纯手工打造Python豆瓣电台客户端（Geek命令行风格）

前段时间Dreamforce终于闲的无聊，发现Douban.fm还真的不错，总觉得它精选的歌曲还可以。所以Dreamforce就准备开始打造了一个简单的豆瓣客户端。

网上虽然有.net,C#,各种平台的，同时还有一些做的相当精致的客户端，如果只是为了使用，这篇文章将不再适合您阅读下去，本篇文章适合为想了解构造简单的豆瓣客户端的人群阅读，纯技术帖。

1.无API？

确实，douban.fm没有公开相关API，也没有文档可以参考。但是这些不能阻拦我们探索的脚本，打开Firefox，打开FireBug开始分析数据包吧,或许很多人没有尝试过HTTP数据包的分析，但是当你迈出第一步的时候，你将会发现，其实很简单。

数据分析前提： 首先要明白，我们是要抓什么样的包？ 我们要何种数据

显然Douban.fm是用FlashPlayer来播放音乐的，而这点我们可以马上想到他的数据来源是JSON数据，后台一定会给他传一个播放列表，里面有每首歌的信息，URL等等，或者这个JSON叫做，songList,playList,musiclist等等。通过这个前期分析后，开始对关键字查找，你能很快的定位结果，Dreamforce用了几分钟的时间发现了，数据的所在：

我们现在已经发现了JSON请求的地址，接下来的事情很好看办了，我们可以试图去请求一下这个地址，看看Response的数据是什么样的

{"r":0,"song":[{"picture":"http:\/\/img1.douban.com\/mpic\/s4623241.jpg","albumtitle":"Femme Fatale","company":"","rating_avg":4.06523,"public_time":"2011","ssid":"cb94","album":"\/subject\/5962329\/","like":0,"artist":"Britney Spears","url":"http:\/\/mr3.douban.com\/201207061300\/6b69329cec5375639e9e98a223f01025\/view\/song\/small\/p1638685.mp3","title":"Trip To Your Heart","subtype":"","length":214,"sid":"1638685","aid":"5962329"},{"picture":"http:\/\/img1.douban.com\/mpic\/s3855454.jpg","albumtitle":"Thriller","company":"","rating_avg":4.73667,"public_time":"2001","ssid":"9939","album":"\/subject\/1422148\/","like":0,"artist":"Michael Jackson","url":"http:\/\/mr5.douban.com\/201207061300\/bc03be07074faf95afd7c48c92ec17fa\/view\/song\/small\/p676071.mp3","title":"Beat It","subtype":"","length":258,"sid":"676071","aid":"1422148"},{"picture":"http:\/\/img3.douban.com\/mpic\/s1400647.jpg","albumtitle":"Lennon Legend: Th...","company":"","rating_avg":4.63824,"public_time":"1998","ssid":"dfbc","album":"\/subject\/1395275\/","like":0,"artist":"John Lennon","url":"http:\/\/mr3.douban.com\/201207061300\/bb88939b7509cf5d5e64384161a72667\/view\/song\/small\/p1403048.mp3","title":"Instant Karma!","subtype":"","length":201,"sid":"1403048","aid":"1395275"},{"picture":"http:\/\/img3.douban.com\/mpic\/s4716636.jpg","albumtitle":"It's Not Me, It's...","company":"","rating_avg":4.03394,"public_time":"2009","ssid":"10e0","album":"\/subject\/3313731\/","like":0,"artist":"Lily Allen","url":"http:\/\/mr3.douban.com\/201207061300\/bbd664422211b8a22517fe5a654d4ace\/view\/song\/small\/p1381366.mp3","title":"Back To The Start","subtype":"","length":251,"sid":"1381366","aid":"3313731"},{"picture":"http:\/\/img5.douban.com\/mpic\/s3765819.jpg","albumtitle":"Holy Wood (In The...","company":"","rating_avg":4.36569,"public_time":"2000","ssid":"95ab","album":"\/subject\/1417966\/","like":0,"artist":"Marilyn Manson","url":"http:\/\/mr3.douban.com\/201207061300\/78f745355bfc6f13db0f8c89e851ecb7\/view\/song\/small\/p501145.mp3","title":"In The Shadow Of The Valley Of","subtype":"","length":249,"sid":"501145","aid":"1417966"},{"picture":"http:\/\/img1.douban.com\/mpic\/s7033620.jpg","albumtitle":"Nimrod","company":"","rating_avg":4.0268,"public_time":"1997","ssid":"572d","album":"\/subject\/1424291\/","like":0,"artist":"Green Day","url":"http:\/\/mr3.douban.com\/201207061300\/7f632f10edc0a45bda1e10c3435c219b\/view\/song\/small\/p1033919.mp3","title":"Walking Alone","subtype":"","length":165,"sid":"1033919","aid":"1424291"},{"picture":"http:\/\/img3.douban.com\/mpic\/s1400298.jpg","albumtitle":"Escape","company":"","rating_avg":4.19888,"public_time":"2001","ssid":"f309","album":"\/subject\/1394999\/","like":0,"artist":"Enrique Iglesias","url":"http:\/\/mr3.douban.com\/201207061300\/c948f73ffb38c92f771a730d8b44000f\/view\/song\/small\/p1385198.mp3","title":"Heroe","subtype":"","length":263,"sid":"1385198","aid":"1394999"},{"picture":"http:\/\/img1.douban.com\/mpic\/s3860021.jpg","albumtitle":"Bury the Hatchet","company":"","rating_avg":4.44362,"public_time":"1999","ssid":"2dfe","album":"\/subject\/1462020\/","like":0,"artist":"The Cranberries","url":"http:\/\/mr3.douban.com\/201207061300\/25ccfae5f111c3b50c1fde8a9775a9ed\/view\/song\/small\/p333016.mp3","title":"Animal Instinct","subtype":"","length":211,"sid":"333016","aid":"1462020"},{"picture":"http:\/\/img1.douban.com\/mpic\/s3762451.jpg","albumtitle":"Queen","company":"","rating_avg":4.25209,"public_time":"1973","ssid":"d1d6","album":"\/subject\/1467981\/","like":0,"artist":"Queen","url":"http:\/\/mr4.douban.com\/201207061300\/cce549b63f73df5e6a1a401b1ce53900\/view\/song\/small\/p1046354.mp3","title":"Liar","subtype":"","length":224,"sid":"1046354","aid":"1467981"}]}

