# 客户端发送大请求体前，先询问服务器是否接受
PUT /api/upload HTTP/1.1
Host: example.com
Content-Length: 104857600
Expect: 100-continue

# 服务器确认
HTTP/1.1 100 Continue

# 客户端继续发送请求体
<binary data...>

import requests

# requests 库自动处理 100 Continue
with open('large-file.zip', 'rb') as f:
    response = requests.put(
        'https://api.example.com/upload',
        data=f,
        headers={'Content-Type': 'application/octet-stream'}
    )

# WebSocket 握手时使用
GET /chat HTTP/1.1
Host: example.com
Upgrade: websocket
Connection: Upgrade

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade

# 服务器正在处理长时间运行的请求
# 客户端应等待最终响应
HTTP/1.1 102 Processing

# 在最终响应前发送预加载提示
HTTP/1.1 103 Early Hints
Link: </style.css>; rel=preload; as=style
Link: </script.js>; rel=preload; as=script

HTTP/1.1 200 OK
Content-Type: text/html
...

# Nginx 配置 Early Hints
location / {
    add_header Link "</style.css>; rel=preload; as=style";
    add_header Link "</script.js>; rel=preload; as=script";
    proxy_pass http://backend;
}

GET /api/users/123 HTTP/1.1

HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: 85

{"id":123,"name":"Alice","email":"alice@example.com"}

POST /api/users HTTP/1.1
Content-Type: application/json

{"name":"Bob","email":"bob@example.com"}

HTTP/1.1 201 Created
Content-Type: application/json
Location: /api/users/456

{"id":456,"name":"Bob","email":"bob@example.com"}

# 请求已接受，但处理尚未完成
POST /api/reports/generate HTTP/1.1
Content-Type: application/json

{"type":"monthly","month":"2026-04"}

HTTP/1.1 202 Accepted
Content-Type: application/json

{"task_id":"abc-123","status":"processing","check_url":"/api/tasks/abc-123"}

DELETE /api/users/123 HTTP/1.1

HTTP/1.1 204 No Content

# 204 没有响应体
response = requests.delete('https://api.example.com/users/123')
if response.status_code == 204:
    print("删除成功，无响应体")
    # response.text 为空

# 断点续传或分块下载
GET /files/large.zip HTTP/1.1
Range: bytes=1024-2047

HTTP/1.1 206 Partial Content
Content-Range: bytes 1024-2047/10240
Content-Length: 1024

<binary data...>

import requests

# 断点续传 — 下载大文件
def download_file(url, filename):
    # 获取文件大小
    head = requests.head(url)
    total_size = int(head.headers['Content-Length'])
    
    downloaded = 0
    with open(filename, 'wb') as f:
        while downloaded < total_size:
            end = min(downloaded + 1024 * 1024, total_size - 1)
            headers = {'Range': f'bytes={downloaded}-{end}'}
            response = requests.get(url, headers=headers)
            f.write(response.content)
            downloaded = end + 1
            print(f"下载进度: {downloaded}/{total_size}")

GET /old-page HTTP/1.1

HTTP/1.1 301 Moved Permanently
Location: /new-page

# Nginx 永久重定向
location /old-page {
    return 301 /new-page;
}

# HTTP 到 HTTPS 重定向
server {
    listen 80;
    return 301 https://$host$request_uri;
}

# 临时重定向（浏览器可能改 POST 为 GET）
GET /temp-redirect HTTP/1.1

HTTP/1.1 302 Found
Location: /other-page

# POST 后重定向到结果页面
POST /api/orders HTTP/1.1
Content-Type: application/json

{"product_id": 42}

HTTP/1.1 303 See Other
Location: /orders/789

GET /api/users HTTP/1.1
If-None-Match: "etag-123"

HTTP/1.1 304 Not Modified
ETag: "etag-123"
Cache-Control: max-age=3600

# 临时重定向（保留请求方法）
POST /api/action HTTP/1.1
Content-Type: application/json

{"data":"value"}

HTTP/1.1 307 Temporary Redirect
Location: /api/new-action
# 客户端应使用 POST 重定向

# 永久重定向（保留请求方法）
POST /api/old-endpoint HTTP/1.1

HTTP/1.1 308 Permanent Redirect
Location: /api/new-endpoint

POST /api/users HTTP/1.1
Content-Type: application/json

{"email": "invalid-email"}

HTTP/1.1 400 Bad Request
Content-Type: application/json

{
    "error": {
        "code": "VALIDATION_ERROR",
        "message": "请求参数验证失败",
        "details": [
            {"field": "email", "message": "邮箱格式不正确"}
        ]
    }
}

# 401 Unauthorized — 未认证
GET /api/admin/users HTTP/1.1

HTTP/1.1 401 Unauthorized
WWW-Authenticate: Bearer realm="api"
Content-Type: application/json

