Apache Mina 2.x 簡易入門解析 – JAVA編程語言程序開發技術文章

最近使用Mina開發一個Java的NIO服務端程序,因此也特意學習瞭Apache的這個Mina框架。
  首先,Mina是個什麼東西?看下官方網站(http://mina.apache.org/)對它的解釋:
  Apache的Mina(Multipurpose Infrastructure Networked Applications)是一個網絡應用框架,可以幫助用戶開發高性能和高擴展性的網絡應用程序;它提供瞭一個抽象的、事件驅動的異步API,使Java NIO在各種傳輸協議(如TCP/IP,UDP/IP協議等)下快速高效開發。
  Apache Mina也稱為:
NIO框架
客戶端/服務端框架(典型的C/S架構)
網絡套接字(networking socket)類庫
事件驅動的異步API(註意:在JDK7中也新增瞭異步API)
總之:我們簡單理解它是一個封裝底層IO操作,提供高級操作API的通訊框架!
 
在Mina的官網、以及網上都有比較豐富的文檔瞭,這裡我就稍微簡單說一下Mina的結構和示例代碼。
因為Mina2.X改進瞭Mina的代碼結構和包結構,降低瞭使用的復雜性和增強瞭健壯性,所以使得API發生瞭比較大的改變,有許多地方已經和Mina1.x不兼容瞭。
這裡使用的是Mina2.0.4
1.Mina的結構

 
Mina的通信流程大致如上圖所示,各個組件功能有:
(1.)  IoService:這個接口在一個線程上負責套接字的建立,擁有自己的Selector,監
聽是否有連接被建立。
(Mina底層使用JAVA NIO, 因此它是典型的使用Reactor模式架構的,采用事件驅動編程 , Mina運行用戶自定義線程模型,可以是單線程、多線程、線程池等 ,
   跟JAVA Socket不一樣, Mina是非阻塞的Socket,它內部已經保證瞭對各個連接(session)的業務和數據的隔離,采用輪詢機制為各個session分配CPU資源,
  所以,你就不需要再去考慮不同Socket連接需要用不同的線程去操縱的問題瞭。)
(2.)  IoProcessor:這個接口在另一個線程上負責檢查是否有數據在通道上讀寫,也就是
說它也擁有自己的Selector,這是與我們使用JAVA NIO 編碼時的一個不同之處,
通常在JAVA NIO 編碼中,我們都是使用一個Selector,也就是不區分IoService
與 IoProcessor 兩個功能接口。另外,IoProcessor 負責調用註冊在IoService 上
的過濾器,並在過濾器鏈之後調用IoHandler。

(3.)  IoFilter:這個接口定義一組攔截器,這些攔截器可以包括日志輸出、黑名單過濾、
數據的編碼(write 方向)與解碼(read 方向)等功能,其中數據的encode 與 decode
是最為重要的、也是你在使用Mina 時最主要關註的地方。

(4.)  IoHandler:這個接口負責編寫業務邏輯,也就是接收、發送數據的地方。
 
2. Mina編程的大致過程.
    2.1 總體流程
        建立服務器端的資源: 包括 Acceptor的建立,之後為Acceptor配置相應的Filter(可以是Mina自帶的Filter或者自定義的Filter),
之後再配置相應基於事件驅動的處理業務邏輯的IoHandler.
       建立客戶端的資源: Mina采用瞭統一的編程模型,所以建立客戶端的過程和建立服務器端的過程大致上是相似的,不過這裡建立的是Connector.
   2.2 示例程序。(使用jar包為 mina-core-2.0.4.jar)
      下面通過一個簡單的示例程序來進一步理解Mina的運行機制。
     該程序實現簡單的即時通訊功能。 即,多個客戶端可以同時臉上服務器,並進行類似於聊天室一樣的通信。
        
       2.2.1 建立自定義的TextLineCodecFacotry
             為瞭瞭解Mina的代碼功能以及運行機制,我們模擬實現瞭類似Mina自帶TextLineCodecFactory。
    該CodecFactory功能是: 配合ProtocolCodecFilter 進行對底層數據(binary二進制數據流)和高層數據(特定類型的數據對象信息,例如String)之間的轉換。
                這裡實現瞭一個斷行讀取功能,即遇到'\n'的時候,就認為是一個String Line , 將這段數據流封裝成String,之後再交給下一個Filter或者Handler處理。
                CodecFactory是一個工廠方法,底層通過一個Decoder和Encoder來提供對數據進行解、編碼的操作,載體是IoBuffer。
                (解碼:將二進制數據轉換成高層數據(對象)    編碼:將高層數據(對象)轉換成二進制數據流)  )
     1)建立Decoder (MyTextLineDecoder)
      實現瞭ProtocolDecoder接口
View Code
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)
      實現瞭ProtocolEncoder接口
View Code
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
      實現瞭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 建立服務器端資源(包括Acceptor的配置、Handler建立)
    1). 建立自定義IoHandler(MyServerHandleDemo1)
      實現瞭IoHandler接口。
    
View Code
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("服務器啟動發生異常,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("服務器成功發送信息: " + 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 ,同時也充當Server端的啟動類 (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("服務器啟動失敗");
        }else{
            System.out.println("服務器啟動成功");
        }
    }

}

  2.2.3 建立Client端資源:
    1)自定義IoHandler(MyClientHandleDemo1)
      實現IoHandler接口
View Code
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("客戶端發瞭一個信息:" + 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();
        }
       
    }

}
  到這裡,基本的Mina通信基礎就建立好瞭。
  接下來實現一個客戶端的GUI界面,方便實際功能的建立和信息交互的演示。
 
  2.2.4 Client Gui界面的建立。(ChatPanel -通過使用SimpleMinaClient來提供實際通信功能)
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 = "遊客" + RandomUtils.nextInt(1000);
                nameText.setText(username);
            }
            connected = true;
            dealUIWithFlag();
        }else{
            connected = false;  
            dealUIWithFlag();
            showMsg("連接服務器失敗。。。");
        }
    }
   
   
    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("連接已斷開…");
            connected = false;
            dealUIWithFlag();
        }else{
            showMsg("無法斷開連接…");
        }
    }
   

   
    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. 運行結果
  首先啟動服務器端,即運行SimpleMinaServer類 , 啟動成功時會在控制臺中打印出“服務器啟動成功"
  接下來運行客戶端ChatPanel。

 

note: 上面隻是一個簡單的信息交互,其實使用Mina比較常用的還是在自定義協議處理這塊。
    所以,比較應該註重學習的是Filter這塊。有時間大傢可以去看看源碼。

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