PHP 로그인(ajax 제출 데이터 및 백그라운드 확인)

<form id="login_form" action="" method="POST">
  <p class="login_frame" style="position:relative";>
    <p class="login_gl" style="margin-top:35px;">
      <span class="login_wz" >后台管理系统</span>
    </p>
    <p class="login_user">
      <input id="username" name="username" type="text" placeholder="请输入您的用户名" value="" style="width:100%;height:32px;border-style:none;font-size:16px;color:#959595;"/>
    </p>
    <p class="login_user">
      <input id="password" name="password" type="password" placeholder="请输入您的密码" value="" style="width:100%;height:32px;border-style:none;font-size:16px;color:#959595;"/>
    </p>
    <p id="login_btn" class="login_log">
      <span style="font-size:16px;">登录</span>
    </p>
  </p>
  </form>
</p>
<script type="text/javascript">
  $("#login_btn").click(function(){
    var username = $.trim($("#username").val());
    var password = $.trim($("#password").val());
    if(username == ""){
      alert("请输入用户名");
      return false;
    }else if(password == ""){
      alert("请输入密码");
      return false;
    }
    //ajax去服务器端校验
    var data= {username:username,password:password};
    $.ajax({
      type:"POST",
      url:"__CONTROLLER__/check_login",
      data:data,
      dataType:&#39;json&#39;,
      success:function(msg){
        //alert(msg);
        if(msg==1){
           window.location.href = "{:U(&#39;Index/personal&#39;)}";  
        }else{
          alert("登录失败，请重试!");
        }
      }
    });
});  
</script>

* */
  public function check_login(){
    $password=I('param.password');
    $username=I('param.username');
    $data["name"]=$username;
    $user=M('systemuser');
    $list=$user->where($data)->find();
    $return=0;
    if($list!=""){
      if($list['password']==md5($password) && $list['status'] == 1){
        //登录时间和登录IP
        $public = new PublicController();
        $lastlogonip=$public->ip_address();
              
        $time=$time=date("Y-m-d H:i:s", time());
        $where=array('id'=>$list['id']);
        
        $user->where($where)->save(array('lastlogonip'=>$lastlogonip,'lastlogontime'=>$time));
        $this->login($list);
        $return=1;//登录成功
      }
    }else{
      $return=2;//登录失败
    }
    $this->ajaxReturn($return);
  }