解决pip安装时出现SSLError的问题

错误代码：

C:\Python27\lib\site-packages\pip\_vendor\urllib3\util\ssl_.py:150: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  InsecurePlatformWarning
  Could not fetch URL https://pypi.org/simple/pygame/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/pygame/ (Caused by SSLError(SSLError(1, '_ssl.c:499: error:1407742E:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version'),)) - skipping

出现这个问题的原因是安装源的证书不受信任，可更改pip的配置文件解决这个问题：
更改配置文件首先要知道配置文件在哪，通过阅读pip的源码：
以下是pip源码

if WINDOWS:
    bin_py = os.path.join(sys.prefix, 'Scripts')
    bin_user = os.path.join(user_site, 'Scripts')
    # buildout uses 'bin' on Windows too?
    if not os.path.exists(bin_py):
        bin_py = os.path.join(sys.prefix, 'bin')
        bin_user = os.path.join(user_site, 'bin')

    config_basename = 'pip.ini'

    legacy_storage_dir = os.path.join(user_dir, 'pip')
    legacy_config_file = os.path.join(
        legacy_storage_dir,
        config_basename,
    )
else:
    bin_py = os.path.join(sys.prefix, 'bin')
    bin_user = os.path.join(user_site, 'bin')

    config_basename = 'pip.conf'

    legacy_storage_dir = os.path.join(user_dir, '.pip')
    legacy_config_file = os.path.join(
        legacy_storage_dir,
        config_basename,
    )
    # Forcing to use /usr/local/bin for standard macOS framework installs
    # Also log to ~/Library/Logs/ for use with the Console.app log viewer
    if sys.platform[:6] == 'darwin' and sys.prefix[:16] == '/System/Library/':
        bin_py = '/usr/local/bin'

可以发现
在windows下的路径为： [用户文件夹]/pip/pip.ini
其他系统为：[用户文件夹]/.pip/pip.conf

我是在windows系统下，依次进入 用户 > Administrator

发现并没有pip文件夹。没关系我们可以自己新建一个文件夹命名为pip

并在pip文件夹下创建pip.ini文件

用记事本打开，输入如下配置信息

[global]  
index-url = http://pypi.douban.com/simple
trusted-host = pypi.douban.com
disable-pip-version-check = true
timeout = 120  

[list]
format = columns

index-url 这里设置的为豆瓣源
trusted-host 意思是信任这个地址（这就免去了ssl验证）
disable-pip-version-check = true 设置不检查版本

format = columns 这里是设置使用pip list命令时输出的样式，输入pip config list
效果:

看到这个效果，证明配置文件已经生效了。