接口类和抽象类【python、java】
https://www.cnblogs.com/Eva-J/articles/7293890.html
- java
# java里的所有类的继承都是单继承,所以抽象类完美的解决了单继承需求中的规范问题
# 但对于多继承的需求，由于java本身语法的不支持，所以创建了接口Interface这个概念来解决多继承的规范问题
# 体会接口就是一种规范
/*
* 接口的使用
* 1.接口使用上也满足多态性
* 2.接口，实际上就是定义了一种规范
* 3.开发中，体会面向接口编程！
*/
public class USBTest {
public static void main(String[] args) {
Computer com = new Computer();
//1.创建了接口的非匿名实现类的非匿名对象
Flash flash = new Flash();
com.transferData(flash);
//2. 创建了接口的非匿名实现类的匿名对象
com.transferData(new Printer());
//3. 创建了接口的匿名实现类的非匿名对象
USB phone = new USB(){
@Override
public void start() {
System.out.println("手机开始工作");
}
@Override
public void stop() {
System.out.println("手机结束工作");
}
};
com.transferData(phone);
//4. 创建了接口的匿名实现类的匿名对象
com.transferData(new USB(){
@Override
public void start() {
System.out.println("mp3开始工作");
}
@Override
public void stop() {
System.out.println("mp3结束工作");
}
});
}
}
class Computer{
public void transferData(USB usb){//USB usb = new Flash();
usb.start();
System.out.println("具体传输数据的细节");
usb.stop();
}
}
interface USB{
//常量：定义了长、宽、最大最小的传输速度等
void start();
void stop();
}
class Flash implements USB{
@Override
public void start() {
System.out.println("U盘开启工作");
}
@Override
public void stop() {
System.out.println("U盘结束工作");
}
}
class Printer implements USB{
@Override
public void start() {
System.out.println("打印机开启工作");
}
@Override
public void stop() {
System.out.println("打印机结束工作");
}
}
- python
# python中没有接口类 ：
# python中自带多继承 所以我们直接用class来实现了接口类
# python中支持抽象类 ： 一般情况下 单继承 不能实例化
# 且可以实现python代码
# 抽象类
import abc #利用abc模块实现抽象类
class All_file(metaclass=abc.ABCMeta):
all_type='file'
@abc.abstractmethod #定义抽象方法，无需实现功能
def read(self):
'子类必须定义读功能'
with open('filaname') as f:
pass
@abc.abstractmethod #定义抽象方法，无需实现功能
def write(self):
'子类必须定义写功能'
pass
class Txt(All_file): #子类继承抽象类，但是必须定义read和write方法
def read(self):
print('文本数据的读取方法')
def write(self):
print('文本数据的读取方法')
class Sata(All_file): #子类继承抽象类，但是必须定义read和write方法
def read(self):
print('硬盘数据的读取方法')
def write(self):
print('硬盘数据的读取方法')
class Process(All_file): #子类继承抽象类，但是必须定义read和write方法
def read(self):
print('进程数据的读取方法')
def write(self):
print('进程数据的读取方法')
wenbenwenjian=Txt()
yingpanwenjian=Sata()
jinchengwenjian=Process()
#这样大家都是被归一化了,也就是一切皆文件的思想
wenbenwenjian.read()
yingpanwenjian.write()
jinchengwenjian.read()
print(wenbenwenjian.all_type)
print(yingpanwenjian.all_type)
print(jinchengwenjian.all_type)
# 接口类
from abc import abstractmethod,ABCMeta
class Swim_Animal(metaclass=ABCMeta):
@abstractmethod
def swim(self):pass
class Walk_Animal(metaclass=ABCMeta):
@abstractmethod
def walk(self):pass
class Fly_Animal(metaclass=ABCMeta):
@abstractmethod
def fly(self):pass
class Tiger(Walk_Animal,Swim_Animal):
def walk(self):
pass
def swim(self):
pass
class OldYing(Fly_Animal,Walk_Animal):pass
class Swan(Swim_Animal,Walk_Animal,Fly_Animal):pass
- 源码中
https://stackoverflow.com/questions/100003/what-are-metaclasses-in-python
https://www.liaoxuefeng.com/wiki/1016959663602400/1017592449371072
#robot
# 定义
# Copied from Jinja2, released under the BSD license.
# https://github.com/mitsuhiko/jinja2/blob/743598d788528921df825479d64f492ef60bef82/jinja2/_compat.py#L88
def with_metaclass(meta, *bases):
"""Create a base class with a metaclass."""
# This requires a bit of explanation: the basic idea is to make a
# dummy metaclass for one level of class instantiation that replaces
# itself with the actual metaclass.
class metaclass(type):
def __new__(cls, name, this_bases, d):
return meta(name, bases, d)
return type.__new__(metaclass, 'temporary_class', (), {})
# 使用
@py2to3
class ModelObject(with_metaclass(SetterAwareType, object)):
__slots__ = []
def copy(self, **attributes):
"""Return shallow copy of this object.
:param attributes: Attributes to be set for the returned copy
automatically. For example, ``test.copy(name='New name')``.
See also :meth:`deepcopy`. The difference between these two is the same
as with the standard ``copy.copy`` and ``copy.deepcopy`` functions
that these methods also use internally.
New in Robot Framework 3.0.1.
"""
copied = copy.copy(self)
for name in attributes:
setattr(copied, name, attributes[name])
return copied
