python编程常用模板总结

Posted 2020-06-13 xingjiarong

在我们编程时，有一些代码是固定的，例如Socket连接的代码，读取文件内容的代码，一般情况下我都是到网上搜一下然后直接粘贴下来改一改，当然如果你能自己记住所有的代码那更厉害，但是自己写毕竟不如粘贴来的快，而且自己写的代码还要测试，而一段经过测试的代码则可以多次使用，所以这里我就自己总结了一下python中常用的编程模板，如果还有哪些漏掉了请大家及时补充哈。

一、读写文件

1、读文件

（1）、一次性读取全部内容

filepath=‘D:/data.txt‘ #文件路径

with open(filepath, ‘r‘) as f:
    print f.read()

（2）读取固定字节大小

# -*- coding: UTF-8 -*-

filepath=‘D:/data.txt‘ #文件路径

f = open(filepath, ‘r‘)
content=""
try:
    while True:
        chunk = f.read(8)
        if not chunk:
            break
        content+=chunk
finally:
    f.close()
    print content

（3）每次读取一行

# -*- coding: UTF-8 -*-

filepath=‘D:/data.txt‘ #文件路径

f = open(filepath, "r")
content=""
try:
    while True:
        line = f.readline()
        if not line:
            break
        content+=line
finally:
    f.close()
    print content

（4）一次读取所有的行

# -*- coding: UTF-8 -*-

filepath=‘D:/data.txt‘ #文件路径

with open(filepath, "r") as f:
    txt_list = f.readlines()

for i in txt_list:
    print i,

2、写文件

# -*- coding: UTF-8 -*-

filepath=‘D:/data1.txt‘ #文件路径

with open(filepath, "w") as f: #w会覆盖原来的文件，a会在文件末尾追加
    f.write(‘1234‘)

二、连接mysql数据库

1、连接

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

import MySQLdb

DB_URL=‘localhost‘
USER_NAME=‘root‘
PASSWD=‘1234‘
DB_NAME=‘test‘

# 打开数据库连接
db = MySQLdb.connect(DB_URL,USER_NAME,PASSWD,DB_NAME)

# 使用cursor()方法获取操作游标 
cursor = db.cursor()

# 使用execute方法执行SQL语句
cursor.execute("SELECT VERSION()")

# 使用 fetchone() 方法获取一条数据库。
data = cursor.fetchone()

print "Database version : %s " % data

# 关闭数据库连接
db.close()

2、创建表

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

import MySQLdb

# 打开数据库连接
db = MySQLdb.connect("localhost","testuser","test123","TESTDB" )

# 使用cursor()方法获取操作游标 
cursor = db.cursor()

# 如果数据表已经存在使用 execute() 方法删除表。
cursor.execute("DROP TABLE IF EXISTS EMPLOYEE")

# 创建数据表SQL语句
sql = """CREATE TABLE EMPLOYEE (
         FIRST_NAME  CHAR(20) NOT NULL,
         LAST_NAME  CHAR(20),
         AGE INT,  
         SEX CHAR(1),
         INCOME FLOAT )"""

cursor.execute(sql)

# 关闭数据库连接
db.close()

3、插入

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

import MySQLdb

# 打开数据库连接
db = MySQLdb.connect("localhost","testuser","test123","TESTDB" )

# 使用cursor()方法获取操作游标 
cursor = db.cursor()

# SQL 插入语句
sql = """INSERT INTO EMPLOYEE(FIRST_NAME,
         LAST_NAME, AGE, SEX, INCOME)
         VALUES (‘Mac‘, ‘Mohan‘, 20, ‘M‘, 2000)"""
try:
   # 执行sql语句
   cursor.execute(sql)
   # 提交到数据库执行
   db.commit()
except:
   # Rollback in case there is any error
   db.rollback()

# 关闭数据库连接
db.close()

4、查询

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

import MySQLdb

# 打开数据库连接
db = MySQLdb.connect("localhost","testuser","test123","TESTDB" )

# 使用cursor()方法获取操作游标 
cursor = db.cursor()

# SQL 查询语句
sql = "SELECT * FROM EMPLOYEE        WHERE INCOME > ‘%d‘" % (1000)
try:
   # 执行SQL语句
   cursor.execute(sql)
   # 获取所有记录列表
   results = cursor.fetchall()
   for row in results:
      fname = row[0]
      lname = row[1]
      age = row[2]
      sex = row[3]
      income = row[4]
      # 打印结果
      print "fname=%s,lname=%s,age=%d,sex=%s,income=%d" %              (fname, lname, age, sex, income )
except:
   print "Error: unable to fecth data"

# 关闭数据库连接
db.close()

5、更新

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

import MySQLdb

# 打开数据库连接
db = MySQLdb.connect("localhost","testuser","test123","TESTDB" )

# 使用cursor()方法获取操作游标 
cursor = db.cursor()

# SQL 更新语句
sql = "UPDATE EMPLOYEE SET AGE = AGE + 1
                          WHERE SEX = ‘%c‘" % (‘M‘)
try:
   # 执行SQL语句
   cursor.execute(sql)
   # 提交到数据库执行
   db.commit()
except:
   # 发生错误时回滚
   db.rollback()

# 关闭数据库连接
db.close()

三、Socket

1、服务器

from socket import *
from time import ctime

HOST = ‘‘
PORT = 21568
BUFSIZ = 1024
ADDR = (HOST, PORT)

tcpSerSock = socket(AF_INET, SOCK_STREAM)
tcpSerSock.bind(ADDR)
tcpSerSock.listen(5)

while True:
    print ‘waiting for connection...‘
    tcpCliSock, addr = tcpSerSock.accept()  
    print ‘...connected from:‘, addr

    while True:
        try:
            data = tcpCliSock.recv(BUFSIZ)  
            print ‘<‘, data
            tcpCliSock.send(‘[%s] %s‘ % (ctime(), data))  
        except:
            print ‘disconnect from:‘, addr
            tcpCliSock.close()  
            break
tcpSerSock.close()

2、客户端

from socket import *

HOST = ‘localhost‘
PORT = 21568
BUFSIZ = 1024
ADDR = (HOST, PORT)

tcpCliSock = socket(AF_INET, SOCK_STREAM)
tcpCliSock.connect(ADDR)  

try:
    while True:
        data = raw_input(‘>‘)
        if data == ‘close‘:
            break
        if not data:
            continue
        tcpCliSock.send(data)  
        data = tcpCliSock.recv(BUFSIZ)  
        print data
except:
    tcpCliSock.close()  

四、多线程

import time, threading

# 新线程执行的代码:
def loop():
    print ‘thread %s is running...‘ % threading.current_thread().name
    n = 0
    while n < 5:
        n = n + 1
        print ‘thread %s >>> %s‘ % (threading.current_thread().name, n)
        time.sleep(1)
    print ‘thread %s ended.‘ % threading.current_thread().name

print ‘thread %s is running...‘ % threading.current_thread().name
t = threading.Thread(target=loop, name=‘LoopThread‘)
t.start()
t.join()
print ‘thread %s ended.‘ % threading.current_thread().name

还请大家积极补充！