运用spring注解实现netty服务器端udp应用程序

netty是JBOSS针对网络开发的一套应用框架，它也是在NIO的基础上发展起来的。netty基于异步的事件驱动，具有高性能、高扩展性等特性，它提供了统一的底层协议接口，使得开发者从底层的网络协议（比如 TCP/IP、UDP）中解脱出来。就使用来说，开发者只要参考 Netty提供的若干例子和它的指南文档，就可以放手开发基于Netty的服务端程序了。

   netty有几个比较重要的概念，在此，仅做介绍，详细可以参考netty文档或源码。

   1). channelBuffer： 是 Netty 的一个基本数据结构，这个数据结构存储了一个字节序列。 类似于 NIO 的 ByteBuffer，但操作起来比ByteBuffer更为简单方便。

   2). ChannelFactory 是一个创建和管理 Channel 通道及其相关资源的工厂接口，它处理所有的 I/O 请求并产生相应的 I/O ChannelEvent 通道事件。

  3).ChannelHandler是所有I/O ChannelEvent事件的响应类，所有消息，包括netty通信异常事件，均在该响应类内处理。

  4).*** Bootstrap 是一个设置服务的帮助类。你甚至可以在这个服务中直接设置一个 Channel 通道。

  现在以实现一个UDP协议下的服务器应用程序为例，演示netty通过spring注解开发服务器端。（在此以maven工具管理项目开发）

  首先，是导入关联jar的POM文件：

 

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.byd.example</groupId>
  <artifactId>nettyTest</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>
  <name>nettyTest</name>
  <url>http://maven.apache.org</url>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
     <groupId>slf4j</groupId>
     <artifactId>slf4j-jdk14</artifactId>
     <version>1.6.1</version>
    </dependency>
    <dependency>
     <groupId>log4j</groupId>
     <artifactId>log4j</artifactId>
     <version>1.2.9</version>
    </dependency>
    <dependency>
     <groupId>org.jboss.netty</groupId>
     <artifactId>netty</artifactId>
     <version>3.2.0.BETA1</version>
    </dependency>
    <dependency>
     <groupId>org.springframework</groupId>
     <artifactId>spring-context</artifactId>
     <version>3.0.2.RELEASE</version>
    </dependency>
    <dependency>
     <groupId>org.springframework</groupId>
     <artifactId>spring-expression</artifactId>
     <version>3.0.2.RELEASE</version>
    </dependency>
    <dependency>
     <groupId>org.springframework</groupId>
     <artifactId>spring-tx</artifactId>
     <version>3.0.2.RELEASE</version>
    </dependency>
    <dependency>
     <groupId>org.springframework</groupId>
     <artifactId>spring-context</artifactId>
     <version>3.0.2.RELEASE</version>
    </dependency>
  </dependencies>
  <repositories>
     <repository>
       <id>repository.jboss.org</id>
          <url>http://repository.jboss.org/nexus/content/groups/public/</url>
         <snapshots>
           <enabled>false</enabled>
         </snapshots>
       </repository>
    </repositories>
    <build>

    </build>
</project>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.byd.example</groupId> <artifactId>nettyTest</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>nettyTest</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>slf4j</groupId> <artifactId>slf4j-jdk14</artifactId> <version>1.6.1</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.9</version> </dependency> <dependency> <groupId>org.jboss.netty</groupId> <artifactId>netty</artifactId> <version>3.2.0.BETA1</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>3.0.2.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-expression</artifactId> <version>3.0.2.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> <version>3.0.2.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>3.0.2.RELEASE</version> </dependency> </dependencies> <repositories> <repository> <id>repository.jboss.org</id> <url>http://repository.jboss.org/nexus/content/groups/public/</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> <build> </build> </project>

接下来是应用程序代码，在本人机器上可以运行并正常工作，如有需要可以试试。

I、Server接口：

 

package com.byd.example.netty;
public interface IServer
{
    /**
     * 启动服务器
     */
    public void start();
    /**
     * 重启程序
     */
    public void restart();

