Gmail API快速入门：Can'；t安装Python Google客户端库

我正试图在我的Mac电脑上运行（Mojave 10.14.5）

我已经安装了Google客户端库，如下所示：

sudo -H pip install --upgrade google-api-python-client google-auth-httplib2 google-auth-oauthlib

这是输出：

DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7.
Requirement already up-to-date: google-api-python-client in /private/var/root/Library/Python/2.7/lib/python/site-packages (1.7.9)
Requirement already up-to-date: google-auth-httplib2 in /private/var/root/Library/Python/2.7/lib/python/site-packages (0.0.3)
Requirement already up-to-date: google-auth-oauthlib in /private/var/root/Library/Python/2.7/lib/python/site-packages (0.3.0)
Requirement already satisfied, skipping upgrade: httplib2<1dev,>=0.9.2 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from google-api-python-client) (0.12.3)
Requirement already satisfied, skipping upgrade: uritemplate<4dev,>=3.0.0 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from google-api-python-client) (3.0.0)
Requirement already satisfied, skipping upgrade: six<2dev,>=1.6.1 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from google-api-python-client) (1.12.0)
Requirement already satisfied, skipping upgrade: google-auth>=1.4.1 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from google-api-python-client) (1.6.3)
Requirement already satisfied, skipping upgrade: requests-oauthlib>=0.7.0 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from google-auth-oauthlib) (1.2.0)
Requirement already satisfied, skipping upgrade: cachetools>=2.0.0 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from google-auth>=1.4.1->google-api-python-client) (3.1.1)
Requirement already satisfied, skipping upgrade: rsa>=3.1.4 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from google-auth>=1.4.1->google-api-python-client) (4.0)
Requirement already satisfied, skipping upgrade: pyasn1-modules>=0.2.1 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from google-auth>=1.4.1->google-api-python-client) (0.2.5)
Requirement already satisfied, skipping upgrade: requests>=2.0.0 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from requests-oauthlib>=0.7.0->google-auth-oauthlib) (2.22.0)
Requirement already satisfied, skipping upgrade: oauthlib>=3.0.0 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from requests-oauthlib>=0.7.0->google-auth-oauthlib) (3.0.1)
Requirement already satisfied, skipping upgrade: pyasn1>=0.1.3 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from rsa>=3.1.4->google-auth>=1.4.1->google-api-python-client) (0.4.5)
Requirement already satisfied, skipping upgrade: urllib3!=1.25.0,!=1.25.1,<1.26,>=1.21.1 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from requests>=2.0.0->requests-oauthlib>=0.7.0->google-auth-oauthlib) (1.25.3)
Requirement already satisfied, skipping upgrade: certifi>=2017.4.17 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from requests>=2.0.0->requests-oauthlib>=0.7.0->google-auth-oauthlib) (2019.3.9)
Requirement already satisfied, skipping upgrade: chardet<3.1.0,>=3.0.2 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from requests>=2.0.0->requests-oauthlib>=0.7.0->google-auth-oauthlib) (3.0.4)
Requirement already satisfied, skipping upgrade: idna<2.9,>=2.5 in /private/var/root/Library/Python/2.7/lib/python/site-packages (from requests>=2.0.0->requests-oauthlib>=0.7.0->google-auth-oauthlib) (2.8)

