检测URL是否真实有效

import java.net.URL;  
import java.net.HttpURLConnection;  
 
public class test2 {  
    private boolean isConnect(String url) {  
        boolean flag = false;  
        int counts = 0;  
        if (url == null || url.length() <= 0) {  
            return flag;  
        }  
        while (counts < 5) {  
            try {  
                HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();  
                int state = connection.getResponseCode();  
                if (state == 200) {
                    flag = true;  
                }  
                break;  
            } catch (Exception ex) {  
                counts++;  
                continue;  
            }  
        }  
        return flag;  
    }  
 
    public static void main(String[] args) {  
     test2 check = new test2();   
        System.out.println(check.isConnect ("http://www.baidu.com/cozone/20/34/203441/images/148_60_1.gif")); 
    }  
}