使用Python抓取网页信息

        之前用C#帮朋友写了一个抓取网页信息的程序，搞得好复杂，今天朋友又要让下网页数据，好多啊，又想偷懒，可是不想用C#了，于是想到了Python，大概花了两个小时，用记事本敲的，然后在IDLE (Python GUI)里面测试。发现Python之类的解释性语言很不错，又不用编译，写个脚本就好了。代码如下：

# -*- coding:gb2312 -*-
import sys
import urllib
import re
 
#从html中解析标题
def ParshTitle(html):
	startPos = html.find('<title>')
	endpos = html.find('</title>')
	
	strTmp = html[startPos+29:endpos]
	strTmp = strTmp.replace('</font>', '')
	return strTmp
 
#从html中解析CPI数据
def ParshCPI(html):
	startPos = html.find('<TBODY>')
	endpos = html.find('</TBODY>')
	
	strTmp = html[startPos:endpos]
	return "<table>" + strTmp + "</table>"
 
 
#从html中解析城镇投资数据
def ParshUrbanInvestment(html):
	startPos = html.find('<TBODY>')
	endpos = html.find('</TBODY>')
	
	strTmp = html[startPos:endpos]
	return "<table>" + strTmp + "</table>"
	
#提取各地区数据
def GetHtmlData(url, htmlfile, bisCPI):
	wp = urllib.urlopen(url)#打开连接
	content = wp.read()	#获取页面内容
	content = content.replace('\r\n', '')
 
	title = ParshTitle(content)
	
	if bisCPI:
		content = ParshCPI(content)
	else:
		content = ParshUrbanInvestment(content)
	
	fl = title + htmlfile
 
	#将文件路径转为gbk编码
	fl = unicode(fl,'gbk')
	f = open(fl, 'w')
	f.write(content)
	f.close()
 
 
if __name__ =="__main__":
	#首先提取CPI数据
	num_list = range(72)        #生成0～71的数字
	strUrl = "http://www.stats.gov.cn/was40/gjtjj_detail_data.jsp?searchword=%28docTitle%21%3D%B9%FA%C4%DA%C9%FA%B2%FA%D7%DC%D6%B5+and+docTitle%21%3D%B3%C7%D5%F2%B5%A5%CE%BB%B4%D3%D2%B5%C8%CB%D4%B1%C0%CD%B6%AF%B1%A8%B3%EA+and+docTitle%21%3D%C5%A9%C1%D6%C4%C1%D3%E6%D2%B5%D7%DC%B2%FA%D6%B5+and+docTitle%21%3D%B8%F7%B5%D8%C7%F8%C5%A9%C1%D6%C4%C1%D3%E6%D2%B5%D7%DC%B