json.load详解 - Python从文件读取JSON数据完整指南

import json

obj = json.load(fp, *, cls=None, object_hook=None,
                 parse_float=None, parse_int=None,
                 parse_constant=None, object_pairs_hook=None, **kw)

import json
import os

# 先创建测试文件
data = {"name": "张三", "age": 25, "skills": ["Python", "Java"]}
with open("user.json", "w", encoding="utf-8") as f:
    json.dump(data, f, ensure_ascii=False, indent=2)

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

print(f"类型: {type(loaded).__name__}")
print(f"姓名: {loaded['name']}")
print(f"年龄: {loaded['age']}")
print(f"技能: {loaded['skills']}")

类型: dict
姓名: 张三
年龄: 25
技能: ['Python', 'Java']

import json
from datetime import datetime

def date_hook(obj):
    """自动转换ISO日期字符串"""
    for key, value in obj.items():
        if isinstance(value, str) and 'T' in value:
            try:
                obj[key] = datetime.fromisoformat(value)
            except ValueError:
                pass
    return obj

# 创建带日期的JSON文件
log_data = {
    "events": [
        {"action": "login", "time": "2024-01-15T09:00:00"},
        {"action": "logout", "time": "2024-01-15T18:00:00"},
    ]
}

with open("events.json", "w", encoding="utf-8") as f:
    json.dump(log_data, f, ensure_ascii=False, indent=2)

# 使用object_hook读取
with open("events.json", "r", encoding="utf-8") as f:
    result = json.load(f, object_hook=date_hook)

for event in result["events"]:
    print(f"  {event['action']}: {event['time']} (类型: {type(event['time']).__name__})")

  login: 2024-01-15 09:00:00 (类型: datetime)
  logout: 2024-01-15 18:00:00 (类型: datetime)

import json
from decimal import Decimal

class DataImporter:
    """多格式数据导入器"""

    @staticmethod
    def import_json(filepath, use_decimal=False):
        """导入JSON文件"""
        kwargs = {}
        if use_decimal:
            kwargs['parse_float'] = Decimal

        with open(filepath, "r", encoding="utf-8") as f:
            return json.load(f, **kwargs)

    @staticmethod
    def import_jsonl(filepath):
        """导入JSONL文件（每行一个JSON对象）"""
        results = []
        with open(filepath, "r", encoding="utf-8") as f:
            for line_num, line in enumerate(f, 1):
                line = line.strip()
                if line:
                    try:
                        results.append(json.loads(line))
                    except json.JSONDecodeError as e:
                        print(f"第{line_num}行解析失败: {e}")
        return results

    @staticmethod
    def validate_schema(data, required_keys):
        """验证数据结构"""
        missing = [k for k in required_keys if k not in data]
        if missing:
            raise ValueError(f"缺少必要字段: {missing}")
        return True

# 使用示例
data = DataImporter.import_json("user.json")
print(f"导入数据: {data}")

# 验证结构
try:
    DataImporter.validate_schema(data, ["name", "age", "email"])
except ValueError as e:
    print(f"验证失败: {e}")

导入数据: {'name': '张三', 'age': 25, 'skills': ['Python', 'Java']}
验证失败: 缺少必要字段: ['email']