直接上代码。

代码部分：

#Python 3.5
#Author: A_lPha
#Blog: http://blog.csdn.net/a_lpha

import json
from urllib.request import urlopen
from urllib.error import HTTPError

print("*" * 8,"网易云音乐下载器", "*" * 8,"\n")
ID = input('请输入歌曲ID:\n>>> ')
url = "http://music.163.com/api/song/detail/?ids=[" + ID + "]" #这个URL比较重要
html = urlopen(url).read().decode("utf-8")
rejson = json.loads(html)
for name in rejson['songs']:
    print('歌曲ID: ',name['id'])
    print('歌曲名称: ',''.join(name['name']))
    print('歌手: ',''.join(names['name'] for names in name['artists']))
    print('mp3链接: ',name['mp3Url'])

num = int(input('\n是否下载?(输入1下载该歌曲,输入其他数字关闭程序.)\n'))
if num == 1:
    try:
        f = open(str(''.join(name['name']) + "-" + ''.join(names['name'] for names in name['artists'])) + ".mp3", "wb")
        req = urlopen(name['mp3Url'])
        buf = req.read()
        f.write(buf)
        f.close()
        print("已保存")
    except HTTPError as e:
        print("遇到错误啦! 错误代码是这个: \n",">>>>>>",e,"<<<<<<","\n我猜这是付费歌曲的'ID'，可能是网站不让下载吧！")
elif num != 1:
    print("已关闭")

找网易云音乐歌曲的ID方法：在网易云音乐搜索到该歌曲，打开播放页面，在浏览器地址栏后显示该歌曲ID。

电影《功夫瑜伽》主题曲

一般情况下可以找到歌曲的链接，付费歌曲也可以找到链接，但是返回404错误。

代码很简单，现在还没发现其他问题。

今天更新了这段代码：

#Python 3.5
#Author: A_lPha
#Blog: http://blog.csdn.net/a_lpha

import json
import time
from urllib.request import urlopen
from urllib.error import HTTPError

print("*" * 8,"网易云音乐下载器", "*" * 8,"\n")

def getId():
    try:
        ID = int(input('请输入歌曲ID:\n>>> '))
        print("正在查询，请稍后...\n")
        time.sleep(0.9)
        return ID
    except:
        print("请输入正确的ID！\n")
        getId()

def getInformations(ID):
    print("--"*4,"查询结果","--"*4)
    try:
        ID = str(ID)
        url = "http://music.163.com/api/song/detail/?ids=["+ID+"]"
        html = urlopen(url).read().decode("utf-8")
        rejson = json.loads(html)
        for informations in rejson['songs']:
            print('歌曲ID: ', informations['id'])
            print('歌曲名称: ', ''.join(informations['name']))
            print('歌手: ', ''.join(names['name'] for names in informations['artists']))
            print('mp3链接: ', informations['mp3Url'])
        song = ''.join(informations['name'])
        name = ''.join(names['name'] for names in informations['artists'])
        mp3url = informations['mp3Url']
        return song,name,mp3url
    except:
        print("这个可能不是正确的ID哦！重新试试吧。")
        id = getId()
        song, name, mp3url = getInformations(id)
        getUrl(song, name, mp3url)
def getUrl(song,name,mp3url):
    print("-"*9, "下载", "-"*9)
    num = int(input('是否下载?(输入1下载该歌曲,输入其他数字关闭程序.)\n'))
    if num == 1:
        try:
            filename = str(song + "-" + name)
            with open(filename + ".mp3", "wb") as mp:
                infor = urlopen(mp3url).read()
                mp.write(infor)
            print("已保存！")
        except HTTPError as e:
            print("遇到错误啦! 错误代码是这个: \n", ">>>>>>", e, "<<<<<<", "\n我猜这是付费歌曲的'ID'，可能是网站不让下载吧！")
    elif num != 1:
        print("已关闭。")

id = getId()
song, name, mp3url = getInformations(id)
getUrl(song, name, mp3url)