java调用回调机制详解

public interface OrderResult {
 /**
 * 订购货物的状态
 *
 * @param state
 * @return
 */
 //参数可以不用, 用不用按照自己的实际需求决定
 public String getOrderResult(String state);
}

public class Store {
 @Getter
 @Setter
 private String name;

 Store(String name) {
 this.name = name;
 }

 /*回调函数, 将结构传给那个我们不能直接调用的方法, 然后获取结果*/
 public String returnOrderGoodsInfo(OrderResult order) {
 String[] s = {"订购中...", "订购失败", "即将发货!", "运输途中...", "已在投递"};
 Random random = new Random();
 int temp = random.nextInt(5);
 String s1 = s[temp];
 return order.getOrderResult(s1);
 }
}

/*同步, 顾客在商店预订商品, 商店通知顾客预订情况*/
public class SyncBuyer implements OrderResult {
 @Getter
 @Setter
 private Store store;//商店
 @Getter
 @Setter
 private String buyerName;//购物者名
 @Getter
 @Setter
 private String goodsName;//所购商品名

 SyncBuyer(Store store, String buyerName, String goodsName) {
 this.store = store;
 this.buyerName = buyerName;
 this.goodsName = goodsName;
 }

 /*调用从商店返回订购物品的信息*/
 public String orderGoods() {
 String goodsState = store.returnOrderGoodsInfo(this);
 System.out.println(goodsState);
 myFeeling();// 测试同步还是异步, 同步需要等待, 异步无需等待
 return goodsState;

 }

 public void myFeeling() {
 String[] s = {"有点小激动", "很期待!", "希望是个好货!"};
 Random random = new Random();
 int temp = random.nextInt(3);
 System.out.println("我是" + this.getBuyerName() + ", 我现在的感觉: " + s[temp]);
 }

 /*被回调的方法, 我们自己不去调用, 这个方法给出的结果, 是其他接口或者程序给我们的, 我们自己无法产生*/
 @Override
 public String getOrderResult(String state) {
 return "在" + this.getStore().getName() + "商店订购的" + this.getGoodsName() + "玩具, 目前的预订状态是: " + state;
 }
}

public class Test2Callback {
 public static void main(String[] args) {
 Store wallMart = new Store("沙中路沃尔玛");
 SyncBuyer syncBuyer = new SyncBuyer(wallMart, "小明", "超能铁扇公主");
 System.out.println(syncBuyer.orderGoods());
 }
}

public interface OrderResult {
 /**
 * 订购货物的状态
 *
 * @param state
 * @return
 */
 //参数可以不用, 用不用按照自己的实际需求决定
 public String getOrderResult(String state);
}

public class Store {
 @Getter
 @Setter
 private String name;

 Store(String name) {
 this.name = name;
 }

 /*回调函数, 将结构传给那个我们不能直接调用的方法, 然后获取结果*/
 public String returnOrderGoodsInfo(OrderResult order) {
 String[] s = {"订购中...", "订购失败", "即将发货!", "运输途中...", "已在投递"};
 Random random = new Random();
 int temp = random.nextInt(5);
 String s1 = s[temp];
 return order.getOrderResult(s1);
 }
}

/*异步*/
@Slf4j
public class NoSyncBuyer implements OrderResult {
 @Getter
 @Setter
 private Store store;//商店
 @Getter
 @Setter
 private String buyerName;//购物者名
 @Getter
 @Setter
 private String goodsName;//所购商品名

 NoSyncBuyer(Store store, String buyerName, String goodsName) {
 this.store = store;
 this.buyerName = buyerName;
 this.goodsName = goodsName;
 }

 /*调用从商店返回订购物品的信息*/
 public String orderGoods() {
 String goodsState = "--";
 MyRunnable mr = new MyRunnable();
 Thread t = new Thread(mr);
 t.start();
 System.out.println(goodsState);
 goodsState = mr.getResult();// 得到返回值
 myFeeling();// 用来测试异步是不是还是按顺序的执行
 return goodsState;
 }

 public void myFeeling() {
 String[] s = {"有点小激动", "很期待!", "希望是个好货!"};
 Random random = new Random();
 int temp = random.nextInt(3);
 System.out.println("我是" + this.getBuyerName() + ", 我现在的感觉: " + s[temp]);
 }

 /*被回调的方法, 我们自己不去调用, 这个方法给出的结果, 是其他接口或者程序给我们的, 我们自己无法产生*/
 @Override
 public String getOrderResult(String state) {
 return "在" + this.getStore().getName() + "商店订购的" + this.getGoodsName() + "玩具, 目前的预订状态是: " + state;
 }

 // 开启另一个线程, 但是没有返回值, 怎么回事
 // 调试的时候, 等待一会儿, 还是可以取到值, 但不是立即取到, 在print显示的时候, 却是null, 需要注意?
 private class MyRunnable implements Runnable {
 @Getter
 @Setter
 private String result;

 @Override
 public void run() {
  try {
  Thread.sleep(10000);
  result = store.returnOrderGoodsInfo(NoSyncBuyer.this);// 匿名函数的时候, 无法return 返回值
  } catch (InterruptedException e) {
  log.error("出大事了, 异步回调有问题了", e);
  }
 }
 }
}

public class Test2Callback {
 public static void main(String[] args) {
 Store wallMart = new Store("沙中路沃尔玛");
 SyncBuyer syncBuyer = new SyncBuyer(wallMart, "小明", "超能铁扇公主");
 System.out.println(syncBuyer.orderGoods());


 System.out.println("\n");
 Store lawson = new Store("沙中路罗森便利店");
 NoSyncBuyer noSyncBuyer = new NoSyncBuyer(lawson, "cherry", "变形金刚");
 System.out.println(noSyncBuyer.orderGoods());
 }
}