Python json模块详解 - 序列化与解码入门教程

import json

# 编码：Python对象 -> JSON字符串
json_str = json.dumps(obj)

# 解码：JSON字符串 -> Python对象
obj = json.loads(json_str)

# 编码到文件
json.dump(obj, file)

# 从文件解码
obj = json.load(file)

import json

# Python 对象
data = {
    "name": "张三",
    "age": 25,
    "scores": [85, 92, 78],
    "is_student": True,
    "address": None,
}

# 编码为 JSON 字符串
json_str = json.dumps(data, ensure_ascii=False)
print(f"类型: {type(json_str).__name__}")
print(f"JSON: {json_str}")

# 解码为 Python 对象
parsed = json.loads(json_str)
print(f"\n类型: {type(parsed).__name__}")
print(f"姓名: {parsed['name']}")
print(f"成绩: {parsed['scores']}")

类型: str
JSON: {"name": "张三", "age": 25, "scores": [85, 92, 78], "is_student": true, "address": null}

类型: dict
姓名: 张三
成绩: [85, 92, 78]

import json

data = {
    "users": [
        {"id": 1, "name": "张三", "role": "admin"},
        {"id": 2, "name": "李四", "role": "user"},
    ],
    "total": 2,
}

# 写入 JSON 文件
with open("data.json", "w", encoding="utf-8") as f:
    json.dump(data, f, ensure_ascii=False, indent=2)
print("已写入 data.json")

# 读取 JSON 文件
with open("data.json", "r", encoding="utf-8") as f:
    loaded = json.load(f)

print(f"用户数: {loaded['total']}")
for user in loaded["users"]:
    print(f"  {user['id']}. {user['name']} ({user['role']})")

已写入 data.json
用户数: 2
  1. 张三 (admin)
  2. 李四 (user)

import json

data = {"name": "Python", "version": 3.11, "features": ["简单", "强大", "优雅"]}

# 不同格式化选项
print("紧凑格式:")
print(json.dumps(data, ensure_ascii=False, separators=(',', ':')))

print("\n缩进格式:")
print(json.dumps(data, ensure_ascii=False, indent=2))

print("\n排序键:")
print(json.dumps(data, ensure_ascii=False, sort_keys=True, indent=2))

# 类型映射验证
json_str = '{"name": "test", "active": true, "count": 0, "data": null}'
parsed = json.loads(json_str)

print("\n类型映射:")
for key, value in parsed.items():
    print(f"  {key}: {value} -> {type(value).__name__}")

紧凑格式:
{"name":"Python","version":3.11,"features":["简单","强大","优雅"]}

缩进格式:
{
  "name": "Python",
  "version": 3.11,
  "features": [
    "简单",
    "强大",
    "优雅"
  ]
}

排序键:
{
  "features": [
    "简单",
    "强大",
    "优雅"
  ],
  "name": "Python",
  "version": 3.11
}

类型映射:
  name: test -> str
  active: True -> bool
  count: 0 -> int
  data: None -> NoneType