flask多app源码分析

from flask import Flask
from werkzeug.wsgi import DispatcherMiddleware
from werkzeug.serving import run_simple
from flask import Flask,current_app

app1=Flask(‘app01‘)

app2 = Flask(‘app02‘)

@app1.route(‘/hello1‘)
def hello_world1():

    return ‘Hello World111!‘


@app2.route(‘/hello2‘)
def hello_world2():

    return ‘Hello World222!‘

# app1这样写 不用加任何前缀 但是如果带了前缀 必须带前缀 访问app2
app = DispatcherMiddleware(app1, {
    ‘/app02‘: app2
})

if __name__ == ‘__main__‘:
    # run_simple 第三个参数 进来执行__call__
    run_simple(‘127.0.0.1‘,5000,app)

class DispatcherMiddleware(object):
    """Combine multiple applications as a single WSGI application.
    Requests are dispatched to an application based on the path it is
    mounted under.

    :param app: The WSGI application to dispatch to if the request
        doesn‘t match a mounted path.
    :param mounts: Maps path prefixes to applications for dispatching.
    """
    """
    app=DispatcherMiddleware(app1,{
    ‘/app02‘:app2
        })
    """

    def __init__(self, app, mounts=None):
        self.app = app
        self.mounts = mounts or {}

    def __call__(self, environ, start_response):
        # 拿到当前请求的url
        script = environ.get("PATH_INFO", "")
        #print("script===>",script)
        path_info = ""
        # 第一次 /app02/hello2 不在 不进if 判断
        # 第二次 /app02 进来之后就找到对应app
        while "/" in script:
            if script in self.mounts:
                app = self.mounts[script]
                break
            # 切割 script, last_item=[/app02,hello2]
            script, last_item = script.rsplit("/", 1)
            # path_info= ‘/hello2‘
            path_info = "/%s%s" % (last_item, path_info)
        else:
            # while else 如果while循环正常循环完成 没有被break 打断就会执行else 否则则执行
            # for else 同理
            # 这里如果默认请求第一个app01 第一次 scrpit 就是/hello1
            # 经过script, last_item = script.rsplit("/", 1) 之后就是hello1 走这里
            app = self.mounts.get(script, self.app)

        original_script_name = environ.get("SCRIPT_NAME", "")
        print("original_script_name===>", original_script_name)
        environ["SCRIPT_NAME"] = original_script_name + script
        # 重新赋值 后续需要使用路由进行匹配视图函数
        environ["PATH_INFO"] = path_info
        # app加括号调用执行__call__方法  后续和但实力一样 蓝图同样可以实现 不过是多个蓝图挂载到一个实例上
        return app(environ, start_response)