实例Python处理XML文件的方法

需求
有一个表，里面数据量比较大，每天一更新，其字段可以通过xml配置文件进行配置，即，可能每次建表的字段不一样。

上游跑时会根据配置从源文件中提取，到入库这一步需要根据配置进行建表。

解决
写了一个简单的xml，配置需要字段及类型

上游读取到对应的数据

入库这一步，先把原表删除，根据配置建新表

XML文件

<?xml version="1.0" encoding="UTF-8"?>
<!-- 表名 ,数据库名  可灵活配置插入哪个库哪个表 -->
<table name="top_query" db_name="evaluting_sys">
<!-- 非业务主键，自增长,可配名，其他 INTEGER UNSIGNED AUTO_INCREMENT -->
<primary_key>
<name>id</name>
</primary_key>
<!-- 字段开始 -->
<field>
<name>query</name>
<type>varchar(200)</type>
<is_index>false</is_index>
<description>query</description>
</field>
<field>
<name>pv</name>
<type>integer</type>
<is_index>false</is_index>
<description>pv</description>
</field>
<field>
<name>avg_money</name>
<type>integer</type>
<is_index>false</is_index>
<description></description>
</field>
<!-- 字段配置结束 -->
</table>

处理脚本

#!/usr/bin/python
# -*- coding:utf-8 -*-
#author: wklken
#desc: use to read db xml config.
#-----------------------
#2012-02-18 created
#----------------------

import sys,os
from xml.dom import minidom, Node

def read_dbconfig_xml(xml_file_path):
 content = {}

root = minidom.parse(xml_file_path)
 table = root.getElementsByTagName("table")[0]

#read dbname and table name.
 table_name = table.getAttribute("name")
 db_name = table.getAttribute("db_name")

if len(table_name) > 0 and len(db_name) > 0:
   db_sql = "create database if not exists `" + db_name +"`; use " + db_name + ";"
   table_drop_sql = "drop " + table_name + " if exists " + table_name + ";"
   content.update({"db_sql" : db_sql})
   content.update({"table_sql" : table_drop_sql })
 else:
   print "Error:attribute is not define well! db_name=" + db_name + " ;table_name=" + table_name
   sys.exit(1)
 #print table_name, db_name

table_create_sql = "create table " + table_name +"("

#read primary cell
 primary_key = table.getElementsByTagName("primary_key")[0]
 primary_key_name = primary_key.getElementsByTagName("name")[0].childNodes[0].nodeValue

table_create_sql += primary_key_name + " INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,"

#print primary_key.toxml()
 #read ordernary field
 fields = table.getElementsByTagName("field")
 f_index = 0
 for field in fields:
   f_index += 1
   name = field.getElementsByTagName("name")[0].childNodes[0].nodeValue
   type = field.getElementsByTagName("type")[0].childNodes[0].nodeValue
   table_create_sql += name + " " + type
   if f_index != len(fields):
   table_create_sql += ","
   is_index = field.getElementsByTagName("is_index")[0].childNodes[0].nodeValue

table_create_sql += ");"
 content.update({"table_create_sql" : table_create_sql})
 #character set latin1 collate latin1_danish_ci;
 print content

if __name__ == "__main__":
read_dbconfig_xml(sys.argv[1])

PYTHON解析XML大文件[SAX]
需求
读取xml数据文件，文件较大，需要实时处理插入到数据库

xml文档

<PERSONS>
<person>
 <id>100000</id>
 <sex>男</sex>
 <address>北京，海淀区</address>
 <fansNum>437</fansNum>
 <summary>1989</summary>
 <wbNum>333</wbNum>
 <gzNum>242</gzNum>
 <blog>null</blog>
 <edu>大学</edu>
 <work></work>
 <renZh>1</renZh>
 <brithday>2月14日</brithday>
</person>
</PERSONS>

