Question

urllib 和urllib2之间的区别

Answer 1

1. urllib 和urllib2都是接受URL请求的相关模块，但是提供了不同的功能。

2. urllib2可以接受一个Request类的实例来设置URL请求的headers，urllib仅可以接受URL。这意味着，你不可以伪装你的User Agent字符串等。

3. urllib提供urlencode方法用来GET查询字符串的产生，而urllib2没有。这是为何urllib常和urllib2一起使用的原因。

4. 提示：如果你仅做HTTP相关的，看一下httplib2，比其他几个模块好用。

5. 参考原文来自国外的《Python: difference between urllib and urllib2》。You might be intrigued by the existence of two separate URL modules in Python -urllib and urllib2. Even more intriguing: they are not alternatives for each other. So what is the difference between urllib and urllib2, and do we need them both? urllib and  urllib2are both Python modules that do URL request related stuff but offer different functionalities. Their two most significant differences are listed below: urllib2 can accept a Request object to set the headers for a URL request,urllib accepts only a URL. That means, you cannot masquerade your User Agent string etc.urllib provides the urlencode method which is used for the generation of GET query strings, urllib2 doesn't have such a function. This is one of the reasons why urllib is often used along with urllib2.For other differences between urllib and urllib2 refer to their documentations, the links are given in the References section. 
   Tip: if you are planning to do HTTP stuff only, check out httplib2, it is much better than httplib or urllib or urllib2.