    /**
     * 停止程序运行
     */
    public void stop();
}

package com.byd.example.netty; public interface IServer { /** * 启动服务器 */ public void start(); /** * 重启程序 */ public void restart(); /** * 停止程序运行 */ public void stop(); } 

 II、ChannelHandler扩张类（继承SimpleChannelHandler）：

 

package com.byd.example.netty;
import java.util.Random;
import org.apache.log4j.Logger;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.DynamicChannelBuffer;
import org.jboss.netty.channel.ChannelFutureListener;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.springframework.stereotype.Component;
@Component("receiverHandler")
public class ReceiverHandler extends SimpleChannelHandler
{
    private static final Logger     logger=Logger.getLogger(ReceiverHandler.class.getName());

    @Override
    public void messageReceived(ChannelHandlerContext ctx,MessageEvent e) throws Exception
    {
        ChannelBuffer buffer=(ChannelBuffer)e.getMessage();
        byte[] recByte=buffer.copy().toByteBuffer().array();
        String recMsg=new String(recByte);
        logger.info("server received:"+recMsg.trim());
        Random random=new Random();
        int backWord=random.nextInt(10000);
        ChannelBuffer responseBuffer=new DynamicChannelBuffer(4);
        responseBuffer.readBytes(backWord);
        e.getChannel().write(responseBuffer);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx,ExceptionEvent e)
    {
        logger.error(e.getCause());
        if(e.getChannel() !=null)
        {
            e.getChannel().close().addListener(ChannelFutureListener.CLOSE);
        }
    }
}

package com.byd.example.netty; import java.util.Random; import org.apache.log4j.Logger; import org.jboss.netty.buffer.ChannelBuffer; import org.jboss.netty.buffer.DynamicChannelBuffer; import org.jboss.netty.channel.ChannelFutureListener; import org.jboss.netty.channel.ChannelHandlerContext; import org.jboss.netty.channel.ExceptionEvent; import org.jboss.netty.channel.MessageEvent; import org.jboss.netty.channel.SimpleChannelHandler; import org.springframework.stereotype.Component; @Component("receiverHandler") public class ReceiverHandler extends SimpleChannelHandler { private static final Logger logger=Logger.getLogger(ReceiverHandler.class.getName()); @Override public void messageReceived(ChannelHandlerContext ctx,MessageEvent e) throws Exception { ChannelBuffer buffer=(ChannelBuffer)e.getMessage(); byte[] recByte=buffer.copy().toByteBuffer().array(); String recMsg=new String(recByte); logger.info("server received:"+recMsg.trim()); Random random=new Random(); int backWord=random.nextInt(10000); ChannelBuffer responseBuffer=new DynamicChannelBuffer(4); responseBuffer.readBytes(backWord); e.getChannel().write(responseBuffer); } @Override public void exceptionCaught(ChannelHandlerContext ctx,ExceptionEvent e) { logger.error(e.getCause()); if(e.getChannel() !=null) { e.getChannel().close().addListener(ChannelFutureListener.CLOSE); } } } 

III、ChannelPipelineFactory实现类，包装ChannelHandler，处理I/O事件。

 

package com.byd.example.netty;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;
@Component("serverChannelPipelineFactory")
public class ServerChannelPipelineFactory implements ChannelPipelineFactory
{
    @Autowired
    @Qualifier("receiverHandler")
    private ReceiverHandler handler;
    @Override
    public ChannelPipeline getPipeline() throws Exception
    {
        ChannelPipeline pipeline=Channels.pipeline();
        pipeline.addLast("handler", this.handler);
        return pipeline;
    }
    public void setHandler(ReceiverHandler handler) {
        this.handler = handler;
    }
}

package com.byd.example.netty; import org.jboss.netty.channel.ChannelPipeline; import org.jboss.netty.channel.ChannelPipelineFactory; import org.jboss.netty.channel.Channels; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Qualifier; import org.springframework.stereotype.Component; @Component("serverChannelPipelineFactory") public class ServerChannelPipelineFactory implements ChannelPipelineFactory { @Autowired @Qualifier("receiverHandler") private ReceiverHandler handler; @Override public ChannelPipeline getPipeline() throws Exception { ChannelPipeline pipeline=Channels.pipeline(); pipeline.addLast("handler", this.handler); return pipeline; } public void setHandler(ReceiverHandler handler) { this.handler = handler; } }

