Cookie

//Cookie的遍历与取值、改值
 Cookie [] cookies =request.getCookies();
 
 for (Cookie cookie : cookies) {         //for循环遍历
 if ("username".equals(cookie.getName())) {  //通过getName取值
 cookie.setValue("lisi");      //通过setValue改值
 response.addCookie(cookie);
 }
 
 }

 Cookie cookie1=new Cookie("key1", "zhang");
 Cookie cookie2=new Cookie("key2", "li");
 cookie1.setMaxAge(0);
 response.addCookie(cookie1);
 response.addCookie(cookie2);

Cookie cookie1=new Cookie("key1", "zhang");
 Cookie cookie2=new Cookie("key2", "li");
 
 cookie1.setMaxAge(0);
 cookie2.setPath(request.getContextPath()+"/1.jsp");
 response.addCookie(cookie1);
 response.addCookie(cookie2);

//Jsp
<form action="${pageContext.request.contextPath}/cookie" method="get">
 用户名：<input type="text" name="username" value=${cookie.value}><br>
 密码： <input type="password" name="pwd" ><br>
 <input type="submit" value="登录">
 
</form>

//servlet中
Cookie cookie=new Cookie("username", "zhangsan");
 response.addCookie(cookie);
 String username = request.getParameter("username");
 String pwd = request.getParameter("pwd");
 if (username.equals(cookie.getValue())) {
 response.sendRedirect(request.getContextPath()+"/1.jsp");
 }
 }