从这里我们可以看出这是一个简单的JSON数据结构，同时没有任何加密，心情大为高兴，剩下的事情就是分为三个点：1，解析数据;2，播放曲目;3.Build APP

应用开发篇

本应用将是使用Python（2.7）语言进行开发，同时Dreamforce最近相当喜欢这门语言

1.解析数据

定义基本属性

#This properties defined in the nameV.py files
songList = None
current  = 0
mp3 = None
threads=[]
aurl = 'http://douban.fm/j/mine/playlist?type=n&'
murl='channel=1'
burl = '&from=mainsite'

#This method defined in the client.py files
def getPlayList():
    print("------------Welcome to Douban Client------------")
    #拼装请求URL，通过Channel进行切换，Channel值是可选的，后面的代码会有示例
    url = str(nameV.aurl)+str(nameV.murl)+str(nameV.burl)
    print(url)
    print('Current Channel is : ' + str(nameV.murl))
    nameV.current = 0
    page_source = None
    try:
        #使用urllib请求
        page_source = urllib.urlopen(url)  
    except Exception,data:
        print Exception,":",data
    print("------------Reading PlayList , please waiting------------")
    #抓取页面数据
    pageData = page_source.read()
    #使用JsonLIB将数据解析为Json，这个LIB让我们省了很多事
    jsonData =json.loads(pageData)
    #将Song里面集合存入songList，这里统一将请求得的数据放到nameV里进行缓存
    nameV.songList = jsonData['song']
    #将列表打印出来
    printPlayList()

2.播放

播放MP3，我们这里不会让你从底层进行解码器开发，Dreamforce也不会解码器的开发，但是我可以使用相关的解码器Lib进行播放，我们这里使用WM解码器内核作为我们MP3的播放内核。
推荐使用mp3play这个LIB包进行开发。非常轻量级的，如果你想做一个UI质感的，功能强劲的播放器的话，可以选择PygameLIB包。
简单的播放：

def play:
    #支持远程流播放
    mp3.load(fileName)
    mp3.play()
    #播放整首歌曲，1秒的间隔结束
    time.sleep(mp3.seconds()+1)
    mp3.stop()

这里是很简单的播放示例，可是真正的做起来，不止这么简单，你要考虑到很多功能点，比如暂停，播放，下一首，切换频道，刷新列表等等。 Dreamforce就不将全部代码贴出来了。
这里友情提示一下，客户端的功能是通过按键监听来实现，那么Python自带的Input功能是完全不能满足的（必须要回车，通过会阻断行为），那么可以引入下面这块代码来实现：

from msvcrt import getch

#监听用户按键行为

getch().upper()

对于歌曲中文编码问题，Dreamforce也友情提示一下：

import codecs
codecs.register(lambda name: name == 'cp65001' and codecs.lookup('utf-8') or None)

上面这块代码可以解决英文操作系统CMD不支持中文的问题，必须要强行进行utf-8的映射
同时使用

encode('gbk')

可以很好的将JSON里面的中文数据转换为可阅读的中文

3. Build APP

当开发完成，就可以进行APP封装，一般情况下是封装为EXE，同时你如果使用的MP3PlayLIB，那这个客户端也只能在Windows上使用，除非你将WM解码器一起打包分发，但这样会将整个APP变的相当臃肿。
使用CX_Freezer进行编译，这里不用详细介绍了，非常简单。

后记：

整个APP的开发相当简单，没有太多的技术难度，但可以让读者了解一下客户端的构建过程。