偶遇此问题，耗时2小时，解决之
问题如下：
Error and Warning: unable to connect to the proxy on port 8080.
Take the package "ape" as an example:
setInternet2(TURE)
source("http://bioconductor.org/biocLite.R")
biocLite("ape")
library(ape)
Bingo!
Note that https:// URLs are only supported if --internet2 or setInternet2(TRUE) was used (to make use of Internet Explorer internals), and then only if the certificate is considered to be valid.
ref: http://127.0.0.1:23750/library/utils/html/download.file.html