library参数实际上负责在library框架中看到的内容，而不是可以上载的内容。它接受：image,audio,video,file 或任何其他mime类型，例如，仅显示pdf：

library: {
    type: \'application/pdf\'
},

要添加参数，请使用：

file_frame.uploader.uploader.param( \'allowed_Type\', \'pdf\');

add_filter(\'wp_handle_upload_prefilter\', \'Validate_upload_file_type\');
function Validate_upload_file_type($file) {
    if (isset($_POST[\'allowed_Type\']) && !empty($_POST[\'allowed_Type\'])){
        //this allows you to set multiple types seperated by a pipe "|"
        $allowed = explode("|", $_POST[\'allowed_Type\']);

        $ext =  substr(strrchr($file[\'name\'],\'.\'),1);
        //first check if the user uploaded the right type
        if (!in_array($ext, (array)$allowed)){
            $file[\'error\'] = __("Sorry, you cannot upload this file type for this field.");
            return $file;
        }
        //check if the type is allowed at all by WordPress
        foreach (get_allowed_mime_types() as $key => $value) {
            if (strpos($key, $ext) || $key == $ext)
                return $file;
        }
        $file[\'error\'] = __("Sorry, you cannot upload this file type for this field.");
    }
    return $file;
}

只是对班纳特的回答稍加修改。我正在使用WP 3.7.1，媒体上传中一定发生了一些变化，因为这一行似乎不适合我：

file_frame.uploader.uploader.param( \'allowed_Type\', \'pdf\');

Uncaught TypeError: Cannot call method \'param\' of undefined
(anonymous function)
x.event.dispatch
v.handle

file_frame.uploader.options.uploader[\'params\'][\'allowed_type\'] = \'pdf\';