mina源码分析---IoEvent和IoFilterEvent类及其联系和区别

IoEvent是MINA提供的IO事件或IO请求的类

package org.apache.mina.core.session;

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

/**
 * An I/O event or an I/O request that MINA provides.
 * Most users won't need to use this class.  It is usually used by internal
 * components to store I/O events.内部用来存储IO事件
 *
 */
public class IoEvent implements Runnable {
    private final IoEventType type;

    private final IoSession session;

    private final Object parameter;

    public IoEvent(IoEventType type, IoSession session, Object parameter) {
        if (type == null) {
            throw new IllegalArgumentException("type");
        }
        if (session == null) {
            throw new IllegalArgumentException("session");
        }
        this.type = type;
        this.session = session;
        this.parameter = parameter;
    }

    public IoEventType getType() {
        return type;
    }

    public IoSession getSession() {
        return session;
    }

    public Object getParameter() {
        return parameter;
    }
    
    public void run() {
        fire();
    }

    /**
     * 这里的fire函数和IoFilterEvent中的fire函数     有区别 
     * 这里是根据事件类型，把事件和信息传递到会话的过滤器链中，也即开始调用第一个过滤器
     */
    public void fire() {// 
        switch (getType()) {
        case MESSAGE_RECEIVED:
            getSession().getFilterChain().fireMessageReceived(getParameter());
            break;
        case MESSAGE_SENT:
            getSession().getFilterChain().fireMessageSent((WriteRequest) getParameter());
            break;
        case WRITE:
            getSession().getFilterChain().fireFilterWrite((WriteRequest) getParameter());
            break;
        case CLOSE:
            getSession().getFilterChain().fireFilterClose();
            break;
        case EXCEPTION_CAUGHT:
            getSession().getFilterChain().fireExceptionCaught((Throwable) getParameter());
            break;
        case SESSION_IDLE:
            getSession().getFilterChain().fireSessionIdle((IdleStatus) getParameter());
            break;
        case SESSION_OPENED:
            getSession().getFilterChain().fireSessionOpened();
            break;
        case SESSION_CREATED:
            getSession().getFilterChain().fireSessionCreated();
            break;
        case SESSION_CLOSED:
            getSession().getFilterChain().fireSessionClosed();
            break;
        default:
            throw new IllegalArgumentException("Unknown event type: " + getType());
        }
    }

    @Override
    public String toString() {
        if (getParameter() == null) {
            return "[" + getSession() + "] " + getType().name();
        }
        
        return "[" + getSession() + "] " + getType().name() + ": "
                    + getParameter();
    }
}

IoFilterEvent是MINA提供给 IoFilter 过滤器的IO事件或IO请求

package org.apache.mina.core.filterchain;

import org.apache.mina.core.filterchain.IoFilter.NextFilter;
import org.apache.mina.core.session.IdleStatus;
import org.apache.mina.core.session.IoEvent;
import org.apache.mina.core.session.IoEventType;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.core.write.WriteRequest;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * An I/O event or an I/O request that MINA provides for {@link IoFilter}s.
 * Most users won't need to use this class.  It is usually used by internal
 * components to store I/O events.
 * 1、IoEvent 事件类实现了Runnable接口,是一个线程类,所以此类也是一个线程类,可以并发执行
 * 2、此过滤事件类继承了IoEvent的run()方法(run方法中调用fire方法),重写了fire()方法
 * 3、IoEvent类的fire()方法表示收到了IO事件通知,并把事件传递给过滤器链
 * 4、IoFilterEvent类的fire()方法表示把收到的事件处理完后继续交给下一个过滤器处理
 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
 */
public class IoFilterEvent extends IoEvent {
    /** A logger for this class */
    static Logger LOGGER = LoggerFactory.getLogger(IoFilterEvent.class);
    
    /** A speedup for logs */
    static boolean DEBUG = LOGGER.isDebugEnabled();

    private final NextFilter nextFilter;

    public IoFilterEvent(NextFilter nextFilter, IoEventType type,
            IoSession session, Object parameter) {
        super(type, session, parameter);

        if (nextFilter == null) {
            throw new IllegalArgumentException("nextFilter must not be null");
        }
        
        this.nextFilter = nextFilter;
    }

    public NextFilter getNextFilter() {
        return nextFilter;
    }

    @Override
    public void fire() {//这里是在过滤器链中传递事件，调用下一个过滤器处理事件和信息
        IoSession session = getSession();
        NextFilter nextFilter = getNextFilter();
        IoEventType type = getType();

        if (DEBUG) {
            LOGGER.debug( "Firing a {} event for session {}",type, session.getId() );
        }

        switch (type) {
        case MESSAGE_RECEIVED:
            Object parameter = getParameter();
            nextFilter.messageReceived(session, parameter);
            break;
            
        case MESSAGE_SENT:
            WriteRequest writeRequest = (WriteRequest)getParameter();
            nextFilter.messageSent(session, writeRequest);
            break;
            
        case WRITE:
            writeRequest = (WriteRequest)getParameter();
            nextFilter.filterWrite(session, writeRequest);
            break;
            
        case CLOSE:
            nextFilter.filterClose(session);
            break;
            
        case EXCEPTION_CAUGHT:
            Throwable throwable = (Throwable)getParameter();
            nextFilter.exceptionCaught(session, throwable);
            break;
            
        case SESSION_IDLE:
            nextFilter.sessionIdle(session, (IdleStatus) getParameter());
            break;
            
        case SESSION_OPENED:
            nextFilter.sessionOpened(session);
            break;
            
        case SESSION_CREATED:
            nextFilter.sessionCreated(session);
            break;
            
        case SESSION_CLOSED:
            nextFilter.sessionClosed(session);
            break;
            
        default:
            throw new IllegalArgumentException("Unknown event type: " + type);
        }
        
        if (DEBUG) {
            LOGGER.debug( "Event {} has been fired for session {}", type, session.getId() );
        }
    }
}