2%FA%D6%B5+and+docTitle%21%3D%D2%DA%D4%AA%D2%D4%C9%CF%C9%CC%C6%B7%BD%BB%D2%D7%CA%D0%B3%A1%D6%F7%D2%AA%D6%B8%B1%EA+and+docTitle%21%3D%B8%F7%B5%D8%C7%F8%D2%DA%D4%AA%D2%D4%C9%CF%C9%CC%C6%B7%BD%BB%D2%D7%CA%D0%B3%A1%BB%F9%B1%BE%C7%E9%BF%F6+and+docTitle%21%3D%B8%F7%B5%D8%C7%F8%C5%A9%B4%E5%BE%D3%C3%F1%BC%D2%CD%A5%C6%BD%BE%F9%C3%BF%C8%CB%CF%D6%BD%F0%CA%D5%C8%EB+and+docTitle%21%3D%B7%D6%B5%D8%C7%F8%B3%C7%D5%F2%B5%A5%CE%BB%BE%CD%D2%B5%C8%CB%D4%B1+and+docTitle%21%3D%B7%D6%B5%D8%C7%F8%B3%C7%D5%F2%B5%A5%CE%BB%BE%CD%D2%B5%C8%CB%D4%B1%C0%CD%B6%AF%B1%A8%B3%EA+and+docTitle%21%3D%C8%AB%B9%FA%D6%F7%D2%AA%C5%A9%B2%FA%C6%B7%C9%FA%B2%FA%BC%DB%B8%F1%D6%B8%CA%FD+and+docTitle%21%3D%B8%F7%B5%D8%C7%F8%C5%A9%B4%E5%BE%D3%C3%F1%BC%D2%CD%A5%C6%BD%BE%F9%C3%BF%C8%CB%CF%D6%BD%F0%D6%A7%B3%F6+and+docTitle%21%3D%C6%F3%D2%B5%BE%B0%C6%F8%D6%B8%CA%FD+and+docTitle%21%3D%C4%BF%C2%BC+and++docTitle%21%3D%B7%D6%B5%D8%C7%F8%B3%C7%D5%F2%B5%A5%CE%BB%BE%CD%D2%B5%C8%CB%D4%B1+and+docTitle%21%3D%B7%D6%B5%D8%C7%F8%B3%C7%D5%F2%B5%A5%CE%BB%BE%CD%D2%B5%C8%CB%D4%B1%C0%CD%B6%AF%B1%A8%B3%EA+and++docTitle%21%3D%C8%AB%B9%FA%D6%F7%D2%AA%C5%A9%B2%FA%C6%B7%C9%FA%B2%FA%BC%DB%B8%F1%D6%B8%CA%FD+and+docTitle%21%3D%B8%F7%B5%D8%C7%F8%C5%A9%B4%E5%BE%D3%C3%F1%BC%D2%CD%A5%C6%BD%BE%F9%C3%BF%C8%CB%CF%D6%BD%F0%D6%A7%B3%F6+and++docTitle%21%3D%B8%F7%B5%D8%C7%F8%B3%C7%D5%F2%BE%D3%C3%F1%BC%D2%CD%A5%CA%D5%D6%A7%BB%F9%B1%BE%C7%E9%BF%F6%29+and+%28docTitle%3D%B8%F7%B5%D8%C7%F8%BE%D3%C3%F1%CF%FB%B7%D1%BC%DB%B8%F1%D6%B8%CA%FD+or+DOCHTMLCONTENT%3D%B8%F7%B5%D8%C7%F8%BE%D3%C3%F1%CF%FB%B7%D1%BC%DB%B8%F1%D6%B8%CA%FD%29&channelid=9951&record="
	for i in num_list:
		if i==0:
			continue
			
