Python案例怎么使用Flask框架？

wen python案例 2026-06-09 13

本文目录导读：

安装 Flask
基础案例：Hello World
URL路由和参数传递
处理GET和POST请求
使用模板（HTML渲染）
RESTful API 案例
文件上传案例
数据库整合（SQLite）
使用蓝图（Blueprint）组织代码
运行配置
实用技巧

我来详细介绍一下 Flask 框架的基本使用方法，包含几个典型案例。

安装 Flask

pip install flask

基础案例：Hello World

# app.py
from flask import Flask
app = Flask(__name__)
@app.route('/')
def hello_world():
    return 'Hello, World!'
if __name__ == '__main__':
    app.run(debug=True)

运行：

python app.py
# 访问 http://localhost:5000

URL路由和参数传递

from flask import Flask
app = Flask(__name__)
# 基本路由
@app.route('/')
def index():
    return '首页'
# 带参数的路由
@app.route('/user/<username>')
def show_user(username):
    return f'用户: {username}'
# 指定参数类型
@app.route('/post/<int:post_id>')
def show_post(post_id):
    return f'文章ID: {post_id}'
# 多参数
@app.route('/user/<username>/<int:age>')
def user_info(username, age):
    return f'用户: {username}, 年龄: {age}'
if __name__ == '__main__':
    app.run(debug=True)

处理GET和POST请求

from flask import Flask, request, jsonify
app = Flask(__name__)
# GET请求
@app.route('/api/data', methods=['GET'])
def get_data():
    # 获取查询参数
    name = request.args.get('name', '默认名称')
    return jsonify({
        'message': f'Hello {name}',
        'method': 'GET'
    })
# POST请求
@app.route('/api/data', methods=['POST'])
def post_data():
    # 获取JSON数据
    data = request.get_json()
    if data:
        name = data.get('name', '匿名')
        return jsonify({
            'message': f'收到POST数据: {name}',
            'method': 'POST'
        })
    return jsonify({'error': '没有数据'}), 400
# 表单数据
@app.route('/login', methods=['POST'])
def login():
    username = request.form.get('username')
    password = request.form.get('password')
    return jsonify({
        'username': username,
        'password': '***'  # 实际项目中不要返回密码
    })
if __name__ == '__main__':
    app.run(debug=True)

使用模板（HTML渲染）

# app.py
from flask import Flask, render_template, request
app = Flask(__name__)
@app.route('/')
def index():
    return render_template('index.html', title='首页')
@app.route('/user/<name>')
def user(name):
    return render_template('user.html', 
                         username=name,
                         age=25,
                         skills=['Python', 'Flask', 'JavaScript'])
@app.route('/search')
def search():
    query = request.args.get('q', '')
    return render_template('search.html', query=query)
if __name__ == '__main__':
    app.run(debug=True)

创建 templates/index.html：

<!DOCTYPE html>
<html>
<head>{{ title }}</title>
</head>
<body>
    <h1>欢迎来到我的网站</h1>
    <p>这是首页内容</p>
    <!-- 表单示例 -->
    <form action="/search" method="GET">
        <input type="text" name="q" placeholder="搜索...">
        <button type="submit">搜索</button>
    </form>
</body>
</html>

创建 templates/user.html：

<!DOCTYPE html>
<html>
<head>{{ username }}的个人页面</title>
</head>
<body>
    <h1>{{ username }}的个人信息</h1>
    <p>年龄: {{ age }}</p>
    <h2>技能列表</h2>
    <ul>
        {% for skill in skills %}
        <li>{{ skill }}</li>
        {% endfor %}
    </ul>
    <!-- 条件判断 -->
    {% if age >= 18 %}
        <p>已成年</p>
    {% else %}
        <p>未成年</p>
    {% endif %}
</body>
</html>

RESTful API 案例

from flask import Flask, request, jsonify
app = Flask(__name__)
# 模拟数据库
books = [
    {'id': 1, 'title': 'Python编程', 'author': '张三'},
    {'id': 2, 'title': 'Flask实战', 'author': '李四'}
]
# 获取所有书籍
@app.route('/api/books', methods=['GET'])
def get_books():
    return jsonify(books)
# 获取单本书籍
@app.route('/api/books/<int:book_id>', methods=['GET'])
def get_book(book_id):
    book = next((b for b in books if b['id'] == book_id), None)
    if book:
        return jsonify(book)
    return jsonify({'error': '书籍不存在'}), 404
# 添加书籍
@app.route('/api/books', methods=['POST'])
def add_book():
    data = request.get_json()
    if not data or 'title' not in data:
        return jsonify({'error': '请提供书名'}), 400
    new_book = {
        'id': len(books) + 1,
        'title': data['title'],
        'author': data.get('author', '未知')
    }
    books.append(new_book)
    return jsonify(new_book), 201
# 更新书籍
@app.route('/api/books/<int:book_id>', methods=['PUT'])
def update_book(book_id):
    book = next((b for b in books if b['id'] == book_id), None)
    if not book:
        return jsonify({'error': '书籍不存在'}), 404
    data = request.get_json()
    book.update(data)
    return jsonify(book)
# 删除书籍
@app.route('/api/books/<int:book_id>', methods=['DELETE'])
def delete_book(book_id):
    global books
    books = [b for b in books if b['id'] != book_id]
    return jsonify({'message': '删除成功'})
if __name__ == '__main__':
    app.run(debug=True)

