ImportError- No module named flask

当(dang)你看到这个错误信息“ImportError: No module named flask”时，这意味着你的Python环境中没(mei)有安装Flask模块，Flask是一个轻量级的Web应用框架，它可(ke)以(yi)让你快速地构建Web应用程序，为了解决这个问题，你(ni)需要按照以下步骤在Python环境中安装Flask模块。（图片来源网络，侵删）

1、检查Python版本

你需要确保(bao)你的Python环境是2.7.x或3.4以上的版本，因为(wei)Flask 0.10及以后的版本不再支(zhi)持Python 2.6和2.7，你(ni)可以通过在命令行中输入以(yi)下命令来查看你的(de)Python版本：

python version

2、安装pip

pip version

如(ru)果(guo)你还没有安装pip，你可(ke)以访问pip官网（https://pip.pypa.io/en/stable/installing/）下载并安装。

3、安装Flask

现在你已经确保了你的Python环境和pip都已经(jing)就绪，接下来就可以安装Flask模块了，在(zai)命令行中输入以下命令：

pip install Flask

等待安装完成后，你就可以在你的Python代码中(zhong)导入Flask模块了。

from flask import Flaskapp = Flask(__name__)@app.route('/')def hello(): return 'Hello, World!'if __name__ == '__main__': app.run()

4、使用虚拟环境

为了(le)避免不同项目之间的依赖冲突，建议你使用虚拟环境（virtualenv）来管理你的(de)Python项目，虚拟环境可以为每个项目创建一个独立的Python运行环境，这样你可以为每个项目安装不同的(de)依赖包，要使用虚拟环境，请按照以下步骤操作(zuo)：

确保(bao)你已(yi)经安装了virtualenv，如果没有，可以通过以下命令安装：

pip install virtualenv

在你的项目目录下创建一个虚拟环境。

virtualenv myproject_env

接下来，激活虚拟环境，在Windows上，输入以下命令：

myproject_envScriptsactivate

在Linux或Mac上，输入以下命令：

source myproject_env/bin/activate

现在，你(ni)可以在虚拟环境中安装Flask和其他依赖包了。

pip install Flask gunicorn httpie requests blinker itsdangerous Jinja2 Werkzeug MarkupSafe click waitress passlib getpass PyYAML configparser urllib3 chardet idna cryptography pyOpenSSL certifi requests[security] twilio requests_oauthlib pythondateutil pytz boto3 googleapipythonclient googleauthhttplib2 googleauthoauthlib googleauthurllib3 gspread oauth2client pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib poplib kazoo cloudpickle msgpackpython simplejson cffi cryptography pyOpenSSL ndghttpsclient pyasn1 rsa pycrypto mock futures backports mockredis six mimetypes email idna chardet dnspython urllib3 netifaces ipaddress ftplib ndghttpsclient pyparsing imapclient imaplib smtplib pop