设置contentType内容类型如下：
Extension MIME Type .doc application/msword .dot application/msword .docx application/vnd.openxmlformats-officedocument.wordprocessingml.document .dotx application/vnd.openxmlformats-officedocument.wordprocessingml.template .docm application/vnd.ms-word.document.macroEnabled.12 .dotm application/vnd.ms-word.template.macroEnabled.12 .xls application/vnd.ms-excel .xlt application/vnd.ms-excel .xla application/vnd.ms-excel .xlsx application/vnd.openxmlformats-officedocument.spreadsheetml.sheet .xltx application/vnd.openxmlformats-officedocument.spreadsheetml.template .xlsm application/vnd.ms-excel.sheet.macroEnabled.12 .xltm application/vnd.ms-excel.template.macroEnabled.12 .xlam application/vnd.ms-excel.addin.macroEnabled.12 .xlsb application/vnd.ms-excel.sheet.binary.macroEnabled.12 .ppt application/vnd.ms-powerpoint .pot application/vnd.ms-powerpoint .pps application/vnd.ms-powerpoint .ppa application/vnd.ms-powerpoint .pptx application/vnd.openxmlformats-officedocument.presentationml.presentation .potx application/vnd.openxmlformats-officedocument.presentationml.template .ppsx application/vnd.openxmlformats-officedocument.presentationml.slideshow .ppam application/vnd.ms-powerpoint.addin.macroEnabled.12 .pptm application/vnd.ms-powerpoint.presentation.macroEnabled.12 .potm application/vnd.ms-powerpoint.template.macroEnabled.12 .ppsm application/vnd.ms-powerpoint.slideshow.macroEnabled.12 .mdb application/vnd.ms-access