Mina读写事件的发生顺序

---

这个Mina Echo Server包括服务器主类Main, 两个Filter类：MyFilter1, MyFilter2, 和一个handler类：EchoProtocolHandler。

import java.net.InetSocketAddress;

import org.apache.mina.transport.socket.SocketAcceptor;

import org.apache.mina.transport.socket.nio.NioSocketAcceptor;

public class Main {

public static void main(String[] args) throws Exception {

SocketAcceptor acceptor = new NioSocketAcceptor();

acceptor.getFilterChain().addLast("myfilter1", new MyFilter1());

acceptor.getFilterChain().addLast("myfilter2", new MyFilter2());

acceptor.setHandler(new EchoProtocolHandler());

acceptor.bind(new InetSocketAddress(8293));

System.out.println("Listening on port " + PORT);

}

}

import org.apache.mina.core.filterchain.IoFilter;

import org.apache.mina.core.filterchain.IoFilterChain;

import org.apache.mina.core.session.IdleStatus;

import org.apache.mina.core.session.IoSession;

import org.apache.mina.core.write.WriteRequest;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

public class MyFilter1 implements IoFilter {

private static final Logger LOGGER = LoggerFactory

.getLogger(MyFilter1.class);

public void messageReceived(NextFilter nextFilter, IoSession session,

Object message) throws Exception {

LOGGER.info("MessageReceived!");

nextFilter.messageReceived(session, message);

}

public void messageSent(NextFilter nextFilter, IoSession session,

WriteRequest writeRequest) throws Exception {

LOGGER.info("messageSent!");

nextFilter.messageSent(session, writeRequest);

}

public void filterWrite(NextFilter nextFilter, IoSession session,

WriteRequest writeRequest) throws Exception {

LOGGER.info("filterWrite!");

nextFilter.filterWrite(session, writeRequest);

}

// some other methods must implemented.

}

import org.apache.mina.core.filterchain.IoFilter;

import org.apache.mina.core.filterchain.IoFilterChain;

import org.apache.mina.core.session.IdleStatus;

import org.apache.mina.core.session.IoSession;

import org.apache.mina.core.write.WriteRequest;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

public class MyFilter2 implements IoFilter {

private static final Logger LOGGER = LoggerFactory

.getLogger(MyFilter2.class);

public void messageReceived(NextFilter nextFilter, IoSession session,

Object message) throws Exception {

LOGGER.info("MessageReceived!");

nextFilter.messageReceived(session, message);

}

public void messageSent(NextFilter nextFilter, IoSession session,

WriteRequest writeRequest) throws Exception {

LOGGER.info("messageSent!");

nextFilter.messageSent(session, writeRequest);

}

public void filterWrite(NextFilter nextFilter, IoSession session,

WriteRequest writeRequest) throws Exception {

LOGGER.info("filterWrite!");

nextFilter.filterWrite(session, writeRequest);

}

// some other methods must implemented.

}

import org.apache.mina.core.buffer.IoBuffer;

import org.apache.mina.core.service.IoHandlerAdapter;

import org.apache.mina.core.session.IoSession;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

public class EchoProtocolHandler extends IoHandlerAdapter {

private static final Logger LOGGER = LoggerFactory

.getLogger(EchoProtocolHandler.class);

@Override

public void exceptionCaught(IoSession session, Throwable cause) {

session.close(true);

}

@Override

public void messageReceived(IoSession session, Object message)

throws Exception {

LOGGER.info("Received : " + message);

session.write(((IoBuffer) message).duplicate());

}

@Override

public void messageSent(IoSession session, Object message) {

LOGGER.info("messageSent " + message);

}

}

用XShell运行telnet localhost 8293，发一个字符串"hi"，运行结果如下：

Listening on port 8293

[INFO] [2012-03-31 14:03:38,575] [com.leechau.mina.echoServer.MyFilter1] - [MessageReceived!]

[INFO] [2012-03-31 14:03:38,576] [com.leechau.mina.echoServer.MyFilter2] - [MessageReceived!]

[INFO] [2012-03-31 14:03:38,577] [com.leechau.mina.echoServer.EchoProtocolHandler] - [Received : HeapBuffer[pos=0 lim=4 cap=2048: 68 69 0D 0A]]

[INFO] [2012-03-31 14:03:38,578] [com.leechau.mina.echoServer.MyFilter2] - [filterWrite!]

[INFO] [2012-03-31 14:03:38,578] [com.leechau.mina.echoServer.MyFilter1] - [filterWrite!]

[INFO] [2012-03-31 14:03:38,580] [com.leechau.mina.echoServer.MyFilter1] - [messageSent!]

[INFO] [2012-03-31 14:03:38,580] [com.leechau.mina.echoServer.MyFilter2] - [messageSent!]

[INFO] [2012-03-31 14:03:38,580] [com.leechau.mina.echoServer.EchoProtocolHandler] - [messageSent HeapBuffer[pos=0 lim=4 cap=2048: 68 69 0D 0A]]

可以看到messageReceived事件从Filter链顶端传播到handler；filterWrite事件发生在handler开始发送消息，但还未写入socket时，仅对Filter链有效，不作用于handler，从链尾向链首传播；messageSent事件发生在socket已被写入之后，从链顶端传播到handler；

---

---