# ─── 通用请求头 ───
Host: api.example.com           # 目标主机（HTTP/1.1 必需）
User-Agent: Mozilla/5.0 ...     # 客户端标识
Accept: application/json        # 期望的响应格式
Accept-Language: zh-CN,en       # 接受的语言
Connection: keep-alive          # 连接复用

# ─── 认证相关 ───
Authorization: Bearer eyJ...    # Bearer Token
Authorization: Basic base64...  # Basic Auth
Cookie: session_id=abc123       # Cookie

# ─── 内容相关 ───
Content-Type: application/json  # 请求体格式
Content-Length: 123             # 请求体长度

# ─── 缓存与控制 ───
Cache-Control: no-cache         # 缓存策略
If-Modified-Since: Mon, ...     # 条件请求

from urllib.request import urlopen, Request
from urllib.parse import urlencode, quote, urlparse
from urllib.error import HTTPError, URLError

# ─── GET 请求 ───
response = urlopen('https://api.example.com/users')
data = response.read().decode('utf-8')   # bytes → str
status = response.status                  # 状态码
headers = response.headers                # 响应头

# ─── POST 请求 ───
data = urlencode({'key': 'value'}).encode()
req = Request('https://api.example.com/post', data=data,
              headers={'Content-Type': 'application/x-www-form-urlencoded'})
response = urlopen(req)

# ─── 自定义请求头 ───
req = Request('https://api.example.com/users',
              headers={
                  'User-Agent': 'Mozilla/5.0',
                  'Authorization': 'Bearer token123'
              })
response = urlopen(req)

# ─── URL 编码 ───
# 中文/特殊字符在 URL 中需要编码
encoded = quote('你好世界')  # %E4%BD%A0%E5%A5%BD...
params = urlencode({'q': 'Python教程', 'page': 1})
# 'q=Python%E6%95%99%E7%A8%8B&page=1'

# ─── URL 解析 ───
parsed = urlparse('https://user:pass@api.com:8080/path?a=1#frag')
# parsed.scheme → 'https'
# parsed.netloc → 'user:pass@api.com:8080'
# parsed.path → '/path'
# parsed.query → 'a=1'

# ─── 异常处理 ───
try:
    response = urlopen('https://api.example.com/nonexistent')
except HTTPError as e:
    print(f"HTTP 错误: {e.code} - {e.reason}")
except URLError as e:
    print(f"URL 错误: {e.reason}")

# urllib 实现一个"简单"的 POST JSON 请求
import json
from urllib.request import Request, urlopen

data = json.dumps({"name": "Alice"}).encode()
req = Request('https://api.example.com/users',
              data=data,
              headers={'Content-Type': 'application/json'})
resp = urlopen(req, timeout=10)
result = json.loads(resp.read().decode())

import requests

# ─── GET 请求 ───
response = requests.get('https://api.example.com/users')
print(response.status_code)     # 200
print(response.json())           # 自动解析 JSON
print(response.text)             # 文本响应体
print(response.content)          # 二进制响应体
print(response.headers)          # 响应头

# 带参数
response = requests.get('https://api.example.com/search',
                        params={'q': 'python', 'page': 1})

# ─── POST 请求 ───
# JSON 数据
response = requests.post('https://api.example.com/users',
                         json={'name': 'Alice', 'age': 30})

# 表单数据
response = requests.post('https://api.example.com/login',
                         data={'username': 'admin', 'password': '123456'})

# 文件上传
files = {'file': open('report.pdf', 'rb')}
response = requests.post('https://api.example.com/upload', files=files)

# 多个文件
files = [
    ('file1', ('report1.pdf', open('report1.pdf', 'rb'), 'application/pdf')),
    ('file2', ('report2.pdf', open('report2.pdf', 'rb'), 'application/pdf')),
]
response = requests.post('https://api.example.com/upload', files=files)

# ─── 请求头 ───
headers = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0)',
    'Authorization': 'Bearer token123',
    'Accept-Language': 'zh-CN',
}
response = requests.get('https://api.example.com/data', headers=headers)

# ─── 超时设置 ───
response = requests.get('https://api.example.com', timeout=5)  # 5秒超时
response = requests.get('https://api.example.com', timeout=(3, 10))  # (连接超时, 读取超时)

# ─── 代理 ───
proxies = {
    'http': 'http://proxy.example.com:8080',
    'https': 'https://proxy.example.com:8080',
}
response = requests.get('https://api.example.com', proxies=proxies)

# ─── SSL 验证 ───
response = requests.get('https://api.example.com', verify=True)     # 默认验证
response = requests.get('https://api.example.com', verify=False)    # ⚠️ 跳过验证

# ─── 重定向 ───
response = requests.get('https://api.example.com', allow_redirects=True)   # 默认自动跟随

# ─── 流式响应 ───
response = requests.get('https://api.example.com/large-file', stream=True)
for chunk in response.iter_content(chunk_size=8192):
    process(chunk)

# ─── urllib ───
from urllib.request import Request, urlopen
import json

data = json.dumps({"key": "value"}).encode()
req = Request("http://api.example.com/data",
              data=data,
              headers={"Content-Type": "application/json"})
resp = urlopen(req, timeout=10)
result = json.loads(resp.read().decode())

# ─── requests ───
import requests

result = requests.post("http://api.example.com/data",
                        json={"key": "value"},
                        timeout=10).json()

import requests

# 创建 Session 对象
session = requests.Session()

# Session 会自动保存 Cookie
session.get('https://httpbin.org/cookies/set?name=alice')

# 后续请求自动携带 Cookie
response = session.get('https://httpbin.org/cookies')
print(response.json())  # {'cookies': {'name': 'alice'}}

# Session 级别的配置（所有请求共享）
session.headers.update({'User-Agent': 'MyApp/1.0'})
session.verify = False  # 所有请求跳过 SSL 验证
session.timeout = 10    # 所有请求默认超时

# 挂载适配器（配置重试）
from requests.adapters import HTTPAdapter
from urllib3.util.retry import Retry

retry_strategy = Retry(
    total=3,                      # 总重试次数
    backoff_factor=1,             # 退避因子（等待 1, 2, 4 秒）
    status_forcelist=[429, 500, 502, 503, 504],  # 重试的状态码
)
adapter = HTTPAdapter(max_retries=retry_strategy)
session.mount('http://', adapter)
session.mount('https://', adapter)

# 使用底层连接池（性能提升）
# requests.Session 底层使用 urllib3 的连接池
# 默认连接池大小 10，可通过适配器调整

import requests

# 查看响应中的 Cookie
response = requests.get('https://httpbin.org/cookies/set?name=alice')
for cookie in response.cookies:
    print(f"{cookie.name}: {cookie.value} (domain={cookie.domain})")

# 手动设置 Cookie
cookies = {'session_id': 'abc123', 'user_pref': 'theme=dark'}
response = requests.get('https://api.example.com/user',
                        cookies=cookies)

# CookieJar 对象
from http.cookiejar import CookieJar

jar = CookieJar()
session = requests.Session()
session.cookies = jar