Netty学习：搭建一个简单的Netty服务(JAVA NIO 类库的异步通信框架)
来源：zzy7075
发布时间：2018-11-21 15:54:15
阅读量：916
Netty学习：搭建一个简单的Netty服务
Netty 是一个基于 JAVA NIO 类库的异步通信框架，它的架构特点是：异步非阻塞、基于事件驱动、高性能、高可靠性和高可定制性。换句话说，Netty是一个NIO框架，使用它可以简单快速地开发网络应用程序，比如客户端和服务端的协议。Netty大大简化了网络程序的开发过程比如TCP和UDP的 Socket的开发。Netty 已逐渐成为 Java NIO 编程的首选框架。
项目官方地址：http://netty.io/index.html
一. Netty 的优点：
API 使用简单，开发门槛低；
功能强大，预置了多种编解码功能，支持多种主流协议；
定制能力强，可以通过 ChannelHandler 对通信框架进行灵活的扩展；
性能高，通过与其它业界主流的 NIO 框架对比，Netty 的综合性能最优；
社区活跃，版本迭代周期短，发现的 BUG 可以被及时修复，同时，更多的新功能会被加入；
经历了大规模的商业应用考验，质量得到验证。在互联网、大数据、网络游戏、企业应用、电信软件等众多行业得到成功商用，证明了它完全满足不同行业的商用标准。
二. 搭建Netty服务：
添加pom依赖
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.0.Final</version>
</dependency>
SimpleServer（服务端）
package com.yingjun.netty.server;
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;
public class SimpleServer {
private int port;
public SimpleServer(int port) {
this.port = port;
}
public void run() throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new SimpleServerHandler());
}
})
.option(ChannelOption.SO_BACKLOG, 128)
.childOption(ChannelOption.SO_KEEPALIVE, true);
ChannelFuture f = b.bind(port).sync();
f.channel().closeFuture().sync();
} finally {
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
new SimpleServer(9999).run();
}
}
SimpleServerHandler（服务端请求处理Handler）
package com.yingjun.netty.server;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
public class SimpleServerHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("SimpleServerHandler.channelRead");
ByteBuf result = (ByteBuf) msg;
byte[] result1 = new byte[result.readableBytes()];
result.readBytes(result1);
String resultStr = new String(result1);
System.out.println("Client said:" + resultStr);
result.release();
String response = "hello client!";
ByteBuf encoded = ctx.alloc().buffer(4 * response.length());
encoded.writeBytes(response.getBytes());
ctx.write(encoded);
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
}
SimpleServer（客户端）
package com.yingjun.netty.server;
import io.netty.bootstrap.Bootstrap;
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;
import io.netty.channel.socket.nio.NioSocketChannel;
public class SimpleClient {
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.SO_KEEPALIVE, true);
b.handler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new SimpleClientHandler());
}
});
ChannelFuture f = b.connect(host, port).sync();
f.channel().closeFuture().sync();
} finally {
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
SimpleClient client=new SimpleClient();
client.connect("127.0.0.1", 9999);
}
}
SimpleServerHandler（客户端请求处理Handler）
package com.yingjun.netty.server;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
public class SimpleClientHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("SimpleClientHandler.channelRead");
ByteBuf result = (ByteBuf) msg;
byte[] result1 = new byte[result.readableBytes()];
result.readBytes(result1);
System.out.println("Server said:" + new String(result1));
result.release();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
String msg = "hello Server!";
ByteBuf encoded = ctx.alloc().buffer(4 * msg.length());
encoded.writeBytes(msg.getBytes());
ctx.write(encoded);
ctx.flush();
}
}
运行结果：
SimpleClientHandler.channelRead
Server said:hello client!
------------------------------------------
SimpleServerHandler.channelRead
Client said:hello Server!
SimpleServerHandler.channelRead
Client said:hello Server!
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