java获取URL响应头

import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class Test{
public static void main(String[] args) throws IOException{
URL url = new URL("http://www.baidu.com");
URLConnection conn = url.openConnection();

Map<String, List<String>> headers = conn.getHeaderFields();
Set<String> keys = headers.keySet();
for( String key : keys ){
String val = conn.getHeaderField(key);
System.out.println(key+"    "+val);
}
}
}

Accept-Ranges    bytes
null    HTTP/1.1 200 OK
Cache-Control    private, no-cache, no-store, proxy-revalidate, no-transform
Server    bfe/1.0.8.18
ETag    "588604e2-94d"
Connection    Keep-Alive
Set-Cookie    BDORZ=27315; max-age=86400; domain=.baidu.com; path=/
Pragma    no-cache
Last-Modified    Mon, 23 Jan 2017 13:28:02 GMT
Content-Length    2381
Date    Mon, 19 Jun 2017 00:56:33 GMT
Content-Type    text/html