首先遇到的问题未：Error - mPDF requires mb_string functions. Ensure that PHP is compiled with php_mbstring.dll enabled.
在windows环境下无任何问题，部署到linux下就遇到了。解决办法就是执行一下命令yum install php-mbstring.x86_64
可以查看stackoverflow的问题，地址连接http://stackoverflow.com/questions/12708855/ensure-that-php-is-compiled-with-php-mbstring-dll-enabled