子类必须能替换成它们的父类(龙生龙，凤生凤，老鼠的儿子会打洞)
可以这么理解，进公司之前人事当然会告诉你公司的制度，如果这个
公司出得米米比较多，你可能会看都不看就签上你的大名，如果有一天
人事告诉你因为你一个月因为连续迟到3天而将被开除，你肯定后悔
没有认真看过制度，这个小例子说明一旦你继承某个类（成为公司员工），
你就不该该改变它的基本行为（一个月迟到3次），否则你将死的很惨.
(或者你是超人，可以拯救全人类)
public interface IWorker {
void eat();
void work();
}
public class Manager {
private IWorker iWorker;
public IWorker getiWorker() {
return iWorker;
}
public void setiWorker(IWorker iWorker) {
this.iWorker = iWorker;
}
public void mange(boolean isWorkingHour)
{
if(isWorkingHour)
iWorker.work();
else
iWorker.eat();
}
}
public class Robert implements IWorker {
@Override
public void eat() {
DebugLog.log("i am R2, i am eating");
}
@Override
public void work() {
DebugLog.log("i am R2, i am eating");
}
}
public class Worker implements IWorker {
@Override
public void eat() {
DebugLog.log("i am Jedi Warrior, i am eating");
}
@Override
public void work() {
DebugLog.log("i am Jedi Warrior, i am working");
}
}
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
IWorker aRobert=new Robert();
IWorker aWorker= new Worker();
Manager aManager=new Manager();
aManager.setiWorker(aWorker);
aManager.mange(true);
aManager.setiWorker(aRobert);
aManager.mange(false);
}
}
工人是人，当然先要吃饭，才能做事，机器人不是人，可以24*7为人类服务
，从代码可以看出，机器人继承了iworker，导致机器人也需要吃饭。解决这个
问题很简单，将吃饭和工作的接口分离出来，机器人只要实现work接口就可以了。
public interface IEatable {
void eat();
}
public interface IWorkable {
void work();
}
public class Manager {
private IWorkable iWorkable;
private IEatable iEatable;
public IWorkable getiWorkable() {
return iWorkable;
}
public void setiWorkable(IWorkable iWorkable) {
this.iWorkable = iWorkable;
}
public IEatable getiEatable() {
return iEatable;
}
public void setiEatable(IEatable iEatable) {
this.iEatable = iEatable;
}
public IWorkable getiWorker() {
return iWorkable;
}
public void mangEatableWork(boolean isWorkingHour) {
if (isWorkingHour)
iWorkable.work();
else
iEatable.eat();
}
public void mangNonEatableWork() {
iWorkable.work();
}
}
public class Robert implements IWorkable{
@Override
public void work() {
DebugLog.log("i am R2, i am working");
}
}
public class Worker implements IWorkable,IEatable {
@Override
public void eat() {
DebugLog.log("i am Jedi Warrior, i am eating");
}
@Override
public void work() {
DebugLog.log("i am Jedi Warrior, i am working");
}
}
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
Robert aRobert=new Robert();
Worker aWorker= new Worker();
Manager aManager=new Manager();
aManager.setiWorkable(aWorker);
aManager.setiEatable(aWorker);
aManager.mangEatableWork(false);
aManager.setiWorkable(aRobert);
aManager.mangNonEatableWork();
}
}