适配器模式 - GeHaha/PythonLibrary GitHub Wiki

适配器模式又叫变压器模式，也叫包装模式（Wrapper），它的核心思想是将一个对象经过包装或转换后使它符合指定的接口，使得调用方可以像使用这接口的一般对象一样使用它。

  • 适配器模式的模型抽象

适配器模式

代码实现如下

`class Page:

"电子书一页的内容"
def __init__(self, pageNum):
    self.__pageNum = pageNum

def getContent(self):
    return "第 " + str(self.__pageNum) + " 页的内容..."

class Catalogue: "目录结构"

def __init__(self, title):
    self.__title = title
    self.__chapters = []
    self.setChapter("第一章")
    self.setChapter("第二章")

def setChapter(self, title):
    self.__chapters.append(title)

def showInfo(self):
    print("标题：" + self.__title)
    for chapter in self.__chapters:
        print(chapter)

class IBook: "电子书文档的接口类"

def parseFile(self, filePath):
    pass

def getCatalogue(self):
    pass

def getPageCount(self):
    pass

def getPage(self, pageNum):
    pass

class TxtBook(IBook): "TXT解析类"

def parseFile(self, filePath):
    # 模拟文档的解析
    print(filePath + " 文件解析成功")
    self.__pageCount = 500
    return True

def getCatalogue(self):
    return Catalogue("TXT电子书")

def getPageCount(self):
    return self.__pageCount

def getPage(self, pageNum):
    return Page(pageNum)

class EpubBook(IBook): "TXT解析类"

def parseFile(self, filePath):
    # 模拟文档的解析
    print(filePath + " 文件解析成功")
    self.__pageCount = 800
    return True

def getCatalogue(self):
    return Catalogue("Epub电子书")

def getPageCount(self):
    return self.__pageCount

def getPage(self, pageNum):
    return Page(pageNum)

class Outline: "第三方PDF解析库的目录类" pass

class PdfPage: "PDF页"

def __init__(self, pageNum):
    self.__pageNum = pageNum

def getPageNum(self):
    return self.__pageNum

class ThirdPdf: "第三方PDF解析库"

def __init__(self):
    self.__pageSize = 0

def open(self, filePath):
    print("第三方解析PDF文件：" + filePath)
    self.__pageSize = 1000
    return True

def getOutline(self):
    return Outline()

def pageSize(self):
    return self.__pageSize

def page(self, index):
    return PdfPage(index)

class PdfAdapterBook(ThirdPdf, IBook): "TXT解析类"

def parseFile(self, filePath):
    # 模拟文档的解析
    rtn = super().open(filePath)
    if(rtn):
        print(filePath + "文件解析成功")
    return rtn

def getCatalogue(self):
    outline = super().getOutline()
    print("将Outline结构的目录转换成Catalogue结构的目录")
    return Catalogue("PDF电子书")

def getPageCount(self):
    return super().pageSize()

def getPage(self, pageNum):
    page = self.page(pageNum)
    print("将PdfPage的面对象转换成Page的对象")
    return Page(page.getPageNum())`
  • 应用场景
  1. 系统需要使用现有的类，而这些类的接口不符合现有系统的要求。
  2. 对已有的系统拓展新功能时，尤其适用于在设计良好的系统框架下增加接入第三方的接口或第三方的 SDK 时。
导入os库

import os

class Reader: "阅读器"

def __init__(self, name):
    self.__name = name
    self.__filePath = ""
    self.__curBook = None
    self.__curPageNum = -1

def __initBook(self, filePath):
    self.__filePath = filePath
    extName = os.path.splitext(filePath)[1]
    if(extName.lower() == ".epub"):
        self.__curBook = EpubBook()
    elif(extName.lower() == ".txt"):
        self.__curBook = TxtBook()
    elif(extName.lower() == ".pdf"):
        self.__curBook = PdfAdapterBook()
    else:
        self.__curBook = None

def openFile(self, filePath):
    self.__initBook(filePath)
    if(self.__curBook is not None):
        rtn = self.__curBook.parseFile(filePath)
        if(rtn):
            self.__curPageNum = 1
        return rtn
    return False

def closeFile(self):
    print("关闭 " + self.__filePath + " 文件")
    return True

def showCatalogue(self):
    catalogue = self.__curBook.getCatalogue()
    catalogue.showInfo()

def prePage(self):
    return self.gotoPage(self.__curPageNum - 1)

def nextPage(self):
    return self.gotoPage(self.__curPageNum + 1)

def gotoPage(self, pageNum):
    if(pageNum < 1 or pageNum > self.__curBook.getPageCount()):
        return None

    self.__curPageNum = pageNum
    print("显示第" + str(self.__curPageNum) + "页")
    page = self.__curBook.getPage(self.__curPageNum)
    page.getContent()
    return page`