常用python编程模板汇总

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！