總的來說簡潔了FutureTask與線程池的配合使用

沒啥太大區(qū)別吧我覺得, 使用方法不一樣, 多了一些方法 ???

futureTask 創(chuàng)建異步任務(wù)

      FutureTask<String> stringFutureTask = new FutureTask<>(() -> {
          return "aa";
      });
      executorService.execute(stringFutureTask);
      System.out.println(stringFutureTask.get());

      CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> {
          return "aa";
      }, executorService); // 不用手動提交了
      System.out.println(future1.get());

還有很多異步回調(diào), 組合處理

創(chuàng)建任務(wù)

1. .supplyAsync

創(chuàng)建一個(gè)帶返回值的任務(wù)

2. .runAsync

創(chuàng)建一個(gè)不帶返回值的任務(wù)

      ExecutorService executorService = Executors.newFixedThreadPool(1);

      // 帶返回值
      CompletableFuture future = CompletableFuture.supplyAsync(() -> {
          try {
              System.out.println("future　" + new Date());
              Thread.sleep(2000);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
          return "aaa";
      }, executorService); // 推薦使用

以上兩個(gè)方法都有兩個(gè)構(gòu)造方法, 默認(rèn)不指定自定義線程池, 他會指定默認(rèn)的提交任務(wù)的方法

  // 查看cpu的核數(shù)是否大于1核
  private static final boolean useCommonPool =
      (ForkJoinPool.getCommonPoolParallelism() > 1);

  // 如果大于1核 則調(diào)用execute方法, 每次創(chuàng)建一個(gè)線程
  private static final Executor asyncPool = useCommonPool ?
      ForkJoinPool.commonPool() : new ThreadPerTaskExecutor();

  static final class ThreadPerTaskExecutor implements Executor {
      public void execute(Runnable r) { new Thread(r).start(); }
  }

所以推薦自定義線程池的方式

異步回調(diào)

指的是 異步任務(wù)結(jié)束后調(diào)用的任務(wù)

1. .thenApply

帶返回值的異步調(diào)用函數(shù), 有入?yún)? 有出參

2. .thenAccept

不帶返回值的異步回調(diào)函數(shù), 有入?yún)?/p>

      CompletableFuture future = CompletableFuture.supplyAsync(() -> {
          try {
              System.out.println("future　" + new Date());
              Thread.sleep(2000);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
          return "aaa";
      }, executorService);

      // future執(zhí)行完之后執(zhí)行的異步任務(wù)
      CompletableFuture<String> thenApply = future.thenApply((result) -> {
          System.out.println("future2　" +new Date());
          System.out.println(result);
          return "bbb" + result;
      });

3. .exceptionally

異步任務(wù)出現(xiàn)異常調(diào)用的回調(diào)方法

      CompletableFuture future = CompletableFuture.supplyAsync(() -> {
          try {
              System.out.println("future　" + new Date());
              Thread.sleep(2000);
              int a = 1 / 0;
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
          return "aaa";
      }, executorService);

      CompletableFuture<String> exceptionally = future.exceptionally((result) -> {
          System.out.println("future3 " + result);
          return "bbb" + result;
      });
      
      // 出現(xiàn)異常則返回異常, 沒異常則返回future的返回值
      System.out.println(exceptionally.get());

去掉異常

4. .whenComplete

當(dāng)主任務(wù)出現(xiàn)異常時(shí), 會終止任務(wù),get的時(shí)候會拋出主任務(wù)的異常, 入?yún)⒅禐閚ull, 否則正常運(yùn)行

      CompletableFuture future = CompletableFuture.supplyAsync(() -> {
          try {
              System.out.println("future　" + new Date());
              Thread.sleep(2000);
              int a = 1/0;
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
          return "aaa";
      }, executorService);

      CompletableFuture<String> exceptionally = future.whenComplete((result, error) -> {
          System.out.println("future3 " + result);
          System.out.println("future3 " + error);
      });
      System.out.println(exceptionally.get());

去掉異常

組合處理

....

就是將多個(gè)任務(wù)組合起來執(zhí)行, 時(shí)間原因, 這里我就不介紹了, 大家另行百度吧

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原文鏈接：https://blog.csdn.net/weixin_44912855/article/details/119269417