php引用prince类，页面提示不能加载pdf

Question

<?php

require 'prince.php';

//print_r() ;

//exit();

$prince = new Prince('D:\\prince\\engine\\bin\\prince.exe');

//$prince = new Prince('D:\prince\engine\bin\prince.exe');

header('Content-Type: application/pdf');

header('Content-Disposition: inline; filename="foo.pdf"');

$prince->convert_file_to_passthru('http://www.baidu.com');

?>

如上代码，打开网页提示不能加载pdf