Netty入门(4) - 附带的ChannelHandler和Codec

使用SSL/TLS创建安全的Netty程序

Java提供了抽象的SslContext和SslEngine，实际上SslContext可以用来获取SslEngine来进行加密和解密。Netty拓展了Java的SslEngine，称SslHandler，用来对网络数据进行加密和解密。

1、制作自签证书

#keytool -genkey -keysize 2048 -validity 365 -keyalg RSA -dnam e "CN=gornix.com" -keypass 654321 -storepass 123456 -keystore gornix.jks

keytool为JDK提供的生成证书工具

• -keysize 2048 密钥长度2048位（这个长度的密钥目前可认为无法被暴力破解）
• -validity 365 证书有效期365天
• -keyalg RSA 使用RSA非对称加密算法
• -dname "CN=gornix.com" 设置Common Name为gornix.com，这是我的域名
• -keypass 654321 密钥的访问密码为654321
• -storepass 123456 密钥库的访问密码为123456（其实这两个密码也可以设置一样，通常都设置一样，方便记）
• -keystore gornix.jks 指定生成的密钥库文件为gornix.jks

2、服务端程序

public class SocketServerHelper {

    private static int WORKER_GROUP_SIZE = Runtime.getRuntime().availableProcessors() * 2; 

    private static EventLoopGroup bossGroup;
    private static EventLoopGroup workerGroup;  

    private static Class<? extends ServerChannel> channelClass;

    public static void startSpiderServer() throws Exception {
        ServerBootstrap b = new ServerBootstrap();
        b.childOption(ChannelOption.TCP_NODELAY, true)
        .childOption(ChannelOption.SO_KEEPALIVE, true)
        .childOption(ChannelOption.SO_REUSEADDR, true)
        .childOption(ChannelOption.ALLOCATOR, new PooledByteBufAllocator(false))
        .childOption(ChannelOption.SO_RCVBUF, 1048576)
        .childOption(ChannelOption.SO_SNDBUF, 1048576);

        bossGroup = new NioEventLoopGroup(1);
        workerGroup = new NioEventLoopGroup(WORKER_GROUP_SIZE);
        channelClass = NioServerSocketChannel.class;
        System.out.println("workerGroup size:" + WORKER_GROUP_SIZE);
        System.out.println("preparing to start spider server...");
        b.group(bossGroup, workerGroup);
        b.channel(channelClass);
        KeyManagerFactory keyManagerFactory = null;
        KeyStore keyStore = KeyStore.getInstance("JKS");
        keyStore.load(new FileInputStream("G:\\ssl.jks"), "123456".toCharArray());
        keyManagerFactory = KeyManagerFactory.getInstance("SunX509");
        keyManagerFactory.init(keyStore,"123456".toCharArray());
        SslContext sslContext = SslContextBuilder.forServer(keyManagerFactory).build();
        b.childHandler(new SslChannelInitializer(sslContext));
        b.bind(9912).sync();
        System.out.println("spider server start sucess, listening on port " + 9912 + ".");
    }

    public static void main(String[] args) throws Exception {
        SocketServerHelper.startSpiderServer();
    }

    public static void shutdown() {
        System.out.println("preparing to shutdown spider server...");
        bossGroup.shutdownGracefully();
        workerGroup.shutdownGracefully();
        System.out.println("spider server is shutdown.");
    }
}

public class SslChannelInitializer extends ChannelInitializer<Channel> {
    private final SslContext context;

    public SslChannelInitializer(SslContext context) {
        this.context = context;
    }

    @Override
    protected void initChannel(Channel ch) throws Exception {
        SSLEngine engine = context.newEngine(ch.alloc());
        engine.setUseClientMode(false);
        ch.pipeline().addFirst("ssl", new SslHandler(engine));
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));
        pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));  //最大16M
        pipeline.addLast("decoder", new StringDecoder(Charset.forName("UTF-8")));
        pipeline.addLast("encoder", new StringEncoder(Charset.forName("UTF-8")));
        pipeline.addLast("spiderServerBusiHandler", new SpiderServerBusiHandler());
    }
}

3、客户端程序

public class SocketClientHelper {
     public static void main(String[] args) {
            Channel channel = SocketClientHelper.createChannel("localhost",9912);
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            SocketHelper.writeMessage(channel, "ssh over tcp test 1");
            SocketHelper.writeMessage(channel, "ssh over tcp test 2");
            SocketHelper.writeMessage(channel, "ssh over tcp test 3");
            SocketHelper.writeMessage(channel, "ssh over tcp test 4");
            SocketHelper.writeMessage(channel, "ssh over tcp test 5");
        }

        public static Channel createChannel(String host, int port) {
            Channel channel = null;
            Bootstrap b = getBootstrap();
            try {
                channel = b.connect(host, port).sync().channel();
                System.out.println(MessageFormat.format("connect to spider server ({0}:{1,number,#}) success for thread [" + Thread.currentThread().getName() + "].", host , port));
            } catch (Exception e) {
                e.printStackTrace();
            }
            return channel;
        }

