练手java thread(四)

用Executor来构建线程池，应该要做的事：

1).调用Executors类中的静态方法newCachedThreadPool(必要时创建新线程，空闲线程会被保留60秒)或newFixedThreadPool(包含固定数量的线程池)等，返回的是一个实现了ExecutorService接口的ThreadPoolExecutor类或者是一个实现了ScheduledExecutorServiece接口的类对象。

2).调用submit提交Runnable或Callable对象。

3).如果想要取消一个任务，或如果提交Callable对象，那就要保存好返回的Future对象。

4).当不再提交任何任务时，调用shutdown方法。

 

举2个例子如下：

package thread.test04;
import java.util.concurrent.*;
public class ThreadTestA {
	public static void main(String[] args) {
		ExecutorService e=Executors.newFixedThreadPool(10);
		e.execute(new MyRunnableA());
		e.execute(new MyRunnableB());
 		e.shutdown();
 	}

}

class MyRunnableA implements Runnable{
	
	public void run(){
		System.out.println("Runnable:run()....");
		int i=0;
		while(i<20){
			i++;
			for(int j=0;j<1000000;j++);
			System.out.println("i="+i);
		}
	}
}

class MyRunnableB implements Runnable{
	public void run(){
		char c='A'-1;
		while(c<'Z'){
			c++;
			for(int j=0;j<1000000;j++);
			System.out.println("c="+c);
		}
	}
}

 ////////////////////////////

package thread.test04;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class ThreadTestB {
	public static void main(String[] args) {
		ExecutorService e=Executors.newFixedThreadPool(10);
		Future f1=e.submit(new MyCallableA());
		Future f2=e.submit(new MyCallableA());
		Future f3=e.submit(new MyCallableA());
		Future f4=e.submit(new MyCallableA());
		Future f5=e.submit(new MyCallableA());
		System.out.println("--Future.get()....");
		try {
			System.out.println(f1.get());
			System.out.println(f2.get());
			System.out.println(f3.get());
			System.out.println(f4.get());
			System.out.println(f5.get());
		} catch (InterruptedException e1) {
			e1.printStackTrace();
		} catch (ExecutionException e1) {
			e1.printStackTrace();
		}
		
		e.shutdown();
		
	}

}

class MyCallableA implements Callable<String>{
	public String call() throws Exception {
		System.out.println("开始执行Callable");
		String[] ss={"zhangsan","lisi"};
		long[] num=new long[2];
		for(int i=0;i<1000000;i++){
			num[(int)(Math.random()*2)]++;
		}
		
		if(num[0]>num[1]){
			return ss[0];
		}else if(num[0]<num[1]){
			throw new Exception("弃权!");
		}else{
			return ss[1];
		}
	}
	
}