Django如何启动源码分析

启动

我们启动Django是通过python manage.py runsever的命令

解决

这句话就是执行manage.py文件，并在命令行发送一个runsever字符串

解析manage.py

#!/usr/bin/env python

import os

import sys

if __name__ == "__main__":

	#os.environ.setdefault 方法可以修改系统环境变量，但是只能os.environ 只能影响到当前运行程序

    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "zx2.settings")

    try:

    	#导入模块，其实这里不单单只是导入execute_from_command_line这个方法，更多的是检查Django的模块，配置是否有问题

        from django.core.management import execute_from_command_line

    except ImportError:

        # The above import may fail for some other reason. Ensure that the

        # issue is really that Django is missing to avoid masking other

        # exceptions on Python 2.

        try:

        	#精准判断是不是django模块的问题

            import django

        except ImportError:

            raise ImportError(

                "Couldn't import Django. Are you sure it's installed and "

                "available on your PYTHONPATH environment variable? Did you "

                "forget to activate a virtual environment?"

            )

        raise

    #sys.argv是从外部获取参数，最后执行下面这个方法

    execute_from_command_line(sys.argv)

测试sys.argv

发现两种启动获取的参数不一样，但是第二个参数一样

命令行启动项目

['manage.py', 'runserver']

pycharm 启动项目

['C:/Users/Administrator/Desktop/01python/django/zx1/manage.py', 'runserver', '127.0.0.1:8000']

解析execute_from_command_line(sys.argv)

项目启动入口

def execute_from_command_line(argv=None):

    """

    管理应用程序的简单方法

    A simple method that runs a ManagementUtility.

    """

    utility = ManagementUtility(argv)

    utility.execute()

ManagementUtility初始化代码

class ManagementUtility(object):

    """

    封装django-admin 和 manage.py的公共逻辑代码

    Encapsulates the logic of the django-admin and manage.py utilities.

    """

    def __init__(self, argv=None):

    	#把argv给self对象

        self.argv = argv or sys.argv[:]

        #返回path最后的文件名。若path以/或\结尾，那么就会返回空值，为zx1

        self.prog_name = os.path.basename(self.argv[0])

        self.settings_exception = None

utility.execute()分析

    def execute(self):

        """

        给定命令行参数，这将确定哪个子命令将要被运行，创建一个适合该命令的解析器，并运行它。

        Given the command-line arguments, this figures out which subcommand is

        being run, creates a parser appropriate to that command, and runs it.

        """

        try:

        	#self.argv[1]值为runserver

            subcommand = self.argv[1]

        except IndexError:

            subcommand = 'help'  # Display help if no arguments were given.

		#预处理选项以提取--settings和--pythonpath。

        # Preprocess options to extract --settings and --pythonpath.

        #这些选项可能会影响可用的命令，因此

        # These options could affect the commands that are available, so they

        #必须提前处理。

        # must be processed early.

        #创建一个命令分析器

        parser = CommandParser(None, usage="%(prog)s subcommand [options] [args]", add_help=False)

        parser.add_argument('--settings')

        parser.add_argument('--pythonpath')

        parser.add_argument('args', nargs='*')  # catch-all

        try:

        	#self.argv[2:]值为'127.0.0.1:8000'，可以推断出这部分可能和启动服务器有关，并且有默认的ip和端口号

            options, args = parser.parse_known_args(self.argv[2:])

            handle_default_options(options)

        except CommandError:

            pass  # Ignore any option errors at this point.

        try:

        #获取app配置信息

            settings.INSTALLED_APPS

        except ImproperlyConfigured as exc:

            self.settings_exception = exc

        if settings.configured:

            # Start the auto-reloading dev server even if the code is broken.

            # The hardcoded condition is a code smell but we can't rely on a

            # flag on the command class because we haven't located it yet.

            #判断外部输入命令，这部分就是启动的核心代码了

            if subcommand == 'runserver' and '--noreload' not in self.argv:

                try:

                    autoreload.check_errors(django.setup)()

                except Exception:

                    # The exception will be raised later in the child process

                    # started by the autoreloader. Pretend it didn't happen by

                    # loading an empty list of applications.

                    apps.all_models = defaultdict(OrderedDict)

                    apps.app_configs = OrderedDict()

                    apps.apps_ready = apps.models_ready = apps.ready = True

                    # Remove options not compatible with the built-in runserver

                    # (e.g. options for the contrib.staticfiles' runserver).

                    # Changes here require manually testing as described in

                    # #27522.

                    _parser = self.fetch_command('runserver').create_parser('django', 'runserver')

                    _options, _args = _parser.parse_known_args(self.argv[2:])

                    for _arg in _args:

                        self.argv.remove(_arg)

            # In all other cases, django.setup() is required to succeed.

            else:

                django.setup()

        self.autocomplete()

        if subcommand == 'help':

            if '--commands' in args:

                sys.stdout.write(self.main_help_text(commands_only=True) + '\n')

            elif len(options.args) < 1:

                sys.stdout.write(self.main_help_text() + '\n')

            else:

                self.fetch_command(options.args[0]).print_help(self.prog_name, options.args[0])

        # Special-cases: We want 'django-admin --version' and

        # 'django-admin --help' to work, for backwards compatibility.

        elif subcommand == 'version' or self.argv[1:] == ['--version']:

            sys.stdout.write(django.get_version() + '\n')

        elif self.argv[1:] in (['--help'], ['-h']):

            sys.stdout.write(self.main_help_text() + '\n')

        else:

            self.fetch_command(subcommand).run_from_argv(self.argv)

后续代码有点看的迷糊了，没有找到socket启动的部分，以后再来