python读取，写入和更新xml文件

def write_xml():
    #1. 创建dom树对象
    doc = minidom.Document()

    #2. 创建根结点，并用dom对象添加根结点
    root_node = doc.createElement("annotation")
    doc.appendChild(root_node)

    #3. 创建结点，结点包含一个文本结点, 再将结点加入到根结点
    folder_node = doc.createElement("folder")
    folder_value = doc.createTextNode(‘user‘)
    folder_node.appendChild(folder_value)
    root_node.appendChild(folder_node)

    filename_node = doc.createElement("filename")
    filename_value = doc.createTextNode(‘0000001.jpg‘)
    filename_node.appendChild(filename_value)
    root_node.appendChild(filename_node)

    path_node = doc.createElement("path")
    path_value = doc.createTextNode(‘/home‘)
    path_node.appendChild(path_value)
    root_node.appendChild(path_node)

    source_node = doc.createElement("source")
    database_node = doc.createElement("database")
    database_node.appendChild(doc.createTextNode("Unknown"))
    source_node.appendChild(database_node)
    root_node.appendChild(source_node)

    size_node = doc.createElement("size")
    for item, value in zip(["width", "height", "depth"], [1920, 1080, 3]):
        elem = doc.createElement(item)
        elem.appendChild(doc.createTextNode(str(value)))
        size_node.appendChild(elem)
    root_node.appendChild(size_node)

    seg_node = doc.createElement("segmented")
    seg_node.appendChild(doc.createTextNode(str(0)))
    root_node.appendChild(seg_node)

    obj_node = doc.createElement("object")
    name_node = doc.createElement("name")
    name_node.appendChild(doc.createTextNode("boat"))
    obj_node.appendChild(name_node)

    pose_node = doc.createElement("pose")
    pose_node.appendChild(doc.createTextNode("Unspecified"))
    obj_node.appendChild(pose_node)

    trun_node = doc.createElement("truncated")
    trun_node.appendChild(doc.createTextNode(str(1)))
    obj_node.appendChild(trun_node)

    trun_node = doc.createElement("difficult")
    trun_node.appendChild(doc.createTextNode(str(0)))
    obj_node.appendChild(trun_node)

    bndbox_node = doc.createElement("bndbox")
    for item, value in zip(["xmin", "ymin", "xmax", "ymax"], [103, 1, 634, 402]):
        elem = doc.createElement(item)
        elem.appendChild(doc.createTextNode(str(value)))
        bndbox_node.appendChild(elem)
    obj_node.appendChild(bndbox_node)
    root_node.appendChild(obj_node)


    with open("0000001.xml", "w", encoding="utf-8") as f:
        # 4.writexml()第一个参数是目标文件对象，第二个参数是根节点的缩进格式，第三个参数是其他子节点的缩进格式，
        # 第四个参数制定了换行格式，第五个参数制定了xml内容的编码。
        doc.writexml(f, indent=‘‘, addindent=‘\t‘, newl=‘\n‘, encoding="utf-8")

    # 每一个结点对象（包括dom对象本身）都有输出XML内容的方法，如：toxml()--字符串, toprettyxml()--美化树形格式。
    # print(doc.toxml(encoding="utf-8"))  # 输出字符串
    # print(doc.toprettyxml(indent=‘‘, addindent=‘\t‘, newl=‘\n‘, encoding="utf-8"))   #输出带格式的字符串
    # doc.writexml() #将prettyxml字符串写入文件

def read_xml(xml_path):
    with open(xml_path, "r", encoding="utf-8") as f:
        doc = minidom.parse(xml_path)  #解析xml文件(句柄或文件路径)
        #doc = minidom.parseString()  #解析xml字符串
        root_node = doc.documentElement  #获得根节点

        #找到xmin结点并更新其对应的文本值
        xmin_node = root_node.getElementsByTagName("xmin")[0]
        print(xmin_node.childNodes[0].data)
        xmin_node.childNodes[0].data = str(200)
        print(xmin_node.childNodes[0].data)

    with open(xml_path, "w", encoding="utf-8") as f:
        doc.writexml(f)

#!/usr/bin/python
# -*- coding: UTF-8 -*-

import xml.sax

class MovieHandler( xml.sax.ContentHandler ):
   def __init__(self):
?      self.CurrentData = ""
?      self.type = ""
?      self.format = ""
?      self.year = ""
?      self.rating = ""
?      self.stars = ""
?      self.description = ""

   # 元素开始事件处理
   def startElement(self, tag, attributes):
?      self.CurrentData = tag
?      if tag == "movie":
?         print "*****Movie*****"
?         title = attributes["title"]
?         print "Title:", title

   # 元素结束事件处理
   def endElement(self, tag):
?      if self.CurrentData == "type":
?         print "Type:", self.type
?      elif self.CurrentData == "format":
?         print "Format:", self.format
?      elif self.CurrentData == "year":
?         print "Year:", self.year
?      elif self.CurrentData == "rating":
?         print "Rating:", self.rating
?      elif self.CurrentData == "stars":
?         print "Stars:", self.stars
?      elif self.CurrentData == "description":
?         print "Description:", self.description
?      self.CurrentData = ""

   # 内容事件处理
   def characters(self, content):
?      if self.CurrentData == "type":
?         self.type = content
?      elif self.CurrentData == "format":
?         self.format = content
?      elif self.CurrentData == "year":
?         self.year = content
?      elif self.CurrentData == "rating":
?         self.rating = content
?      elif self.CurrentData == "stars":
?         self.stars = content
?      elif self.CurrentData == "description":
?         self.description = content

if ( __name__ == "__main__"):

   # 创建一个 XMLReader
   parser = xml.sax.make_parser()
   # turn off namepsaces
   parser.setFeature(xml.sax.handler.feature_namespaces, 0)

   # 重写 ContextHandler
   Handler = MovieHandler()
   parser.setContentHandler( Handler )

   parser.parse("movies.xml")