展示一个简单的使用ThreadFactory来创建自己的Thread。工厂模式来创建自己的Thread。在创建线程的同时,记录线程创建的个数,并记录每个线程创建的时间等信息。
package MyThread;
import java.util.concurrent.ThreadFactory;
import java.util.ArrayList;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
public class MyThreadFactory implements ThreadFactory {
private int counter;
private String name;
private List<String> stats;
public MyThreadFactory(String name) {
counter = 0;
this.name = name;
stats = new ArrayList<String>();
}
@Override
public Thread newThread(Runnable run) {
Thread t = new Thread(run, name + "-Thread-" + counter);
counter++;
stats.add(String.format("Created thread %d with name %s on%s\n" ,t.getId() ,t.getName() ,new Date()));
return t;
}
public String getStas() {
StringBuffer buffer = new StringBuffer();
Iterator<String> it = stats.iterator();
while(it.hasNext()) {
buffer.append(it.next());
// buffer.append("\n");
}
return buffer.toString();
}
public static void main(String[] args) {
MyThreadFactory factory = new MyThreadFactory("MyThreadFactory");
Task task = new Task();
Thread thread = null;
for(int i = 0; i < 10; i++) {
thread = factory.newThread(task);
thread.start();
}
System.out.printf("Factory stats:\n");
System.out.printf("%s\n",factory.getStas());
}
}
class Task implements Runnable{
@Override
public void run() {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
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运行结果:
Factory stats:
Created thread 9 with name MyThreadFactory-Thread-0 onSun Jun 05 15:42:25 CST 2016
Created thread 10 with name MyThreadFactory-Thread-1 onSun Jun 05 15:42:25 CST 2016
Created thread 11 with name MyThreadFactory-Thread-2 onSun Jun 05 15:42:25 CST 2016
Created thread 12 with name MyThreadFactory-Thread-3 onSun Jun 05 15:42:25 CST 2016
Created thread 13 with name MyThreadFactory-Thread-4 onSun Jun 05 15:42:25 CST 2016
Created thread 14 with name MyThreadFactory-Thread-5 onSun Jun 05 15:42:25 CST 2016
Created thread 15 with name MyThreadFactory-Thread-6 onSun Jun 05 15:42:25 CST 2016
Created thread 16 with name MyThreadFactory-Thread-7 onSun Jun 05 15:42:25 CST 2016
Created thread 17 with name MyThreadFactory-Thread-8 onSun Jun 05 15:42:25 CST 2016
Created thread 18 with name MyThreadFactory-Thread-9 onSun Jun 05 15:42:25 CST 2016