最近使用Mina开发一个Java的NIO服务端程序，因此也特意学习了Apache的这个Mina框架。
首先，Mina是个什么东西？看下官方网站（http://mina.apache.org/）对它的解释：
Apache的Mina（Multipurpose Infrastructure Networked Applications）是一个网络应用框架，可以帮助用户开发高性能和高扩展性的网络应用程序；它提供了一个抽象的、事件驱动的异步API，使Java NIO在各种传输协议（如TCP/IP，UDP/IP协议等）下快速高效开发。
Apache Mina也称为：
- NIO框架
- 客户端/服务端框架（典型的C/S架构）
- 网络套接字（networking socket）类库
- 事件驱动的异步API(注意：在JDK7中也新增了异步API)
总之：我们简单理解它是一个封装底层IO操作，提供高级操作API的通讯框架！
在Mina的官网、以及网上都有比较丰富的文档了，这里我就稍微简单说一下Mina的结构和示例代码。
因为Mina2.X改进了Mina的代码结构和包结构，降低了使用的复杂性和增强了健壮性，所以使得API发生了比较大的改变，有许多地方已经和Mina1.x不兼容了。
这里使用的是Mina2.0.4
1.Mina的结构
Mina的通信流程大致如上图所示，各个组件功能有：
(1.) IoService：这个接口在一个线程上负责套接字的建立，拥有自己的Selector，监
听是否有连接被建立。
（Mina底层使用JAVA NIO， 因此它是典型的使用Reactor模式架构的,采用事件驱动编程 , Mina运行用户自定义线程模型，可以是单线程、多线程、线程池等 ,
跟JAVA Socket不一样， Mina是非阻塞的Socket，它内部已经保证了对各个连接(session)的业务和数据的隔离，采用轮询机制为各个session分配CPU资源，
所以，你就不需要再去考虑不同Socket连接需要用不同的线程去操纵的问题了。)
(2.) IoProcessor：这个接口在另一个线程上负责检查是否有数据在通道上读写，也就是
说它也拥有自己的Selector，这是与我们使用JAVA NIO 编码时的一个不同之处，
通常在JAVA NIO 编码中，我们都是使用一个Selector，也就是不区分IoService
与 IoProcessor 两个功能接口。另外，IoProcessor 负责调用注册在IoService 上
的过滤器，并在过滤器链之后调用IoHandler。
(3.) IoFilter：这个接口定义一组拦截器，这些拦截器可以包括日志输出、黑名单过滤、
数据的编码（write 方向）与解码（read 方向）等功能，其中数据的encode 与 decode
是最为重要的、也是你在使用Mina 时最主要关注的地方。
(4.) IoHandler：这个接口负责编写业务逻辑，也就是接收、发送数据的地方。
2. Mina编程的大致过程.
2.1 总体流程
建立服务器端的资源： 包括 Acceptor的建立，之后为Acceptor配置相应的Filter(可以是Mina自带的Filter或者自定义的Filter），
之后再配置相应基于事件驱动的处理业务逻辑的IoHandler.
建立客户端的资源： Mina采用了统一的编程模型，所以建立客户端的过程和建立服务器端的过程大致上是相似的，不过这里建立的是Connector.
