Java 并发编程之CompletableFuture 异步编程实战指南

// 无返回值
CompletableFuture<Void> future = CompletableFuture.runAsync(() -> {
    System.out.println("异步任务执行");
});
// 有返回值
CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
    return "Hello CompletableFuture";
});

CompletableFuture<String> result = CompletableFuture.supplyAsync(() -> fetchData())
    .thenApply(data -> processData(data))
    .thenApply(processed -> transformToJson(processed))
    .exceptionally(ex -> handleError(ex));

CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> getUserInfo());
CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> getOrderInfo());
CompletableFuture<String> combined = future1.thenCombine(future2, (user, order) -> {
    return mergeInfo(user, order);
});

public class AsyncOrderService {
    private ExecutorService executor = Executors.newFixedThreadPool(10);
    public CompletableFuture<Order> processOrder(Long orderId) {
        return CompletableFuture.supplyAsync(() -> validateOrder(orderId), executor)
            .thenCompose(valid -> fetchInventory(valid))
            .thenApply(inventory -> calculatePrice(inventory))
            .thenAccept(price -> sendNotification(price))
            .orTimeout(5, TimeUnit.SECONDS);
    }
}