netty之編解碼

　　1、netty的編碼和解碼，在數據傳輸的時候，考慮數據安全，數據完整性都是很有必要的。這里主要是介紹netty3和netty5的編解碼方式。其實從StringEncoder和StringDecoder中也可以獲取源碼的編解碼規則。然后改變成自己的編解碼規則也是可以的。

　　2、netty3和netty5的編解碼方式還是存在一定差別的。個人感覺netty5來的更加實用和方便。

　　3、netty3的編解碼規則

　　1）數據編碼規則（我這里只是用於顯示，數據規則很簡單）

　　包頭+模塊+數據（請求編解碼）

　　包頭+模塊+狀態+數據（響應編解碼）

　　2）目錄

　　

　　3）請求和相應對象

package com.troy.data.domain;

//請求數據
public class Request {

    //模塊類型
    private int model;
    //數據
    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;

//響應數據
public class Response {

    //模塊類型
    private int model;
    //狀態碼
    private int status;
    //數據
    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（這里的包頭，因為是固定的就寫了一個常量）

package com.troy.data.constant;

//常量
public class ConsantUtil {

    //固定常量用於數據拼接，確認
    public static final int PACKAGE_HEADER = -32523523;

}

　　5）請求編解碼

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;

//請求數據解碼
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）響應編解碼

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;

//響應編碼器
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;

//響應解碼
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）設置對應的管道編解碼就可以了

　　a、客戶端

　　　　 //設置管道工廠
        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、服務端

        //設置管道流
        serverBootstrap.setPipelineFactory(new ChannelPipelineFactory() {

            public ChannelPipeline getPipeline() throws Exception {
                ChannelPipeline channelPipeline = Channels.pipeline();
                //添加處理方式
                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的編解碼規則

　　1）數據結構、目錄結構、對象、常量都是一樣。

　　2）編解碼的編寫方式有些不一樣

　　a、請求編解碼

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.Sharable
public 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;

//請求數據解碼
@ChannelHandler.Sharable
public class RequestDecode extends MessageToMessageDecoder<ByteBuf>{

    protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception {
        if (ConsantUtil.PACKAGE_HEADER == byteBuf.readInt()) {
            //當數據超過指定值的時候跳過這部分數據
            if (byteBuf.readableBytes() > 2048) {
                byteBuf.skipBytes(byteBuf.readableBytes());
            }
            //一個字節一個字節的讀取，知道讀取到包頭
            while(true) {
                byteBuf.markReaderIndex();
                if (ConsantUtil.PACKAGE_HEADER == byteBuf.readInt()) {
                    break;
                }
                byteBuf.resetReaderIndex();
                byteBuf.readByte();
            }
            Request request = new Request();
            request.setModel(byteBuf.readInt());
            byte[] bytes = new byte[byteBuf.readableBytes()];
            byteBuf.readBytes(bytes);
            request.setData(bytes);
            list.add(request);
        }
    }
}

　　b、響應編解碼

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;

//響應編碼器
@ChannelHandler.Sharable
public 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;

//響應解碼
@ChannelHandler.Sharable
public class ResponseDecode extends MessageToMessageDecoder<ByteBuf>{

    protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception {
        if (ConsantUtil.PACKAGE_HEADER == byteBuf.readInt()) {
            //當數據超過指定值的時候跳過這部分數據
            if (byteBuf.readableBytes() > 2048) {
                byteBuf.skipBytes(byteBuf.readableBytes());
            }
            //一個字節一個字節的讀取，知道讀取到包頭
            while(true) {
                byteBuf.markReaderIndex();
                if (ConsantUtil.PACKAGE_HEADER == byteBuf.readInt()) {
                    break;
                }
                byteBuf.resetReaderIndex();
                byteBuf.readByte();
            }
            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）處理上面基本上都是一樣的。

　　5、netty的編解碼，主要目的就是處理通訊問題，對數據進行自定義處理！

 　　6、源碼下載：https://pan.baidu.com/s/1nvUnmEt