acknowledgedmessagesextension.java

来自「jetty SERVER連接資料庫用的軟體」· Java 代码 · 共 65 行

package org.mortbay.cometd.ext;

import java.util.Map;

import org.cometd.Bayeux;
import org.cometd.Client;
import org.cometd.Extension;
import org.cometd.Message;
import org.mortbay.cometd.ClientImpl;
import org.mortbay.log.Log;
import org.mortbay.util.ajax.JSON;

/**
 * Acknowledged Messages extension.
 * 
 * Installing this extension in a bayeux server allows it to handle 
 * the ack extension if a client also supports it.
 * 
 * The main role of this extension is to install the {@link AcknowledgedMessagesClientExtension}
 * on the {@link Client} instances created during handshake for clients that
 * also support the ack extension.
 *
 */
public class AcknowledgedMessagesExtension implements Extension
{
    JSON.Literal _replyExt = new JSON.Literal("{\"ack\":true}");
    
    public Message rcv(Client from, Message message)
    {
        return message;
    }

    public Message rcvMeta(Client from, Message message)
    {
        return message;
    }

    public Message send(Client from, Message message)
    {
        return message;
    }

    public Message sendMeta(Client from, Message message)
    {
        if (message.getChannel().equals(Bayeux.META_HANDSHAKE) && Boolean.TRUE.equals(message.get(Bayeux.SUCCESSFUL_FIELD)))
        {
            Message rcv = message.getAssociated();
            
            Map<String, Object> ext = rcv.getExt(false);
            boolean clientRequestedAcks = ext != null && ext.get("ack")==Boolean.TRUE;

            if (clientRequestedAcks && from!=null) {
                Log.info("Enabled message acknowledgement for client " + from);
                from.addExtension(new AcknowledgedMessagesClientExtension(from));
                ((ClientImpl)from).setMetaConnectDeliveryOnly(true);
            }
            
            message.put(Bayeux.EXT_FIELD, _replyExt);
        }

        return message;
    }

}