1、netty的编码和解码，在数据传输的时候，考虑数据安全，数据完整性都是很有必要的。这里主要是介绍netty3和netty5的编解码方式。其实从StringEncoder和StringDecoder中也可以获取源码的编解码规则。然后改变成自己的编解码规则也是可以的。
2、netty3和netty5的编解码方式还是存在一定差别的。个人感觉netty5来的更加实用和方便。
3、netty3的编解码规则
1）数据编码规则（我这里只是用于显示，数据规则很简单）
包头+模块+数据（请求编解码）
包头+模块+状态+数据（响应编解码）
2）目录
3）请求和相应对象
package com.troy.data.domain;//请求数据public class Request { ???//模块类型 ???private int model; ???//数据 ???private byte[] data; ???public int getModel() { ???????return model; ???} ???public void setModel(int model) { ???????this.model = model; ???} ???public byte[] getData() { ???????return data; ???} ???public void setData(byte[] data) { ???????this.data = data; ???} ???@Override ???public String toString() { ???????return "Request{" + ???????????????"model=" + model + ???????????????", data=" + new String(data) + ???????????????‘}‘; ???}}package com.troy.data.domain;import java.util.Arrays;//响应数据public class Response { ???//模块类型 ???private int model; ???//状态码 ???private int status; ???//数据 ???private byte[] data; ???public int getModel() { ???????return model; ???} ???public void setModel(int model) { ???????this.model = model; ???} ???public int getStatus() { ???????return status; ???} ???public void setStatus(int status) { ???????this.status = status; ???} ???public byte[] getData() { ???????return data; ???} ???public void setData(byte[] data) { ???????this.data = data; ???} ???@Override ???public String toString() { ???????return "Response{" + ???????????????"model=" + model + ???????????????", status=" + status + ???????????????", data=" + new String(data) + ???????????????‘}‘; ???}}4）常量（这里的包头，因为是固定的就写了一个常量）
package com.troy.data.constant;//常量public class ConsantUtil { ???//固定常量用于数据拼接，确认 ???public static final int PACKAGE_HEADER = -32523523;}5）请求编解码
package com.troy.data.codec;import com.troy.data.constant.ConsantUtil;import com.troy.data.domain.Request;import org.jboss.netty.buffer.ChannelBuffer;import org.jboss.netty.buffer.ChannelBuffers;import org.jboss.netty.channel.Channel;import org.jboss.netty.channel.ChannelHandlerContext;import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;public class RequestEncode extends OneToOneEncoder { ???protected Object encode(ChannelHandlerContext channelHandlerContext, Channel channel, Object o) throws Exception { ???????Request request = (Request) o; ???????ChannelBuffer channelBuffer = ChannelBuffers.dynamicBuffer(); ???????channelBuffer.writeInt(ConsantUtil.PACKAGE_HEADER); ???????channelBuffer.writeInt(ConsantUtil.PACKAGE_HEADER); ???????channelBuffer.writeBytes(request.getData()); ???????return channelBuffer; ???}}package com.troy.data.codec;import com.troy.data.constant.ConsantUtil;import com.troy.data.domain.Request;import org.jboss.netty.buffer.ChannelBuffer;import org.jboss.netty.channel.Channel;import org.jboss.netty.channel.ChannelHandlerContext;import org.jboss.netty.handler.codec.oneone.OneToOneDecoder;//请求数据解码public class RequestDecode extends OneToOneDecoder { ???protected Object decode(ChannelHandlerContext channelHandlerContext, Channel channel, Object o) throws Exception { ???????ChannelBuffer channelBuffer = (ChannelBuffer) o; ???????if (ConsantUtil.PACKAGE_HEADER == channelBuffer.readInt()) { ???????????Request request = new Request(); ???????????request.setModel(channelBuffer.readInt()); ???????????byte[] bytes = new byte[channelBuffer.readableBytes()]; ???????????channelBuffer.readBytes(bytes); ???????????request.setData(bytes); ???????????return request; ???????} ???????return null; ???}}6）响应编解码
