本質(zhì)：JBoss做的一個(gè)Jar包
目的：快速開(kāi)發(fā)高性能、高可靠性的網(wǎng)絡(luò)服務(wù)器和客戶(hù)端程序
優(yōu)點(diǎn)：提供異步的、事件驅(qū)動(dòng)的網(wǎng)絡(luò)應(yīng)用程序框架和工具
通俗的說(shuō)：一個(gè)好使的處理Socket的東東
如果沒(méi)有Netty？
遠(yuǎn)古：java.net + java.io
近代：java.nio
其他：Mina，Grizzly
為什么不是Mina？
1、都是Trustin Lee的作品，Netty更晚；
2、Mina將內(nèi)核和一些特性的聯(lián)系過(guò)于緊密，使得用戶(hù)在不需要這些特性的時(shí)候無(wú)法脫離，相比下性能會(huì)有所下降，Netty解決了這個(gè)設(shè)計(jì)問(wèn)題；
3、Netty的文檔更清晰，很多Mina的特性在Netty里都有；
4、Netty更新周期更短，新版本的發(fā)布比較快；
5、它們的架構(gòu)差別不大，Mina靠apache生存，而Netty靠jboss，和jboss的結(jié)合度非常高，Netty有對(duì)google protocal buf的支持，有更完整的ioc容器支持(spring,guice,jbossmc和osgi)；
6、Netty比Mina使用起來(lái)更簡(jiǎn)單，Netty里你可以自定義的處理upstream events 或/和 downstream events，可以使用decoder和encoder來(lái)解碼和編碼發(fā)送內(nèi)容；
7、Netty和Mina在處理UDP時(shí)有一些不同，Netty將UDP無(wú)連接的特性暴露出來(lái)；而Mina對(duì)UDP進(jìn)行了高級(jí)層次的抽象，可以把UDP當(dāng)成"面向連接"的協(xié)議，而要Netty做到這一點(diǎn)比較困難。
Netty的特性
設(shè)計(jì)
統(tǒng)一的API，適用于不同的協(xié)議（阻塞和非阻塞）
基于靈活、可擴(kuò)展的事件驅(qū)動(dòng)模型
高度可定制的線程模型
可靠的無(wú)連接數(shù)據(jù)Socket支持（UDP）
性能
更好的吞吐量，低延遲
更省資源
盡量減少不必要的內(nèi)存拷貝
安全
完整的SSL/TLS和STARTTLS的支持
能在Applet與Android的限制環(huán)境運(yùn)行良好
健壯性
不再因過(guò)快、過(guò)慢或超負(fù)載連接導(dǎo)致OutOfMemoryError
不再有在高速網(wǎng)絡(luò)環(huán)境下NIO讀寫(xiě)頻率不一致的問(wèn)題
易用
完善的JavaDoc，用戶(hù)指南和樣例
簡(jiǎn)潔簡(jiǎn)單
僅信賴(lài)于JDK1.5
看例子吧！
Server端：
Java代碼
- package me.hello.netty;
-
- import org.jboss.netty.bootstrap.ServerBootstrap;
- import org.jboss.netty.channel.*;
- import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
- import org.jboss.netty.handler.codec.string.StringDecoder;
- import org.jboss.netty.handler.codec.string.StringEncoder;
-
- import java.net.InetSocketAddress;
- import java.util.concurrent.Executors;
-
- /**
- * God Bless You!
- * Author: Fangniude
- * Date: 2013-07-15
- */
- public class NettyServer {
- public static void main(String[] args) {
- ServerBootstrap bootstrap = new ServerBootstrap(new NioServerSocketChannelFactory(Executors.newCachedThreadPool(), Executors.newCachedThreadPool()));
-
- // Set up the default event pipeline.
- bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
- @Override
- public ChannelPipeline getPipeline() throws Exception {
- return Channels.pipeline(new StringDecoder(), new StringEncoder(), new ServerHandler());
- }
- });
-
- // Bind and start to accept incoming connections.
