当前位置:网站首页>模式-“里氏替换原则”
模式-“里氏替换原则”
2022-07-05 20:48:00 【全栈程序员站长】
大家好,又见面了,我是全栈君
里氏替换原则是,同组的有类的两个子类,在使用子类A这个地方(方法/属性)您可以使用子类 B代替.对于面向接口编程,我只需要确保同样的行为代码;基类的所有子类必须全部 实现,换过来,子类的方法基类不一定都有; 如果:有一个基类Base;其子类是Concrete;那么method(Base b)的调用能够转换成 method(Concrete c); 策略模式:一般,我们把解决某个问题的方法称为一个”算法”,而把解决一类问题的算法封装 成一个接口,那么实现算法的多种方式作为子类;在某个时候,在调用中我们使用算法A替换 算法B,这就是策略模式在里氏代换原则中的应用; ***************策略模式************************************ >准备一组算法,并将每个封装起来使的他们能够互换.
Context
/**
* @author Lean @date:2014-10-17
*/
public class Context {
public static Strategy strategy;
public static void main(String[] args) {
strategy=new ConcreteStrategyA();
strategy.calculate();
}
}
abstract class Strategy{
public abstract void calculate();
}
class ConcreteStrategyA extends Strategy{
@Override
public void calculate() {
System.out.println("ConcreteStrategyA is called !");
}
}
class ConcreteStrategyB extends Strategy{
@Override
public void calculate() {
System.out.println("ConcreteStrategyB is called !");
}
IChoiceStrategy
/**
* 选择策略
*
* @author Lean @date:2014-10-17
*/
public abstract class IChoiceStrategy {
/**
* @return 返回列表名字
*/
public abstract String[] getNames();
/**
* @return 返回相应码
*/
public abstract int getCode(String name);
}
/**
* @author Lean @date:2014-10-17
*/
public class SortChoiceStrategy extends IChoiceStrategy {
private HashMap<String, Integer> mSortMap;
public String name;
public SortChoiceStrategy() {
initSortMap();
}
private void initSortMap() {
mSortMap=new HashMap<String, Integer>();
mSortMap.put("最新上架", 0);
mSortMap.put("销量最高", 1);
mSortMap.put("价格最高", 2);
mSortMap.put("价格最低", 3);
name="最新上架";
}
@Override
public String[] getNames() {
Set<String> set=mSortMap.keySet();
Object[] tempObj=set.toArray();
String[] result=new String[tempObj.length];
for (int i = 0; i < tempObj.length; i++) {
result[i]=(String) tempObj[i];
}
return result;
}
@Override
public int getCode(String name) {
return mSortMap.get(name);
}
}
/**
* @author Lean @date:2014-10-17
*/
public class StatusChoiceStrategy extends IChoiceStrategy {
private HashMap<String, Integer> mStatusMap;
public String name;
public StatusChoiceStrategy() {
initStatusMap();
}
private void initStatusMap() {
mStatusMap=new HashMap<String, Integer>();
mStatusMap.put("定制中", 1);
mStatusMap.put("已完毕", 2);
name="定制中";
}
@Override
public String[] getNames() {
Set<String> set=mStatusMap.keySet();
Object[] tempObj=set.toArray();
String[] result=new String[tempObj.length];
for (int i = 0; i < tempObj.length; i++) {
result[i]=(String) tempObj[i];
}
return result;
}
@Override
public int getCode(String name) {
return mStatusMap.get(name);
}
}
***********************************************************
代理模式:代理和被代理对象相同拥有一样的行为,我们把它封装成一个接口,那么,在被 代理对象被调用的地方都能够使用代理对象替换以隐藏实现细节; ***************代理模式************************************ 如果一个场景,A想去买票,但A没时间,于是A托B到电影院帮他买票; 换成面向对象思维:如果有一个对象A,和一个新的对象C,如今C想使用对象A,而A临时还 不符合C的要求,这时能够间接的使用B以达到使用A的目的,同一时候,B又能够对使用过程进行
拦截,如打印日志;(像这样的利用中间层来达到目的的模式还有适配器模式)
/**
* @author Lean @date:2014-10-17
*/
public abstract class IPerson {
public abstract void buyTicket();
}
/**
* @author Lean @date:2014-10-17
*/
public class RealSeePerson extends IPerson {
@Override
public void buyTicket() {
System.out.println("RealSeePerson get the ticket !");
}
}
/**
* @author Lean @date:2014-10-17
*/
public class BuyTicketPerson extends IPerson{
public RealSeePerson target;
private void preBuyTicket(){
//TODO do th. before buy ticket
target=new RealSeePerson();
}
@Override
public void buyTicket() {
preBuyTicket();
if (target!=null) {
target.buyTicket();
}
postBuyTicket();
}
public void postBuyTicket(){
//TODO do th. after buy thicket
}
}
>代理和被代理对象实现共同接口,代理对象被调用时调用被代理对象的托付;
动态代理实现监听:
/**
* @author Lean @date:2014-10-17
*/
public class VectorProxy implements InvocationHandler {
private Object proxyobj;
public VectorProxy(Object obj) {
proxyobj=obj;
}
public static Object factor(Object obj){
Class cls=obj.getClass();
return Proxy.newProxyInstance(cls.getClassLoader(),cls.getInterfaces(),new VectorProxy(obj));
}
@Override
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
System.out.println("method:"+method.getName());
if (args!=null) {
for (int i = 0; i < args.length; i++) {
System.out.println(args[i]+"");
}
}
//反射调用
Object obj=method.invoke(proxyobj, args);
System.out.println("*********");
return obj;
}
public static void main(String[] args) {
List v=null;
//返回代理对象,并调用代理对象的add方法
v=(List) factor(new Vector(10));
v.add("New");
}
}
