netty4.0 Server和Client的通信

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netty4.0 Server和Client的通信

创建一个maven项目

添加Netty依赖

<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.16.Final</version>
</dependency>


Server端开发

public class HelloServer {
public void start(int port) {
ServerBootstrap serverBootstrap = new ServerBootstrap();//注意和 client 的区别
EventLoopGroup boosGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup(); serverBootstrap.group(boosGroup, workerGroup);
serverBootstrap.channel(NioServerSocketChannel.class);//注意和 client 端的区别，client 端是 NioSocketChannel
serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
protected void initChannel(SocketChannel socketChannel) throws Exception {
ChannelPipeline pipeline = socketChannel.pipeline();
pipeline.addLast(new HelloServerInHandler());
}
});
serverBootstrap.option(ChannelOption.SO_BACKLOG, 128);
serverBootstrap.childOption(ChannelOption.SO_KEEPALIVE, true);
try {
// 绑定端口，开始接收进来的连接
ChannelFuture f = serverBootstrap.bind(port).sync();
// 等待服务器 socket 关闭 。
// 在这个例子中，这不会发生，但你可以优雅地关闭你的服务器。
f.channel().closeFuture().sync();
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
boosGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
} public static void main(String[] args) {
HelloServer helloServer = new HelloServer();
int port = 8080;
if (args.length > 0) {
port = Integer.parseInt(args[0]);
}
helloServer.start(port);
}
}


server 消息处理

@ChannelHandler.Sharable
public class HelloServerInHandler extends ChannelInboundHandlerAdapter { @Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
try{
ByteBuf inMsg = (ByteBuf) msg;
byte[] bytes = new byte[inMsg.readableBytes()];
inMsg.readBytes(bytes);
String inStr = new String(bytes);
System.out.println("client send msg: " + inStr); String response = "i am ok!";
ByteBuf outMsg = ctx.alloc().buffer(4 * response.length());
outMsg.writeBytes(response.getBytes());
ctx.writeAndFlush(outMsg);
}finally {
ReferenceCountUtil.release(msg);
}
} @Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
super.channelReadComplete(ctx);
ctx.flush();
} @Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
super.exceptionCaught(ctx, cause);
ctx.close();
}
}


client 开发

public class HelloClient {
public void connect(String host, int port) {
EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
Bootstrap bootstrap = new Bootstrap(); //注意和 server 的区别
bootstrap.group(eventLoopGroup);
bootstrap.channel(NioSocketChannel.class);//注意和 server 端的区别，server 端是 NioServerSocketChannel
bootstrap.handler(new ChannelInitializer<SocketChannel>() {
protected void initChannel(SocketChannel socketChannel) throws Exception {
ChannelPipeline pipeline = socketChannel.pipeline();
pipeline.addLast(new HelloClientIntHandler());
}
});
bootstrap.option(ChannelOption.SO_KEEPALIVE, true); try {
// Start the client.
ChannelFuture future = bootstrap.connect(host, port).sync();
// 等待服务器 socket 关闭 。
future.channel().closeFuture().sync();
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
eventLoopGroup.shutdownGracefully();
}
} public static void main(String[] args) {
HelloClient client = new HelloClient();
client.connect("127.0.0.1", 8080);
}
}


client 消息处理

public class HelloClientIntHandler extends ChannelInboundHandlerAdapter { // 连接成功后，向server发送消息
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("connected server. start send msg.");
String msg = "r u ok?";
ByteBuf encoded = ctx.alloc().buffer(4 * msg.length());
encoded.writeBytes(msg.getBytes());
ctx.writeAndFlush(encoded);
} // 接收server端的消息，并打印出来
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
try {
ByteBuf result = (ByteBuf) msg;
byte[] serverMsg = new byte[result.readableBytes()];
result.readBytes(serverMsg);
System.out.println("Server said:" + new String(serverMsg));
} finally {
ReferenceCountUtil.release(msg);
}
}
}


测试

分别启动server端和client端

server端会输出如下内容：

client send msg: r u ok?


client端会输出如下内容：

Server said:i am ok!