异步回调

        异步回调

• Future 设计的初衷： 对将来的某个事件的结果进行建模

• 

• /**
   * 异步调用： CompletableFuture
   * 异步执行
   * 成功回调
   * 失败回调
   */
  public class Test01 {
      public static void main(String[] args) throws ExecutionException, InterruptedException {
          /*
          // 没有返回值的 runAsync 异步回调
          CompletableFuturecompletableFuture = CompletableFuture.runAsync(()->{
              try {
                  TimeUnit.SECONDS.sleep(2);
              } catch (InterruptedException e) {
                  e.printStackTrace();
              }
              System.out.println(Thread.currentThread().getName()+"runAsync=>void");
          });
          System.out.println("123");
          completableFuture.get();  //获取阻塞执行结果
          */
  
          // 有返回值的 supplyAsync 异步回调
          // 类似于 ajax，成功和失败的回调
          // 返回的是错误信息；
          CompletableFuturecompletableFuture = CompletableFuture.supplyAsync(() -> {
              System.out.println(Thread.currentThread().getName() + "supplyAsync=>Integer");
              int i = 10 / 0;
              return 1;
          });
          System.out.println(completableFuture.whenComplete((t, u) -> {
              System.out.println("t=>" + t); // 正常的返回结果
              System.out.println("u=>" + u); // 错误信息： java.util.concurrent.CompletionException: java.lang.ArithmeticException: / by zero
          }).exceptionally((e) -> {
              e.getMessage();
              return 0;       // 可以获取到错误的返回结果
          }).get());
      }
  }