***********************************************************
合成模式:上面两中模式都是里氏代换原则在方法方面的应用.合成模式使用树结果描写叙述 总体和部分的关系,由于单纯元素和复合元素相同实现抽象,那么在抽象使用的地方, 都能够这2种元素替代; ***************合成模式************************************
合成模式分为透明式和安全式
透明:指抽象接口声明了枝叶全部的全部接口方法,在叶子类中。对该方法进行空实现;
/**
* @author Lean @date:2014-10-20
*/
public interface Component {
void sampleOperation();
Composite getComposite();
void add(Component component);
void remove(Component component);
Enumeration<Component> components();
}
/**
* @author Lean @date:2014-10-20
*/
public class Composite implements Component {
private Vector<Component> componentVector=new Vector<Component>();
@Override
public Composite getComposite() {
return this;
}
@Override
public void sampleOperation() {
Enumeration<Component> enumeration=components();
while (enumeration.hasMoreElements()) {
Component component = (Component) enumeration.nextElement();
component.sampleOperation();
}
}
@Override
public void add(Component component) {
componentVector.addElement(component);
}
@Override
public void remove(Component component) {
componentVector.removeElement(component);
}
@Override
public Enumeration<Component> components() {
return componentVector.elements();
}
}
/**
* @author Lean @date:2014-10-20
*/
public class Leaf implements Component {
@Override
public Composite getComposite() {
return null;
}
@Override
public void sampleOperation() {
System.out.println(" call leaf here !");
}
@Override
public void add(Component component) {
}
@Override
public void remove(Component component) {
}
@Override
public Enumeration<Component> components() {
return null;
}
}
安全:指抽象接口仅仅声明叶子全部的方法,树枝类除了继承还包含了自己的管理叶子类方法;典型应用:Android的View,ViewGroup
/**
* @author Lean @date:2014-10-20
*/
public interface Component {
Composite getComposite();
void sampleOperation();
}
/**
* @author Lean @date:2014-10-20
*/
public class Composite implements Component {
private Vector componentVector=new Vector();
@Override
public void sampleOperation() {
Enumeration enumeration=components();
while (enumeration.hasMoreElements()) {
((Component) enumeration.nextElement()).sampleOperation();
}
}
@Override
public Composite getComposite() {
return this;
}
public Enumeration components(){
return componentVector.elements();
}
public void add(Component component){
componentVector.addElement(component);
}
public void remove(Component component){
componentVector.removeElement(component);
}
}
/**
* @author Lean @date:2014-10-20
*/
public class Leaf implements Component {
@Override
public Composite getComposite() {
return null;
}
@Override
public void sampleOperation() {
System.out.println("leaf is called !");
}
}
由于分支机构基本继承抽象类,在抽象方法只支持类,那里可以换成一个叶子。例如,在安全模式。叶类可以换成棒/多叶;在透明模式下可以互换。这是与里氏代换原则;
***********************************************************
发布者:全栈程序员栈长,转载请注明出处:https://javaforall.cn/117666.html原文链接:https://javaforall.cn
边栏推荐
- Duchefa s0188 Chinese and English instructions of spectinomycin hydrochloride pentahydrate
- National Eye Care Education Conference, 2022 the Fourth Beijing International Youth eye health industry exhibition
- 基于AVFoundation实现视频录制的两种方式
- Open source SPL eliminates tens of thousands of database intermediate tables
- Selenium element information
- Kubernetes resource object introduction and common commands (V) - (configmap & Secret)
- Typhoon is coming! How to prevent typhoons on construction sites!
- ViewRootImpl和WindowManagerService笔记
- [UE4] unrealinsight obtains the real machine performance test report
- 3.3 project evaluation
猜你喜欢
随机推荐
Kubernetes resource object introduction and common commands (V) - (configmap & Secret)
Duchefa丨P1001植物琼脂中英文说明书
小程序代码的构成
Codeforces Round #804 (Div. 2) - A, B, C
[UE4] unrealinsight obtains the real machine performance test report
Applet event binding
haas506 2.0开发教程 - 阿里云ota - pac 固件升级(仅支持2.2以上版本)
Classic implementation method of Hongmeng system controlling LED
2.8 basic knowledge of project management process
Leetcode (347) - top k high frequency elements
Chemical properties and application instructions of prosci Lag3 antibody
Duchefa d5124 md5a medium Chinese and English instructions
Which is the best online collaboration product? Microsoft loop, notion, flowus
XML建模
Duchefa p1001 plant agar Chinese and English instructions
Prosci LAG-3 recombinant protein specification
AI automatically generates annotation documents from code
2. < tag hash table, string> supplement: Sword finger offer 50 The first character DBC that appears only once
mysql全面解析json/数组
Return to blowing marshland -- travel notes of zhailidong, founder of duanzhitang