Java 實例 - 取得 URL 回應頭訊息

/*
 author by w3cschool.cc
 Main.java
 */import java.io.IOException;import java.net.URL;import java.net.URLConnection;import java.util.Map;import java.util.Set;public class Main {
    public static void main(String[] args) throws IOException{
        URL url = new URL("http://www.w3cschool.cc");
        URLConnection conn = url.openConnection();
        
        Map headers = conn.getHeaderFields();
        Set<String> keys = headers.keySet();
        for( String key : keys ){
            String val = conn.getHeaderField(key);
            System.out.println(key+"    "+val);
        }
        System.out.println( conn.getLastModified() );
    }}