		strTemp = strUrl + str(i)
		strTxt = "_CPI.htm"
		GetHtmlData(strTemp, strTxt, True)
		print (str(i) + "/72") 
	
	#再提取城镇投资数据
	num_list = range(56)        #生成0～55的数字
	strUrl = "http://www.stats.gov.cn/was40/gjtjj_detail_data.jsp?searchword=%B8%F7%B5%D8%C7%F8%B3%C7%D5%F2%CD%B6%D7%CA&presearchword=%28docTitle%21%3D%B9%FA%C4%DA%C9%FA%B2%FA%D7%DC%D6%B5+and+docTitle%21%3D%B3%C7%D5%F2%B5%A5%CE%BB%B4%D3%D2%B5%C8%CB%D4%B1%C0%CD%B6%AF%B1%A8%B3%EA+and+docTitle%21%3D%C5%A9%C1%D6%C4%C1%D3%E6%D2%B5%D7%DC%B2%FA%D6%B5+and+docTitle%21%3D%B8%F7%B5%D8%C7%F8%C5%A9%C1%D6%C4%C1%D3%E6%D2%B5%D7%DC%B2%FA%D6%B5+and+docTitle%21%3D%D2%DA%D4%AA%D2%D4%C9%CF%C9%CC%C6%B7%BD%BB%D2%D7%CA%D0%B3%A1%D6%F7%D2%AA%D6%B8%B1%EA+and+docTitle%21%3D%B8%F7%B5%D8%C7%F8%D2%DA%D4%AA%D2%D4%C9%CF%C9%CC%C6%B7%BD%BB%D2%D7%CA%D0%B3%A1%BB%F9%B1%BE%C7%E9%BF%F6+and+docTitle%21%3D%B8%F7%B5%D8%C7%F8%C5%A9%B4%E5%BE%D3%C3%F1%BC%D2%CD%A5%C6%BD%BE%F9%C3%BF%C8%CB%CF%D6%BD%F0%CA%D5%C8%EB+and+docTitle%21%3D%B7%D6%B5%D8%C7%F8%B3%C7%D5%F2%B5%A5%CE%BB%BE%CD%D2%B5%C8%CB%D4%B1+and+docTitle%21%3D%B7%D6%B5%D8%C7%F8%B3%C7%D5%F2%B5%A5%CE%BB%BE%CD%D2%B5%C8%CB%D4%B1%C0%CD%B6%AF%B1%A8%B3%EA+and+docTitle%21%3D%C8%AB%B9%FA%D6%F7%D2%AA%C5%A9%B2%FA%C6%B7%C9%FA%B2%FA%BC%DB%B8%F1%D6%B8%CA%FD+and+docTitle%21%3D%B8%F7%B5%D8%C7%F8%C5%A9%B4%E5%BE%D3%C3%F1%BC%D2%CD%A5%C6%BD%BE%F9%C3%BF%C8%CB%CF%D6%BD%F0%D6%A7%B3%F6+and+docTitle%21%3D%C6%F3%D2%B5%BE%B0%C6%F8%D6%B8%CA%FD+and+docTitle%21%3D%C4%BF%C2%BC+and++docTitle%21%3D%B7%D6%B5%D8%C7%F8%B3%C7%D5%F2%B5%A5%CE%BB%BE%CD%D2%B5%C8%CB%D4%B1+and+docTitle%21%3D%B7%D6%B5%D8%C7%F8%B3%C7%D5%F2%B5%A5%CE%BB%BE%CD%D2%B5%C8%CB%D4%B1%C0%CD%B6%AF%B1%A8%B3%EA+and++docTitle%21%3D%C8%AB%B9%FA%D6%F7%D2%AA%C5%A9%B2%FA%C6%B7%C9%FA%B2%FA%BC%DB%B8%F1%D6%B8%CA%FD+and+docTitle%21%3D%B8%F7%B5%D8%C7%F8%C5%A9%B4%E5%BE%D3%C3%F1%BC%D2%CD%A5%C6%BD%BE%F9%C3%BF%C8%CB%CF%D6%BD%F0%D6%A7%B3%F6+and++docTitle%21%3D%B8%F7%B5%D8%C7%F8%B3%C7%D5%F2%BE%D3%C3%F1%BC%D2%CD%A5%CA%D5%D6%A7%BB%F9%B1%BE%C7%E9%BF%F6%29+and+%28docTitle%3D%B8%F7%B5%D8%C7%F8%BE%D3%C3%F1%CF%FB%B7%D1%BC%DB%B8%F1%D6%B8%CA%FD+or+DOCHTMLCONTENT%3D%B8%F7%B5%D8%C7%F8%BE%D3%C3%F1%CF%FB%B7%D1%BC%DB%B8%F1%D6%B8%CA%FD%29&channelid=9951&record="
	for i in num_list:
		if i==0:
			continue
 
		strTemp = strUrl + str(i)
		strTxt = "_UI.htm"
		GetHtmlData(strTemp, strTxt, False)
		print (str(i) + "/56") 

        对上面的代码稍微做个说明：这个主要是用来抓取国家统计局网站的统计数据，包括各地区居民消费价格指数和各地区城镇投资数据。同学要的数据是2006年1月到现在的，在统计局的网站上查询发现，所有的数据的URL都一样，只有最后的一个id值是从1开始递增，最近的是1，时间之前的慢慢递增。统计局的这个URL好长啊！！

        代码中写了三个函数，分别是获取网页的Tilte，用来作为保存的文件的文件名。

        一个函数是从html中解析各地区居民消费价格指数，另外一个提取各地区城镇投资数据，其实目前的代码这两个函数是一样的，我比较懒，没有提取里面的详细信息，目前只是把网页的那个Table的tbody给拿出来了，呵呵。如果可以的话，可以使用正则表达式，只把里面的数据提取出来。

        上次用C#写了好久才搞定，Python果然不一样，写简单的工具的话，还是比较推荐Python的，第一，简单，第二，不用编译，直接写个txt，放到解释器里面就好了。