{"error":{"code":"UNAUTHORIZED","message":"请先登录"}}

# 403 Forbidden — 已认证但无权限
GET /api/admin/users HTTP/1.1
Authorization: Bearer <valid-token-without-admin-role>

HTTP/1.1 403 Forbidden
Content-Type: application/json

{"error":{"code":"FORBIDDEN","message":"无管理员权限"}}

GET /api/users/99999 HTTP/1.1

HTTP/1.1 404 Not Found
Content-Type: application/json

{"error":{"code":"NOT_FOUND","message":"用户不存在"}}

POST /api/users HTTP/1.1
Content-Type: application/json

{"email": "alice@example.com"}

HTTP/1.1 409 Conflict
Content-Type: application/json

{"error":{"code":"CONFLICT","message":"该邮箱已被注册","existing_user_id":123}}

GET /api/data HTTP/1.1

HTTP/1.1 429 Too Many Requests
Retry-After: 60
X-RateLimit-Limit: 100
X-RateLimit-Remaining: 0
X-RateLimit-Reset: 1715328000
Content-Type: application/json

{"error":{"code":"RATE_LIMITED","message":"请求过于频繁，请 60 秒后重试"}}

import requests
import time

def request_with_retry(url, max_retries=3):
    for attempt in range(max_retries):
        response = requests.get(url)
        
        if response.status_code == 429:
            retry_after = int(response.headers.get('Retry-After', 60))
            print(f"速率限制，等待 {retry_after} 秒...")
            time.sleep(retry_after)
            continue
        
        return response
    
    raise Exception("超过最大重试次数")

GET /api/users HTTP/1.1

HTTP/1.1 500 Internal Server Error
Content-Type: application/json

{
    "error": {
        "code": "INTERNAL_ERROR",
        "message": "服务器内部错误",
        "request_id": "req-abc-123"
    }
}

HTTP/1.1 503 Service Unavailable
Retry-After: 120
Content-Type: text/html

<html>
<body>
    <h1>503 Service Unavailable</h1>
    <p>系统维护中，预计 2 分钟后恢复。</p>
</body>
</html>

# Nginx 维护页面
server {
    listen 80;
    server_name example.com;
    
    # 维护模式
    if (-f /tmp/maintenance.flag) {
        return 503;
    }
    
    error_page 503 @maintenance;
    location @maintenance {
        rewrite ^(.*)$ /maintenance.html break;
    }
}

# 自定义状态码示例
from http.server import HTTPServer, BaseHTTPRequestHandler

class CustomHandler(BaseHTTPRequestHandler):
    def do_GET(self):
        if self.path == '/api/payment':
            # 自定义 451 表示需要支付
            self.send_response(451)
            self.send_header('Content-Type', 'application/json')
            self.end_headers()
            self.wfile.write(b'{"error":{"code":"PAYMENT_REQUIRED","message":"请先支付"}}')
        elif self.path == '/api/blocked':
            # 自定义 450 表示被封禁
            self.send_response(450)
            self.send_header('Content-Type', 'application/json')
            self.end_headers()
            self.wfile.write(b'{"error":{"code":"BLOCKED","message":"账号已被封禁"}}')

# RFC 7725 — 因法律原因不可用
GET /content/forbidden-article HTTP/1.1

HTTP/1.1 451 Unavailable For Legal Reasons
Link: <https://legal-info.example.com>; rel="blocked-by"
Content-Type: application/json

{"error":{"code":"LEGAL_BLOCK","message":"该内容因法律原因不可用"}}

{
    "error": {
        "code": "VALIDATION_ERROR",
        "message": "请求参数验证失败",
        "details": [
            {
                "field": "email",
                "code": "INVALID_FORMAT",
                "message": "邮箱格式不正确"
            },
            {
                "field": "age",
                "code": "OUT_OF_RANGE",
                "message": "年龄必须在 0-150 之间"
            }
        ],
        "request_id": "req-550e8400-e29b-41d4",
        "documentation_url": "https://api.example.com/docs/errors#VALIDATION_ERROR"
    }
}

// 错误中间件
class AppError extends Error {
    constructor(statusCode, code, message, details = null) {
        super(message);
        this.statusCode = statusCode;
        this.code = code;
        this.details = details;
    }
}

// 使用
app.get('/api/users/:id', async (req, res, next) => {
    try {
        const user = await db.users.findById(req.params.id);
        if (!user) {
            throw new AppError(404, 'NOT_FOUND', '用户不存在');
        }
        res.json(user);
    } catch (err) {
        next(err);
    }
});

// 全局错误处理
app.use((err, req, res, next) => {
    const statusCode = err.statusCode || 500;
    const response = {
        error: {
            code: err.code || 'INTERNAL_ERROR',
            message: statusCode === 500 ? '服务器内部错误' : err.message,
            request_id: req.headers['x-request-id']
        }
    };
    
    if (err.details) {
        response.error.details = err.details;
    }
    
    // 生产环境隐藏 500 错误详情
    if (statusCode === 500 && process.env.NODE_ENV === 'production') {
        console.error(err);
    }
    
    res.status(statusCode).json(response);
});