Customize the codec to deal with the problem of TCP sticky packet unpacking
Specific code implementation
Custom codec
PersonProtocol
public class PersonProtocol {
private int length;
private byte[] content;
public int getLength() {
return length;
}
public void setLength(int length) {
this.length = length;
}
public byte[] getContent() {
return content;
}
public void setContent(byte[] content) {
this.content = content;
}
}
MyPersonDecoder
// 编写解码器
public class MyPersonDecoder extends ReplayingDecoder<Void> {
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
System.out.println("MyPersonDecoder decode invoked!");
int length = in.readInt();
byte[] content = new byte[length];
in.readBytes(content);
PersonProtocol personProtocol = new PersonProtocol();
personProtocol.setLength(length);
personProtocol.setContent(content);
out.add(personProtocol);
}
}
MyPersonEncoder
// Encoder
public class MyPersonEncoder extends MessageToByteEncoder<PersonProtocol> {
@Override
protected void encode(ChannelHandlerContext ctx, PersonProtocol msg, ByteBuf out) throws Exception {
System.out.println("MyPersonEncoder encode invoked!");
out.writeInt(msg.getLength());
out.writeBytes(msg.getContent());
}
}
服务端
MyClient
public class MyClient {
public static void main(String[] args) throws Exception{
// Event thread group eventLoopGroup
EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap(); // 启动服务
bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class).
handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline= ch.pipeline();
pipeline.addLast(new MyPersonEncoder());
pipeline.addLast(new MyPersonDecoder());
pipeline.addLast(new MyClientHandler());
}
}); // channel initialization
ChannelFuture channelFuture = bootstrap.connect("localhost",8899).sync();
channelFuture.channel().closeFuture().sync();
}finally {
eventLoopGroup.shutdownGracefully();
}
}
}
MyClientHandler
public class MyClientHandler extends SimpleChannelInboundHandler<PersonProtocol> {
private int count;
@Override
protected void channelRead0(ChannelHandlerContext ctx, PersonProtocol msg) throws Exception {
int length=msg.getLength();
byte[] content = msg.getContent();
System.out.println("The client received the message");
System.out.println("长度："+length);
System.out.println("内容："+new String(content, Charset.forName("utf-8")));
System.out.println("The number of messages received by the client: "+(++count));
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
for(int i=0;i<10;i++){
String messageToBeSent = "发送自客户端";
byte[] content = messageToBeSent.getBytes(Charset.forName("utf-8"));
int length = messageToBeSent.getBytes(Charset.forName("utf-8")).length;
PersonProtocol personProtocol = new PersonProtocol();
personProtocol.setLength(length);
personProtocol.setContent(content);
ctx.writeAndFlush(personProtocol);
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
服务端
MyServer
public class MyServer {
public static void main(String[]args) throws Exception{
//Two thread groups
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try { ServerBootstrap serverBootstrap = new ServerBootstrap();//Start the server serverBootstrap.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class) .handler(new LoggingHandler(LogLevel.INFO)). //Specify the log level of the log handler for bossGroup childHandler(new MyServerInitialzer());//Specify log level for workerGroup
ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();//Bind port
channelFuture.channel().closeFuture().sync();
}finally { bossGroup.shutdownGracefully();//Close thread group workerGroup.shutdownGracefully (); } } }
MyServerInitialzer
public class MyServerInitialzer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast(new MyPersonDecoder());
pipeline.addLast(new MyPersonEncoder());
pipeline.addLast(new MyServerHandler());
}
}
MyServerHandler
public class MyServerHandler extends SimpleChannelInboundHandler<PersonProtocol> {
private int count;
@Override
protected void channelRead0(ChannelHandlerContext ctx, PersonProtocol msg) throws Exception {
int length = msg.getLength();
byte[] content = msg.getContent();
System.out.println("The server received data:");
System.out.println("Length: "+length);
System.out.println("Content: "+new String (content, Charset.forName( "utf-8")));
System.out.println("The number of messages received by the server: "+(++count));
String responseMessage= UUID.randomUUID().toString();
int responseLength = responseMessage.getBytes("utf-8").length;
byte[] responseContent = responseMessage.getBytes("utf-8");
PersonProtocol personProtocol = new PersonProtocol();
personProtocol.setContent(responseContent);
personProtocol.setLength(responseLength);
ctx.writeAndFlush(personProtocol);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}