//------------以下部分为控制cookies----------

function setCookie (name, value) {//设置永久有效的cookies
  document.cookie = name + "=" + value + "; path=/;expires=Thursday,01-Jan-2099 00:00:00 GMT";
}

function getCookie(name) { //读取cookies
  var search;

  search = name + "=";
  offset = document.cookie.indexOf(search); 
  if (offset != -1) {
    offset += search.length ;
    end = document.cookie.indexOf(";", offset) ;
    if (end == -1)
      end = document.cookie.length;
    return unescape(document.cookie.substring(offset, end));
  }
  else
    return "";
}

function deleteCookie(name) {//删除cookies
  setCookie(name, "");
}


//------------以下部分为控制用户登陆----------

function checklogin() { //登陆时需要用户名和密码
  if(form1.username.value==""){
    alert('请输入用户名！');
    form1.username.focus();
    return false;
  }
  if(form1.password.value==""){
    alert('请输入密码！');
    form1.password.focus();
    return false;
  }
  setCookie("username",form1.username.value)
  return true;
}

function readusername(){  //用户名从cookies中读取并自动调入用户名文本框
  var cvalue = getCookie("username");
  form1.username.value=cvalue;
}