java | netty future

参考

• java | jdk future

同步

package com.redisc;

import io.netty.channel.EventLoop;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.util.concurrent.Future;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.util.concurrent.*;

@Slf4j(topic = "c.MultiThreadServer")
public class MultiThreadServer {

    public static void main(String[] args) throws IOException, ExecutionException, InterruptedException {
        NioEventLoopGroup nioEventLoopGroup = new NioEventLoopGroup();
        EventLoop eventLoop = nioEventLoopGroup.next();

        Future<Integer> future = eventLoop.submit(new Callable<Integer>() {
            @Override
            public Integer call() throws Exception {
                log.debug("执行计算");
                Thread.sleep(1000);
                return 50;
            }
        });
        // 阻塞拿返回
        log.debug("等待结果");
        log.debug("结果是 {}", future.get());
    }
}

输出

16:16:20.794 [main] DEBUG c.MultiThreadServer - 等待结果
16:16:20.795 [nioEventLoopGroup-2-1] DEBUG c.MultiThreadServer - 执行计算
16:16:21.799 [main] DEBUG c.MultiThreadServer - 结果是 50

异步

package com.redisc;

import io.netty.channel.EventLoop;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.GenericFutureListener;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.util.concurrent.*;

@Slf4j(topic = "c.MultiThreadServer")
public class MultiThreadServer {

    public static void main(String[] args) throws IOException, ExecutionException, InterruptedException {
        NioEventLoopGroup nioEventLoopGroup = new NioEventLoopGroup();
        EventLoop eventLoop = nioEventLoopGroup.next();

        Future<Integer> future = eventLoop.submit(new Callable<Integer>() {
            @Override
            public Integer call() throws Exception {
                log.debug("执行计算");
                Thread.sleep(1000);
                return 50;
            }
        });
        future.addListener(new GenericFutureListener<Future<? super Integer>>() {
            @Override
            public void operationComplete(Future<? super Integer> future) throws Exception {
                // 虽然 getNow 是非阻塞的，但是，只要回调执行，就说明结果已经返回了
                log.debug("结果是 {}", future.getNow());

            }
        });
    }
}

输出

16:18:26.934 [nioEventLoopGroup-2-1] DEBUG c.MultiThreadServer - 执行计算
16:18:27.939 [nioEventLoopGroup-2-1] DEBUG c.MultiThreadServer - 结果是 50