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require 'open-uri'
class Downloader
def self.download(url, name, dir = nil)
data = URI(url).read
file = dir ? File.join(dir, name) : name
open(file, "wb", 0755) {|f| f.write(data)}
rescue => e
raise "failed to download #{name}\n#{e.message}: #{url}"
end
# Update a file from url if newer version is available.
# Creates the file if the file doesn't yet exist; however, the
# directory where the file is being created has to exist already.
# Example usage:
# download_if_modified_since 'http://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt',
# 'enc/unicode/data/UnicodeData.txt'
def self.download_if_modified_since(url, name, dir=nil, since=nil)
file = dir ? File.join(dir, name) : name
since = Date.new(1980,1,1) unless File.exist? file # use very old date to assure file creation
since = File.mtime file unless since # get last modification time for file
since = since.to_datetime if since.respond_to? :to_datetime # convert Time/Date to DateTime
since = since.httpdate if since.respond_to? :httpdate # convert DateTime to String
open(url, 'If-Modified-Since' => since) do |r|
body = r.read
open(file, 'wb', 0755) { |f| f.write(body) }
end
rescue OpenURI::HTTPError => http_error
unless http_error.message =~ /^304 / # 304 Not Modified
raise "Failed to (check for) downloading #{url}: #{http_error.message}"
end
end
end
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