一、netty可以运用在那些领域
1分布式进程通信
例如: hadoop、dubbo、akka等具有分布式功能的框架,底层RPC通信都是基于netty实现的,这些框架使用的版本通常都还在用netty3.x
2、游戏服务器开发
最新的游戏服务器有部分公司可能已经开始采用netty4.x 或 netty5.x
二、服务端与客户端代码案例
1.netty服务端hello world案例
代码如下:
HelloHandler.java
package com.server; import org.jboss.netty.channel.ChannelHandlerContext; import org.jboss.netty.channel.ChannelStateEvent; import org.jboss.netty.channel.ExceptionEvent; import org.jboss.netty.channel.MessageEvent; import org.jboss.netty.channel.SimpleChannelHandler; /** * 消息接受处理类 * @author -琴兽- * */ public class HelloHandler extends SimpleChannelHandler { /** * 接收消息 */ @Override public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception { String s = (String) e.getMessage(); System.out.println(s); //回写数据 ctx.getChannel().write("hi"); super.messageReceived(ctx, e); } /** * 捕获异常 */ @Override public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception { System.out.println("exceptionCaught"); super.exceptionCaught(ctx, e); } /** * 新连接 */ @Override public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception { System.out.println("channelConnected"); super.channelConnected(ctx, e); } /** * 必须是链接已经建立,关闭通道的时候才会触发 */ @Override public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception { System.out.println("channelDisconnected"); super.channelDisconnected(ctx, e); } /** * channel关闭的时候触发 */ @Override public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception { System.out.println("channelClosed"); super.channelClosed(ctx, e); } }
Server.java
package com.server; import java.net.InetSocketAddress; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import org.jboss.netty.bootstrap.ServerBootstrap; import org.jboss.netty.channel.ChannelPipeline; import org.jboss.netty.channel.ChannelPipelineFactory; import org.jboss.netty.channel.Channels; import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory; import org.jboss.netty.handler.codec.string.StringDecoder; import org.jboss.netty.handler.codec.string.StringEncoder; /** * netty服务端入门 * @author -琴兽- * */ public class Server { public static void main(String[] args) { //服务类 ServerBootstrap bootstrap = new ServerBootstrap(); //boss线程监听端口,worker线程负责数据读写 他们里面都会负责一个selector。 ExecutorService boss = Executors.newCachedThreadPool(); ExecutorService worker = Executors.newCachedThreadPool(); //设置niosocket工厂 bootstrap.setFactory(new NioServerSocketChannelFactory(boss, worker)); //设置管道的工厂 bootstrap.setPipelineFactory(new ChannelPipelineFactory() { @Override public ChannelPipeline getPipeline() throws Exception { ChannelPipeline pipeline = Channels.pipeline(); pipeline.addLast("decoder", new StringDecoder()); pipeline.addLast("encoder", new StringEncoder()); pipeline.addLast("helloHandler", new HelloHandler()); return pipeline; } }); bootstrap.bind(new InetSocketAddress(10101)); System.out.println("start!!!"); } }
部分事件如下:
SimpleChannelHandler 处理消息接收和写
{messageReceived接收消息
channelConnected新连接,通常用来检测IP是否是黑名单,非法攻击,恶意访问检测等等
channelDisconnected链接关闭,可以再用户断线的时候清楚用户的缓存数据等
}
2、netty客户端hello world案例
HiHandler.java
package com.client; import org.jboss.netty.channel.ChannelHandlerContext; import org.jboss.netty.channel.ChannelStateEvent; import org.jboss.netty.channel.ExceptionEvent; import org.jboss.netty.channel.MessageEvent; import org.jboss.netty.channel.SimpleChannelHandler; /** * 消息接受处理类 * @author -琴兽- * */ public class HiHandler extends SimpleChannelHandler { /** * 接收消息 */ @Override public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception { String s = (String) e.getMessage(); System.out.println(s); super.messageReceived(ctx, e); } /** * 捕获异常 */ @Override public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception { System.out.println("exceptionCaught"); super.exceptionCaught(ctx, e); } /** * 新连接 */ @Override public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception { System.out.println("channelConnected"); super.channelConnected(ctx, e); } /** * 必须是链接已经建立,关闭通道的时候才会触发 */ @Override public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception { System.out.println("channelDisconnected"); super.channelDisconnected(ctx, e); } /** * channel关闭的时候触发 */ @Override public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception { System.out.println("channelClosed"); super.channelClosed(ctx, e); } }
Client.java
package com.client; import java.net.InetSocketAddress; import java.util.Scanner; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import org.jboss.netty.bootstrap.ClientBootstrap; import org.jboss.netty.channel.Channel; import org.jboss.netty.channel.ChannelFuture; import org.jboss.netty.channel.ChannelPipeline; import org.jboss.netty.channel.ChannelPipelineFactory; import org.jboss.netty.channel.Channels; import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory; import org.jboss.netty.handler.codec.string.StringDecoder; import org.jboss.netty.handler.codec.string.StringEncoder; /** * netty客户端入门 * @author -琴兽- * */ public class Client { public static void main(String[] args) { //服务类 ClientBootstrap bootstrap = new ClientBootstrap(); //线程池 ExecutorService boss = Executors.newCachedThreadPool(); // ExecutorService worker = Executors.newCachedThreadPool(); // //socket工厂 bootstrap.setFactory(new NioClientSocketChannelFactory(boss, worker)); //管道工厂 bootstrap.setPipelineFactory(new ChannelPipelineFactory() { @Override public ChannelPipeline getPipeline() throws Exception { ChannelPipeline pipeline = Channels.pipeline(); pipeline.addLast("decoder", new StringDecoder()); pipeline.addLast("encoder", new StringEncoder()); pipeline.addLast("hiHandler", new HiHandler()); return pipeline; } }); //连接服务端 可以创建多个客户端连接 ChannelFuture connect = bootstrap.connect(new InetSocketAddress("127.0.0.1", 10101)); Channel channel = connect.getChannel(); System.out.println("client start"); Scanner scanner = new Scanner(System.in); while(true){ System.out.println("请输入"); channel.write(scanner.next()); } } }channelDisconnected与channelClosed的区别:
channelDisconnected只有在连接建立后断开才会调用
channelClosed无论连接是否成功都会调用关闭资源