PHP实现字母数字混合验证码功能

 Vendor('Vcode.Vcode', '', '.class.php'); 
 $config = array("width" => 100, "height" => 36, "count" => 4, "str" => 2); //配置 
 $vcode = new \Vcode($config); 
 $vcode->getCode(); //获取验证码 
 $vcode->getImg(); //输出图片 
 exit;

 <img src="__APP__/code/" id="code" onclick="changeCode($('#code'))"/>

 function changeCode(obj) { 
  obj.attr("src", '__APP__/code/?' + Math.random()); 
 }

 <input type="text" id="input_code" class="input"/> 
 <input type="button" value="提交" class="btn" onclick="checkCode()"/>
 function checkCode() { 
   $.post("__APP__/Code/check", {code: $("#input_code").val()}, function(data) { 
     if (data == '1') { 
       alert("验证码正确！"); 
     } else { 
       alert("验证码错误！"); 
     } 
   }, "json") 
 }

 public function check() { 
     $code = I('post.code'); 
     if (strtolower($code) == $_SESSION["sucaihuo_code"]) { 
       echo "1"; 
     } else { 
       echo "-1"; 
     } 
 }