设计模式_状态模式

标签：状态模式   设计模式   

    Allow an object to alter its behavior when its internal state changes.The object will appear to change its class.(当一个对象内在状态改变时，允许其改变行为，这个对象看起来像改变了其类)

状态模式适应

public abstract class LiftState {
 protected Context context;
 
 public void setContext(Context _context){
  this.context=_context;
 }
 
 public abstract void open();
 public abstract void close();
 public abstract void run();
 public abstract void stop();
}

public class ClosingState extends LiftState {
 @Override
 public void close() {
  System.out.println("close the lift");
 }
 @Override
 public void open() {
  super.context.setLiftState(Context.openningState);
  super.context.getLiftState().open();
 }
 @Override
 public void run() {
  super.context.setLiftState(Context.runningState);
  super.context.getLiftState().run();
 }
 @Override
 public void stop() {
  super.context.setLiftState(Context.stoppingState);
  super.context.getLiftState().stop();
 }
}

public class StoppingState extends LiftState {
 @Override
 public void close() {
  //do nothing
 }
 @Override
 public void open() {
  super.context.setLiftState(Context.openningState);
  super.context.getLiftState().open();
 }
 @Override
 public void run() {
  super.context.setLiftState(Context.runningState);
  super.context.getLiftState().run();
 }
 @Override
 public void stop() {
  System.out.println("the lift is stoped");
 }
}

public class RunningState extends LiftState {
 @Override
 public void close() {
  //do nothing
 }
 @Override
 public void open() {
  //do nothing
 }
 @Override
 public void run() {
  System.out.println("lift is runing...");
 }
 @Override
 public void stop() {
  super.context.setLiftState(Context.stoppingState);
  super.context.getLiftState().stop();
 }
}

public class OpenningState extends LiftState {
 @Override
 public void close() {
   super.context.setLiftState(Context.closingState);  //调用的是Context中的方法
   super.context.getLiftState().close();      //通过Context调用另一个状态的方法
 }
 @Override
 public void open() {
  System.out.println("lift is open...");
 }
 @Override
 public void run() {
  //do nothing
 }
 @Override
 public void stop() {
  //do nothing
 }
}

public class Context {
 public final static OpenningState openningState=new OpenningState();
 public final static ClosingState closingState=new ClosingState();
 public final static RunningState runningState=new RunningState();
 public final static StoppingState stoppingState=new StoppingState();
 
 private LiftState liftState;
 public LiftState getLiftState() {
  return liftState;
 }
 public void setLiftState(LiftState liftState) {
  this.liftState = liftState;
  this.liftState.setContext(this); //将该状态设置上下文对象
 }
 
 public void close() {
   this.liftState.close();
 }
 public void open() {
  this.liftState.open();
 }
 public void run() {
  this.liftState.run();
 }
 public void stop() {
  this.liftState.stop();
 }
}

public class Client {
 public static void main(String[] args) {
  Context context=new Context();
  context.setLiftState(Context.closingState);
  context.open();
  context.close();
  context.run();
  context.stop();
 }
}
/*
上下文对象Context，成员属性LiftState,可设置四种状态，获取和改变状态，相当于一个公共容器
四种状态的抽象LiftState，成员属性Context,可设置上下文对象，让四种状态都拥有同一个Context
你中有我，我中有你，通过容器Context可以进行状态的切换，将四者联合成一体
当状态改变时，通过父类的统一Context改变了LiftState状态，然后调用了改变后状态的方法
也就是说
*/

lift is open...
close the lift
lift is runing...
the lift is stoped

设计模式_状态模式

标签：状态模式   设计模式   

原文地址：http://blog.csdn.net/cjvs9k/article/details/47066297