2.2 示例程序。(使用jar包为 mina-core-2.0.4.jar）
下面通过一个简单的示例程序来进一步理解Mina的运行机制。
该程序实现简单的即时通讯功能。 即，多个客户端可以同时脸上服务器，并进行类似于聊天室一样的通信。
2.2.1 建立自定义的TextLineCodecFacotry
为了了解Mina的代码功能以及运行机制，我们模拟实现了类似Mina自带TextLineCodecFactory。
该CodecFactory功能是： 配合ProtocolCodecFilter 进行对底层数据(binary二进制数据流)和高层数据(特定类型的数据对象信息，例如String)之间的转换。
这里实现了一个断行读取功能，即遇到'\n'的时候，就认为是一个String Line ， 将这段数据流封装成String，之后再交给下一个Filter或者Handler处理。
CodecFactory是一个工厂方法，底层通过一个Decoder和Encoder来提供对数据进行解、编码的操作,载体是IoBuffer。
（解码：将二进制数据转换成高层数据(对象) 编码：将高层数据(对象)转换成二进制数据流) )
1）建立Decoder (MyTextLineDecoder)
实现了ProtocolDecoder接口
package com.mai.mina.diyCodecFilter;
import java.nio.charset.Charset;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.ProtocolDecoder;
import org.apache.mina.filter.codec.ProtocolDecoderOutput;
public class MyTextLineDecoder implements ProtocolDecoder{
Charset charset = Charset.forName("UTF-8");
IoBuffer buf = IoBuffer.allocate(100).setAutoExpand(true);
@Override
public void decode(IoSession session, IoBuffer in, ProtocolDecoderOutput output)
throws Exception {
// TODO Auto-generated method stub
while(in.hasRemaining()){
byte b = in.get();
if(b == '\n'){
buf.flip();
byte[] bytes = new byte[buf.limit()];
buf.get(bytes);
String message = new String(bytes,charset);
buf = IoBuffer.allocate(100).setAutoExpand(true);
output.write(message);
}else{
buf.put(b);
}
}
}
@Override
public void dispose(IoSession arg0) throws Exception {
// TODO Auto-generated method stub
}
@Override
public void finishDecode(IoSession arg0, ProtocolDecoderOutput arg1)
throws Exception {
// TODO Auto-generated method stub
}
}
2）建立Encoder （MyTextLineEncoder)
实现了ProtocolEncoder接口
package com.mai.mina.diyCodecFilter;
import java.nio.charset.Charset;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.ProtocolEncoder;
import org.apache.mina.filter.codec.ProtocolEncoderOutput;
import org.apache.mina.filter.codec.textline.LineDelimiter;
public class MyTextLineEncoder implements ProtocolEncoder{
Charset charset = Charset.forName("UTF-8");
@Override
public void dispose(IoSession session) throws Exception {
// TODO Auto-generated method stub
}
@Override
public void encode(IoSession session, Object message, ProtocolEncoderOutput output)
throws Exception {
// TODO Auto-generated method stub
IoBuffer buf = IoBuffer.allocate(100).setAutoExpand(true);
buf.putString(message.toString(), charset.newEncoder());
buf.putString(LineDelimiter.DEFAULT.getValue(), charset.newEncoder());
buf.flip();
output.write(buf);
}
}
3）建立MyTextLineCodecFactory
实现了ProtocolCodecFactory接口
package com.mai.mina.diyCodecFilter;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.ProtocolCodecFactory;
import org.apache.mina.filter.codec.ProtocolDecoder;
import org.apache.mina.filter.codec.ProtocolEncoder;
public class MyTextLineCodecFactory implements ProtocolCodecFactory{
@Override
public ProtocolDecoder getDecoder(IoSession arg0) throws Exception {
// TODO Auto-generated method stub
return new MyTextLineDecoder();
}
@Override
public ProtocolEncoder getEncoder(IoSession arg0) throws Exception {
// TODO Auto-generated method stub
return new MyTextLineEncoder();
}
}
2.2.2 建立服务器端资源（包括Acceptor的配置、Handler建立)
1). 建立自定义IoHandler（MyServerHandleDemo1)
实现了IoHandler接口。
package com.mai.mina.diyChat;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.Date;
import java.util.logging.Logger;
import org.apache.mina.core.future.CloseFuture;
import org.apache.mina.core.future.IoFuture;
import org.apache.mina.core.future.IoFutureListener;
import org.apache.mina.core.service.IoHandler;
import org.apache.mina.core.session.IdleStatus;
import org.apache.mina.core.session.IoSession;
public class MyServerHandleDemo1 implements IoHandler{
private Logger logger = Logger.getLogger(this.getClass().getName());
@Override
public void exceptionCaught(IoSession session, Throwable arg1)
throws Exception {
// TODO Auto-generated method stub
