JWT 授权 FastAPI：代码和模式

在FastAPI中实现JWT认证：完整代码指南

JWT（JSON Web Token）为API提供无状态身份验证。令牌由三部分组成：头部、载荷和签名，以base64编码并通过点号分隔。

头部指定签名算法：

{
  "alg": "HS256",
  "typ": "JWT"
}

载荷包含用户ID（sub）、签发时间（iat）和过期时间（exp）等声明。

{
  "sub": "user_id_123",
  "exp": 1735689600,
  "iat": 1735603200
}

签名使用HMAC-SHA256与密钥确保数据完整性。

生产环境建议采用双令牌机制：

• 访问令牌（15–30分钟）——用于API请求
• 刷新令牌（7–30天）——用于续期访问令牌

项目架构

分层结构便于测试与扩展：

project/
├── app/
│   ├── core/          # config.py, security.py, dependencies.py
│   ├── models/        # user.py (SQLAlchemy)
│   ├── schemas/       # user.py, token.py (Pydantic)
│   ├── routers/       # auth.py, users.py
│   ├── services/      # user.py
│   └── main.py
├── requirements.txt
└── .env

路由处理HTTP逻辑，模式校验输入，模型定义数据库结构，服务层封装业务规则。

配置与安全工具

在 core/config.py 中：

from pydantic_settings import BaseSettings

class Settings(BaseSettings):
    SECRET_KEY: str = "your-secret-key-change-in-production"
    ALGORITHM: str = "HS256"
    ACCESS_TOKEN_EXPIRE_MINUTES: int = 30
    REFRESH_TOKEN_EXPIRE_DAYS: int = 7
    
    class Config:
        env_file = ".env"

settings = Settings()

core/security.py 中的关键函数：

from datetime import datetime, timedelta
from jose import JWTError, jwt
from passlib.context import CryptContext
from .config import settings

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password: str) -> str:
    return pwd_context.hash(password)

def create_access_token(data: dict, expires_delta: timedelta = None) -> str:
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt

def create_refresh_token(data: dict) -> str:
    to_encode = data.copy()
    expire = datetime.utcnow() + timedelta(days=settings.REFRESH_TOKEN_EXPIRE_DAYS)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt

def decode_token(token: str) -> dict:
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        return payload
    except JWTError:
        return None

Pydantic数据校验模式

schemas/user.py：

from pydantic import BaseModel, EmailStr

class UserCreate(BaseModel):
    email: EmailStr
    password: str
    full_name: str

class UserResponse(BaseModel):
    id: int
    email: EmailStr
    full_name: str
    
    class Config:
        from_attributes = True

schemas/token.py：

from pydantic import BaseModel

class Token(BaseModel):
    access_token: str
    refresh_token: str
    token_type: str = "bearer"

class TokenData(BaseModel):
    user_id: int

当前用户依赖注入

core/dependencies.py 实现 OAuth2PasswordBearer：

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login")

async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: Session = Depends(get_db)
) -> User:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    
    payload = decode_token(token)
    if payload is None:
        raise credentials_exception
    
    user_id = payload.get("sub")
    if user_id is None:
        raise credentials_exception
    
    token_data = TokenData(user_id=int(user_id))
    user = db.query(User).filter(User.id == token_data.user_id).first()
    if user is None:
        raise credentials_exception
    
    return user

认证接口

在 routers/auth.py 中：

• POST /api/auth/register — 使用bcrypt哈希创建用户
• POST /api/auth/login — 返回访问与刷新令牌
• POST /api/auth/refresh — 刷新访问令牌

完整登录实现：

@router.post("/login", response_model=Token)
def login(
    form_data: OAuth2PasswordRequestForm = Depends(),
    db: Session = Depends(get_db)
):
    user = db.query(User).filter(User.email == form_data.username).first()
    if not user or not verify_password(form_data.password, user.hashed_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect email or password",
            headers={"WWW-Authenticate": "Bearer"},
        )
    
    access_token = create_access_token(data={"sub": str(user.id)})
    refresh_token = create_refresh_token(data={"sub": str(user.id)})
    
    return {
        "access_token": access_token,
        "refresh_token": refresh_token,
        "token_type": "bearer"
    }

受保护资源

routers/users.py：

@router.get("/me", response_model=UserResponse)
def get_current_user_info(current_user: User = Depends(get_current_user)):
    return current_user

此接口需在Authorization头中携带Bearer令牌。

主应用配置

main.py：

from fastapi import FastAPI
from .routers import auth, users

app = FastAPI(title="FastAPI JWT Auth", version="1.0.0")

app.include_router(auth.router)
app.include_router(users.router)

@app.get("/")
def root():
    return {"message": "Welcome to FastAPI JWT Auth API"}

核心要点

• 使用 HS256 算法并设置强密钥（至少32位字符）
• 刷新令牌存储于 HttpOnly Cookie 中，防范XSS攻击
• 每次刷新时启用 刷新令牌轮换
• 记录 失败的认证尝试
• 测试 过期令牌（检查exp字段）

— Editorial Team