Python 實用腳本集錦：隨機數、檔案操作、正則、資料庫與 GUI

1. 產生隨機數

import random
rnd = random.randint(1, 500)  # 1~500 整數

2. 讀取檔案

with open(r"c:\1.txt", "r") as f:
    for line in f:
        print(line.rstrip())

3. 寫入檔案

with open(r"c:\1.txt", "r+") as f:
    f.write("123")

4. 正則擷取 Tomcat 日誌日期

import re
regex = r"\d{4}-\d{2}-\d+"
with open(r"c:\stdout.log", "r") as f:
    for i, line in enumerate(f):
        if re.search(regex, line):
            print(line.rstrip())
        if i > 10: break

5. 連接 PostgreSQL (pgdb)

import pgdb
conn = pgdb.connect(host='localhost', database='qingfeng',
                    user='qingfeng', password='123')
cur = conn.cursor()
cur.execute("select * from dream")
print(cur.rowcount)

6. 網路程式與 RPC 範例

程式碼較長，請參考原文連結：JavaEye 討論串

7. SAX 解析 XML

import string
from xml.sax import saxlib, saxexts

class QuotationHandler(saxlib.HandlerBase):
    def __init__(self):
        self.in_quote = 0
        self.thisquote = ''

    def startDocument(self):
        print('--- Begin Document ---')

    def startElement(self, name, attrs):
        if name == 'quotation':
            print('QUOTATION:')
            self.in_quote = 1
        else:
            self.thisquote += '{'

    def endElement(self, name):
        if name == 'quotation':
            print(' '.join(string.split(self.thisquote[:230])) + '...',
                  f'({len(self.thisquote)} bytes)\n')
            self.thisquote = ''
            self.in_quote = 0
        else:
            self.thisquote += '}'

    def characters(self, ch, start, length):
        if self.in_quote:
            self.thisquote += ch[start:start+length]

if __name__ == '__main__':
    parser = saxexts.XMLParserFactory.make_parser()
    handler = QuotationHandler()
    parser.setDocumentHandler(handler)
    parser.parseFile(open("sample.xml"))
    parser.close()

8. Tkinter 簡易 GUI

import Tkinter
root = Tkinter.Tk()
label = Tkinter.Label(root, text="Welcome to Python's world")
label.pack()
root.mainloop()

標準 GUI 庫為 Tkinter，亦可使用 PyQt/PySide (Qt) 或 wxPython。