设计模式之代理模式

设计模式之代理模式

from abc import ABCMeta,abstractmethod


# -------------------------接口,用于约束
class Theme(metaclass=ABCMeta):
    @abstractmethod
    def get_content(self):
        pass

class RealTheme(Theme):
    def __init__(self,filepath):
        self.filepath = filepath
        print('获取文件%s详情'%self.filepath)
        f = open(filepath)
        self.content = f.read()
        f.close()
    def get_content(self):
        return self.content
    def set_content(self,content):
        #
        f = open(self.filepath,'w')
        f.write(content)
        f.close()


class ProxyA(Theme):
    def __init__(self,filepath):
        self.theme = RealTheme(filepath)
    def get_content(self):
        return self.theme.get_content()



class ProxyB(Theme):
    # 虚代理
    def __init__(self,filepath):
        self.filepath = filepath
        self.theme = None
    def get_content(self):
        # 按需分配,根据需要去创建对象,减少资源的浪费
        if not self.theme:
            self.theme = RealTheme(self.filepath)
        return self.theme.get_content()



class ProxyC(Theme):
    # 保护代理
    def __init__(self,filepath):
        self.theme = RealTheme(filepath)
    def get_content(self):
        return self.theme.get_content()
    def set_content(self):
        # 进行权限配置,根据不同身份来配置权限控制用户的写操作
        raise PermissionError


    
# b = ProxyB('abc.txt')
# print(b.get_content())

c = ProxyC('abc.txt')
print(c.get_content())