文件上传案例

from flask import Flask, request, jsonify, render_template
import os
from werkzeug.utils import secure_filename
app = Flask(__name__)
app.config['UPLOAD_FOLDER'] = 'uploads'
app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 * 1024  # 16MB限制
# 确保上传目录存在
os.makedirs(app.config['UPLOAD_FOLDER'], exist_ok=True)
@app.route('/upload')
def upload_page():
    return render_template('upload.html')
@app.route('/api/upload', methods=['POST'])
def upload_file():
    if 'file' not in request.files:
        return jsonify({'error': '没有文件'}), 400
    file = request.files['file']
    if file.filename == '':
        return jsonify({'error': '未选择文件'}), 400
    if file:
        # 安全文件名
        filename = secure_filename(file.filename)
        filepath = os.path.join(app.config['UPLOAD_FOLDER'], filename)
        # 保存文件
        file.save(filepath)
        return jsonify({
            'message': '上传成功',
            'filename': filename,
            'filepath': filepath
        })
if __name__ == '__main__':
    app.run(debug=True)

创建 templates/upload.html：

<!DOCTYPE html>
<html>
<head>文件上传</title>
</head>
<body>
    <h1>文件上传</h1>
    <form action="/api/upload" method="POST" enctype="multipart/form-data">
        <input type="file" name="file" required>
        <button type="submit">上传</button>
    </form>
</body>
</html>

数据库整合（SQLite）

from flask import Flask, request, jsonify
import sqlite3
from contextlib import closing
app = Flask(__name__)
def init_db():
    with closing(sqlite3.connect('database.db')) as conn:
        cur = conn.cursor()
        cur.execute('''CREATE TABLE IF NOT EXISTS users
                      (id INTEGER PRIMARY KEY AUTOINCREMENT,
                       name TEXT NOT NULL,
                       email TEXT UNIQUE NOT NULL)''')
        conn.commit()
@app.route('/api/users', methods=['GET'])
def get_users():
    conn = sqlite3.connect('database.db')
    cur = conn.cursor()
    cur.execute('SELECT * FROM users')
    users = [{'id': row[0], 'name': row[1], 'email': row[2]} 
             for row in cur.fetchall()]
    conn.close()
    return jsonify(users)
@app.route('/api/users', methods=['POST'])
def add_user():
    data = request.get_json()
    try:
        conn = sqlite3.connect('database.db')
        cur = conn.cursor()
        cur.execute('INSERT INTO users (name, email) VALUES (?, ?)',
                   (data['name'], data['email']))
        conn.commit()
        user_id = cur.lastrowid
        conn.close()
        return jsonify({'id': user_id, **data}), 201
    except sqlite3.IntegrityError:
        return jsonify({'error': '邮箱已存在'}), 400
# 初始化数据库
init_db()
if __name__ == '__main__':
    app.run(debug=True)

使用蓝图（Blueprint）组织代码

# app.py
from flask import Flask
from blueprints.user import user_bp
from blueprints.admin import admin_bp
app = Flask(__name__)
# 注册蓝图
app.register_blueprint(user_bp, url_prefix='/user')
app.register_blueprint(admin_bp, url_prefix='/admin')
if __name__ == '__main__':
    app.run(debug=True)

# blueprints/user.py
from flask import Blueprint, jsonify
user_bp = Blueprint('user', __name__)
@user_bp.route('/list')
def user_list():
    return jsonify({'users': ['张三', '李四', '王五']})
@user_bp.route('/profile/<int:user_id>')
def user_profile(user_id):
    return jsonify({'user_id': user_id, 'name': f'用户{user_id}'})

# blueprints/admin.py
from flask import Blueprint, jsonify
admin_bp = Blueprint('admin', __name__)
@admin_bp.route('/dashboard')
def dashboard():
    return jsonify({'status': 'admin dashboard'})
@admin_bp.route('/settings')
def settings():
    return jsonify({'setting': 'admin settings'})

运行配置

# config.py
class Config:
    DEBUG = False
    SECRET_KEY = 'your-secret-key'
    DATABASE_URI = 'sqlite:///app.db'
class DevelopmentConfig(Config):
    DEBUG = True
class ProductionConfig(Config):
    DEBUG = False
    DATABASE_URI = 'mysql://user:password@localhost/db'
# app.py
from flask import Flask
app = Flask(__name__)
app.config.from_object('config.DevelopmentConfig')
if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5000)