如何在java中獲得響應標頭

Question

我想在java中獲得響應標頭。

URL obj = new URL("http://mkyong.com"); 

    //get all headers 
    Map<String, List<String>> map = conn.getHeaderFields(); 
    for (Map.Entry<String, List<String>> entry : map.entrySet()) { 
     System.out.println("Key : " + entry.getKey() + 
       " ,Value : " + entry.getValue()); 
    } 

    //get header by 'key' 
    String server = conn.getHeaderField("Server"); 

請告訴我什麼是錯在我的代碼？

Answer 1

URL obj = new URL("http://mkyong.com"); 
    URLConnection conn = obj.openConnection(); 

    //get all headers 
    Map<String, List<String>> map = conn.getHeaderFields(); 
    for (Map.Entry<String, List<String>> entry : map.entrySet()) { 
     System.out.println("Key : " + entry.getKey() + 
       " ,Value : " + entry.getValue()); 
    } 

    //get header by 'key' 
    String server = conn.getHeaderField("Server");