验证码类 支持数字，字母，汉字，混合

width    =  $width;
            $this->height     =  $height;
            $this->codeNum    =  $codeNum;
            $this->codeType   =  $codeType;
            $this->fontSize  =  $fontSize;
            $this->fontType   =  $fontType;
            $this->codeStr    =  $codeStr;
            $this->strNum = strlen($this->codeStr)/3-1;
            $this->imageType =  $imageType;
            $this->checkCode =  $this->getCheckCode();
        }

      //+--------------------------------------------------------------------------------
      //* 生成验证码字符
      //+--------------------------------------------------------------------------------
      //* @return string
      //+--------------------------------------------------------------------------------
        public function __toString(){
            $string = implode('', $this->getCheckCode());
            $_SESSION["code"]=$string;  //加到session中
            $this->getImage();              //输出验证码
            return '';
        }
        protected function getCheckCode(){
            $string = array();
            switch($this->codeType){
                case 1:
                    //数字字符串
                    $string =  array_rand(range(0,9), $this->codeNum);
                    break;
                case 2:
                    //大字母字符串
                    $string = array_rand(array_flip(range('A', 'Z')), $this->codeNum);
                    break;
                case 3:
                    //汉字字符串

                    for($i=0; $icodeNum); $i++){
                        $start = mt_rand(0, $this->strNum);
                        $string[$i]= self::msubstr($this->codeStr,$start);
                    }
                    break;
                case 4:
                    //混合字符串
                    for($i=0; $icodeNum); $i++){
                        $rand=mt_rand(0,2);
                        switch($rand){
                            case 0:
                                $ascii = mt_rand(48,57);
                                $string[$i] = sprintf('%c',$ascii);
                                break;

                       

           

2. [图片] 混合.jpg    

                       

           

3. [图片] 数字.jpg    

                       

           

4. [图片] 中文.jpg    

                       

           

5. [图片] 字母.jpg