$dirExplorer = new DirExplorerClass();
$dirExplorer->getDirExplorer('D:/test1/test2/');                                  //遍历目录D:/test1/test2/
$dirExplorer->modifyFileBy_replace('aa','QQ','shift-jis','UTF-8','txt','TXT');    //将所有文件内容中的aa替换为QQ,文件编码从shift-jis转换为UTF-8,将所有txt的后缀名改为TXT

class DirExplorerClass{
    var $dirPath_array = array();//遍历文件结果集合

    function __construct(){
        //donothing
    }

    /*
    *  return a directory handle or die
        */
    private function openDir($dirPath_target) {
        if (is_dir($dirPath_target)) {
            return opendir($dirPath_target);
        }else {
            die("$dirPath_target is Not a Directory");
        }
    }

    /*
    *  close a directory handle
        */
    private function closeDir($dirHander) {
        closedir($dirHander);
    }

    /*
    *  遍历指定目录，返回其下的文件名集合
    *
    *  Parameters:
    *      1 dirPath:需要遍历的文件夹
    *      2 extension:只返回指定后缀名的文件 
    *  Return:
    *      遍历文件结果集合
        */
    function getDirExplorer($dirPath,$extension=''){
        $dirHander=$this->openDir($dirPath);
        while($fileName = readdir($dirHander)){
            if($fileName !='.' && $fileName !='..'){
                $path = $dirPath."/" . $fileName;
                if(is_dir($path)){
                    $this->getDirExplorer($path);
                }else{
                    if(isset($extension) && $extension != ''){
                        $fileExtension = end(explode('.',$fileName));
                        if($fileExtension != $extension){
                            continue;
                        }
                    }
                    $this->dirPath_array[]=$path;
                }
            }
        }
        $this->closeDir($dirHander);
        return $this->dirPath_array;
    }

    /*
    *  字符串替换文件内容（区别大小写）、编码、后缀名
    *
    *  Parameters:
    *      1 search:    需要替换的字符串 （数组可)
    *      2 replace:    替换后的字符串 （数组可)
    *      3 in_charset:    原编码
    *      4 out_charset:    新编码
    *      5 in_extension:    原后缀名
    *      6 out_extension:新后缀名
    *  Return:
    *      true or false
        */
    function modifyFileBy_replace($search, $replace, $in_charset='', $out_charset='', $in_extension='', $out_extension=''){
        /* input check */
        if(
            !isset($search) || !isset($replace) || 
            (strlen($in_charset)!=0 && strlen($in_charset)==0)  || (strlen($in_charset)==0 && strlen($in_charset)!=0) ||
            (strlen($in_extension)!=0 && strlen($out_extension)==0)  || (strlen($in_extension)==0 && strlen($out_extension)!=0)
        ){
            return false;
        }

        foreach($this->dirPath_array as $key=>$file) {
            $content = file_get_contents($file);//read contents
            $content = str_replace($search, $replace, $content);

            if(strlen($in_charset)!=0 && strlen($out_charset)!=0){
                /* change the encode */
                $this->changeCharset($in_charset, $out_charset, 1, $content);
            }

            unlink($file);

            if(strlen($in_extension)!=0 && strlen($out_extension)!=0){
                /* change file's extension */
                $this->changeExtension($in_extension, $out_extension, 1, $file);
            }

            file_put_contents($file, $content);
            unset($content);

            /* 更新遍历文件名结果集 */
            $this->dirPath_array[$key] = $file;
        }