弃用：Python 2.7将于2020年1月1日结束其生命周期。请升级您的Python，因为Python 2.7将在该日期后不再维护。pip的未来版本将放弃对Python2.7的支持。
需求已经是最新的：google api python client in/private/var/root/Library/python/2.7/lib/python/site-packages（1.7.9）
需求已经更新：google-auth-httplib2 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（0.0.3）
需求已经更新：googleauth oauthlib in/private/var/root/Library/Python/2.7/lib/Python/site-packages（0.3.0）
已满足要求，跳过升级：httplib2=0.9.2 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（来自google api Python客户端）（0.12.3）
已满足要求，跳过升级：uritemplate=3.0.0 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（来自google api Python客户端）（3.0.0）
已满足要求，跳过升级：six=1.6.1 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（来自google api Python客户端）（1.12.0）
已满足要求，跳过升级：google auth>=1.4.1 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（来自google api Python客户端）（1.6.3）
已满足要求，跳过升级：在/private/var/root/Library/Python/2.7/lib/Python/site-packages中请求oauthlib>=0.7.0（来自google auth oauthlib）（1.2.0）
已满足要求，跳过升级：cachetools>=2.0.0 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（来自google auth>=1.4.1->google api Python客户端）（3.1.1）
已满足要求，跳过升级：rsa>=3.1.4 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（来自google auth>=1.4.1->google api Python客户端）（4.0）
已满足要求，跳过升级：pyasn1模块>=0.2.1 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（来自google auth>=1.4.1->google api Python客户端）（0.2.5）
已满足要求，跳过升级：在/private/var/root/Library/Python/2.7/lib/Python/site-packages中请求>=2.0.0（来自请求oauthlib>=0.7.0->google auth oauthlib）（2.22.0）
已满足要求，跳过升级：oauthlib>=3.0.0 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（从请求oauthlib>=0.7.0->google auth oauthlib）（3.0.1）
已满足要求，跳过升级：pyasn1>=0.1.3 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（来自rsa>=3.1.4->google auth>=1.4.1->google api Python客户端）（0.4.5）
已满足要求，正在跳过升级：urllib3=1.25.0,!=1.25.1，=1.21.1 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（从请求>=2.0.0->请求oauthlib>=0.7.0->谷歌认证oauthlib）（1.25.3）
已满足要求，跳过升级：certifi>=2017.4.17 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（从请求>=2.0.0->请求oauthlib>=0.7.0->谷歌认证oauthlib）（2019.3.9）
已满足要求，跳过升级：chardet=3.0.2 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（从请求>=2.0.0->请求oauthlib>=0.7.0->谷歌认证oauthlib）（3.0.4）
已满足要求，跳过升级：idna=2.5 in/private/var/root/Library/Python/2.7/lib/Python/site-packages（从请求>=2.0.0->请求oauthlib>=0.7.0->谷歌认证oauthlib）（2.8）

但当我尝试运行快速启动时：

>python quickstart.py 
Traceback (most recent call last):
  File "quickstart.py", line 4, in <module>
    from googleapiclient.discovery import build
ImportError: No module named googleapiclient.discovery

>python quickstart.py
回溯（最近一次呼叫最后一次）：
文件“quickstart.py”，第4行，在
从GoogleAppClient.discovery导入生成
ImportError:没有名为GoogleAppClient.discovery的模块

现在如果我把第4行注释掉，我会得到：

>python quickstart.py 
Traceback (most recent call last):
  File "quickstart.py", line 5, in <module>
    from google_auth_oauthlib.flow import InstalledAppFlow
ImportError: No module named google_auth_oauthlib.flow

>python quickstart.py 
Traceback (most recent call last):
  File "quickstart.py", line 6, in <module>
    from google.auth.transport.requests import Request
ImportError: No module named google.auth.transport.request

>python quickstart.py
回溯（最近一次呼叫最后一次）：
文件“quickstart.py”，第5行，在
从google_auth_oauthlib.flow导入安装的应用程序流
ImportError:没有名为google_auth_oauthlib.flow的模块

如果我把第5行注释掉，我会得到：

>python quickstart.py 
Traceback (most recent call last):
  File "quickstart.py", line 5, in <module>
    from google_auth_oauthlib.flow import InstalledAppFlow
ImportError: No module named google_auth_oauthlib.flow

>python quickstart.py 
Traceback (most recent call last):
  File "quickstart.py", line 6, in <module>
    from google.auth.transport.requests import Request
ImportError: No module named google.auth.transport.request

>python quickstart.py
回溯（最近一次呼叫最后一次）：
文件“quickstart.py”，第6行，在
从google.auth.transport.requests导入请求
ImportError:没有名为google.auth.transport.request的模块

我还尝试重新启动我的终端，也尝试重新启动我的机器

---

为什么找不到任何Google客户端库模块？

我不知道为什么-但可能Python 2.x不受支持

一旦我转到Python 3.x，一切都正常了：

安装：

sudo -H pip3 install --upgrade google-api-python-client google-auth-httplib2 google-auth-oauthlib

运行脚本：

python3 quickstart.py

---

我不知道为什么——但也许Python2.x不受支持

一旦我转到Python 3.x，一切都正常了：

安装：

sudo -H pip3 install --upgrade google-api-python-client google-auth-httplib2 google-auth-oauthlib

运行脚本：

python3 quickstart.py

---

pip指向python3吗？

/Library/Python/2.7/site-packages/pip（Python 2.7）

pip指向python3吗？

/Library/Python/2.7/site-packages/pip（Python 2.7）中的pip-V pip 19.1.1

您还应该添加一些解释。您还应该添加一些解释。