python文件处理
1、读取txt文件
# 读取stu_info.txt文件内容，并将文件中所有学生名称显示出来
f = open('stu_info.txt', 'r')
lines = f.readlines()
print(lines)
for line in lines:
print(line.split(',')[0])
f.close()
2、CSV文件读写
'''
读写csv文件，csv即为逗号分隔值(Comma-Separated Values,CSV)，
有时也称为字符分隔值，其文件以纯文本形式存储表格数据(数字和文本)
'''
import csv
fr=open('stu_info.csv', 'r')
csv_file = csv.reader(fr)
for stu in csv_file:
print(stu)
fr.close()
#对stu_info.csv文件追加写入两个学生信息Marry和Rom
stu=['Marry',28,'Changsha']
stu1=['Rom',23,'Chengdu']
out=open('stu_info.csv','a',newline='')
csv_write=csv.write(out,dialect='excel')
csv_write.writerow(stu)
csv_write.writerow(stu1)
out.close()
3、读取xml文件元素节点
<?xml version="1.0" encoding="UTF-8"?> <Class> <student> <name>Jack</name> <age>28</age> <city>Beijing</city> </student> <student> <name>Bob</name> <age>22</age> <city>Shanghai</city> </student> <student> <name>Marry</name> <age>89</age> <city>Shenzhen</city> </student> <student> <name>Marry</name> <age>89</age> <city>Shenzhen</city> </student> <teacher> <name>Nancy</name> <age>90</age> <city>Shenzhen</city> </teacher> <account> <login username="student" password="123456"/> <login username="teacher" password="88888888"/> </account> </Class>
#查看class_info.xml文件里Class节点对属性(节点名称、节点值，结点类型)
from xml.dom import minidom
#加载xml文件
dom=minidom.parse('class_info.xml')
#加载dom对象元素
root=dom.documentElement
#打印结点信息
print(root.nodeName)
print(root.nodeValue)
print(root.nodeType)
'''
nodeName节点名称
nodeValue返回文本节点的值
nodeType属性，返回以数字值指定的节点的节点类型
如果节点是元素节点，则nodeType属性将返回1
如果节点是属性节点，则nodeType属性将返回2
'''
4、读取xml文本节点
#分别打印出class_info.xml里面学生和老师的详细信息(姓名、年龄、城市)
from xml.dom import minidom
#获取标签对的值
dom=minidom.parse('class_info.xml')
#获取文档对象元素
root=dom.documentElement
#根据标签名称获取标签对象
names=root.getElementsByTagName('name')
ages=root.getElementsByTagName('age')
citys=root.getElementsByTagName('city')
#分别打印显示xml文档标签对里面对内容
for i in range(4):
print(names[i].firstChild.data)
print(ages[i].firstChild.data)
print(citys[i].firstChild.data)
print("----------------")
5、读取xml文件属性节点的值
# 读取属性节点的值：分别读取打印老师和学生的账号密码
from xml.dom import minidom
dom = minidom.parse('class_info.xml')
root = dom.documentElement
logins = dom.documentElement
logins = root.getElementsByTagName('login')
# 获取login标签username属性
for i in range(2):
username = logins[i].getAttribute('username')
print(username)
password = logins[i].getAttribute('password')
print(password)
6、读取子节点信息
'''
读取子节点信息
nodeName 节点名称
nodeValue 节点值
nodeType 节点类型
'''
from xml.dom import minidom
dom=minidom.parse('class_info.xml')
root=dom.documentElement
tags=root.getElementsByTagName('student')
print(tags[0].nodeName)
print(tags[0].tagName)
print(tags[0].nodeType)
print(tags[0].nodeValue)
7、多线程
# 多线程
from time import ctime, sleep
import threading
def talk(content, loop):
for i in range(loop):
print('Start Talk %s %s' % (content, ctime()))
sleep(3)
def write(content, loop):
for i in range(loop):
print('Start Write %s %s' % (content, ctime()))
sleep(2)
# 定义和加载读写线程
threads = []
t1 = threading.Thread(target=talk, args=('Speak: Hello world', 5))
threads.append(t1)
# 执行多线程
t2 = threading.Thread(target=write, args=('Write: gogogo', 5))
threads.append(t2)
if __name__ == '__main__':
for t in threads:
t.start()
for t in threads:
t.join()
print('All the End %r' % ctime())
8、多进程
# 多进程
from time import ctime, sleep
import multiprocessing
def talk(content, loop):
for i in range(loop):
print('Start Talk %s %s' % (content, ctime()))
sleep(3)
def write(content, loop):
for i in range(loop):
print('Start Write %s %s' % (content, ctime()))
sleep(2)
# 定义和加载读写进程
processs = []
p1 = multiprocessing.Process(target=talk, args=('Speak: Hello world', 5))
processs.append(p1)
# 执行多线程
p2 = multiprocessing.Process(target=write, args=('Write: gogogo', 5))
processs.append(p2)
if __name__ == '__main__':
for p in processs:
p.start()
for p in processs:
p.join()
print('All the End %r' % ctime())
