Python如何解析JSON？数据交换格式详解

json.loads()

import json

# 假设这是我们从网络上获取到的JSON字符串
json_string = '''
{
    "name": "张三",
    "age": 30,
    "isStudent": false,
    "courses": ["数学", "物理", "化学"],
    "address": {
        "street": "科技园路1号",
        "city": "深圳"
    },
    "grades": null
}
'''

# 使用json.loads()解析字符串
try:
    data = json.loads(json_string)
    print("解析成功！数据类型：", type(data))
    print("姓名：", data['name'])
    print("第一门课程：", data['courses'][0])
    print("城市：", data['address']['city'])
except json.JSONDecodeError as e:
    print(f"解析JSON字符串时出错：{e}")

.json

json.load()

import json
import os

# 模拟创建一个JSON文件
file_name = 'config.json'
file_content = '''
{
    "database": {
        "host": "localhost",
        "port": 5432,
        "user": "admin"
    },
    "api_keys": {
        "google": "xyz123",
        "baidu": "abc456"
    }
}
'''

with open(file_name, 'w', encoding='utf-8') as f:
    f.write(file_content)

# 使用json.load()解析文件
try:
    with open(file_name, 'r', encoding='utf-8') as f:
        config_data = json.load(f)
    print("\n从文件解析成功！")
    print("数据库主机：", config_data['database']['host'])
    print("百度API密钥：", config_data['api_keys']['baidu'])
except FileNotFoundError:
    print(f"文件 '{file_name}' 未找到。")
except json.JSONDecodeError as e:
    print(f"解析JSON文件时出错：{e}")
finally:
    # 清理：删除模拟文件
    if os.path.exists(file_name):
        os.remove(file_name)

{
    "company": {
        "name": "Tech Solutions Inc.",
        "location": "San Francisco",
        "departments": [
            {
                "name": "Engineering",
                "employees": [
                    {"id": "E001", "name": "Alice", "skills": ["Python", "Java"]},
                    {"id": "E002", "name": "Bob", "skills": ["JavaScript", "Node.js"]}
                ]
            },
            {
                "name": "Marketing",
                "employees": [
                    {"id": "M001", "name": "Charlie", "campaigns": ["Spring Sale", "Winter Promo"]}
                ]
            }
        ]
    },
    "metadata": {
        "version": "1.0",
        "last_updated": "2023-10-27"
    }
}

import json

complex_json_string = '''
{
    "company": {
        "name": "Tech Solutions Inc.",
        "location": "San Francisco",
        "departments": [
            {
                "name": "Engineering",
                "employees": [
                    {"id": "E001", "name": "Alice", "skills": ["Python", "Java"]},
                    {"id": "E002", "name": "Bob", "skills": ["JavaScript", "Node.js"]}
                ]
            },
            {
                "name": "Marketing",
                "employees": [
                    {"id": "M001", "name": "Charlie", "campaigns": ["Spring Sale", "Winter Promo"]}
                ]
            }
        ]
    },
    "metadata": {
        "version": "1.0",
        "last_updated": "2023-10-27"
    }
}
'''

data = json.loads(complex_json_string)

# 获取公司名称
company_name = data['company']['name']
print(f"公司名称: {company_name}")

# 获取Engineering部门的Bob的技能
# data['company'] 是一个字典
# data['company']['departments'] 是一个列表
# data['company']['departments'][0] 是列表的第一个元素，即Engineering部门的字典
# data['company']['departments'][0]['employees'] 是Engineering部门员工的列表
# data['company']['departments'][0]['employees'][1] 是Bob的字典
# data['company']['departments'][0]['employees'][1]['skills'] 是Bob的技能列表
bob_skills = data['company']['departments'][0]['employees'][1]['skills']
print(f"Bob的技能: {bob_skills}")

# 获取Marketing部门第一个员工的ID
# data['company']['departments'][1] 是Marketing部门的字典
# data['company']['departments'][1]['employees'][0] 是Marketing部门第一个员工的字典
marketing_first_employee_id = data['company']['departments'][1]['employees'][0]['id']
print(f"Marketing部门第一个员工的ID: {marketing_first_employee_id}")

# 获取元数据中的版本号
metadata_version = data['metadata']['version']
print(f"元数据版本: {metadata_version}")

KeyError

IndexError

get()

try-except

# 尝试安全地获取一个可能不存在的值
# 如果'company'下没有'address'键，返回None而不是抛出错误
company_address = data.get('company', {}).get('address', '地址未知')
print(f"公司地址: {company_address}")

# 尝试获取一个可能不存在的员工的技能
try:
    non_existent_employee_skills = data['company']['departments'][0]['employees'][99]['skills']
    print(f"不存在员工的技能: {non_existent_employee_skills}")
except (KeyError, IndexError) as e:
    print(f"获取不存在员工技能时捕获到错误: {e}")