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java | channel 关闭

发表于 分类于 ， ， ， ， Valine：

客户端代码如下。

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package com.redisc;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.Scanner;

@Slf4j
public class Client {
    public static void main(String[] args) throws IOException, InterruptedException {
        ChannelFuture channelFuture = new Bootstrap()
                .group(new NioEventLoopGroup())
                .channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<NioSocketChannel>() {
                    @Override
                    protected void initChannel(NioSocketChannel nioSocketChannel) throws Exception {
                        nioSocketChannel.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));
                        nioSocketChannel.pipeline().addLast(new StringEncoder());

                    }
                })
                // 连接服务器
                // 异步非阻塞，调用线程是 main 线程
                // 真正执行连接的是另一个线程，是一个 NIO 线程
                .connect(new InetSocketAddress("localhost", 8000));
        Channel channel = channelFuture.sync().channel();
        new Thread(() -> {
            Scanner scanner = new Scanner(System.in);
            while (true) {
                String line = scanner.nextLine();
                if ("q".equals(line)) {
                    channel.close();
                    log.debug("close");
                    break;
                }
                channel.writeAndFlush("213");
            }
        }, "input").start();
    }
}

上面代码，42、43 处

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channel.close();
log.debug("close");

希望 channel 关闭后，执行下面的操作，但是，真正执行下来

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q
01:05:50.042 [input] DEBUG com.redisc.Client - close
01:05:50.043 [nioEventLoopGroup-2-1] DEBUG io.netty.handler.logging.LoggingHandler - [id: 0x9914e527, L:/127.0.0.1:59995 - R:localhost/127.0.0.1:8000] CLOSE
01:05:50.048 [nioEventLoopGroup-2-1] DEBUG io.netty.handler.logging.LoggingHandler - [id: 0x9914e527, L:/127.0.0.1:59995 ! R:localhost/127.0.0.1:8000] INACTIVE
01:05:50.048 [nioEventLoopGroup-2-1] DEBUG io.netty.handler.logging.LoggingHandler - [id: 0x9914e527, L:/127.0.0.1:59995 ! R:localhost/127.0.0.1:8000] UNREGISTERED

是先执行了 log.debug("close"); 然后执行了 channel.close()

这是因为，他们分属于两个线程，执行顺序完全是无法预计的。

同步关闭

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package com.redisc;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.Scanner;

@Slf4j
public class Client {
    public static void main(String[] args) throws IOException, InterruptedException {
        ChannelFuture channelFuture = new Bootstrap()
                .group(new NioEventLoopGroup())
                .channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<NioSocketChannel>() {
                    @Override
                    protected void initChannel(NioSocketChannel nioSocketChannel) throws Exception {
                        nioSocketChannel.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));
                        nioSocketChannel.pipeline().addLast(new StringEncoder());

                    }
                })
                // 连接服务器
                // 异步非阻塞，调用线程是 main 线程
                // 真正执行连接的是另一个线程，是一个 NIO 线程
                .connect(new InetSocketAddress("localhost", 8000));
        Channel channel = channelFuture.sync().channel();
        new Thread(() -> {
            Scanner scanner = new Scanner(System.in);
            while (true) {
                String line = scanner.nextLine();
                if ("q".equals(line)) {
                    channel.close();
                    break;
                }
                channel.writeAndFlush("213");
            }
        }, "input").start();

        // 获取 closeFuture 对象
        ChannelFuture channelFuture1 = channel.closeFuture();
        // 同步情况
        channelFuture1.sync();
        log.debug("关闭后执行的操作");
    }
}

异步关闭

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package com.redisc;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.Scanner;

@Slf4j
public class Client {
    public static void main(String[] args) throws IOException, InterruptedException {
        ChannelFuture channelFuture = new Bootstrap()
                .group(new NioEventLoopGroup())
                .channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<NioSocketChannel>() {
                    @Override
                    protected void initChannel(NioSocketChannel nioSocketChannel) throws Exception {
                        nioSocketChannel.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));
                        nioSocketChannel.pipeline().addLast(new StringEncoder());

                    }
                })
                // 连接服务器
                // 异步非阻塞，调用线程是 main 线程
                // 真正执行连接的是另一个线程，是一个 NIO 线程
                .connect(new InetSocketAddress("localhost", 8000));
        Channel channel = channelFuture.sync().channel();
        new Thread(() -> {
            Scanner scanner = new Scanner(System.in);
            while (true) {
                String line = scanner.nextLine();
                if ("q".equals(line)) {
                    channel.close();
                    break;
                }
                channel.writeAndFlush("213");
            }
        }, "input").start();

        // 获取 closeFuture 对象
        ChannelFuture channelFuture1 = channel.closeFuture();
        // 异步情况
        channelFuture1.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture channelFuture) throws Exception {
                log.debug("123");
            }
        });
    }
}

但是，上面两个结束，最后程序都没有停下来，这是因为，还有一部分 NioEventLoopGroup() 这里面的线程没有关闭。

用异步为例做一个优化关闭

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package com.redisc;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.Scanner;

@Slf4j
public class Client {
    public static void main(String[] args) throws IOException, InterruptedException {
        NioEventLoopGroup nioEventLoopGroup = new NioEventLoopGroup();
        ChannelFuture channelFuture = new Bootstrap()
                .group(nioEventLoopGroup)
                .channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<NioSocketChannel>() {
                    @Override
                    protected void initChannel(NioSocketChannel nioSocketChannel) throws Exception {
                        nioSocketChannel.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));
                        nioSocketChannel.pipeline().addLast(new StringEncoder());

                    }
                })
                // 连接服务器
                // 异步非阻塞，调用线程是 main 线程
                // 真正执行连接的是另一个线程，是一个 NIO 线程
                .connect(new InetSocketAddress("localhost", 8000));
        Channel channel = channelFuture.sync().channel();
        new Thread(() -> {
            Scanner scanner = new Scanner(System.in);
            while (true) {
                String line = scanner.nextLine();
                if ("q".equals(line)) {
                    channel.close();
                    break;
                }
                channel.writeAndFlush("213");
            }
        }, "input").start();

        // 获取 closeFuture 对象
        ChannelFuture channelFuture1 = channel.closeFuture();
        // 异步情况
        channelFuture1.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture channelFuture) throws Exception {
                log.debug("执行关闭操作");
                // 优雅的关闭
                nioEventLoopGroup.shutdownGracefully();
            }
        });
    }
}
请我喝杯咖啡吧～