使用命令行将任意文档转换为PDF

I'm looking for a simple (free) way to convert an arbitrary document to a PDF from within a program. There are any number of free PDF printers, but I need to be able to call the conversion within a program without human intervention. The program is being developed in Java, but will run exclusively in a Windows environment so calling an exe seems like a good solution if such a conversion program exists.I'm looking for a simple (free) way to convert