如何通过HttpURLConnection得到http 302的跳转地址

package com.zuidaima; 
  
import java.net.HttpURLConnection;  
import java.net.URL;  
  
/** 
 * 如何通过HttpURLConnection得到http 302的跳转地址 
 *  
 * @author javaniu 
 *  
 */  
public class Http302 {  
  
    public static void main(String[] args) {  
        try {  
            String url = "url";  
            System.out.println("访问地址:" + url);  
            URL serverUrl = new URL(url);  
            HttpURLConnection conn = (HttpURLConnection) serverUrl  
                    .openConnection();  
            conn.setRequestMethod("GET");  
            // 必须设置false，否则会自动redirect到Location的地址  
            conn.setInstanceFollowRedirects(false);  
  
            conn.addRequestProperty("Accept-Charset", "UTF-8;");  
            conn.addRequestProperty("User-Agent",  
                    "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.2.8) Firefox/3.6.8");  
            conn.addRequestProperty("Referer", "url");  
            conn.connect();  
            String location = conn.getHeaderField("Location");  
  
            serverUrl = new URL(location);  
            conn = (HttpURLConnection) serverUrl.openConnection();  
            conn.setRequestMethod("GET");  
  
            conn.addRequestProperty("Accept-Charset", "UTF-8;");  
            conn.addRequestProperty("User-Agent",  
                    "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.2.8) Firefox/3.6.8");  
            conn.addRequestProperty("Referer", "url");  
            conn.connect();  
            System.out.println("跳转地址:" + location);  
  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
    }  
  
}