在Java中如何实现异步IO操作？

Path path = Paths.get("example.txt");
AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.READ);

ByteBuffer buffer = ByteBuffer.allocate(1024);
fileChannel.read(buffer, 0, buffer, new CompletionHandler<Integer, ByteBuffer>() {
    @Override
    public void completed(Integer result, ByteBuffer attachment) {
        attachment.flip();
        System.out.println("Read: " + new String(attachment.array(), 0, result));
    }

    @Override
    public void failed(Throwable exc, ByteBuffer attachment) {
        System.out.println("Failed to read file: " + exc.getMessage());
    }
});

import java.nio.file.*;
import java.nio.channels.*;
import java.nio.*;
import java.util.concurrent.*;

public class AsyncFileReadExample {
    public static void main(String[] args) throws Exception {
        Path path = Paths.get("example.txt");
        AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.READ);

        ByteBuffer buffer = ByteBuffer.allocate(1024);
        Future<Integer> future = fileChannel.read(buffer, 0); // 异步读取文件

        // 可以在此处做其他工作，不阻塞当前线程
        System.out.println("Doing other tasks while reading file...");

        // 等待读取完成
        while (!future.isDone()) {
            System.out.println("Waiting for IO...");
        }

        // 获取读取结果
        int bytesRead = future.get();
        buffer.flip();
        System.out.println("Read " + bytesRead + " bytes: " + new String(buffer.array(), 0, bytesRead));
    }
}

AsynchronousSocketChannel client = AsynchronousSocketChannel.open();
client.connect(new InetSocketAddress("localhost", 8080), null, new CompletionHandler<Void, Void>() {
    @Override
    public void completed(Void result, Void attachment) {
        System.out.println("Connected to server");
    }

    @Override
    public void failed(Throwable exc, Void attachment) {
        System.out.println("Failed to connect: " + exc.getMessage());
    }
});

CompletableFuture.supplyAsync(() -> {
    // 异步任务
    return "Result";
}).thenAccept(result -> {
    System.out.println("Received: " + result);
});