MINA是一个网络应用框架，在不牺牲性能和可扩展性的前提下用于解决如下问题：
1： 快速开发自己的英勇。
2：高可维护性，高可复用性：网络I/O编码，消息的编/解码，业务逻辑互相分离。
3：相对容易的进行单元测试。
3.1 IoFilters：
IoFilter为MINA的功能扩展提供了接口。它拦截所有的IO事件进行事件的预处理和后处理 (AOP)。我们可以把它想象成
Servlet的filters。
IoFilter能够实现以下几种目的：
事件日志
性能 检测
数据转换(e.g. SSL support)，codec
防火墙…等等
3.2 codec: ProtocolCodecFactory
MINA提供了方便的Protocol支持。如上说讲，codec在 IoFilters中设置。
通过它的Encoder和Decoder，可以方便的扩展并支持各种基于Socket的网络协议，比如HTTP服务 器、FTP服务器、Telnet服务器等等。
要实现自己的编码/解码器(codec)只需要实现interface: ProtocolCodecFactory即可.
在MINA 1.0版本，MINA已经实现了几个常用的(codec factory):
DemuxingProtocolCodecFactory,
NettyCodecFactory,
ObjectSerializationCodecFactory,
TextLineCodecFactory
其中：
TextLineCodecFactory:
A ProtocolCodecFactory that performs encoding and decoding between a text line data and a Java
string object. This codec is useful especially when you work with a text-based protocols such as SMTP and IMAP.
ObjectSerializationCodecFactory:
A ProtocolCodecFactory that serializes and deserializes Java objects. This codec is very useful when
you have to prototype your application rapidly without any specific codec.
DemuxingProtocolCodecFactory：
A composite ProtocolCodecFactory that consists of multiple MessageEncoders and MessageDecoders. ProtocolEncoder
and ProtocolDecoder this factory returns demultiplex incoming messages and buffers to appropriate MessageEncoders
and MessageDecoders.
NettyCodecFactory:
A MINA ProtocolCodecFactory that provides encoder and decoder for Netty2 Messages and MessageRecognizers.
3.3 business logic: IoHandler
MINA中，所有的业务逻辑都有实现了IoHandler的class完成
interfaceHandles:
all protocol events fired by MINA. There are 6 event handler methods, and they are all invoked by MINA automatically.
当事件发生时，将触发IoHandler中的方 法:
sessionCreated, sessionOpened, sessionClosed, sessionIdle, exceptionCaught, messageReceived, messageSent
MINA 1.O中，IoHandler的实现类：
ChainedIoHandler, DemuxingIoHandler, IoHandlerAdapter, SingleSessionIoHandlerDelegate, StreamIoHandler
具体 细节可参考javadoc。
3.4 MINA的高级主题：线程模式
MINA通过它灵活的filter机制来提供多种线程模型。
没有线程池过滤器被使用时 MINA运行在一个单线程模式。
如果添加了一个IoThreadPoolFilter到IoAcceptor，将得到一个leader- follower模式的线程池。
如果再添加一个ProtocolThreadPoolFilter，server将有两个线程池；
一个 (IoThreadPoolFilter)被用于对message对象进行转换，另外一个(ProtocolThreadPoolFilter)被用于处 理业务逻辑。
SimpleServiceRegistry加上IoThreadPoolFilter和 ProtocolThreadPoolFilter的缺省实现即可适用于需
要高伸缩性的应用。如果想使用自己的线程模型，请参考 SimpleServiceRegistry的源代码，并且自己
初始化Acceptor。
IoThreadPoolFilter threadPool = new IoThreadPoolFilter();threadPool.start();
IoAcceptor acceptor = new SocketAcceptor();
acceptor.getFilterChain().addLast( "threadPool", threadPool);
ProtocolThreadPoolFilter threadPool2 = new ProtocolThreadPoolFilter();
threadPool2.start();
ProtocolAcceptor acceptor2 = new IoProtocolAcceptor( acceptor );
acceptor2.getFilterChain().addLast( "threadPool", threadPool2 );
...
threadPool2.stop();
threadPool.stop();
采用MINA进行socket开发，一般步骤如下：
1：
server:
IoAcceptor acceptor = new SocketAcceptor(); //建立client接收器
or client:
SocketConnector connector = new SocketConnector(); //建立一个连接器
2：server的属性配置：
SocketAcceptorConfig cfg = new SocketAcceptorConfig();
cfg.setReuseAddress(true);
cfg.getFilterChain().addLast(
"codec",
new ProtocolCodecFilter( new ObjectSerializationCodecFactory() ) ); //对象序列化 codec factory
cfg.getFilterChain().addLast( "logger", new LoggingFilter() );
3：绑定 address和business logic
server:
acceptor.bind(
new InetSocketAddress( SERVER_PORT ),
new ServerSessionHandler( ), cfg ); // 绑定address和handler
client:
connector.connect(new InetSocketAddress( HOSTNAME, PORT ),
new ClientSessionHandler(msg), cfg );
下面的这个简单的example演示client和server传递object的过程：
Message.java
public class Message implements Serializable {
private int type;
private int status;
private String msgBody;
public Message(int type, int status, String msgBody)
{
this.type = type;
this.status = status;
this.msgBody = msgBody;
}
public String getMsgBody() {
return msgBody;
}
public void setMsgBody(String msgBody) {
this.msgBody = msgBody;
}
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public int getType() {
return type;
}
public void setType(int type) {
this.type = type;
}
}
Client.java
public class Client
{
private static final String HOSTNAME = "localhost";
private static final int PORT = 8080;
private static final int CONNECT_TIMEOUT = 30; // seconds
public static void main( String[] args ) throws Throwable
{
SocketConnector connector = new SocketConnector();
// Configure the service.
