<form id="form22" name="form22" action="checklogin.action" method="post" >
 <div class="username" >
  <label>用户名：</label>
  <input type="text" name="username" id="userName" />
  <span id="myuser" ></span>
 </div>

 <div class="password">
  <label>密&nbsp;码：</label>
  <input name="password" id="passWord" type="password" />
  <span id="mypass" ></span>
 </div>

 <div class="user_type" >
  <label>&nbsp;&nbsp;</label>
  <input type="checkbox" id="saveUserName"  /> 
  <span> 记住用户</span>  
 </div>

 <input type="button" value="" class="btn_login" id="btn_login" onclick="checkform();"/>

</form>

function setCookie (name, value) {
  var Days = 30; //此 cookie 将被保存 30 天
  var exp = new Date();
  exp.setTime(exp.getTime() + 1000);
  if(value==""||value=="null"
   ||value=="null"||value==" "){
  }else{
  document.cookie = name + "="+ escape(value) +";expires=Sun, 17-Jan-2038 19:14:07 GMT";
  }
}
function getCookie(sName){
  var aCookie = document.cookie.split("; ");
  for (var i=0; i < aCookie.length; i++)
  {
   var aCrumb = aCookie[i].split("=");
   if (sName == aCrumb[0])
   {
    return aCrumb[1];
   }
  }
  return null;
}
function checkCookieExist(name){
 if (getCookie(name))
  return true;
 else
  return false;
}

function deleteCookie(name, path, domain){
 var strCookie;
 // 检查Cookie是否存在
 if (checkCookieExist(name)){
  // 设置Cookie的期限为己过期
  strCookie = name + "=";
  strCookie += (path) ? "; path=" + path : "";
  strCookie += (domain) ? "; domain=" + domain : "";
  strCookie += "; expires=Thu, 01-Jan-70 00:00:01 GMT";
  document.cookie = strCookie;
 }
}
function saveCookie(name, value, expires, path, domain, secure){
 var strCookie = name + "=" + value;
 if (expires){
  // 计算Cookie的期限, 参数为天数
  var curTime = new Date();
  curTime.setTime(curTime.getTime() + expires*24*60*60*1000);
  strCookie += "; expires=" + curTime.toGMTString();
 }
 // Cookie的路径
 strCookie += (path) ? "; path=" + path : "";
 // Cookie的Domain
 strCookie += (domain) ? "; domain=" + domain : "";
 // 是否需要保密传送,为一个布尔值
 strCookie += (secure) ? "; secure" : "";
 document.cookie = strCookie;
}

window.onload = function(){
 //console.log("ctx: " + "${ctx}");

 var name = getCookie("loginUserName");
 document.getElementById("passWord").value="";
 if(name != null && name != "") {
  document.getElementById("userName").value = name;      

  document.getElementById("passWord").focus();
 } else {  document.getElementById("userName").focus();
 }

}

function checkform(){
 ......
 var isChecked = document.getElementById("saveUserName").checked;
 if(isChecked) {
  setCookie("loginUserName",userName);
 } 
 ......
}

<form class="form-signin">
　　<input type="text" id="username" name="account" autofocus required placeholder="用户名" class="form-control" >
　　<input type="password" id="password" name="password" required placeholder="密码" class="form-control" >
　　<br/>
　　<input id="remember_me" type="checkbox" name="remember_me" onkeydown="check_enter(event)" >
　　<span for="remember_me" onkeydown="check_enter(event)" >记住我</span>
　　<br/><br/>
　　<span class="btn btn-lg btn-primary btn-block">登 录</span>
</form>
<script src="jquery.js" type="text/javascript"></script>
　　<script src="jquery.cookie.js" type="text/javascript"></script>

if ($("#remember_me").attr("checked")) {
　　　　$.cookie("rmbUser", "true", { expires: 7 }); //存储一个带7天期限的cookie
　　　　$.cookie("username", account, { expires: 7 });
　　　　$.cookie("password", password, { expires: 7 });
}
else {
　　　　$.cookie("rmbUser", "false", { expire: -1 });
　　　　$.cookie("username", "", { expires: -1 });
　　　　$.cookie("password", "", { expires: -1 });
}

$().ready(function(){
　　　　//获取cookie的值
　　　　var username = $.cookie('username');
　　　　var password = $.cookie('password');

　　　　//将获取的值填充入输入框中
　　　　$('#username').val(username);
　　　　$('#password').val(password); 
　　　　if(username != null && username != '' && password != null && password != ''){
  //选中保存秘密的复选框
　　　　 $("#remember_me").attr('checked',true);
}