标签：android style blog color io os ar 使用 java
里氏代换原则是指拥有相同基类的两个子类,在使用子类A的地方(方法/属性)可以用子类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 返回对应码
*/
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("已完成", 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);
}
}
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代理模式:代理和被代理对象同样拥有一样的行为,我们把它封装成一个接口,那么,在被拦截,如打印日志;(像这种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委托;
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");
}
}
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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述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所有的所有接口方法，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：指抽象接口只声明叶子所有的方法，树枝类除了继承还包括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 !");
}
}
因为枝叶基本继承了抽象类，在一个只支持抽象方法的类中，可以替换成另一个枝叶；比如在安全模式中，叶子类可以替换成枝/叶类；在透明模式中可以互相替换；这就符合了里氏代换原则；
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标签：android style blog color io os ar 使用 java
原文地址：http://blog.csdn.net/qq285016127/article/details/40299589
