how to install xlsx in R on ubuntu?

ok,I just use the ubuntu 16.04 64,when I want to read a xlsx file,I find I should install RODBC or xlsx. This page
will tell us how to install the xlsx package in R on ubuntu.
first,we should install java.
       sudo apt-get install default-jdk
then,we shold use the line to observe the R and Java:
        sudo R CMD javareconf
but,I think,the first time,there is something wrong.
then,we should install java once a time,
sudo apt-get install default-jdk
sudo R CMD javareconf
ok,if there is no error,you should restart your ubuntu,and then
you can install xlsx in R.
use the line: install.packages('xlsx',dependencies=T)
I think the next question is how can type chinese on ubuntu