Apache Mina Server 是一个网络通信应用框架,也就是说,它主要是对基于 TCP/IP、UDP/IP协议栈的通信框架(当然,也可以提供 JAVA 对象的序列化服务、虚拟机管道通信服务等),Mina 可以帮助我们快速开发高性能、高扩展性的网络通信应用,Mina 提供了事件驱动、异步(Mina 的异步 IO 默认使用的是 JAVA NIO 作为底层支持)操作的编程模型。从官网文档“MINA based Application Architecture”中可以看到Mina作为一个通信层框架,在实际应用所处的位置,如图所示:
Mina位于用户应用程序和底层Java网络API(和in-VM通信)之间,我们开发基于Mina的网络应用程序,就无需关心复杂的通信细节。
应用整体架构
再看一下,Mina提供的基本组件,如图所示:
也就是说,无论是客户端还是服务端,使用Mina框架实现通信的逻辑分层在概念上统一的,即包含如下三层:
- I/O Service – Performs actual I/O
- I/O Filter Chain – Filters/Transforms bytes into desired Data Structures and vice-versa
- I/O Handler – Here resides the actual business logic
想要开发基于MIna的应用程序,你只需要做如下事情:
- Create an I/O service – Choose from already available Services (*Acceptor) or create your own
- Create a Filter Chain – Choose from already existing Filters or create a custom Filter for transforming request/response
- Create an I/O Handler – Write business logic, on handling different messages
下面看一下使用Mina的应用程序,在服务器端和客户端的架构细节:
服务器端架构
服务器端监听指定端口上到来的请求,对这些请求经过处理后,回复响应。它也会创建并处理一个链接过来的客户会话对象(Session)。服务器端架构如图所示:
对服务器端的说明,引用官网文档,如下所示:
- IOAcceptor listens on the network for incoming connections/packets
- For a new connection, a new session is created and all subsequent request from IP Address/Port combination are handled in that Session
- All packets received for a Session, traverses the Filter Chain as specified in the diagram. Filters can be used to modify the content of packets (like converting to Objects, adding/removing information etc). For converting to/from raw bytes to High Level Objects, PacketEncoder/Decoder are particularly useful
- Finally the packet or converted object lands in IOHandler. IOHandlers can be used to fulfill business needs.
客户端架构
客户端主要做了如下工作:
- 连接到服务器端
- 向服务器发送消息
- 等待服务器端响应,并处理响应
客户端架构,如图所示:
对客户端架构的说明,引用官网文档内容,如下所示:
- Client first creates an IOConnector (MINA Construct for connecting to Socket), initiates a bind with Server
- Upon Connection creation, a Session is created and is associated with Connection
- Application/Client writes to the Session, resulting in data being sent to Server, after traversing the Filter Chain
- All the responses/messages received from Server are traverses the Filter Chain and lands at IOHandler, for processing
应用实例开发
下面根据上面给出的架构设计描述,看一下Mina(版本2.0.7)自带的例子,如何实现一个简单的C/S通信的程序,非常容易。
服务端
首先,服务器端需要使用的组件有IoAdaptor、IoHandler、IoFilter,其中IoFilter可选.
我们基于Mina自带的例子进行了简单地修改,实现服务端IoHandler的代码如下所示:
01 |
package org.shirdrn.mina.server;
|
03 |
import org.apache.mina.core.service.IoHandlerAdapter;
|
04 |
import org.apache.mina.core.session.IdleStatus;
|
05 |
import org.apache.mina.core.session.IoSession;
|
06 |
import org.slf4j.Logger;
|
07 |
import org.slf4j.LoggerFactory;
|
09 |
public class TinyServerProtocolHandler extends IoHandlerAdapter {
|
10 |
private final static Logger LOGGER = LoggerFactory.getLogger(TinyServerProtocolHandler. class );
|
13 |
public void sessionCreated(IoSession session) {
|
14 |
session.getConfig().setIdleTime(IdleStatus.BOTH_IDLE, 10 );
|
18 |
public void sessionClosed(IoSession session) throws Exception {
|
19 |
LOGGER.info( "CLOSED" );
|
23 |
public void sessionOpened(IoSession session) throws Exception {
|
24 |
LOGGER.info( "OPENED" );
|
28 |
public void sessionIdle(IoSession session, IdleStatus status) {
|
29 |
LOGGER.info( "*** IDLE #" + session.getIdleCount(IdleStatus.BOTH_IDLE) + " ***" );
|
33 |
public void exceptionCaught(IoSession session, Throwable cause) {
|
38 |
public void messageReceived(IoSession session, Object message)
|
40 |
LOGGER.info( "Received : " + message );
|
41 |
if (!session.isConnected()) {
|
这个版本中,IoHandlerAdapter实现了IoHandler接口,里面封装了一组用于事件处理的空方法,其中包含服务端和客户端的事件。在实际应用中,客户端可以选择客户端具有的事件,服务器端选择服务器端具有的事件,然后分别对这两类事件进行处理(有重叠的事件,如连接事件、关闭事件、异常事件等)。
客户端的IoHandler的具体实现也是类似的,不过多累述。
下面看启动服务器的主方法类,代码如下所示:
01 |
package org.shirdrn.mina.server;
|
03 |
import java.net.InetSocketAddress;
