java查询域名是否可用

	public static int useable(String net){
		long lo = System.currentTimeMillis();
		int re= 0;
        URL url;    
        try {    
             url = new URL(net.trim());    
             URLConnection co =  url.openConnection();  
             co.setConnectTimeout(2000);  
             co.connect();  
             re=1;
            // System.out.println("连接可用");    
        } catch (Exception e1) {   
        	 re=-1;
             //System.out.println("连接打不开!");    
             url = null;    
        }    
       // System.out.println(System.currentTimeMillis()-lo);
		
		return re;
	}