logger.warning("服务器启动发生异常，have a exception : " + arg1.getMessage());
}
@Override
public void messageReceived(IoSession session, Object message) throws Exception {
// TODO Auto-generated method stub
String messageStr = message.toString();
DateFormat format = new SimpleDateFormat("yyyy-MM-dd H:m:s");
String dateStr = format.format(new Date());
logger.info(messageStr + "\t" + dateStr);
Collection<IoSession> sessions = session.getService().getManagedSessions().values();
for(IoSession tempSession : sessions){
tempSession.write(messageStr + "\t" + dateStr);
}
}
@Override
public void messageSent(IoSession session, Object message) throws Exception {
// TODO Auto-generated method stub
logger.info("服务器成功发送信息: " + message.toString());
}
@Override
public void sessionClosed(IoSession session) throws Exception {
// TODO Auto-generated method stub
logger.info("there is a session closed");
CloseFuture future = session.close(true);
future.addListener(new IoFutureListener(){
public void operationComplete(IoFuture future){
if(future instanceof CloseFuture){
((CloseFuture)future).setClosed();
logger.info("have do the future set to closed");
}
}
});
}
@Override
public void sessionCreated(IoSession session) throws Exception {
// TODO Auto-generated method stub
logger.info("there is a session created");
session.write("welcome to the chat room");
}
@Override
public void sessionIdle(IoSession session, IdleStatus arg1) throws Exception {
// TODO Auto-generated method stub
logger.info(session.getId() + "(SesssionID) is idle in the satate-->" + arg1);
}
@Override
public void sessionOpened(IoSession arg0) throws Exception {
// TODO Auto-generated method stub
}
}
2).建立Acceptor ，同时也充当Server端的启动类 (SimpleMinaServer)
package com.mai.mina.diyChat;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.charset.Charset;
import org.apache.mina.core.session.IdleStatus;
import org.apache.mina.filter.codec.ProtocolCodecFilter;
import org.apache.mina.filter.codec.textline.LineDelimiter;
import org.apache.mina.filter.codec.textline.TextLineCodecFactory;
import org.apache.mina.filter.logging.LogLevel;
import org.apache.mina.filter.logging.LoggingFilter;
import org.apache.mina.transport.socket.SocketAcceptor;
import org.apache.mina.transport.socket.nio.NioSocketAcceptor;
public class SimpleMinaServer {
SocketAcceptor acceptor = null;
SimpleMinaServer(){
acceptor = new NioSocketAcceptor();
}
public boolean bind(){
acceptor.getFilterChain().addLast("codec", new ProtocolCodecFilter(
new MyTextLineCodecFactory()); //配置CodecFactory
LoggingFilter log = new LoggingFilter();
log.setMessageReceivedLogLevel(LogLevel.INFO);
acceptor.getFilterChain().addLast("logger", log);
acceptor.setHandler(new MyServerHandleDemo1()); //配置handler
acceptor.getSessionConfig().setIdleTime(IdleStatus.BOTH_IDLE, 30);
try {
acceptor.bind(new InetSocketAddress(8888));
return true;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return false;
}
}
public static void main(String args[]){
SimpleMinaServer server = new SimpleMinaServer();
if(!server.bind()){
System.out.println("服务器启动失败");
}else{
System.out.println("服务器启动成功");
}
}
}
2.2.3 建立Client端资源： 1）自定义IoHandler(MyClientHandleDemo1)
实现IoHandler接口
package com.mai.mina.diyChat;
import java.util.logging.Logger;
import org.apache.mina.core.service.IoHandlerAdapter;
import org.apache.mina.core.session.IoSession;
public class MyClientHandleDemo1 extends IoHandlerAdapter{
private ChatPanel messagePanel = null;
private Logger logger = Logger.getLogger(this.getClass().getName());
MyClientHandleDemo1(){
}
MyClientHandleDemo1(ChatPanel messagePanel){
this.messagePanel = messagePanel;
}
public void messageReceived(IoSession session, Object message) throws Exception {
// TODO Auto-generated method stub
String messageStr = message.toString();
logger.info("receive a message is : " + messageStr);
