Flask 框架
$ pip install flask写一个app.py，处理3个URL，分别是：
GET /：首页，返回Home；GET /signin：登录页，显示登录表单；POST /signin：处理登录表单，显示登录结果。
from flask import Flask
from flask import request
app = Flask(__name__)
@app.route('/', methods=['GET', 'POST'])
def home():
return '<h1>Home</h1>'
@app.route('/signin', methods=['GET'])
def signin_form():
return '''<form action="/signin" method="post">
<p><input name="username"></p>
<p><input name="password" type="password"></p>
<p><button type="submit">Sign In</button></p>
</form>'''
@app.route('/signin', methods=['POST'])
def signin():
if request.form['username']=='admin' and request.form['password']=='password':
return '<h3>Hello, admin!</h3>'
return '<h3>Bad username or password.</h3>'
if __name__ == '__main__':
app.run()使用模板
Flask默认支持的模板是jinja2，所以我们先安装jinja2：
$ pip install jinja2修改app.py：
# app.py
from flask import Flask, request, render_template
app = Flask(__name__)
@app.route('/', methods=['GET', 'POST'])
def home():
return render_template('home.html')
@app.route('/signin', methods=['GET'])
def signin_form():
return render_template('form.html')
@app.route('/signin', methods=['POST'])
def signin():
username = request.form['username']
password = request.form['password']
if username=='admin' and password=='password':
return render_template('signin-ok.html', username=username)
return render_template('form.html', message='Bad username or password', username=username)
if __name__ == '__main__':
app.run()增加模板文件：
# templates/form.html
<html>
<head>
<title>Please Sign In</title>
</head>
<body>
{% if message %}
<p style="color:red">{{ message }}</p>
{% endif %}
<form action="/signin" method="post">
<legend>Please sign in:</legend>
<p><input name="username" placeholder="Username" value="{{ username }}"></p>
<p><input name="password" placeholder="Password" type="password"></p>
<p><button type="submit">Sign In</button></p>
</form>
</body>
</html># templates/signin-ok.html
<html>
<head>
<title>Welcome, {{ username }}</title>
</head>
<body>
<p>Welcome, {{ username }}!</p>
</body>
</html>运行：
$ python app.py
* Running on http://127.0.0.1:5000/除了Flask，常见的Python Web框架还有：
python
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