Java异步任务执行方法及CompletableFuture应用

// 示例：异步获取用户信息
CompletableFuture future = CompletableFuture.supplyAsync(() -> {
    // 模拟耗时操作
    try {
        Thread.sleep(1000);
    } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
    }
    return "User Data";
});

// 非阻塞地处理结果
future.thenAccept(data -> System.out.println("Received: " + data));

ExecutorService executor = Executors.newFixedThreadPool(4);
CompletableFuture asyncTask = CompletableFuture.supplyAsync(() -> {
    return 2 + 3;
}, executor);

// 记得关闭线程池
executor.shutdown();

CompletableFuture result = CompletableFuture
    .supplyAsync(() -> "Hello")
    .thenApply(s -> s + " World")
    .thenApply(String::toUpperCase);

CompletableFuture task1 = CompletableFuture.supplyAsync(() -> 10);
CompletableFuture task2 = CompletableFuture.supplyAsync(() -> 20);

CompletableFuture sum = task1.thenCombine(task2, Integer::sum);
sum.thenAccept(total -> System.out.println("Sum: " + total)); // 30

CompletableFuture allDone = CompletableFuture.allOf(task1, task2);
allDone.thenRun(() -> System.out.println("All tasks completed."));

CompletableFuture faulty = CompletableFuture.supplyAsync(() -> {
    throw new RuntimeException("Something went wrong");
});

faulty
    .exceptionally(ex -> {
        System.err.println("Error: " + ex.getMessage());
        return "Fallback Value";
    })
    .thenAccept(System.out::println); // 输出 Fallback Value

CompletableFuture handled = future.handle((result, ex) -> {
    if (ex != null) {
        return "Error occurred: " + ex.getMessage();
    }
    return "Success: " + result;
});