HttpURLConnection响应head内容的编码方式，如何正确识别，100分在线等

我用HttpUrlConnection 连接下载一个mp3
地址如下：
http://zhangmenshiting.baidu.com/data2/music/91731224/91731224.mp3?xcode=35364211a9bc8d289ad59150fa1ad1eb5dc4eabdf6e0aebb
返回的 response head中可以读取到文件名字
如下：
Content-Disposition:attachment; filename="²»ÖµµÃ.mp3"
现在我的需求是，正确识别这个filename的编码方式
这是个汉字名字，我用 new String(str.getBytes("iso-8859-1"),"gbk");
能正确的到名字，但是我希望能不是由我代码写死的来转成gbk，而是有代码或者其他方式动态识别出来

注：用浏览器访问这个地址，是可以获得正确的文件名的，指定浏览器编码方式并不会导致乱码，希望有经验的或者做过浏览器的指点指点，浏览器是如何做到的

下面是完整测试代码，拷贝即可运行：

import java.io.UnsupportedEncodingException;

import java.net.HttpURLConnection;

import java.net.URL;

import java.util.LinkedHashMap;

import java.util.Locale;

import java.util.Map;





public class T1 {

    public static void main(String[] args) throws UnsupportedEncodingException, Throwable {

        String downloadUrl = "http://zhangmenshiting.baidu.com/data2/music/91731224/91731224.mp3?xcode=35364211a9bc8d289ad59150fa1ad1eb5dc4eabdf6e0aebb";

        URL url = new URL(downloadUrl);

        // 打开HttpURLConnection

        HttpURLConnection conn = (HttpURLConnection) url.openConnection();

        // 设置 HttpURLConnection的断开时间

        conn.setConnectTimeout(5000);

        // 设置 HttpURLConnection的请求方式

        conn.setRequestMethod("GET");

        // 设置 HttpURLConnection的接收的文件类型

        conn.setRequestProperty(

                "Accept",

                "image/gif, image/jpeg, image/pjpeg, image/pjpeg, "

                        + "application/x-shockwave-flash, application/xaml+xml, "

                        + "application/vnd.ms-xpsdocument, application/x-ms-xbap, application/x-ms-application, "

                        + "application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*");

        // 设置 HttpURLConnection的接收语音

        conn.setRequestProperty("Accept-Language", Locale.getDefault().toString());

        // 指定请求uri的源资源地址

        conn.setRequestProperty("Referer", downloadUrl);

        // 设置 HttpURLConnection的字符编码

        conn.setRequestProperty("Accept-Charset", "UTF-8");

        // 检查浏览页面的访问者在用什么操作系统（包括版本号）浏览器（包括版本号）和用户个人偏好

//        conn.setRequestProperty(

//                "User-Agent",

//                "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.2;"

//                        + " Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; "

//                        + ".NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152;"

//                        + " .NET CLR 3.5.30729)");

        conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.101 Safari/537.36");

        conn.setRequestProperty("Connection", "Keep-Alive");

        

        conn.connect();

        

        printResponseHeader(conn);

    }

    

    private static void printResponseHeader(HttpURLConnection http) throws UnsupportedEncodingException {

        Map<String, String> header = getHttpResponseHeader(http);

        for (Map.Entry<String, String> entry : header.entrySet()) {

            String key = entry.getKey() != null ? entry.getKey() + ":" : "";

            System.out.println(key + entry.getValue());

        }

    }

    

    private static Map<String, String> getHttpResponseHeader(

            HttpURLConnection http) throws UnsupportedEncodingException {

        Map<String, String> header = new LinkedHashMap<String, String>();

        for (int i = 0;; i++) {

            String mine = http.getHeaderField(i);

            if (mine == null)

                break;

            header.put(http.getHeaderFieldKey(i), mine);

        }

        return header;

    }

}

下面是我的运行结果:

HTTP/1.1 200 OK

Server:JSP2/1.0.16

Date:Mon, 04 Nov 2013 03:06:26 GMT

Content-Type:audio/mpeg

Connection:close

Content-Length:2518244

Accept-Ranges:bytes

Last-Modified:Wed, 23 Oct 2013 02:56:23 GMT

Expires:Fri, 22 Nov 2013 12:20:18 GMT

x-bs-version:9AB3778C345E22493B1B8D3D1E7D92C1

ETag:f05c8c3e7e7328b5ec3913051c256170

x-bs-request-id:MTAuNDYuMjI4LjQ0OjgwODA6Mjk3MDIxMTc1NToyMy9PY3QvMjAxMyAyMDoyMDoxOCA=

Content-Disposition:attachment; filename="²»ÖµµÃ.mp3"

x-bs-meta-crc32:657750654

Content-MD5:f05c8c3e7e7328b5ec3913051c256170

x-bs-client-ip:NTguMjE1LjEyMy45Mg==

x-bs-uncopyable:enable

Cache-Control:max-age=2592000