报错：The type org.apache.poi.ss.usermodel.Workbook cannot be resolved. It is indirectly referenced from required .class files
原因：缺少poi相关的jar包，如：poi-3.11-20141221.jar，poi-excelant-3.11-20141221.jar，poi-ooxml-3.11-20141221.jar，poi-ooxml-schemas-3.11-20141221.jar，poi-scratchpad-3.11-20141221.jar