Netty实现自定义简单的编解码器（一）
关于编解码器的介绍，请看我另一篇文章：http://my.oschina.net/xinxingegeya/blog/282878
在这里实现的编解码器很简单，实现int->bytes的编码和bytes->int的解码
具体细节请看代码，注释很全面，运行结果很能说明问题
编码器
package codec.encoder;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
public class IntegerToByteEncoder extends MessageToByteEncoder<Integer> {
@Override
public void encode(ChannelHandlerContext ctx, Integer msg, ByteBuf out)
throws Exception {
System.err.println("IntegerToByteEncoder encode msg is " + msg);
out.writeInt(msg);
}
}
解码器
package codec.decoder;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import java.util.List;
/**
* 把字节转换为int
* 继承抽象类ByteToMessageDecoder实现解码器
*/
public class ByteToIntegerDecoder extends ByteToMessageDecoder {
@Override
public void decode(ChannelHandlerContext ctx, ByteBuf in,
List<Object> out) throws Exception {
if (in.readableBytes() >= 4) { // Check if there are at least 4 bytes readable
int n = in.readInt();
System.err.println("ByteToIntegerDecoder decode msg is " + n);
out.add(n); //Read integer from inbound ByteBuf, add to the List of decodec messages
}
}
}
服务器端程序
package codec;
import codec.decoder.ByteToIntegerDecoder;
import codec.encoder.IntegerToByteEncoder;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
/**
* 主要思路：
* 实现了一个编码器IntegerToByteEncoder和一个解码器ByteToIntegerDecoder
* 客户端直接发送一个数字
* 服务器端接收后向客户端发送一个数字
* 在这过程中可以看到解码器和编码器所起的作用
*/
public class HelloServer {
public void start(int port) throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 128)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
// 注册handler
ch.pipeline().addLast(
new IntegerToByteEncoder(),
new ByteToIntegerDecoder(),
new HelloServerInHandler());
}
});
ChannelFuture f = b.bind(port).sync();
f.channel().closeFuture().sync();
} finally {
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
HelloServer server = new HelloServer();
server.start(12345);
}
}
package codec;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
// 该handler是InboundHandler类型
public class HelloServerInHandler extends ChannelInboundHandlerAdapter {
@Override
public boolean isSharable() {
System.out.println("==============handler-sharable==============");
return super.isSharable();
}
@Override
public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
System.out.println("==============channel-register==============");
}
@Override
public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
System.out.println("==============channel-unregister==============");
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("==============channel-active==============");
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
System.out.println("==============channel-inactive==============");
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("==============channel-read==============");
System.out.println("the msg type is " + msg.getClass().getName());
Integer integer = (Integer) msg;
System.out.println("服务器端接收到的客户端的数字是" + integer);
System.out.println("服务器向客户端写入整型数字2000");
ctx.writeAndFlush(2000);
ctx.close();
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
System.out.println("==============channel-read-complete==============");
ctx.flush();
}
}
客户端程序
package codec;
import codec.decoder.ByteToIntegerDecoder;
import codec.encoder.IntegerToByteEncoder;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
public class HelloClient {
public void connect(String host, int port) throws Exception {
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(workerGroup);
b.channel(NioSocketChannel.class);
b.option(ChannelOption.AUTO_READ, true);
b.handler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(
new IntegerToByteEncoder(),
new ByteToIntegerDecoder(),
new HelloClientIntHandler());
}
});
ChannelFuture f = b.connect(host, port).sync();
f.channel().closeFuture().sync();
} finally {
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
HelloClient client = new HelloClient();
client.connect("192.168.0.102", 12345);
}
}
package codec;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
//InboundHandler类型
public class HelloClientIntHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
System.out.println("==============channel--register==============");
}
@Override
public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
System.out.println("==============channel--unregistered==============");
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
System.out.println("==============channel--inactive==============");
}
// 连接成功后，向server发送消息
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("==============channel--active==============");
System.out.println("向服务器端写入1991数字");
ctx.write(1991);
ctx.flush();
}
// 接收server端的消息，并打印出来
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("==============channel--read==============");
System.out.println("the msg type is " + msg.getClass().getName());
Integer result = (Integer) msg;
System.out.println("接收到服务器数据整形是" + result);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
cause.printStackTrace();
ctx.close();
}
}
运行结果：
服务器端
==============handler-sharable==============
==============channel-register==============
==============channel-active==============
==============channel-read==============
the msg type is java.lang.Integer
服务器端接收到的客户端的数字是1991
服务器向客户端写入整型数字2000
ByteToIntegerDecoder decode msg is 1991
IntegerToByteEncoder encode msg is 2000
==============channel-read-complete==============
==============channel-inactive==============
==============channel-unregister==============
客户端
==============channel--register==============
==============channel--active==============
向服务器端写入1991数字
IntegerToByteEncoder encode msg is 1991
ByteToIntegerDecoder decode msg is 2000
==============channel--read==============
the msg type is java.lang.Integer
接收到服务器数据整形是2000
==============channel--inactive==============
==============channel--unregistered==============
Process finished with exit code 0