Java使用CompletableFuture实现异步编程

import java.util.concurrent.CompletableFuture;

public class CompletableFutureExample {
    public static void main(String[] args) {
        // 创建一个异步任务
        CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
            try {
                Thread.sleep(1000); // 模拟耗时操作
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
            return "Hello, CompletableFuture!";
        });

        // 非阻塞地获取结果
        future.thenAccept(result -> System.out.println("Result: " + result));

        System.out.println("Main thread is not blocked");

        // 防止主线程退出过早
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

Main thread is not blocked
Result: Hello, CompletableFuture!

CompletableFuture<Integer> future = CompletableFuture.supplyAsync(() -> "42")
    .thenApply(Integer::parseInt)
    .thenApply(num -> num * 2);

future.thenAccept(result -> System.out.println("Final Result: " + result));

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> "Hello")
    .thenCompose(s -> CompletableFuture.supplyAsync(() -> s + " World!"));

future.thenAccept(System.out::println);

CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> "Hello");
CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> "World");

CompletableFuture<String> result = future1.thenCombine(future2, (s1, s2) -> s1 + " " + s2);
result.thenAccept(System.out::println);

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
    if (true) {
        throw new RuntimeException("Something went wrong");
    }
    return "Success";
}).exceptionally(ex -> {
    System.out.println("Exception: " + ex.getMessage());
    return "Default Value";
});

future.thenAccept(System.out::println);

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
    if (true) {
        throw new RuntimeException("Error occurred");
    }
    return "Success";
}).handle((result, ex) -> {
    if (ex != null) {
        System.out.println("Exception: " + ex.getMessage());
        return "Recovered from error";
    }
    return result;
});

future.thenAccept(System.out::println);

CompletableFuture<Void> allTasks = CompletableFuture.allOf(
    CompletableFuture.runAsync(() -> System.out.println("Task 1")),
    CompletableFuture.runAsync(() -> System.out.println("Task 2")),
    CompletableFuture.runAsync(() -> System.out.println("Task 3"))
);

allTasks.thenRun(() -> System.out.println("All tasks completed"));

CompletableFuture<Object> anyTask = CompletableFuture.anyOf(
    CompletableFuture.supplyAsync(() -> "Task 1 completed"),
    CompletableFuture.supplyAsync(() -> "Task 2 completed")
);

anyTask.thenAccept(result -> System.out.println("First completed: " + result));