netty初認識
Netty是什麽?
本質:JBoss做的一個Jar包
目的:快速開發高性能、高可靠性的網絡服務器和客戶端程序
優點:提供異步的、事件驅動的網絡應用程序框架和工具
通俗的說:一個好使的處理Socket的東東
如果沒有Netty?
遠古:java.net + java.io
近代:java.nio
其他:Mina,Grizzly
為什麽不是Mina?
1、都是Trustin Lee的作品,Netty更晚;
2、Mina將內核和一些特性的聯系過於緊密,使得用戶在不需要這些特性的時候無法脫離,相比下性能會有所下降,Netty解決了這個設計問題;
3、Netty的文檔更清晰,很多Mina的特性在Netty裏都有;
4、Netty更新周期更短,新版本的發布比較快;
5、它們的架構差別不大,Mina靠apache生存,而Netty靠jboss,和jboss的結合度非常高,Netty有對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使用起來更簡單,Netty裏你可以自定義的處理upstream events 或/和 downstream events,可以使用decoder和encoder來解碼和編碼發送內容;
7、Netty和Mina在處理UDP時有一些不同,Netty將UDP無連接的特性暴露出來;而Mina對UDP進行了高級層次的抽象,可以把UDP當成"面向連接"的協議,而要Netty做到這一點比較困難。
Netty的特性
設計
統一的API,適用於不同的協議(阻塞和非阻塞)
基於靈活、可擴展的事件驅動模型
高度可定制的線程模型
可靠的無連接數據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存拷貝
安全
完整的SSL/TLS和STARTTLS的支持
能在Applet與Android的限制環境運行良好
健壯性
不再因過快、過慢或超負載連接導致OutOfMemoryError
不再有在高速網絡環境下NIO讀寫頻率不一致的問題
易用
完善的JavaDoc,用戶指南和樣例
簡潔簡單
僅信賴於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已經啟動,監聽端口: " + bind.getLocalAddress() + ", 等待客戶端註冊。。。");
- }
- 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發來:" + message);
- e.getChannel().write("Server已收到剛發送的:" + message);
- System.out.println("\n等待客戶端輸入。。。");
- }
- 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("有一個客戶端註冊上來了。。。");
- System.out.println("Client:" + e.getChannel().getRemoteAddress());
- System.out.println("Server:" + e.getChannel().getLocalAddress());
- System.out.println("\n等待客戶端輸入。。。");
- super.channelConnected(ctx, e);
- }
- }
- }
客戶端:
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等待客戶端輸入。。。");
- }
- super.messageReceived(ctx, e);
- }
- @Override
- public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
- System.out.println("已經與Server建立連接。。。。");
- System.out.println("\n請輸入要發送的信息:");
- super.channelConnected(ctx, e);
- e.getChannel().write(sin.readLine());
- }
- }
- }
Netty整體架構
Netty組件
ChannelFactory
Boss
Worker
Channel
ChannelEvent
Pipeline
ChannelContext
Handler
Sink
Server端核心類
NioServerSocketChannelFactory
NioServerBossPool
NioWorkerPool
NioServerBoss
NioWorker
NioServerSocketChannel
NioAcceptedSocketChannel
DefaultChannelPipeline
NioServerSocketPipelineSink
Channels
ChannelFactory
Channel工廠,很重要的類
保存啟動的相關參數
NioServerSocketChannelFactory
NioClientSocketChannelFactory
NioDatagramChannelFactory
這是Nio的,還有Oio和Local的
SelectorPool
Selector的線程池
NioServerBossPool 默認線程數: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
負責和底層的交互
如bind,Write,Close等
NioServerSocketPipelineSink
NioClientSocketPipelineSink
NioDatagramPipelineSink
Pipeline
負責維護所有的Handler
ChannelContext
一個Channel一個,是Handler和Pipeline的中間件
Handler
對Channel事件的處理器
ChannelPipeline
優秀的設計----事件驅動
優秀的設計----線程模型
註意事項
解碼時的Position
Channel的關閉
更多Handler
Channel的關閉
用完的Channel,可以直接關閉;
1、ChannelFuture加Listener
2、writeComplete
一段時間沒用,也可以關閉
TimeoutHandler
轉自: http://lippeng.iteye.com/blog/1907279
netty初認識