IV、Iserver接口的实现类。

 

package com.byd.example.netty;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.concurrent.Executors;
import org.apache.log4j.Logger;
import org.jboss.netty.bootstrap.ConnectionlessBootstrap;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelFutureListener;
import org.jboss.netty.channel.socket.DatagramChannelFactory;
import org.jboss.netty.channel.socket.nio.NioDatagramChannelFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;
@Component("serverNettyImpl")
public class ServerNettyImpl implements IServer {
    @Autowired
    @Qualifier("serverChannelPipelineFactory")
    private ServerChannelPipelineFactory pipelineFactory;
    private Channel channel;
    private static final Logger logger = Logger.getLogger(ServerNettyImpl.class
            .getName());
    @Override
    public void start() {
        DatagramChannelFactory udpChannelFactory = new NioDatagramChannelFactory(
                Executors.newCachedThreadPool());
        ConnectionlessBootstrap bootstrap = new ConnectionlessBootstrap(udpChannelFactory);
        bootstrap.setOption("reuseAddress", false);
        bootstrap.setOption("child.reuseAddress", false);
        bootstrap.setOption("readBufferSize", 1024);
        bootstrap.setOption("writeBufferSize", 1024);
        bootstrap.setPipelineFactory(this.pipelineFactory);
        SocketAddress serverAddress = new InetSocketAddress(5000);
        this.channel = bootstrap.bind(serverAddress);
        logger.info("server start on " + serverAddress);
    }
    @Override
    public void restart() {
        this.stop();
        this.start();
    }
    @Override
    public void stop() {
        if (this.channel != null) {
            this.channel.close().addListener(ChannelFutureListener.CLOSE);
        }
    }
}

package com.byd.example.netty; import java.net.InetSocketAddress; import java.net.SocketAddress; import java.util.concurrent.Executors; import org.apache.log4j.Logger; import org.jboss.netty.bootstrap.ConnectionlessBootstrap; import org.jboss.netty.channel.Channel; import org.jboss.netty.channel.ChannelFutureListener; import org.jboss.netty.channel.socket.DatagramChannelFactory; import org.jboss.netty.channel.socket.nio.NioDatagramChannelFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Qualifier; import org.springframework.stereotype.Component; @Component("serverNettyImpl") public class ServerNettyImpl implements IServer { @Autowired @Qualifier("serverChannelPipelineFactory") private ServerChannelPipelineFactory pipelineFactory; private Channel channel; private static final Logger logger = Logger.getLogger(ServerNettyImpl.class .getName()); @Override public void start() { DatagramChannelFactory udpChannelFactory = new NioDatagramChannelFactory( Executors.newCachedThreadPool()); ConnectionlessBootstrap bootstrap = new ConnectionlessBootstrap(udpChannelFactory); bootstrap.setOption("reuseAddress", false); bootstrap.setOption("child.reuseAddress", false); bootstrap.setOption("readBufferSize", 1024); bootstrap.setOption("writeBufferSize", 1024); bootstrap.setPipelineFactory(this.pipelineFactory); SocketAddress serverAddress = new InetSocketAddress(5000); this.channel = bootstrap.bind(serverAddress); logger.info("server start on " + serverAddress); } @Override public void restart() { this.stop(); this.start(); } @Override public void stop() { if (this.channel != null) { this.channel.close().addListener(ChannelFutureListener.CLOSE); } } } 

V、应用程序入口：

 

package com.byd.example;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.byd.example.netty.IServer;
public class NettyTestRun
{
    public static void main( String[] args )
    {
        ApplicationContext context=new ClassPathXmlApplicationContext("classpath*:nettyTest-context.xml");
        IServer server=(IServer)context.getBean("serverNettyImpl");
        server.start();
    }
}

package com.byd.example; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.byd.example.netty.IServer; public class NettyTestRun { public static void main( String[] args ) { ApplicationContext context=new ClassPathXmlApplicationContext("classpath*:nettyTest-context.xml"); IServer server=(IServer)context.getBean("serverNettyImpl"); server.start(); } }