        public static Bootstrap getBootstrap(){
            EventLoopGroup group;
            Class<? extends Channel> channelClass = NioSocketChannel.class;
            group = new NioEventLoopGroup();
            Bootstrap b = new Bootstrap();
            b.group(group).channel(channelClass);
            b.option(ChannelOption.SO_KEEPALIVE, true);
            b.option(ChannelOption.TCP_NODELAY, true);
            b.option(ChannelOption.SO_REUSEADDR, true);
            b.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 5000);
            TrustManagerFactory tf = null;
            try {
                KeyStore keyStore = KeyStore.getInstance("JKS");
                keyStore.load(new FileInputStream("G:\\ssl.jks"), "123456".toCharArray());
                tf = TrustManagerFactory.getInstance("SunX509");
                tf.init(keyStore);
                SslContext sslContext = SslContextBuilder.forClient().trustManager(tf).build();
                b.handler(new SslChannelInitializer(sslContext));
                return b;
            } catch(Exception e) {
                e.printStackTrace();
            }
            return null;
        }
}

public class SslChannelInitializer extends ChannelInitializer<Channel> {

    private final SslContext context;

    public SslChannelInitializer(SslContext context) {
        this.context = context;
    }

    @Override
    protected void initChannel(Channel ch) throws Exception {
        SSLEngine engine = context.newEngine(ch.alloc());
        engine.setUseClientMode(true);
        ch.pipeline().addFirst("ssl", new SslHandler(engine));
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));
        pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));  //最大16M
        pipeline.addLast("decoder", new StringDecoder(Charset.forName("UTF-8")));
        pipeline.addLast("encoder", new StringEncoder(Charset.forName("UTF-8")));
        pipeline.addLast("spiderClientBusiHandler", new SpiderClientBusiHandler());
    }
}

可见SSL也没什么神秘的，就是在普通的TCP连接基础上包了一层处理而已（但如果要自己实现这层处理那可是相当复杂的），这层处理体现在Netty中就是一个SslHandler，把这个SslHandler加入到TCP连接的处理管线中即可。

PS：我们也可以使用基于认证和报文头加密的方式实现安全性。

处理空闲和超时

IdleStateHandler：当一个通道没有进行读写或者运行了一段时间后发出IdleStateEvent

ReadTimeoutHandler：在指定时间没没有接收到任何数据将抛出ReadTimeoutException

WriteTimeoutHandler：在指定时间内没有写入数据将抛出WriteTimeoutException

public class IdleStateHandlerInitializer extends ChannelInitializer<Channel> {

    @Override
    protected void initChannel(Channel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new IdleStateHandler(0, 0, 60, TimeUnit.SECONDS));
        pipeline.addLast(new HeartbeatHandler());
    }

    public static final class HeartbeatHandler extends ChannelInboundHandlerAdapter {

        private static final ByteBuf HEARTBEAT_SEQ = Unpooled.unreleasableBuffer(Unpooled.copiedBuffer("HEARTBEAT", CharsetUtil.UTF_8));

        @Override
        public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
            if (evt instanceof IdleStateEvent) {
                ctx.writeAndFlush(HEARTBEAT_SEQ.duplicate()).addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
            } else {
                super.userEventTriggered(ctx, evt);
            }
        }

    }
}

分隔符协议

DelimiterBasedFrameDecoder，解码器，接收ByteBuf由一个或者多个分隔符拆分，如NUL或者换行符。

LineBasedFrameDecoder，解码器，接收ByteBuf以分隔符结束，如"\n"和"\r\n"

public class LineBasedHandlerInitializer extends ChannelInitializer<Channel> {

    @Override
    protected void initChannel(Channel ch) throws Exception {
        ch.pipeline().addLast(new LineBasedFrameDecoder(65*1024), new FrameHandler());
    }

    public static final class FrameHandler extends SimpleChannelInboundHandler<ByteBuf> {

        @Override
        protected void channelRead0(ChannelHandlerContext arg0, ByteBuf arg1) throws Exception {
            // do something
        }

    }
}

长度为基础的协议

FixedLengthFrameDecoder：解码器，固定长度提取帧

LengthFieldBasedFrameDecoder：解码器，读取头部长度并提取帧的长度

public class LengthBasedInitializer extends ChannelInitializer<Channel> {

    @Override
    protected void initChannel(Channel ch) throws Exception {
        ch.pipeline().addLast(new LengthFieldBasedFrameDecoder(65*1024, 0, 8))
                        .addLast(new FrameHandler());
    }

    public static final class FrameHandler extends SimpleChannelInboundHandler<ByteBuf> {

        @Override
        protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
            // do something
        }

    }

}

写大数据

写大量的数据的一个有效的方法就是使用异步框架，如果内存和网络都处于爆满负荷状态，你需要停止写，Netty提供zero-memory-copy机制，这种方法在将文件内容写到网络堆栈空间时可以获得最大的性能：

public class WriteBigData extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        File file = new File("");
        FileInputStream fis = new FileInputStream(file);
        FileRegion region = new DefaultFileRegion(fis.getChannel(), 0, file.length());
        Channel channel = ctx.channel();
        channel.writeAndFlush(region).addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                if (!future.isSuccess()) {
                    Throwable cause = future.cause();
                    // do something
                }
            }
        });
    }

