设计模式之状态模式

package com.hml.state;

public interface State {
    public void handle(Context c);
}

package com.hml.state;

public class ConcreteStateA implements State{

    public void handle(Context c) {
      c.setState(new ConcreteStateB());
    }

}

package com.hml.state;

public class ConcreteStateB implements State{

    public void handle(Context c) {
      c.setState(new ConcreteStateA());
    }

}

package com.hml.state;

public class Context {
    
    private State state;

    public State getState() {
        return state;
    }

    public void setState(State state) {
        System.out.println(state.getClass().getName());
        this.state = state;
    }

    public Context(State state) {
        super();
        this.state = state;
    }
    
    public void request() {
        state.handle(this);
    }
}

package com.hml.state;

public class Test {
    public static void main(String[] args) {
         Context c = new Context(new ConcreteStateA());
         c.request();
         c.request();
         c.request();
         c.request();
         c.request();
    }
}