- Channel bind = bootstrap.bind(new InetSocketAddress(8000));
- System.out.println("Server已經(jīng)啟動(dòng)，監(jiān)聽(tīng)端口: " + bind.getLocalAddress() + "， 等待客戶(hù)端注冊(cè)。。。");
- }
-
- private static class ServerHandler extends SimpleChannelHandler {
- @Override
- public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
- if (e.getMessage() instanceof String) {
- String message = (String) e.getMessage();
- System.out.println("Client發(fā)來(lái):" + message);
-
- e.getChannel().write("Server已收到剛發(fā)送的:" + message);
-
- System.out.println("\n等待客戶(hù)端輸入。。。");
- }
-
- super.messageReceived(ctx, e);
- }
-
- @Override
- public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
- super.exceptionCaught(ctx, e);
- }
-
- @Override
- public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
- System.out.println("有一個(gè)客戶(hù)端注冊(cè)上來(lái)了。。。");
- System.out.println("Client:" + e.getChannel().getRemoteAddress());
- System.out.println("Server:" + e.getChannel().getLocalAddress());
- System.out.println("\n等待客戶(hù)端輸入。。。");
- super.channelConnected(ctx, e);
- }
- }
- }
客戶(hù)端：
Java代碼
- package me.hello.netty;
-
- import org.jboss.netty.bootstrap.ClientBootstrap;
- import org.jboss.netty.channel.*;
- import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;
- import org.jboss.netty.handler.codec.string.StringDecoder;
- import org.jboss.netty.handler.codec.string.StringEncoder;
-
- import java.io.BufferedReader;
- import java.io.InputStreamReader;
- import java.net.InetSocketAddress;
- import java.util.concurrent.Executors;
-
- /**
- * God Bless You!
- * Author: Fangniude
- * Date: 2013-07-15
- */
- public class NettyClient {
-
- public static void main(String[] args) {
- // Configure the client.
- ClientBootstrap bootstrap = new ClientBootstrap(new NioClientSocketChannelFactory(Executors.newCachedThreadPool(), Executors.newCachedThreadPool()));
-
- // Set up the default event pipeline.
- bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
- @Override
- public ChannelPipeline getPipeline() throws Exception {
- return Channels.pipeline(new StringDecoder(), new StringEncoder(), new ClientHandler());
- }
- });
-
- // Start the connection attempt.
- ChannelFuture future = bootstrap.connect(new InetSocketAddress("localhost", 8000));
-
- // Wait until the connection is closed or the connection attempt fails.
- future.getChannel().getCloseFuture().awaitUninterruptibly();
-
- // Shut down thread pools to exit.
- bootstrap.releaseExternalResources();
- }
-
- private static class ClientHandler extends SimpleChannelHandler {
- private BufferedReader sin = new BufferedReader(new InputStreamReader(System.in));
-
- @Override
- public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
- if (e.getMessage() instanceof String) {
- String message = (String) e.getMessage();
- System.out.println(message);
-
- e.getChannel().write(sin.readLine());
-
- System.out.println("\n等待客戶(hù)端輸入。。。");
- }
-
- super.messageReceived(ctx, e);
- }
-
- @Override
- public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
- System.out.println("已經(jīng)與Server建立連接。。。。");
- System.out.println("\n請(qǐng)輸入要發(fā)送的信息：");
- super.channelConnected(ctx, e);
-
- e.getChannel().write(sin.readLine());
- }
- }
- }
Netty整體架構(gòu)
Netty組件
ChannelFactory
Boss
Worker
Channel
ChannelEvent
Pipeline
ChannelContext
Handler
Sink
Server端核心類(lèi)
NioServerSocketChannelFactory
NioServerBossPool
NioWorkerPool
NioServerBoss
NioWorker
NioServerSocketChannel
NioAcceptedSocketChannel
DefaultChannelPipeline
NioServerSocketPipelineSink
Channels
ChannelFactory
Channel工廠，很重要的類(lèi)
保存啟動(dòng)的相關(guān)參數(shù)
NioServerSocketChannelFactory
NioClientSocketChannelFactory
NioDatagramChannelFactory
這是Nio的，還有Oio和Local的
SelectorPool
Selector的線程池
NioServerBossPool 默認(rèn)線程數(shù)：1
NioClientBossPool 1
NioWorkerPool 2 * Processor
NioDatagramWorkerPool
Selector
選擇器，很核心的組件
NioServerBoss
NioClientBoss
NioWorker
NioDatagramWorker
Channel
通道
NioServerSocketChannel
NioClientSocketChannel
NioAcceptedSocketChannel
NioDatagramChannel
Sink
負(fù)責(zé)和底層的交互
如bind，Write，Close等
NioServerSocketPipelineSink
NioClientSocketPipelineSink
NioDatagramPipelineSink
Pipeline
負(fù)責(zé)維護(hù)所有的Handler
ChannelContext
一個(gè)Channel一個(gè)，是Handler和Pipeline的中間件
Handler
對(duì)Channel事件的處理器
ChannelPipeline
優(yōu)秀的設(shè)計(jì)----事件驅(qū)動(dòng)
優(yōu)秀的設(shè)計(jì)----線程模型
注意事項(xiàng)
解碼時(shí)的Position
Channel的關(guān)閉
更多Handler
Channel的關(guān)閉
用完的Channel，可以直接關(guān)閉；
1、ChannelFuture加Listener
2、writeComplete
一段時(shí)間沒(méi)用，也可以關(guān)閉
TimeoutHandler