java 检测可用端口

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检测本机正在使用的服务端口，尽量快完成，计算消耗时间：

轮询：

public class test implements Runnable {
    //private static String host="210.39.3.164";
    private static int i=0;
    static Date one,two;
    public synchronized int get(){
        if(i>=1024)notifyAll();
        return i++;
    }
    
    public static void main(String argv[]){
        one=new Date();
        //long time=one.getTime()-two.getTime();
        //System.out.println(time);
        ExecutorService pool = Executors.newFixedThreadPool(30);
        for(int j=0;j<15;j++){
            pool.submit(new Thread(new test()));
        }
        pool.shutdown();
        while(true){
            if(pool.isTerminated()){
                System.out.println(two.getTime()-one.getTime());
                break;
            }
        }
    }
    
    public void run(){
        int temp;
        while((temp=get())<1024){
            try {    
                Socket s=new Socket(InetAddress.getLocalHost(),temp);
                System.out.println("服务端口:   "+temp);
                s.close();
            } catch (UnknownHostException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch(ConnectException e){
                System.out.println(temp+"不是服务端口");
            }catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            if(temp==1023){
                two=new Date();
            }
        }
    }
}

尽量多开线程：

public class test {
	public static void main(String argv[]){
		int i;
		Date d=new Date();
		ExecutorService pool = Executors.newFixedThreadPool(1204);
		for(i=1;i<=1024;i++){
			pool.submit(new Thread(new thread(i)));
		}
		pool.shutdown();
		while(true){
			if(pool.isTerminated()){
				Date last=new Date();
				System.out.println(last.getTime()-d.getTime());
				break;
			}
		}
		
	}
}


class thread implements Runnable{
	int i;
	thread(int i){
		this.i=i;
	}
	
	public void run(){
		try {	
			Socket s=new Socket(InetAddress.getLocalHost(),i);
			System.out.println("服务端口:   "+i);
			s.close();
		} catch (UnknownHostException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch(ConnectException e){
			//System.out.println(i+"不是服务端口");
		}catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

　　

轮询方法使用了线程同步，但是没有多开线程方法速度快

 

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