package com.troy.data.codec;import com.troy.data.constant.ConsantUtil;import com.troy.data.domain.Response;import org.jboss.netty.buffer.ChannelBuffer;import org.jboss.netty.buffer.ChannelBuffers;import org.jboss.netty.channel.Channel;import org.jboss.netty.channel.ChannelHandlerContext;import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;//响应编码器public class ResponseEncode extends OneToOneEncoder { ???protected Object encode(ChannelHandlerContext channelHandlerContext, Channel channel, Object o) throws Exception { ???????Response response = (Response) o; ???????ChannelBuffer channelBuffer = ChannelBuffers.dynamicBuffer(); ???????channelBuffer.writeInt(ConsantUtil.PACKAGE_HEADER); ???????channelBuffer.writeInt(response.getModel()); ???????channelBuffer.writeInt(response.getStatus()); ???????channelBuffer.writeBytes(response.getData()); ???????return channelBuffer; ???}}package com.troy.data.codec;import com.troy.data.constant.ConsantUtil;import com.troy.data.domain.Response;import org.jboss.netty.buffer.ChannelBuffer;import org.jboss.netty.channel.Channel;import org.jboss.netty.channel.ChannelHandlerContext;import org.jboss.netty.handler.codec.oneone.OneToOneDecoder;//响应解码public class ResponseDecode extends OneToOneDecoder{ ???protected Object decode(ChannelHandlerContext channelHandlerContext, Channel channel, Object o) throws Exception { ???????????ChannelBuffer channelBuffer = (ChannelBuffer) o; ???????if (ConsantUtil.PACKAGE_HEADER == channelBuffer.readInt()) { ???????????Response response = new Response(); ???????????response.setModel(channelBuffer.readInt()); ???????????response.setStatus(channelBuffer.readInt()); ???????????byte[] bytes = new byte[channelBuffer.readableBytes()]; ???????????channelBuffer.readBytes(bytes); ???????????response.setData(bytes); ???????????return response; ???????} ???????return null; ???}}7）设置对应的管道编解码就可以了
a、客户端
//设置管道工厂 ???????clientBootstrap.setPipelineFactory(new ChannelPipelineFactory() { ???????????public ChannelPipeline getPipeline() throws Exception { ???????????????ChannelPipeline channelPipeline = Channels.pipeline(); ???????????????channelPipeline.addLast("decode",new RequestEncode()); ???????????????channelPipeline.addLast("encode",new ResponseDecode()); ???????????????channelPipeline.addLast("client",new ClientHandler()); ???????????????return channelPipeline; ???????????} ???????}); @Override ???public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception { ???????Response response = (Response) e.getMessage(); ???????System.out.println(response.toString()); ???????super.messageReceived(ctx, e); ???}b、服务端
???????//设置管道流 ???????serverBootstrap.setPipelineFactory(new ChannelPipelineFactory() { ???????????public ChannelPipeline getPipeline() throws Exception { ???????????????ChannelPipeline channelPipeline = Channels.pipeline(); ???????????????//添加处理方式 ???????????????channelPipeline.addLast("idle",new IdleStateHandler(new HashedWheelTimer(),60,60,60)); ???????????????channelPipeline.addLast("decode",new RequestDecode()); ???????????????channelPipeline.addLast("encode",new ResponseEncode()); ???????????????channelPipeline.addLast("server",new ServerHandler()); ???????????????return channelPipeline; ???????????} ???????}); ??????? @Override ???public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception { ???????Request request = (Request) e.getMessage(); ???????System.out.println("client:"+request.toString()); ???????Response response = new Response(); ???????response.setModel(1); ???????response.setStatus(1); ???????response.setData("hello client".getBytes()); ???????ctx.getChannel().write(response); ???????super.messageReceived(ctx, e); ???}4、netty5的编解码规则
