public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/**
* 1.獲取所有的cookie，判斷是否是第一次訪問
* 
*/
//設定中文亂碼問題
response.setContentType("text/html;charset=UTF-8");
//獲取所有的cookie
Cookie[] cookies = request.getCookies();
//通過指定Cookie名稱來查詢Cookie Cookie c = new Cookie("last","當前時間");
Cookie cookie = MyCookieUtil.getCookieByName(cookies,"last");
//判斷是否為空，如果是空，說明第一次訪問
if(cookie == null){
response.getWriter().write("<h3>welcome</h3>");
}else{
String value = cookie.getValue();

response.getWriter().write("<h3>welcome again "+"上次"+value+"</h3>");
}
//記錄當前時間
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd hh:mm:ss");
String sDate = sdf.format(date);


//回寫到瀏覽器
Cookie c = new Cookie("last",sDate);
response.addCookie(c);

}

package utils;


import javax.servlet.http.Cookie;


public class MyCookieUtil {

public static Cookie getCookieByName(Cookie[] cookies,String name){

if(cookies == null){
return null;
}else{
//迴圈遍歷，和name匹配，成功返回當前的COOKIE
for(Cookie cookie : cookies){

if(cookie.getName().equals(name)){
return cookie;
}
}
}
return null;
}
}