设计模式之状态模式

实现代码

public interface State {    void handle();}/** * 空闲状态 * @author Administrator * */public class FreeState implements State {    @Override    public void handle() {        System.out.println("房间空闲！！！没人住！");    }}/** * 已入住状态 * @author Administrator * */public class CheckedInState implements State {    @Override    public void handle() {        System.out.println("房间已入住！请勿打扰！");    }}/** * 已预订状态 * @author Administrator * */public class BookedState implements State {    @Override    public void handle() {        System.out.println("房间已预订！别人不能定！");    }}

/** * 房间对象 * @author Administrator * */public class HomeContext {    //如果是银行系统，这个Context类就是账号。根据金额不同，切换不同的状态！    private State state;    public void setState(State s){        System.out.println("修改状态！");        state = s;        state.handle();    }}

public class Client {    public static void main(String[] args) {        HomeContext ctx = new HomeContext();        ctx.setState(new FreeState());        ctx.setState(new BookedState());    }}