http://www.douban.com/note/491745257/
背景：需要使用一个有些奇葩的第三方接口。
python部分：
1.urllib.urlencode(query, doseq=0)
接受参数形式为：[(key1, value1), (key2, value2),...] 和 {\'key1\': \'value1\', \'key2\': \'value2\',...}
返回的是形如\'key2=value2&key1=value1\'字符串。
>>>urllib.urlencode({\'name\': u\'老王\'.encode(\'utf8\'), \'sex\': u\'男\'.encode(\'utf8\')})
\'name=%E8%80%81%E7%8E%8B&sex=%E7%94%B7\'
2.urllib.quote(s, safe=\'/\')
接受参数s为字符串，safe是指定某字符不被urlencode，默认为\'/\'，
如指定\'+\'、\'/\'不需转换，传 \'+/\' 和 \'+ /\' 均可。另外此方法会将“空格”转换为“%20”
>>> urllib.quote(u\'老王 /+\'.encode(\'utf8\'))
\'%E8%80%81%E7%8E%8B%20/%2B\'
3.urllib.quote_plus(s, safe=\'\')
此方法的源码为:
def quote_plus(s, safe=\'\'):
"""Quote the query fragment of a URL; replacing \' \' with \'+\'"""
if \' \' in s:
s = quote(s, safe + \' \')
return s.replace(\' \', \'+\')
return quote(s, safe)
可以看出它比quote多一些功能，但是会将“空格”转换成“加号”，默认safe为空。
>>> urllib.quote_plus(u\'老王 /+\'.encode(\'utf8\'))
\'%E8%80%81%E7%8E%8B+%2F%2B\'
具体使用哪个方法，看需求。
urlencode部分：
并不是所有相关字符都需要转码，有哪些字符需要urlencode并且为什么？
ASCII Control characters
Why: These characters are not printable.
Characters: Includes the ISO-8859-1 (ISO-Latin) character ranges 00-1F hex (0-31 decimal) and 7F (127 decimal.)
Non-ASCII characters
Why: These are by definition not legal in URLs since they are not in the ASCII set.
Characters: Includes the entire "top half" of the ISO-Latin set 80-FF hex (128-255 decimal.)
"Reserved characters"
Why: URLs use some characters for special use in defining their syntax. When these characters are not used in their special role inside a URL, they need to be encoded.
Characters: $ & + ; / : , = ? @
"Unsafe characters"
Why: Some characters present the possibility of being misunderstood within URLs for various reasons. These characters should also always be encoded.
Characters:< > # % { } | \ ~ ^ [ ] `
详见：URL Encoding (or: \'What are those "%20" codes in URLs?\')