“Failed to connect to ”url“ port 80: Timed Out” in R, how can I solve?

问题

I'm trying to test this code:

library(XML)
library(RCurl)

url <- "http://en.wikipedia.org/wiki/List_of_countries_by_population"
urldata <- getURL(url)

When I press enter, the R returns:

Failed to connect to en.wikipedia.org port 80: Timed out

How can I solve this?

来源：https://stackoverflow.com/questions/42399895/failed-to-connect-to-url-port-80-timed-out-in-r-how-can-i-solve