}

如果只想发送指定的数据块，可以使用ChunkedFile、ChunkedNioFile、ChunkedStream、ChunkedNioStream等。

Protobuf序列化传输

ProtobufDecoder、ProtobufEncoder、ProtobufVarint32FrameDecoder、ProtobufVarint32LengthPrepender，使用Protobuf需要映入protobuf-java-2.5.0.jar

1、下载编译器，将protoc.exe配置到环境变量：https://github.com/google/protobuf/releases

2、编写.proto文件，参考：https://blog.csdn.net/hry2015/article/details/70766603

syntax = "proto3"; // 声明可以选择protobuf的编译器版本(v2和v3)
option java_outer_classname = "MessageProto"; // 指定生成的java类的类名
message Message {  // 相当于c语言中的struct语句，表示定义一个信息，其实也就是类。
  string id = 1; // 要传输的字段了，子段后面需要有一个数字编号，从1开始递增
  string content = 2;
}

3、CMD执行编译操作

protoc ./Message.proto --java_out=./

4、引入maven

<!-- https://mvnrepository.com/artifact/com.google.protobuf/protobuf-java -->
<dependency>
   <groupId>com.google.protobuf</groupId>
   <artifactId>protobuf-java</artifactId>
   <version>3.5.1</version>
</dependency>

5、服务端

public class ServerPoHandlerProto extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        MessageProto.Message message = (MessageProto.Message) msg;
        if (ConnectionPool.getChannel(message.getId()) == null) {
            ConnectionPool.putChannel(message.getId(), ctx);
        }
        System.err.println("server:" + message.getId());
        ctx.writeAndFlush(message);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

bootstrap.group(bossGroup, workerGroup)
                .channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    public void initChannel(SocketChannel ch) throws Exception {
                        // 实体类传输数据，protobuf序列化
                        ch.pipeline().addLast("decoder",
                                new ProtobufDecoder(MessageProto.Message.getDefaultInstance()));
                        ch.pipeline().addLast("encoder",
                                new ProtobufEncoder());
                        ch.pipeline().addLast(new ServerPoHandlerProto());

                    }
                })
                .option(ChannelOption.SO_BACKLOG, 128)
                .childOption(ChannelOption.SO_KEEPALIVE, true);

6、客户端

public class ClientPoHandlerProto extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        MessageProto.Message message = (MessageProto.Message) msg;
        System.out.println("client:" + message.getContent());
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }

}

Bootstrap b = new Bootstrap();
            b.group(workerGroup);
            b.channel(NioSocketChannel.class);
            b.option(ChannelOption.SO_KEEPALIVE, true);
            b.handler(new ChannelInitializer<SocketChannel>() {
                @Override
                public void initChannel(SocketChannel ch) throws Exception {
                    // 实体类传输数据，protobuf序列化
                    ch.pipeline().addLast("decoder",
                            new ProtobufDecoder(MessageProto.Message.getDefaultInstance()));
                    ch.pipeline().addLast("encoder",
                            new ProtobufEncoder());
                    ch.pipeline().addLast(new ClientPoHandlerProto());

                }
            });

单元测试

package com.netty.learn.demo6;

import java.util.List;
import java.util.Random;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.handler.codec.ByteToMessageDecoder;

public class EmbeddedChannelInboundTest {
    public static void main(String[] args) {
        Random r = new Random();
        ByteBuf byteBuf = Unpooled.buffer();
        for (int i = 0; i < 3; i++) {
            int one = r.nextInt();
            byteBuf.writeInt(one);
            System.out.println("generate one: " + one);
        }

        EmbeddedChannel embeddedChannel = new EmbeddedChannel();

        // 获取channelPipeLine
        ChannelPipeline channelPipeline = embeddedChannel.pipeline();
        channelPipeline.addFirst(new DecodeTest());
        channelPipeline.addLast(new SimpleChannelInBoundHandlerTest());

        // 写入测试数据
        embeddedChannel.writeInbound(byteBuf);
        embeddedChannel.finish();

        // 验证测试数据
        System.out.println("embeddedChannel readInbound:" + embeddedChannel.readInbound());
        System.out.println("embeddedChannel readInbound:" + embeddedChannel.readInbound());
        System.out.println("embeddedChannel readInbound:" + embeddedChannel.readInbound());
    }

}

// 解码器
class DecodeTest extends ByteToMessageDecoder {
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        if (in.readableBytes() >= 4) {
            out.add(in.readInt());
        }
    }
}

// channelHandler
@SuppressWarnings("rawtypes")
class SimpleChannelInBoundHandlerTest extends SimpleChannelInboundHandler {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("Received message:" + msg);
        ctx.fireChannelRead(msg);
    }
}