处理
sax处理时并不会像dom一样可以以类似节点的维度进行读取,它只有 开始标签 内容 结束标签 之分

处理思想是：通过一个handler，对开始标签，内容，结束标签各有一个处理函数

代码及注解
person 处理类

from xml.sax import handler,parseString
class PersonHandler(handler.ContentHandler):
def __init__(self, db_ops):
 #db op obj
 self.db_ops = db_ops
 #存储一个person的map
 self.person = {}
 #当前的tag
 self.current_tag = ""
 #是否是tag之间的内容 ，目的拿到tag间内容，不受空白的干扰
 self.in_quote = 0
#开始，清空map
def startElement(self, name, attr):
 #以person，清空map
 if name == "person":
  self.person = {}
 #记录 状态
 self.current_tag = name
 self.in_quote = 1
#结束，插入数据库
def endElement(self, name):
 #以person结尾 代表读取一个person的信息结束
 if name == "person":
  #do something
  in_fields = tuple([ ('"' + self.person.get(i,"") + '"') for i in fields ])
  print in_sql ％ in_fields
  db_ops.insert( in_sql％(in_fields))
 #处理
 self.in_quote = 0
def characters(self, content):
 #若是在tag之间的内容，更新到map中
 if self.in_quote:
  self.person.update({self.current_tag: content})

加上入库的完整代码

#!/usr/bin/python
# -*- coding:utf-8 -*-
#parse_person.py
#version : 0.1
#author : wukunliang@163.com
#desc : parse person.xml and out sql

import sys,os
import MySQLdb

reload(sys)
sys.setdefaultencoding('utf-8')

in_sql = "insert into person(id,sex,address,fansNum,summary,wbNum,gzNum,blog,edu,work,renZh,brithday) values(％s, ％s, ％s, ％s, ％s, ％s,
    ％s, ％s, ％s, ％s, ％s, ％s)"

fields = ("id","sex","address","fansNum","summary","wbNum","gzNum","blog","edu","work","renZh","brithday")

#数据库方法
class Db_Connect:
 def __init__(self, db_host, user, pwd, db_name, charset="utf8", use_unicode = True):
   print "init begin"
   print db_host, user, pwd, db_name, charset , use_unicode
   self.conn = MySQLdb.Connection(db_host, user, pwd, db_name, charset=charset , use_unicode=use_unicode)
   print "init end"

def insert(self, sql):
   try:
     n = self.conn.cursor().execute(sql)
     return n
   except MySQLdb.Warning, e:
     print "Error: execute sql '",sql,"' failed"

def close(self):
   self.conn.close()

#person 处理类
from xml.sax import handler,parseString
class PersonHandler(handler.ContentHandler):
 def __init__(self, db_ops):
   #db op obj
   self.db_ops = db_ops
   #存储一个person的map
   self.person = {}
   #当前的tag
   self.current_tag = ""
   #是否是tag之间的内容
   self.in_quote = 0
 #开始，清空map
 def startElement(self, name, attr):
   #以person，清空map
   if name == "person":
    self.person = {}
   #记录 状态
   self.current_tag = name
   self.in_quote = 1
 #结束，插入数据库
 def endElement(self, name):
   #以person结尾 代表读取一个person的信息结束
   if name == "person":
     #do something
     in_fields = tuple([ ('"' + self.person.get(i,"") + '"') for i in fields ])
     print in_sql ％ in_fields
     db_ops.insert( in_sql％(in_fields))
   #处理
   self.in_quote = 0
 def characters(self, content):
   #若是在tag之间的内容，更新到map中
   if self.in_quote:
     self.person.update({self.current_tag: content})

if __name__ == "__main__":
 f = open("./person.xml")
 #如果源文件gbk 转码   若是utf-8，去掉decode.encode
 db_ops = Db_Connect("127.0.0.1", "root", "root", "test")
 parseString(f.read().decode("gbk").encode("utf-8"), PersonHandler(db_ops))
 f.close()
 db_ops.close()