微软office在线预览解决方案
https://view.officeapps.live.com/op/view.aspx?src=http://storage.xuetangx.com/public_assets/xuetangx/PDF/1.xls
https://view.officeapps.live.com/op/view.aspx?src=http://dsideal-yy.oss-cn-qingdao.aliyuncs.com/down/Material/01/0100449C-E3C0-E321-520F-2A7687E3F8EC.ppt
https://view.officeapps.live.com/op/view.aspx?src=http://dsideal-yy.oss-cn-qingdao.aliyuncs.com/down/Material/01/010A415E-F604-B28D-12D4-B2C6A6DC69DC.ppt
https://view.officeapps.live.com/op/embed.aspx?src=http://dsideal-yy.oss-cn-qingdao.aliyuncs.com/down/Material/01/0100449C-E3C0-E321-520F-2A7687E3F8EC.ppt
自行搭建Office web apps
https://www.jianshu.com/p/d58c720b6990
https://www.cnblogs.com/yanweidie/p/4516164.html
https://blog.csdn.net/jiaqu2177/article/details/81944185
永中office在线预览解决方案
http://www.yozodcs.com/example/ppt/ppttest_hd.html