1.下载安装对应系统位数的JDK包（Java SE Development Kit）
2.完成后,安装rJava包-low-level r to Java Interface
install.packages(“rJava”)
3.安装xlsxjars包-package required POI jars for the xlsx package
install.packages(“xlsxjars”)
4.安装xlsx包-read,write,format Excel 2007 and Excel 97/2000/XP/2003 files
install.packages(“xlsx”)
library(“xlsx”)