SocketConnectorConfig cfg = new SocketConnectorConfig();
cfg.setConnectTimeout( CONNECT_TIMEOUT );
cfg.getFilterChain().addLast(
"codec",
new ProtocolCodecFilter( new ObjectSerializationCodecFactory() ) );
cfg.getFilterChain().addLast( "logger", new LoggingFilter() );
IoSession session;
Message msg = new Message(0,1,"hello");
connector.connect(new InetSocketAddress( HOSTNAME, PORT ),
new ClientSessionHandler(msg), cfg );
}
}
ClientSessionHandler.java
public class ClientSessionHandler extends IoHandlerAdapter
{
private Object msg;
public ClientSessionHandler(Object msg)
{
this.msg = msg;
}
public void sessionOpened( IoSession session )
{
session.write(this.msg);
}
public void messageReceived( IoSession session, Object message )
{
System.out.println("in messageReceived!");
Message rm = (Message ) message;
SessionLog.debug(session, rm.getMsgBody());
System.out.println("message is: " + rm.getMsgBody());
session.write(rm);
}
public void exceptionCaught( IoSession session, Throwable cause )
{
session.close();
}
}
Server.java
public class Server
{
private static final int SERVER_PORT = 8080;
public static void main( String[] args ) throws Throwable
{
IoAcceptor acceptor = new SocketAcceptor();
// Prepare the service configuration.
SocketAcceptorConfig cfg = new SocketAcceptorConfig();
cfg.setReuseAddress( true );
cfg.getFilterChain().addLast(
"codec",
new ProtocolCodecFilter( new ObjectSerializationCodecFactory() ) );
cfg.getFilterChain().addLast( "logger", new LoggingFilter() );
acceptor.bind(
new InetSocketAddress( SERVER_PORT ),
new ServerSessionHandler( ), cfg );
System.out.println( "The server Listening on port " + SERVER_PORT );
}
}
ServerSessionHandler.java
public class ServerSessionHandler extends IoHandlerAdapter
{
public void sessionOpened( IoSession session )
{
// set idle time to 60 seconds
session.setIdleTime( IdleStatus.BOTH_IDLE, 60 );
session.setAttribute("times",new Integer(0));
}
public void messageReceived( IoSession session, Object message )
{
System.out.println("in messageReceived");
int times = ((Integer)(session.getAttribute("times"))).intValue();
System.out.println("tiems = " + times);
// communicate 30 times,then close the session.
if (times < 30)
{
times++;
session.setAttribute("times", new Integer(times));
Message msg;
msg = (Message) message;
msg.setMsgBody("in server side: " + msg.getMsgBody());
System.out.println("begin send msg: " + msg.getMsgBody());
session.write(msg);
}
else
{
session.close();
}
}
public void sessionIdle( IoSession session, IdleStatus status )
{
SessionLog.info( session, "Disconnecting the idle." );
// disconnect an idle client
session.close();
}
public void exceptionCaught( IoSession session, Throwable cause )
{
// close the connection on exceptional situation
session.close();
}
}
MINA自己附带的Demo已经很好的说明了它的运用。
值得一提的是它 的SumUp：客户端发送几个数字，服务端求和后并返回结果。这个简单的程序演示了如何自己实现CODEC。
补充提示：
下载并运行MINA的demo程序还颇非周折:
运行MINA demo appli擦tion：
1:在JDK5
产 生错误:
Exception in thread "main" java.lang.NoClassDefFoundError: edu/emory/mathcs/backport/java/util/concurrent/Executor
at org.apache.mina.example.reverser.Main.main(Main.java:44)
察看mina的 QA email:
http://www.mail-archive.com/mina-dev@directory.apache.org/msg02252.html
原来需要下载:backport-util-concurrent.jar并加入classpath
http://dcl.mathcs.emory.edu/util/backport-util-concurrent/
继续运行还是报错:
Exception in thread "main" java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory
原来MINA采用了slf4j项目作为log，继续下载
slf4j-simple.jar等，并加入classpath:
http://www.slf4j.org/download.html