if(messagePanel != null)
messagePanel.showMsg(messageStr);
}
public void messageSent(IoSession session , Object message) throws Exception{
logger.info("客户端发了一个信息：" + message.toString());
}
}
2) 建立Connector (SimpleMinaClient)
View Code
package com.mai.mina.diyChat;
import java.net.InetSocketAddress;
import java.nio.charset.Charset;
import org.apache.mina.core.future.CloseFuture;
import org.apache.mina.core.future.ConnectFuture;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.ProtocolCodecFilter;
import org.apache.mina.filter.codec.textline.LineDelimiter;
import org.apache.mina.filter.codec.textline.TextLineCodecFactory;
import org.apache.mina.filter.logging.LogLevel;
import org.apache.mina.filter.logging.LoggingFilter;
import org.apache.mina.transport.socket.SocketConnector;
import org.apache.mina.transport.socket.nio.NioSocketConnector;
public class SimpleMinaClient {
public SocketConnector connector = null;
public ConnectFuture future;
public IoSession session = null;
private ChatPanel messagePanel = null;
SimpleMinaClient(){
}
SimpleMinaClient(ChatPanel messagePanel){
this.messagePanel = messagePanel;
}
boolean connect(){
try{
connector = new NioSocketConnector();
connector.setConnectTimeoutMillis(3000);
connector.getFilterChain().addLast("codec", new ProtocolCodecFilter(
new MyTextLineCodecFactory());
LoggingFilter log = new LoggingFilter();
log.setMessageReceivedLogLevel(LogLevel.INFO);
connector.getFilterChain().addLast("logger", log);
connector.setHandler(new MyClientHandleDemo1(messagePanel));
future = connector.connect(new InetSocketAddress("127.0.0.1" , 8888));
future.awaitUninterruptibly();
session = future.getSession();
return true;
}catch(Exception e){
e.printStackTrace();
return false;
}
}
public void setAttribute(Object key , Object value){
session.setAttribute(key, value);
}
void sentMsg(String message){
session.write(message);
}
boolean close(){
CloseFuture future = session.getCloseFuture();
future.awaitUninterruptibly(1000);
connector.dispose();
return true;
}
public SocketConnector getConnector() {
return connector;
}
public IoSession getSession() {
return session;
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
SimpleMinaClient client = new SimpleMinaClient();
if(client.connect()){
client.sentMsg("hello , sever !");
client.close();
}
}
}
到这里，基本的Mina通信基础就建立好了。
接下来实现一个客户端的GUI界面，方便实际功能的建立和信息交互的演示。
2.2.4 Client Gui界面的建立。(ChatPanel -通过使用SimpleMinaClient来提供实际通信功能)
View Code
package com.mai.mina.diyChat;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import org.apache.commons.lang.math.RandomUtils;
public class ChatPanel extends javax.swing.JPanel {
private JPanel northPanel;
private JLabel headLabel;
private JScrollPane jScrollPane1;
private JScrollPane jScrollPane2;
private JButton exitB;
private JButton clearMsgB;
private JButton sentB;
private JButton connectB;
private JTextArea messageText;
private JTextField nameText;
private JLabel nameLabel;
private JTextArea messageArea;
private JPanel southPanel;
private SimpleMinaClient client = null;
private boolean connected = false;
private String username = null;
{
//Set Look & Feel
try {
javax.swing.UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
} catch(Exception e) {
e.printStackTrace();
}
}
public void connect(){
if(client.connect()){
username = nameText.getText().trim();
if(username == null || "".equals(username)){
username = "游客" + RandomUtils.nextInt(1000);
nameText.setText(username);
}
connected = true;
dealUIWithFlag();
}else{
connected = false;
dealUIWithFlag();
showMsg("连接服务器失败。。。");
}
}
public void showMsg(String msg){
messageArea.append(msg);
messageArea.append("\n");
messageArea.selectAll();
messageArea.lostFocus(null, this);
}
public void sentMsg(){
String message = username + ":" + messageText.getText();
client.sentMsg(message);
messageText.setText("");
messageText.requestFocus();
}
