java | 短链接解决方案

java | 短链接解决方案 | 犀牛的博客

客户端建立连接，发送完一次消息就断开链接。

由于客户端连接断开，所以，服务端会收到 -1。

建立十个短链接。

package com.redisc;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;

public class Client {
    static final Logger log = LoggerFactory.getLogger(Client.class);

public static void main(String[] args) throws IOException, InterruptedException {
        for (int i = 0; i < 10; i++) {
            send();
        }
    }

public static void send() {
        NioEventLoopGroup worker = new NioEventLoopGroup();

try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.channel(NioSocketChannel.class);
            bootstrap.group(worker);
            bootstrap.handler(new ChannelInitializer<SocketChannel>() {
                @Override
                protected void initChannel(SocketChannel socketChannel) throws Exception {
                    socketChannel.pipeline().addLast(new ChannelInboundHandlerAdapter() {
                        @Override
                        // 会在连接 channel 建立成功后，触发 active 事件
                        public void channelActive(ChannelHandlerContext ctx) throws Exception {
                            ByteBuf byteBuf = ctx.alloc().buffer(16);
                            byteBuf.writeBytes(new byte[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17});
                            ctx.writeAndFlush(byteBuf);
                            ctx.channel().close();
                        }
                    });
                }
            });
            ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 8000);
            channelFuture.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            log.error("error", e);
        } finally {
            worker.shutdownGracefully();
        }
    }
}

里面加了一句

// 调整 netty 接收缓冲区 bytebuf
serverBootstrap.childOption(ChannelOption.RCVBUF_ALLOCATOR, new AdaptiveRecvByteBufAllocator(16, 16, 16));

package com.redisc;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.AdaptiveRecvByteBufAllocator;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;


@Slf4j
public class Server {

public static void main(String[] args) throws IOException {
        NioEventLoopGroup boss = new NioEventLoopGroup();
        NioEventLoopGroup worker = new NioEventLoopGroup();

try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.channel(NioServerSocketChannel.class);
            // 调整 netty 接收缓冲区 bytebuf
            serverBootstrap.childOption(ChannelOption.RCVBUF_ALLOCATOR, new AdaptiveRecvByteBufAllocator(16, 16, 16));
            serverBootstrap.group(boss, worker);
            serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
                @Override
                protected void initChannel(SocketChannel socketChannel) throws Exception {
                    socketChannel.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));
                }
            });
            ChannelFuture channelFuture = serverBootstrap.bind(8000).sync();
            channelFuture.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            log.error("error", e);
        } finally {
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }

}
}

服务端输出 「一部分」

         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 |................|
+--------+-------------------------------------------------+----------------+
15:52:04.878 [nioEventLoopGroup-3-10] DEBUG io.netty.channel.DefaultChannelPipeline - Discarded inbound message PooledUnsafeDirectByteBuf(ridx: 0, widx: 16, cap: 16) that reached at the tail of the pipeline. Please check your pipeline configuration.
15:52:04.879 [nioEventLoopGroup-3-2] DEBUG io.netty.handler.logging.LoggingHandler - [id: 0x71a37eb2, L:/127.0.0.1:8000 - R:/127.0.0.1:64999] READ: 16B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 |................|
+--------+-------------------------------------------------+----------------+
...
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 11                                              |.               |
+--------+-------------------------------------------------+----------------+
15:52:04.879 [nioEventLoopGroup-3-7] DEBUG io.netty.handler.logging.LoggingHandler - [id: 0x5e2701f9, L:/127.0.0.1:8000 - R:/127.0.0.1:65004] READ: 1B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 11                                              |.               |
+--------+-------------------------------------------------+----------------+

和 java | 粘包 & 半包 对照看。

从服务端输出可以看出

• 确实按照每包输出，解决了粘包问题
• 由于设置了 netty 接收缓冲区大小
  • 存在半包问题