netty深入学习之一: 入门篇
本文代码下载：
http://download.csdn.net/detail/cheungmine/8497549
1）Netty是什么
Netty是Java NIO之上的网络库（API）。Netty 提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序。
2）Netty的特性
统一的API，适用于不同的协议（阻塞和非阻塞）。基于灵活、可扩展的事件驱动模型。高度可定制的线程模型。可靠的无连接数据Socket支持（UDP）性能。更好的吞吐量，低延迟。更省资源，尽量减少不必要的内存拷贝。完整的SSL/ TLS和STARTTLS的支持。能在Applet和Android的限制环境运行良好。健壮性：不再因过快、过慢或超负载连接导致OutOfMemoryError。不再有在高速网络环境下NIO读写频率丌一致的问题。易用：完善的Java doc，用户指南和样例，简洁简单。仅依赖于JDK1.5。
3）Netty快速上手
俗话说，万事开头难，因此我构建了一个Netty项目模板：avro-channel。目的是结合Netty和Avro实现异步数据传输和RPC（远程过程调用）。avro-channel最初的目的是为了实现一套RPC服务，发现了Netty功能如此强大之后，就想使用Netty构建整个后端体系。因此，本文的例子代码提供了一个简单的Netty入门：HelloWorldServer和HelloWorldClient。
构建项目很简单，第一步，手工安装依赖jar到你的机器上，进入项目pom.xml所在目录：
$ python ./mvn-install-lib.py
上面这个命令把lib/下的jar包安装到你的机器上。然后执行下面的命令构建：
$ mvn clean compile package assembly:assembly
最后打开2个终端a,b，分别执行下面的服务器和客户端：
a 启动服务器：
$ java -jar ./target/avro-channel-1.0-PRE.jar
或
$ java -cp ./target/avro-channel-1.0-PRE.jar avro.channel.server.netty.HelloWorldServer
b 启动客户端：
$ java -cp ./target/avro-channel-1.0-PRE.jar avro.channel.client.netty.HelloWorldClient
4）例子工程结构
avro-channel是标准的maven(3.05)工程，目录结构如下：
lib/netty包含jboss.netty和io.netty二个版本系列。最后让我们看看完整的pom.xml：
<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>
<description>avro-channel is a java framework for data transport and rpc. created by zhangliang</description>
<!--
build all:
$ mvn clean compile package assembly:assembly
-->
<groupId>avro.channel</groupId>
<artifactId>avro-channel</artifactId>
<packaging>jar</packaging>
<version>1.0-PRE</version>
<name>avro-channel</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<compiler-plugin.version>2.3.2</compiler-plugin.version>
<avro.version>1.7.7</avro.version>
<slf4j.version>1.7.10</slf4j.version>
<jackson.version>1.9.13</jackson.version>
<jboss.netty.version>3.2.10.Final</jboss.netty.version>
<io.netty.version>5.0.0.Alpha2</io.netty.version>
<!-- test server class: HelloWorldServer -->
<!-- test client class: HelloWorldClient -->
<main.class>avro.channel.server.netty.HelloWorldServer</main.class>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.jboss.netty</groupId>
<artifactId>netty</artifactId>
<version>${jboss.netty.version}</version>
</dependency>
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>${io.netty.version}</version>
</dependency>
<dependency>
<groupId>org.apache.avro</groupId>
<artifactId>avro</artifactId>
<version>${avro.version}</version>
</dependency>
<dependency>
<groupId>org.apache.avro</groupId>
<artifactId>avro-ipc</artifactId>
<version>${avro.version}</version>
</dependency>
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-core-asl</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>${jackson.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${compiler-plugin.version}</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.avro</groupId>
<artifactId>avro-maven-plugin</artifactId>
<version>${avro.version}</version>
<executions>
<execution>
<id>schemas</id>
<phase>generate-sources</phase>
<goals>
<goal>schema</goal>
<goal>protocol</goal>
<goal>idl-protocol</goal>
</goals>
<configuration>
<sourceDirectory>${project.basedir}/src/main/avro/</sourceDirectory>
<outputDirectory>${project.basedir}/src/main/java/</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
<!--
1) Build project jar and copy all dependencies into lib/:
$ mvn clean compile
$ mvn package
2) Start Server:
$ java -jar ./target/avro-channel-1.0-PRE.jar
or
$ java -cp ./target/avro-channel-1.0-PRE.jar avro.channel.server.netty.HelloWorldServer
3) Start Client:
$ java -cp ./target/avro-channel-1.0-PRE.jar avro.channel.client.netty.HelloWorldClient
-->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>${main.class}</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
<!--
1) Package all jars in one: ${name}-jar-with-dependencies.jar
$ mvn assembly:assembly
2) Run server:
$ java -jar ./target/avro-channel-1.0-PRE-jar-with-dependencies.jar
or
$ java -cp ./target/avro-channel-1.0-PRE-jar-with-dependencies.jar avro.channel.server.netty.HelloWorldServer
3) Run client:
$ java -cp ./target/avro-channel-1.0-PRE-jar-with-dependencies.jar avro.channel.client.netty.HelloWorldClient
-->
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2</version>
<configuration>
<archive>
<manifest>
<mainClass>${main.class}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
</project>