portscan.java

这是《Java案例精粹150例（上册）》一书配套的源代码。

import java.net.*;
import java.io.*;

public class PortScan {
	public static void main(String[] args) {
		String host = "localhost";
		if (args.length > 0) {
			host = args[0];
		}
		// 扫描端口号小于1024的端口
		for (int i = 1; i < 1024; i++) {
			try {
				Socket s = new Socket(host, i);
				System.out.println("There is a server on port " + i + " of "
						+ host);
			} catch (UnknownHostException e) {
				System.err.println(e);
				break;
			} catch (IOException e) { 
			}
		}
	}
}