HttpURLConnection如何实现重定向、获取及设置cookie呢?

实现思路:
   HttpURLConnection在请求头中设置cookie的代码如下:
       conn.setRequestMethod("POST");
       conn.setRequestProperty("Cookie", firstCookie);

HttpURLConnection获取重定向地址和cookie代码如下

public  void first() throws Exception{
		Map<String, String> paramsHashMap = new HashMap<String, String>();
		paramsHashMap.put("testabc", "99999");
		paramsHashMap.put("websitename", "java265");
		firstRequest(API_HTTP, paramsHashMap, "UTF-8");
	}
 
   private  void firstRequest(String path, Map<String, String> params, String encoding) throws Exception{		
		StringBuilder sb = new StringBuilder();
		if(params!=null && !params.isEmpty()){
			for(Map.Entry<String, String> entry : params.entrySet()){
				sb.append(entry.getKey()).append('=');
				sb.append(URLEncoder.encode(entry.getValue(), encoding));
				sb.append('&');
			}
			sb.deleteCharAt(sb.length() - 1);
		}
		byte[] entity = sb.toString().getBytes();
		HttpURLConnection conn = (HttpURLConnection) new URL(path).openConnection();
		conn.setInstanceFollowRedirects(true);
		conn.setConnectTimeout(5000);
		conn.setRequestMethod("POST");
		conn.setDoOutput(true);
		conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
		conn.setRequestProperty("Content-Length", String.valueOf(entity.length));
		OutputStream outStream = conn.getOutputStream();
		outStream.write(entity);
		//获取重定向地址
		redictURL= conn.getHeaderField("Location");
 
		System.out.println("第一次请求重定向地址 location="+redictURL);
		System.out.println("第一次请求 conn.getResponseCode()="+conn.getResponseCode());
		
		//获取cookie
		Map<String,list<String>> map=conn.getHeaderFields();
		Set<String> set=map.keySet();
		for (Iterator iterator = set.iterator(); iterator.hasNext();) {
			String key = (String) iterator.next();
			if (key.equals("Set-Cookie")) {
				System.out.println("key=" + key+",开始获取cookie");
				List<String> list = map.get(key);
				StringBuilder builder = new StringBuilder();
				for (String str : list) {
					builder.append(str).toString();
				}
				firstCookie=builder.toString();
				System.out.println("第一次得到的cookie="+firstCookie);
			}
		}	
	}