1）数据结构、目录结构、对象、常量都是一样。
2）编解码的编写方式有些不一样
a、请求编解码
package com.troy.data.codec;import com.troy.data.constant.ConsantUtil;import com.troy.data.domain.Request;import io.netty.buffer.ByteBuf;import io.netty.buffer.Unpooled;import io.netty.channel.ChannelHandler;import io.netty.channel.ChannelHandlerContext;import io.netty.handler.codec.MessageToMessageEncoder;import java.util.List;@ChannelHandler.Sharablepublic class RequestEncode extends MessageToMessageEncoder<Request> { ???protected void encode(ChannelHandlerContext channelHandlerContext, Request request, List<Object> list) throws Exception { ???????ByteBuf byteBuf = Unpooled.buffer(); ???????byteBuf.writeInt(ConsantUtil.PACKAGE_HEADER); ???????byteBuf.writeInt(request.getModel()); ???????byteBuf.writeBytes(request.getData()); ???????list.add(byteBuf); ???}}package com.troy.data.codec;import com.troy.data.constant.ConsantUtil;import com.troy.data.domain.Request;import io.netty.buffer.ByteBuf;import io.netty.channel.ChannelHandler;import io.netty.channel.ChannelHandlerContext;import io.netty.handler.codec.MessageToMessageDecoder;import java.util.List;//请求数据解码@ChannelHandler.Sharablepublic class RequestDecode extends MessageToMessageDecoder<ByteBuf>{ ???protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception { ???????if (ConsantUtil.PACKAGE_HEADER == byteBuf.readInt()) { ???????????Request request = new Request(); ???????????request.setModel(byteBuf.readInt()); ???????????byte[] bytes = new byte[byteBuf.readableBytes()]; ???????????byteBuf.readBytes(bytes); ???????????request.setData(bytes); ???????????list.add(request); ???????} ???}}b、响应编解码
package com.troy.data.codec;import com.troy.data.constant.ConsantUtil;import com.troy.data.domain.Response;import io.netty.buffer.ByteBuf;import io.netty.buffer.Unpooled;import io.netty.channel.ChannelHandler;import io.netty.channel.ChannelHandlerContext;import io.netty.handler.codec.MessageToMessageEncoder;import java.util.List;//响应编码器@ChannelHandler.Sharablepublic class ResponseEncode extends MessageToMessageEncoder<Response> { ???protected void encode(ChannelHandlerContext channelHandlerContext, Response response, List<Object> list) throws Exception { ???????ByteBuf byteBuf = Unpooled.buffer(); ???????byteBuf.writeInt(ConsantUtil.PACKAGE_HEADER); ???????byteBuf.writeInt(response.getModel()); ???????byteBuf.writeInt(response.getStatus()); ???????byteBuf.writeBytes(response.getData()); ???????list.add(byteBuf); ???}}package com.troy.data.codec;import com.troy.data.constant.ConsantUtil;import com.troy.data.domain.Response;import io.netty.buffer.ByteBuf;import io.netty.channel.ChannelHandler;import io.netty.channel.ChannelHandlerContext;import io.netty.handler.codec.MessageToMessageDecoder;import java.util.List;//响应解码@ChannelHandler.Sharablepublic class ResponseDecode extends MessageToMessageDecoder<ByteBuf>{ ???protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception { ???????if (ConsantUtil.PACKAGE_HEADER == byteBuf.readInt()) { ???????????Response response = new Response(); ???????????response.setModel(byteBuf.readInt()); ???????????response.setStatus(byteBuf.readInt()); ???????????byte[] bytes = new byte[byteBuf.readableBytes()]; ???????????byteBuf.readBytes(bytes); ???????????response.setData(bytes); ???????????list.add(response); ???????} ???}}3）处理上面基本上都是一样的。
5、netty的编解码，主要目的就是处理通讯问题，对数据进行自定义处理！
6、源码下载：https://pan.baidu.com/s/1nvUnmEt
netty之编解码
原文地址：http://www.cnblogs.com/ll409546297/p/8036954.html