VI、context配置文件：

 

<?xml version="1.0" encoding="UTF-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
    http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    <context:component-scan base-package="com.byd.example"/>
    <context:annotation-config/>
</beans>

<?xml version="1.0" encoding="UTF-8" ?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <context:component-scan base-package="com.byd.example"/> <context:annotation-config/> </beans>

 VII、日志配置文件：

 

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd" >
<log4j:configuration xmlns:log4j='http://jakarta.apache.org/log4j/' >
    <appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender">
    <param name="target" value="System.out"/>
    <layout class="org.apache.log4j.PatternLayout">
        <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss}-%m%n" />
    </layout>
    <!--过滤器设置输出的级别-->
    <filter class="org.apache.log4j.varia.LevelRangeFilter">
        <param name="levelMin" value="debug" />
        <param name="levelMax" value="warn" />
        <param name="AcceptOnMatch" value="true" />
    </filter>
</appender>
    <appender name="FILE" class="org.apache.log4j.RollingFileAppender">
        <!-- 设置日志输出文件名 -->
        <param name="File" value="./target/output.log" />
        <!-- 设置是否在重新启动服务时，在原有日志的基础添加新日志 -->
        <param name="Append" value="true" />
        <param name="MaxBackupIndex" value="10" />
        <param name="encoding" value="UTF-8"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss}-%m%n" />
        </layout>
    </appender>
    <appender name="activexAppender" class="org.apache.log4j.DailyRollingFileAppender">
        <param name="File" value="./target/activex.log" />
        <param name="DatePattern" value="'.'yyyy-MM-dd'.log'" />
        <layout class="org.apache.log4j.PatternLayout">
         <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss}-%m%n" />
        </layout>
    </appender>

<!--
    <logger name="com.runway.bssp.activeXdemo" additivity="false">
        <priority value ="info"/>
        <param name="Level" value="DEBUG"/>
        <appender-ref ref="activexAppender" />
    </logger> -->


    <!-- 根logger的设置-->
    <root>
        <priority value ="debug"/>
        <appender-ref ref="CONSOLE"/>
        <appender-ref ref="FILE"/>
    </root>
</log4j:configuration>

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd" > <log4j:configuration xmlns:log4j='http://jakarta.apache.org/log4j/' > <appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender"> <param name="target" value="System.out"/> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss}-%m%n" /> </layout> <!--过滤器设置输出的级别--> <filter class="org.apache.log4j.varia.LevelRangeFilter"> <param name="levelMin" value="debug" /> <param name="levelMax" value="warn" /> <param name="AcceptOnMatch" value="true" /> </filter> </appender> <appender name="FILE" class="org.apache.log4j.RollingFileAppender"> <!-- 设置日志输出文件名 --> <param name="File" value="./target/output.log" /> <!-- 设置是否在重新启动服务时，在原有日志的基础添加新日志 --> <param name="Append" value="true" /> <param name="MaxBackupIndex" value="10" /> <param name="encoding" value="UTF-8"/> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss}-%m%n" /> </layout> </appender> <appender name="activexAppender" class="org.apache.log4j.DailyRollingFileAppender"> <param name="File" value="./target/activex.log" /> <param name="DatePattern" value="'.'yyyy-MM-dd'.log'" /> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss}-%m%n" /> </layout> </appender> <!-- <logger name="com.runway.bssp.activeXdemo" additivity="false"> <priority value ="info"/> <param name="Level" value="DEBUG"/> <appender-ref ref="activexAppender" /> </logger> --> <!-- 根logger的设置--> <root> <priority value ="debug"/> <appender-ref ref="CONSOLE"/> <appender-ref ref="FILE"/> </root> </log4j:configuration>

整理上面的代码，运行起来，可以看到服务器侦听在5000端口并接受客户端的信息并返回一个int随机数。

后记：netty当然也可以应用在TCP和客户端的程序，具体的使用可以参考netty API文档。