Google doc viewer api

I need help from you guys.I had problem with my spring and Hibernate project.In that i have used amazon infrastructure.My project is online document selling but before customer purchase this document it give them some preview of that document.that preview can be 2-3 pages. i have used amazon infrastructure for storing file.url is from amazon.Admin can upload book and using s3 bucket and s/w upload it to server. For book preview i have used google doc viewer it works fine for .pdf and .doc but it creates problem with .xls file. so can any one suggest the best tool for this type of functionality?

Thanks in advanced