用ruby写了一个搜索下载歌曲的工具

 require "net/http" 

 class Fetcher
  
  def fetch(url)
    host = url.scan(/\/\/(.*?)\//m)[0][0]
    path = url.split(/#{host}\//)[1]
   # print "host: ",host,"\n"
   # print "path: ",path,"\n"
    h = Net::HTTP.new(host,80)
    resp = h.get("/#{path}",nil)
   
    if resp.message == "OK"
     # puts "建立连接成功..." 
      return resp.body     
    end 
    return ""
  end

end

class Parser
public
  def initialize()
    @fetcher = Fetcher.new
  end

  def parse_mp3(html)
    urls = html.scan(/<a href="(.*?)"/m)
    download_hosts_urls = {}
    parse_threads = []
    for url in urls do
        if url[0] =~ /.*?\.mp3,,.*?/
           parse_threads << Thread.new(url) do |url|
              song_url = url[0].gsub(" ","%20")
              download_url = parse_download_url(song_url)
              if download_url
              	host =  download_url.scan(/\/\/(.*?)\//m)[0][0] 
              	#We only want to find the best download url,so we needn't care duplicate key
              	download_hosts_urls[host] = download_url
              end 
           end
        end
    end
    parse_threads.each{|t| t.join}
    puts "已经搜索到#{download_hosts_urls.size}个链接可以下载..."
    exit(1) if download_hosts_urls.size == 0
    puts "正在选择速度最快的链接..."
    host = select_best_host(download_hosts_urls.keys)
    download_hosts_urls[host]
  end

private
  def select_best_host(hosts)
    times_hosts = {}
    threads = []
    hosts.each do |host|
      threads << Thread.new(host) do |host|
           response = `ping -c 1 -W 30 #{host}` #use`ping -n 1 -w 30 #{host}` in windows
           r_t = response.scan(/time=(\d+)/m) #only get integer part
           times_hosts[r_t[0][0]] = host unless r_t.empty? #duplicate key no problem 
      end
    end
   
    threads.each{|t| t.join}
   
    times = times_hosts.keys
    min = times.min
    times_hosts[min]
  end

  def parse_download_url(song_url)
     html = @fetcher.fetch(song_url)
     urls = html.scan(/<a href="(.*?)"/m)
     return nil if urls.empty? || urls[0][0] =~ /.*?\.html/
     return urls[0][0]      
  end
end

 require "open-uri"
require "parser"
require "fetcher"

class Download
public
  def initialize(song_name)
    @song_name = song_name
    @search_url = "http://mp3.baidu.com/m?f=ms&tn=baidump3&ct=134217728&lf=&rn=&word=#@song_name&lm=0"
    @parser = Parser.new
    @fetcher = Fetcher.new
  end
 
  def download
    puts "正在建立连接..."
    html = @fetcher.fetch(@search_url)
    puts "正在获取搜索结果..."
    url = @parser.parse_mp3(html)
    puts "已经获得最快的下载连接:#{url}.\n开始下载..."
    doDownload(url)    
    puts "下载完毕..."
  end
private
  def doDownload(url)
    open(url) do |fin|
  	size = fin.size
  	download_size = 0
  	puts "大小: #{size / 1024}KB"
  	filename = url[url.rindex('/')+1, url.length-1]
  	puts "歌曲名: #{filename}"
  	open(File.basename("./#{filename}"),"wb") do |fout|
     	    while buf = fin.read(1024) do
       		fout.write buf
       		download_size += buf.size
                print "已经下载： #{download_size * 100 / size}%\r"
                STDOUT.flush 
           end
       end
    end 
    puts
  end
end

download = Download.new(ARGV[0])
download.download

同意，lz的代码一点没有ruby风格啊。。。
比如：

 require "net/http" 

 class Fetcher
  
  def fetch(url)
    host = url.scan(/\/\/(.*?)\//m)[0][0]
    path = url.split(/#{host}\//)[1]
   # print "host: ",host,"\n"
   # print "path: ",path,"\n"
    h = Net::HTTP.new(host,80)
    resp = h.get("/#{path}",nil)
   
    if resp.message == "OK"
     # puts "建立连接成功..." 
      return resp.body     
    end 
    return ""
  end

end

 可以这样：

 require "net/http" 

 class Fetcher
  
  def fetch(url)
    url=URI.parse url
 
    h = Net::HTTP.new(url.host,url.port)
    resp = h.get(url.request_uri)
   
    if resp.code == "200"
     # puts "建立连接成功..." 
      resp.body     
    end 
  end
end

 还有那个for循环，完全可以这样：

html.scan(/<a href="(.*?)"/im) .flatten.each do |url|
  #do someting here
end

 还有：

song_url = url[0].gsub(" ","%20")

 可以这样：

requrie'cgi'
song_url=CGI::escape url[0]

最后/<a href="(.*?)"/m最好这样写：

/<a\s+href="(.*?)"/im