netty案例，netty4.1基础入门篇九《自定义编码解码器》

itstack-demo-netty-1-09
└── src
    ├── main
    │   └── java
    │       └── org.itstack.demo.netty
    │           ├── codec
    │           │   ├── MyDecoder.java
    │           │   └── MyEncoder.java
    │           └── server
    │               ├── MyChannelInitializer.java
    │               ├── MyServerHandler.java
    │               └── NettyServer.java
    └── test
         └── java
             └── org.itstack.demo.test
                 └── ApiTest.java

/**
 * 自定义解码器
 * 虫洞栈：https://bugstack.cn
 * 公众号：bugstack虫洞栈  ｛关注获取学习源码｝
 * 虫洞群：①群5398358 ②群5360692
 * Create by fuzhengwei on 2019
 */
public class MyDecoder extends ByteToMessageDecoder {
    @Override
    protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf in, List<Object> out) throws Exception {
        int size = in.readableBytes();
        byte[] data = new byte[size];
        in.readBytes(data);
        byte begin = data[0];     //开始符02
        byte end = data[size - 1];//结束符03
        //无开始符，只有结束符，数据丢包
        if (begin != 0x02 && end == 0x03){
            System.out.println("公众号：bugstack虫洞栈 提示；byteBuf数据，无开始符，只有结束符，数据丢包。");
            channelHandlerContext.writeAndFlush("error");
            return; //直接返回，不置位指针
        }
        //有开始符，无结束符号，数据半包。置位指针，接收余下数据
        if (begin != 0x02 || end != 0x03) {
            in.resetReaderIndex();
            System.out.println("公众号：bugstack虫洞栈 提示；byteBuf数据，有开始符，无结束符号，数据半包。置位指针，接收余下数据。");
            return;
        }
        //数据完整，解析处理
        System.out.println(JSON.toJSONString(data));
        //越过02 03位
        ByteBuf copy = in.copy(1, size - 1);
        //转换
        String msg = copy.toString(Charset.forName("GBK"));
        //填充
        out.add(msg);
    }
}

/**
 * 自定义编码器
 * 虫洞栈：https://bugstack.cn
 * 公众号：bugstack虫洞栈  ｛关注获取学习源码｝
 * 虫洞群：①群5398358 ②群5360692
 * Create by fuzhengwei on 2019
 */
public class MyEncoder extends MessageToByteEncoder {
    @Override
    protected void encode(ChannelHandlerContext channelHandlerContext, Object in, ByteBuf out) throws Exception {
        String msg = in.toString();
        byte[] bytes = msg.getBytes();
        byte[] send = new byte[bytes.length + 2];
        System.arraycopy(bytes, 0, send, 1, bytes.length);
        send[0] = 0x02;
        send[send.length - 1] = 0x03;
        out.writeInt(send.length);
        out.writeBytes(send);
    }
}

/**
 * 虫洞栈：https://bugstack.cn
 * 公众号：bugstack虫洞栈  ｛关注获取学习源码｝
 * 虫洞群：①群5398358 ②群5360692
 * Create by fuzhengwei on 2019
 */
public class MyChannelInitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel channel) {
        //自定义解码器
        channel.pipeline().addLast(new MyDecoder());
        //自定义编码器
        channel.pipeline().addLast(new MyEncoder());
        //在管道中添加我们自己的接收数据实现方法
        channel.pipeline().addLast(new MyServerHandler());
    }
}

/**
 * 虫洞栈：https://bugstack.cn
 * 公众号：bugstack虫洞栈  ｛关注获取学习源码｝
 * 虫洞群：①群5398358 ②群5360692
 * Create by fuzhengwei on 2019
 */
public class MyServerHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        SocketChannel channel = (SocketChannel) ctx.channel();
        System.out.println("链接报告开始 {公众号：bugstack虫洞栈 >获取学习源码}");
        System.out.println("链接报告信息：有一客户端链接到本服务端");
        System.out.println("链接报告IP:" + channel.localAddress().getHostString());
        System.out.println("链接报告Port:" + channel.localAddress().getPort());
        System.out.println("链接报告完毕");
    }
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        //接收msg消息{与上一章节相比，此处已经不需要自己进行解码}
        System.out.println(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()) + " 接收到消息：" + msg);
        ctx.writeAndFlush("hi I'm ok");
    }
}

itstack-demo-netty server start done. {关注公众号：bugstack虫洞栈，获取源码}
链接报告开始 {公众号：bugstack虫洞栈 >获取学习源码}
链接报告信息：有一客户端链接到本服务端
链接报告IP:192.168.1.121
链接报告Port:7397
链接报告完毕
"AmhpILmr1tq6xaO6YnVnc3RhY2uz5ra01bsgAw=="
2019-08-18 15:32:47 接收到消息：hi 公众号：bugstack虫洞栈 
"AmhpILmr1tq6xaO6YnVnc3RhY2uz5ra01bsgAw=="
2019-08-18 15:32:48 接收到消息：hi 公众号：bugstack虫洞栈 
"AmhpILmr1tq6xaO6YnVnc3RhY2uz5ra01bsgAw=="
2019-08-18 15:32:49 接收到消息：hi 公众号：bugstack虫洞栈 
"AmhpILmr1tq6xaO6YnVnc3RhY2uz5ra01bsgAw=="
2019-08-18 15:32:49 接收到消息：hi 公众号：bugstack虫洞栈 
"AmhpILmr1tq6xaO6YnVnc3RhY2uz5ra01bsgAw=="
2019-08-18 15:32:50 接收到消息：hi 公众号：bugstack虫洞栈 
"AmhpILmr1tq6xaO6YnVnc3RhY2uz5ra01bsgAw=="
2019-08-18 15:32:51 接收到消息：hi 公众号：bugstack虫洞栈 
"AmhpILmr1tq6xaO6YnVnc3RhY2uz5ra01bsgAw=="
2019-08-18 15:32:51 接收到消息：hi 公众号：bugstack虫洞栈 
Process finished with exit code -1