行为型模式-状态模式
// 抽象状态类
public interface OrderState {
void handle();
}
// 具体状态类：待支付
public class PendingState implements OrderState {
@Override
public void handle() {
System.out.println("订单处于待支付状态。");
}
}
// 具体状态类：已支付
public class PaidState implements OrderState {
@Override
public void handle() {
System.out.println("订单处于已支付状态。");
}
}
// 具体状态类：已完成
public class CompletedState implements OrderState {
@Override
public void handle() {
System.out.println("订单已完成。");
}
}
// 上下文类
public class OrderContext {
private OrderState state;
// 设置状态
public void setState(OrderState state) {
this.state = state;
}
// 调用当前状态对应的行为
public void handle() {
if (state != null) {
state.handle();
}
}
}
// 测试
public class Main {
public static void main(String[] args) {
OrderContext context = new OrderContext();
// 设置为待支付状态
context.setState(new PendingState());
context.handle();
// 设置为已支付状态
context.setState(new PaidState());
context.handle();
// 设置为已完成状态
context.setState(new CompletedState());
context.handle();
}
}