thinphp3.2 +ajax登录

ajax登录带来良好的用户体验，下面是个简单的案例，给大家看看：

html代码：

<form role="form">
    <div class="form-group">
        
        <h4 style="color:#428bca;"><i class="icon-coffee green"></i>专业网站管理系统</h4>
    </div>
    <div class="form-group">
        <label>用户名</label>
        <input type="text" name="username" id="username" class="form-control">
    </div>
    <div class="form-group">
        <label>密码</label>
        <input type="password" name="password" id="password" class="form-control">
    </div>
    <div class="form-group">
        <input type="text" style="width:120px; height:40px; float:left;"placeholder="验证码" 
        name="yzm" maxlength="4" class="form-control" id="yzm">
        <img style="cursor:pointer; height:40px; width:200px;" src="__APP__/Home/Login/yzm/
        Verify()" alt="点击更换" onclick="this.src='__APP__/Home/Login/yzm/Verify()'+Math.random()" />
    </div>
    <div class="form-group sub">
    <button style="margin-top:20px;" class="btn btn btn-primary pull-right" type="button" id="btn">
        登 录
    </button>
    </div>
</form>


<script type="text/javascript">
  $(function(){
    $('#btn').click(function(){
      var username=$("#username").val();
      var password=$("#password").val();
      var yzm=$("#yzm").val();
      if(username==""){
        $("<a id='msg'>").html('账号不能为空！').appendTo(".sub").fadeOut(4000);
        $("#username").focus();
        return false;
      }
      if(password==""){
        $("<a id='msg'>").html('密码不能为空！').appendTo(".sub").fadeOut(4000);
        $("#password").focus();
        return false;
      }
      if(yzm==""){
        $("<a id='msg'>").html('验证码不能为空！').appendTo(".sub").fadeOut(4000);
        return false;
      }
      // ajax登录
      $.ajax({
        url:"{:U('Login/login')}",
        type:'post',
        data:{"username":$("#username").val(),"password":$("#password").val(),"yzm":$("#yzm").val()},
        timeout:5000,
        datatype:'text',
        success:function(msg){
          if(msg=="yes"){
            alert('登录成功！');
            location.href="{:U('Home/Index/index')}"; 
          }
          else if(msg=="zm"){
             $("<a id='msg'>").html("账号或密码错误！").appendTo(".sub").fadeOut(4000);
        // return false;
          }
          else if(msg=="yz"){
            $("<a id='msg'>").html("验证码错误").appendTo(".sub").fadeOut(4000);
        $("#yzm").focus();
          }
          else{
            alert('登录失败！');
          }
        },
      });
    })
  })

</script>

控制器代码：

public function login(){
        $username=$_POST['username'];
        $yzm=$_POST['yzm'];
        $password=md5(md5($_POST['password']));
        $rst=$this->check_verify(I('post.yzm'));
                if($rst===false){
                    echo "yz";exit;
                }
        $re=M('user')->where(array('username'=>I('username')))->find();
        if($username!=$re['username']||$password!=$re['password']){
            echo "zm";exit;
        }else{
            $_SESSION['adminCount']=$re;
            echo "yes";exit;
        }

    }