(jsp语言)登录实例(JS聚集回车键,并通过Ajax判断用户名,密码的正确性)
下面是一个简单的登录实例(JS聚集回车键,并通过Ajax判断用户名,密码的正确性)

//jsp页面
function checkManageLogin(){

var XMLHttp;
    XMLHttp = createXMLHttpRequest();
    ajaxUrl = "<%=path%>/userAction.do?act=login&name="+document.forms[0].loginname.value+"&password="+document.forms[0].password.value;
    XMLHttp.open("post",ajaxUrl,false);
    XMLHttp.send(null);
    count = XMLHttp.responseText ;
    XMLHttp.abort();

    if(count == 2){
    alert("Password is wrong!");
    document.forms[0].password.select();
        return false;
    }else{
    if(count == 3){
       alert("Username is not exsit!");
       document.forms[0].loginname.select();
       return false;
    }else{
       document.forms[0].action="<%=path%>/backend/frame.jsp";
       document.forms[0].submit();
       return true;
    }
    }
}

function createXMLHttpRequest() {
   try{
    this.XMLHttp=new XMLHttpRequest();
   }catch(trymicrosoft){
    try{
     this.XMLHttp=new ActiveXObject("Msxml2.XMLHTTP");
    
    }catch (othermicrosoft) {
     try{
      this.XMLHttp= ActiveXObject("Microsoft.XMLHTTP");
     }catch (failed) {
      this.XMLHttp=null;
     }
    }
   }
   return this.XMLHttp;
}

</script>


<script language="javascript">  
   function isKeyTrigger(e,keyCode){   

    var argv = isKeyTrigger.arguments;   
    var argc = isKeyTrigger.arguments.length;   
    var bCtrl = false;   
    if(argc > 2){   
        bCtrl = argv[2];   
    }   
    var bAlt = false;   
    if(argc > 3){   
        bAlt = argv[3];   
    }   
    var nav4 = window.Event ? true : false;   
    if(typeof e == 'undefined') {   
        e = event;   
    }   
    if(bCtrl &&   
        !((typeof e.ctrlKey != 'undefined') ?    
        e.ctrlKey :   
        e.modifiers & Event.CONTROL_MASK > 0)) {   
        return false;   
    }   
    if( bAlt &&   
        !((typeof e.altKey != 'undefined') ?    
            e.altKey : e.modifiers & Event.ALT_MASK > 0)){   
        return false;   
    }   
    var whichCode = 0;   
    if (nav4)
    whichCode = e.which;
    else if (e.type == "keypress" || e.type == "keydown") whichCode = e.keyCode;   
    else whichCode = e.button;   
    return (whichCode == keyCode);   
}   
  
function ctrlEnter(e){  
// var ie = navigator.appName == "Microsoft Internet Explorer" ? true : false; //(可以判断是什么浏览器)
      if(isKeyTrigger(e,13)){
         checkManageLogin();
         }
}   
  
</script>  

//下面是个Java语言方法,一般写在action中

public ActionForward login(ActionMapping mapping, ActionForm form,
    HttpServletRequest request, HttpServletResponse response) {
   try {
    int flag = 0;
    String username = request.getParameter("name");
    String password = request.getParameter("password");
    List<GsaUser> userList = userDao.getFrameList("from "
      + GsaUser.class.getName()
      + " as user where user.usertype is null and user.flag=0");
    for (GsaUser saoUser : userList) {
     if ((saoUser.getLoginname()).equals(username)
       || (saoUser.getLoginname()) == username) {
      if (password.equals(saoUser.getPassword())) {
       HttpSession session = request.getSession();
       session.setAttribute("managerId", saoUser.getUserid());
       session.setAttribute("managerName", saoUser
         .getLoginname());
       flag = 1;
       response.getWriter().println(flag);
       return null;
      } else {
       flag = 2;
       response.getWriter().println(flag);
       return null;
      }
     }
    }
    flag = 3;
    response.getWriter().println(flag);
    return null;
   } catch (Exception ex) {
    log.error("UserAction login error...." + ex.getMessage(), ex);
    return mapping.findForward("userError");
   }
}