Netty入门之客户端与服务端通信(二)
一.简介
在上一篇博文中笔者写了关于Netty入门级的Hello World程序。书接上回，本博文是关于客户端与服务端的通信，感觉也没什么好说的了，直接上代码吧。
二.客户端与服务端的通信
2.1 服务端启动程序
public class MyServer {
public static void main(String[] args) throws InterruptedException {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try{
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new MyInitializer());
ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
channelFuture.channel().closeFuture().sync();
}finally{
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}
2.2 服务端通道初始化程序
public class MyInitializer extends ChannelInitializer<SocketChannel>{
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
/**
* LengthFieldBasedFrameDecoder: 基于长度属性的帧解码器。
* 客户端传递过来的数据格式为：
* BEFORE DECODE (14 bytes) AFTER DECODE (14 bytes)
* +--------+----------------+ +--------+----------------+
* | Length | Actual Content |----->| Length | Actual Content |
* | 0x000C | "HELLO, WORLD" | | 0x000C | "HELLO, WORLD" |
* +--------+----------------+ +--------+----------------+
* 5个参数依次为：1.(maxFrameLength)每帧数据的最大长度.
* 2.(lengthFieldOffset)length属性在帧中的偏移量。
* 3.(lengthFieldLength)length属性的长度，需要与客户端 LengthFieldPrepender设置的长度一致，
* 值的取值只能为1, 2, 3, 4, 8
* 4.(lengthAdjustment)长度调节值, 当信息长度包含长度时候，用于修正信息的长度。
* 5.(initialBytesToStrip)在获取真实的内容的时候，需要忽略的长度(通常就是length的长度)。
*
* 参考： http://blog.csdn.net/educast/article/details/47706599
*/
pipeline.addLast("lengthFieldBasedFrameDecoder",
new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 2, 0, 2));
/**
* LengthFieldPrepender: length属性在帧中的长度。只能为1,2,3,4,8。
* 该值与对应的客户端(或者服务端)在解码时候使用LengthFieldBasedFrameDecoder中所指定的lengthFieldLength
* 的值要保持一致。
*/
pipeline.addLast("lengthFieldPrepender", new LengthFieldPrepender(3));
//StringDecoder字符串的解码器, 主要用于处理编码格式
pipeline.addLast("stringDecoder", new StringDecoder(CharsetUtil.UTF_8));
//StringDecoder字符串的编码器，主要用于指定字符串的编码格式
pipeline.addLast("stringEncoder", new StringEncoder(CharsetUtil.UTF_8));
pipeline.addLast(new MyHandler()); //自定义的Handler
}
}
2.3 自定义Handler
public class MyHandler extends SimpleChannelInboundHandler<String>{
@Override
protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
System.out.println(ctx.channel().remoteAddress() + ":" + msg);
ctx.channel().writeAndFlush("from server: *");
}
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
System.out.println(System.currentTimeMillis() + "********");
System.out.println("server handler added**********");
}
@Override
public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
System.out.println(System.currentTimeMillis() + "********");
System.out.println("server channel register****");
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println(System.currentTimeMillis() + "********");
System.out.println("server channel actieve****");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
2.4客户端启动程序
public class MyClient {
public static void main(String[] args) throws InterruptedException {
EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
try{
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class).handler(new ClientInitializer());
ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 8899).sync();
channelFuture.channel().closeFuture().sync();
}finally{
eventLoopGroup.shutdownGracefully();
}
}
}
2.5客户端通道初始化
public class ClientInitializer extends ChannelInitializer<SocketChannel>{
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast("lengthFieldBasedFrameDecoder",
new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 2, 0, 2));
pipeline.addLast("lengthFieldPrepender", new LengthFieldPrepender(3));
pipeline.addLast("stringDecoder", new StringDecoder(CharsetUtil.UTF_8));
pipeline.addLast("stringEncoder", new StringEncoder(CharsetUtil.UTF_8));
pipeline.addLast(new MyClientHandler());
}
}
2.5客户端自定义Handler
public class MyClientHandler extends SimpleChannelInboundHandler<String>{
@Override
protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
System.out.println(ctx.channel().remoteAddress());
System.out.println(msg);
ctx.channel().writeAndFlush("to Server: *");
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println(System.currentTimeMillis() + "...........");
ctx.channel().writeAndFlush("来自于客户端的问候！");
System.out.println("client channel Active...");
}
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
System.out.println(System.currentTimeMillis() + "...........");
System.out.println("client hanlder added...");
}
@Override
public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
System.out.println(System.currentTimeMillis() + "...........");
System.out.println("client channel register...");
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
System.out.println("client channel inactive...");
}
@Override
public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
System.out.println("client channel unregister...");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
三. 运行测试
运行服务端启动代码，然后在运行客户端启动代码，就可以看见千万只"*"在崩腾。