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本节内容是代码实现服务器与客户端完整连接过程。整体把控netty的工作流程。我们先不要被某个类，某个api的封装深入挖掘，这样你会踩很多坑，陷入进去而拔不出来，后面我会一一讲解，源码剖析工作原理。这就是我个人学习技术的一种方法，深入浅出，慢慢彻底熟悉netty。我们先学会用，然后把它切分若干块，慢慢吞噬。
代码实现：
详细：
package com.zhurong.netty.test2;
import com.zhurong.netty.test1.TestServerInitializer;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
/**
* Description:
* User: zhurong
* Date: 2018-09-19 23:17
*/
public class NettyServer {
public static void main(String[] args) {
//接收连接
EventLoopGroup bossGroup = new NioEventLoopGroup();
//连接发送给work
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
System.out.println("服务器启动成功！");
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class).
childHandler(new NettyInitializer());
ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
channelFuture.channel().closeFuture().sync();
} catch (Exception e) {
e.printStackTrace();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}
package com.zhurong.netty.test2;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
/**
* 此处定义客户端和服务器端传递的是字符串所以用了String
* Description:
* User: zhurong
* Date: 2018-09-19 23:30
*/
public class NettyServerHandler extends SimpleChannelInboundHandler<String> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
System.out.println(ctx.channel().remoteAddress()+"------>"+msg);
//返回数据给客户端,是一个异步的操作
ctx.channel().writeAndFlush("server tell you hello");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
package com.zhurong.netty.test2;
import com.zhurong.netty.test1.TestHttpServerHandler;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;
/**
* Description: 客户端与服务器端连接一旦创建，这个类中方法就会被回调
* User: zhurong
* Date: 2018-09-19 21:29
*/
public class NettyInitializer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
//解码器
pipeline.addLast(new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE,0,4,0,4));
//编码器，长度值是以二进制的形式加进去
pipeline.addLast(new LengthFieldPrepender(4));
pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
pipeline.addLast(new NettyServerHandler());
}
}
package com.zhurong.netty.test2;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
/**
* Description:
* User: zhurong
* Date: 2018-09-19 23:37
*/
public class NettyClient {
public static void main(String[] args) throws InterruptedException {
EventLoopGroup eventExecutors = new NioEventLoopGroup();
try {
System.out.println("客户端启动成功");
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(eventExecutors).channel(NioSocketChannel.class).handler(new NettyClientInitializer());
ChannelFuture channelFuture = bootstrap.connect("localhost",8899).sync();
channelFuture.channel().closeFuture().sync();
}finally {
eventExecutors.shutdownGracefully();
}
}
}
package com.zhurong.netty.test2;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
/**
* Description:
* User: zhurong
* Date: 2018-09-23 22:01
*/
public class NettyClientHandler extends SimpleChannelInboundHandler<String> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
System.out.println("收到服务器的消息："+ctx.channel().remoteAddress());
System.out.println("msg:"+ msg);
// ctx.writeAndFlush("from client "+ System.currentTimeMillis());
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
ctx.writeAndFlush("客户端第一条信息");
}
}
package com.zhurong.netty.test2;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;
/**
* Description: 客户端与服务器端连接一旦创建，这个类中方法就会被回调
* User: zhurong
* Date: 2018-09-19 21:29
*/
public class NettyClientInitializer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
//解码器
pipeline.addLast(new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE,0,4,0,4));
//编码器，长度值是以二进制的形式加进去
pipeline.addLast(new LengthFieldPrepender(4));
pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
pipeline.addLast(new NettyClientHandler());
}
}
