状态模式(status Pattern)
定义:允许一个对象在其内部状态改变时改变它的行为,对象看起来似乎修改了它的类。其别名为状态对象(Objects for States)。与命令模式称为兄弟模式。
简单来说,状态模式就是通过对象的状态来改变其行为,博主凭借模糊的记忆,简单还原一下许久之前看过的《大话设计模式》一书中的例子(这本书中的demo特别精致,推荐一读):
类图:老毛病,以后画(美名曰日后复习)
代码:
1、状态的接口,所有状态接口继承此类:
package com.pat.status;
/**
* 状态接口
* @author ZX
*/
public interface Status {
public void writeProgram(Work work);
}
2、状态实现类,这里定义了上午中午下午三个子状态:
package com.pat.status;
/**
* 状态1,上午的状态
* @author Administrator
*
*/
public class MorningStatus implements Status{
@Override
public void writeProgram(Work work) {
if(work==null) {return;}
if(work.getHour()<=12) {//小于12点
System.out.println("当前"+work.getHour()+"点,做上午工作");
}else {//大于12点进入中午的状态
work.setCurrerntStatus(new NoonStatus());
work.doWork();
}
}
}
package com.pat.status;
/**
* 状态2:中午的状态
* @author Administrator
*
*/
public class NoonStatus implements Status{
@Override
public void writeProgram(Work work) {
if(work==null) {return;}
if(work.getHour()<=13) {//小于1点
System.out.println("当前"+work.getHour()+"点,休息");
}else {//大于1点进入中午的状态
work.setCurrerntStatus(new AfternoonStatus());
work.doWork();
}
}
}
package com.pat.status;
/**
* 状态3:下午的状态
* @author Administrator
*
*/
public class AfternoonStatus implements Status{
@Override
public void writeProgram(Work work) {
if(work==null) {return;}
if(work.getHour()<=18) {//小于18点
System.out.println("当前"+work.getHour()+"点,下午工作");
}else {//大于18点进入中午的状态
System.out.println("干毛线,下班了还干");
}
}
}
3、工作类:
package com.pat.status;
/**
* 工作类
* @author ZX
*
*/
public class Work {
private int hour;
private boolean isFinshed;
private Status currerntStatus;
//constructor
public Work() {
//设置初始状态-早上的状态
this.currerntStatus= new MorningStatus();
}
public void doWork() {
currerntStatus.writeProgram(this);
}
public int getHour() {
return hour;
}
public void setHour(int hour) {
this.hour = hour;
}
public boolean isFinshed() {
return isFinshed;
}
public void setFinshed(boolean isFinshed) {
this.isFinshed = isFinshed;
}
public Status getCurrerntStatus() {
return currerntStatus;
}
public void setCurrerntStatus(Status currerntStatus) {
this.currerntStatus = currerntStatus;
}
}
4、测试:
package com.pat.status;
public class Test {
public static void main(String[] args) {
Work work = new Work();
//当前9点
work.setHour(9);
work.doWork();
//当前13点
work.setHour(13);
work.doWork();
work.setHour(16);
work.doWork();
work.setHour(20);
work.doWork();
}
}