public void dealUIWithFlag(){
if(connected){
nameText.setEnabled(false);
connectB.setEnabled(false);
sentB.setEnabled(true);
clearMsgB.setEnabled(true);
exitB.setEnabled(true);
}else{
nameText.setEnabled(true);
connectB.setEnabled(true);
sentB.setEnabled(false);
clearMsgB.setEnabled(false);
exitB.setEnabled(false);
}
}
public void closeTheClient(){
if(client.close()){
showMsg("连接已断开...");
connected = false;
dealUIWithFlag();
}else{
showMsg("无法断开连接...");
}
}
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.getContentPane().add(new ChatPanel());
frame.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public ChatPanel() {
super();
client = new SimpleMinaClient(this);
initGUI();
dealUIWithFlag();
}
private void initGUI() {
try {
this.setPreferredSize(new java.awt.Dimension(400, 339));
this.setLayout(null);
{
northPanel = new JPanel();
BorderLayout northPanelLayout = new BorderLayout();
northPanel.setLayout(northPanelLayout);
this.add(northPanel);
northPanel.setBounds(0, 0, 400, 188);
{
headLabel = new JLabel();
northPanel.add(headLabel, BorderLayout.NORTH);
headLabel.setText("\u6b22\u8fce\u4f7f\u7528 (\u6d4b\u8bd5Ip:port --> 127.0.0.1:8888)");
headLabel.setPreferredSize(new java.awt.Dimension(397, 19));
}
{
jScrollPane1 = new JScrollPane();
northPanel.add(jScrollPane1, BorderLayout.CENTER);
jScrollPane1.setPreferredSize(new java.awt.Dimension(400, 169));
{
messageArea = new JTextArea();
jScrollPane1.setViewportView(messageArea);
messageArea.setPreferredSize(new java.awt.Dimension(398, 145));
messageArea.setEditable(false);
messageArea.setLineWrap(true);
messageArea.setWrapStyleWord(true);
}
}
}
{
southPanel = new JPanel();
this.add(southPanel);
southPanel.setBounds(0, 194, 400, 145);
southPanel.setLayout(null);
{
nameLabel = new JLabel();
southPanel.add(nameLabel);
nameLabel.setText("\u6635\u79f0:");
nameLabel.setBounds(10, 12, 35, 15);
}
{
nameText = new JTextField();
southPanel.add(nameText);
nameText.setText("\u6e38\u5ba2");
nameText.setBounds(45, 9, 96, 21);
}
{
jScrollPane2 = new JScrollPane();
southPanel.add(jScrollPane2);
jScrollPane2.setBounds(15, 37, 364, 69);
{
messageText = new JTextArea();
jScrollPane2.setViewportView(messageText);
messageText.setBounds(101, 72, 362, 75);
messageText.setPreferredSize(new java.awt.Dimension(362, 54));
messageText.setLineWrap(true);
messageText.setWrapStyleWord(true);
}
}
{
connectB = new JButton();
southPanel.add(connectB);
connectB.setText("\u8fde\u63a5\u670d\u52a1\u5668");
connectB.setBounds(179, 8, 93, 23);
connectB.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
System.out.println("connectB.actionPerformed, event="+evt);
//TODO add your code for connectB.actionPerformed
connect();
}
});
}
{
sentB = new JButton();
southPanel.add(sentB);
sentB.setText("\u53d1\u9001");
sentB.setBounds(261, 116, 57, 23);
sentB.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
System.out.println("sentB.actionPerformed, event="+evt);
//TODO add your code for sentB.actionPerformed
sentMsg();
}
});
}
{
clearMsgB = new JButton();
southPanel.add(clearMsgB);
clearMsgB.setText("\u6e05\u7a7a");
clearMsgB.setBounds(324, 116, 57, 23);
clearMsgB.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
System.out.println("clearMsgB.actionPerformed, event="+evt);
//TODO add your code for clearMsgB.actionPerformed
messageText.setText("");
}
});
}
{
exitB = new JButton();
southPanel.add(exitB);
exitB.setText("\u6ce8\u9500");
exitB.setBounds(282, 8, 57, 23);
exitB.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
System.out.println("exitB.actionPerformed, event="+evt);
//TODO add your code for exitB.actionPerformed
closeTheClient();
}
});
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
3. 运行结果
首先启动服务器端，即运行SimpleMinaServer类 ， 启动成功时会在控制台中打印出“服务器启动成功"
接下来运行客户端ChatPanel。
note: 上面只是一个简单的信息交互，其实使用Mina比较常用的还是在自定义协议处理这块。
所以，比较应该注重学习的是Filter这块。有时间大家可以去看看源码。