|
05 |
import org.apache.mina.filter.codec.ProtocolCodecFilter;
|
06 |
import org.apache.mina.filter.codec.textline.TextLineCodecFactory;
|
07 |
import org.apache.mina.transport.socket.SocketAcceptor;
|
08 |
import org.apache.mina.transport.socket.nio.NioSocketAcceptor;
|
09 |
import org.slf4j.Logger;
|
10 |
import org.slf4j.LoggerFactory;
|
12 |
public class TinyMinaServer {
|
14 |
private final static Logger LOG = LoggerFactory.getLogger(TinyMinaServer. class );
|
15 |
/** Choose your favorite port number. */
|
16 |
private static final int PORT = 8080 ;
|
18 |
public static void main(String[] args) throws Exception {
|
19 |
SocketAcceptor acceptor = new NioSocketAcceptor();
|
20 |
acceptor.setReuseAddress( true );
|
21 |
acceptor.getFilterChain().addLast( "codec" , new ProtocolCodecFilter( new TextLineCodecFactory()));
|
24 |
acceptor.setHandler( new TinyServerProtocolHandler());
|
25 |
acceptor.bind( new InetSocketAddress(PORT));
|
26 |
LOG.info( "Listening on port " + PORT);
|
28 |
LOG.info( "Server started!" );
|
31 |
LOG.info( "R: " + acceptor.getStatistics().getReadBytesThroughput() + ", W: " + acceptor.getStatistics().getWrittenBytesThroughput());
|
客户端
实现客户端IoHandler的代码如下所示:
01 |
package org.shirdrn.mina.client;
|
03 |
import org.apache.mina.core.service.IoHandlerAdapter;
|
04 |
import org.apache.mina.core.session.IdleStatus;
|
05 |
import org.apache.mina.core.session.IoSession;
|
06 |
import org.slf4j.Logger;
|
07 |
import org.slf4j.LoggerFactory;
|
09 |
public class TinyClientProtocolHandler extends IoHandlerAdapter {
|
11 |
private final static Logger LOGGER = LoggerFactory
|
12 |
.getLogger(TinyClientProtocolHandler. class );
|
15 |
public void sessionCreated(IoSession session) {
|
16 |
LOGGER.info( "CLIENT::CREATED" );
|
20 |
public void sessionClosed(IoSession session) throws Exception {
|
21 |
LOGGER.info( "CLIENT::CLOSED" );
|
25 |
public void sessionOpened(IoSession session) throws Exception {
|
26 |
LOGGER.info( "CLIENT::OPENED" );
|
30 |
public void sessionIdle(IoSession session, IdleStatus status) {
|
31 |
LOGGER.info( "CLIENT::*** IDLE #"
|
32 |
+ session.getIdleCount(IdleStatus.BOTH_IDLE) + " ***" );
|
36 |
public void exceptionCaught(IoSession session, Throwable cause) {
|
37 |
LOGGER.info( "CLIENT::EXCEPTIONCAUGHT" );
|
38 |
cause.printStackTrace();
|
41 |
public void messageSent(IoSession session, Object message) throws Exception {
|
42 |
LOGGER.info( "CLIENT::MESSAGESENT: " + message);
|
下面看启动客户端的主方法类,代码如下所示:
01 |
package org.shirdrn.mina.client;
|
03 |
import java.net.InetSocketAddress;
|
05 |
import org.apache.mina.core.future.ConnectFuture;
|
06 |
import org.apache.mina.filter.codec.ProtocolCodecFilter;
|
07 |
import org.apache.mina.filter.codec.textline.TextLineCodecFactory;
|
08 |
import org.apache.mina.transport.socket.SocketConnector;
|
09 |
import org.apache.mina.transport.socket.nio.NioSocketConnector;
|
10 |
import org.slf4j.Logger;
|
11 |
import org.slf4j.LoggerFactory;
|
13 |
public class TinyMinaClient {
|
15 |
private final static Logger LOG = LoggerFactory.getLogger(TinyMinaClient. class );
|
16 |
/** Choose your favorite port number. */
|
17 |
private static final int PORT = 8080 ;
|
19 |
public static void main(String[] args) throws Exception {
|
20 |
SocketConnector connector = new NioSocketConnector();
|
23 |
connector.getFilterChain().addLast( "codec" , new ProtocolCodecFilter( new TextLineCodecFactory()));
|
24 |
connector.setHandler( new TinyClientProtocolHandler());
|
26 |
for ( int i = 0 ; i < 10 ; i++) {
|
27 |
ConnectFuture future = connector.connect( new InetSocketAddress(PORT));
|
28 |
LOG.info( "Connect to port " + PORT);
|
29 |
future.awaitUninterruptibly();
|
30 |
future.getSession().write(String.valueOf(i));
|
我们只是发送了十个数字,每发一次间隔1500ms。
测试上述服务器端与客户端交互,首先启动服务器端,监听8080端口。
接着启动客户端,连接到服务器端8080端口,然后发送消息,服务器端接收到消息后,直接将到客户端的连接关闭掉。