原理：哈弗赛恩公式

import math

def calculate_distance(lat1, lon1, lat2, lon2):
    R = 6371  # 地球半径，单位为千米
    rad = lambda angle: angle * math.pi / 180  # 将角度转换为弧度

    lat1_rad = rad(lat1)
    lon1_rad = rad(lon1)
    lat2_rad = rad(lat2)
    lon2_rad = rad(lon2)

    dLat = lat2_rad - lat1_rad
    dLon = lon2_rad - lon1_rad

    a = math.sin(dLat / 2) ** 2 + math.cos(lat1_rad) * math.cos(lat2_rad) * math.sin(dLon / 2) ** 2
    c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a))

    distance = R * c  # 返回单位为千米的距离
    return distance

# 示例用法
lat1 = 34.444444  # 北京的经纬度
lon1 = 112.257778
lat2 = 34.419  # 上海的经纬度
lon2 = 111.876

distance = calculate_distance(lat1, lon1, lat2, lon2)
print(distance)  # 输出直线距离（单位：千米）