urldemo2.java

JAVA的高级应用以及网络编程

import java.io.*;
import java.net.*;
import java.util.*;
class URLDemo2{
	public static void main (String [] args) throws IOException{
		if (args.length != 1){
			System.err.println ("usage: java URLDemo2 url");
			return;
		}
		URL url = new URL (args [0]);
		// 返回代表某个资源的连接的新的特定协议对象的引用
		URLConnection uc = url.openConnection ();
		// 进行连接
		uc.connect ();
		// 打印多种头部字段的内容
		Map m = uc.getHeaderFields ();
		Iterator i = m.entrySet ().iterator ();
		while (i.hasNext ())
		System.out.println (i.next ());
		// 如果资源允许输入和输出操作就找出来
		System.out.println ("Input allowed = " +uc.getDoInput ());
		System.out.println ("Output allowed = " +uc.getDoOutput ());
	}
}