the progressbar and Tempfile

https://github.com/peleteiro/progressbar

gem install progressbar

gem 'progressbar', '~> 0.21.0'

% irb --simple-prompt -r progressbar
>> pbar = ProgressBar.new("test", 100)
=> (ProgressBar: 0/100)
>> 100.times {sleep(0.1); pbar.inc}; pbar.finish
test:          100% |oooooooooooooooooooooooooooooooooooooooo| Time: 00:00:10
=> nil

>> pbar = ProgressBar.new("test", 100)
=> (ProgressBar: 0/100)
>> (1..100).each{|x| sleep(0.1); pbar.set(x)}; pbar.finish
test:           67% |oooooooooooooooooooooooooo              | ETA:  00:00:03

>> ProgressBar.new("test", 100) do |pbar|
>>   100.times { sleep(0.1); pbar.inc }
>> end
test:          100% |oooooooooooooooooooooooooooooooooooooooo| Time: 00:00:10

def download_apk!
  require 'open-uri'
  require 'digest'
  require 'fileutils'

  return false if is_dead_download_url?
  return false if is_apk_downloaded?

  tmp_file = Tempfile.new [package_name, ".apk"]
  File.open(tmp_file, 'wb') do |file_to_save|
    pbar = nil

    open(download_url, "rb", :content_length_proc => lambda {|t|
      if t && 0 < t

        pbar = ProgressBar.new("...", t)
　　　　　pbar.file_transfer_mode
      end
    },
    :progress_proc => lambda {|s|
      pbar.set s if pbar
    }) { |file_to_download| file_to_save.write(file_to_download.read) }  
  end

  apk_md5 = Digest::MD5.file(tmp_file).hexdigest
  apk_path = File.join Settings.apks_dir, "#{package_name}.#{apk_md5}.apk"

  FileUtils.mkdir_p Settings.apks_dir
  FileUtils.mv tmp_file, apk_path

  package_info = dump_package_info apk_path
  update_attributes package_info.merge(md5: apk_md5)
  apk_path
rescue OpenURI::HTTPError, OpenURI::HTTPRedirect
  false
end

http://www.ruby-doc.org/stdlib-1.9.3/libdoc/tempfile/rdoc/Tempfile.html

Tempfile

默认存储路径是 /tmp
A utility class for managing temporary files. When you create a Tempfile object, it will create a temporary file with a unique filename. A Tempfile objects behaves just like a File object, and you can perform all the usual file operations on it: reading data, writing data, changing its permissions, etc. So although this class does not explicitly document all instance methods supported by File, you can in fact call any File instance method on a Tempfile object.

require 'tempfile'

file = Tempfile.new('foo')
file.path      # => A unique filename in the OS's temp directory,
               #    e.g.: "/tmp/foo.24722.0"
               #    This filename contains 'foo' in its basename.
file.write("hello world")
file.rewind
file.read      # => "hello world"
file.close
file.unlink    # deletes the temp file