聊天服务器-解密陌生人（9）聊天消息转发

提示： 因为工程稍微有点大对我个人来说，所以可能在某些方面讲的不清楚或逻辑性不够强，如果有问题请@我。
原工程：https://github.com/LineChen/

五、转发信息
因为客户端和服务器是保持长连接的，所以可以根据用户Id得到用户的会话session，得到session就可以发送消息。
对于聊天，主要分聊天双方都在线和一方离线的情况。都在线的情况好办，直接转发；一方离线时，需要在数据库中保存离线消息，等到离线好友登录时会发送给ta。保存离线消息需要注意的是，要根据消息类型做相应的处理（文本消息、语音消息、图片消息）。
/**
* 发送信息给单个用户
*
* @param moMoMsg
* @param getterId
*/
private void sendMsgToUser(iMoMoMsg moMoMsg, String getterId) {
if (ManageClientSession.isContainsId(getterId)) {
ManageClientSession.getSession(getterId).write(moMoMsg);
// System.out.println(“转发成功..”);
} else {
SqlModel model = new SqlModel();
if (!model.isTableExists(“mc_” + getterId))// “mc_” + userId
model.createCacheTable(getterId);// 创建缓存数据库
MsgDb msgDb = MsgTranceUtil.getInstance().Trance_Net2Db(moMoMsg);
if (model.insertCacheMsg(msgDb, getterId)) {
// System.out.println(“缓存成功”);
} else {
// System.out.println(“缓存失败”);
}
}
}

下面是存储在数据库的离线消息和发送的消息转化类：
package com.imomo_msg;

import java.text.SimpleDateFormat;
import java.util.Date;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.server_utils.FileTools;
import com.server_utils.StaticValues;

/**
* 消息包转换工具
*
* @author Administrator
*
*/
public class MsgTranceUtil {

public static MsgTranceUtil getInstance() {
    return new MsgTranceUtil();
}

/**
 * 数据库存数消息转化为网络传输消息
 * 
 * @param msgDb
 * @return
 */
public iMoMoMsg Trance_Db2Net(MsgDb msgDb) {
    iMoMoMsg moMsg = new iMoMoMsg();
    switch (msgDb.msgType) {
    case iMoMoMsgTypes.CHATING_TEXT_MSG:
        moMsg.symbol = ‘+‘;
        moMsg.msgJson = msgDb.msgJson;
        break;
    case iMoMoMsgTypes.CHATING_IMAGE_MSG:
        JSONObject json = JSON.parseObject(msgDb.msgJson);
        moMsg.symbol = ‘-‘;
        String imagePath = json.getString(MsgKeys.imagePath);
        moMsg.msgBytes = FileTools.getInstance().getMultyFileBytes(
                imagePath);
        json.remove(MsgKeys.imagePath);
        moMsg.msgJson = json.toJSONString();
        //删除本地缓存图片
        FileTools.getInstance().deleteFile(imagePath);
        break;
    case iMoMoMsgTypes.CHATING_VOICE_MSG:
        moMsg.symbol = ‘-‘;
        JSONObject json2 = JSON.parseObject(msgDb.msgJson);
        String voicePath = json2.getString(MsgKeys.voicePath);
        moMsg.msgBytes = FileTools.getInstance().getMultyFileBytes(
                voicePath);
        json2.remove(MsgKeys.voicePath);
        moMsg.msgJson = json2.toJSONString();
        FileTools.getInstance().deleteFile(voicePath);
        break;

    case iMoMoMsgTypes.ADD_FRIEND:
        moMsg.symbol = ‘+‘;
        moMsg.msgJson = msgDb.msgJson;
        break;

    case iMoMoMsgTypes.RESET_HEAD:
        JSONObject resetHeadjson = JSON.parseObject(msgDb.msgJson);
        moMsg.symbol = ‘-‘;
        String headPath = resetHeadjson.getString(MsgKeys.imagePath);
        moMsg.msgBytes = FileTools.getInstance().getMultyFileBytes(
                headPath);
        resetHeadjson.remove(MsgKeys.imagePath);
        moMsg.msgJson = resetHeadjson.toJSONString();
        //删除本地缓存图片
        FileTools.getInstance().deleteFile(headPath);
        break;

    }
    return moMsg;
}

/**
 * 网络消息转化为数据库存储消息
 * 
 * @param moMsg
 * @return
 */
public MsgDb Trance_Net2Db(iMoMoMsg moMsg) {
    MsgDb msgDb = new MsgDb();
    JSONObject json = JSON.parseObject(moMsg.msgJson);
    int msgtype = json.getIntValue(MsgKeys.msgType);
    switch (msgtype) {
    case iMoMoMsgTypes.CHATING_TEXT_MSG:
        break;
    case iMoMoMsgTypes.CHATING_IMAGE_MSG:
        String imagePath = StaticValues.MSG_CACHE_IMA_P_PATH
                + json.getString(MsgKeys.userId) + "_"
                + System.currentTimeMillis() + ".png";
        FileTools.getInstance().saveMultyFile(imagePath, moMsg.msgBytes);
        json.put(MsgKeys.imagePath, imagePath);
        break;
    case iMoMoMsgTypes.CHATING_VOICE_MSG:
        String voicePath = StaticValues.MSG_CACHE_VOI_P_PATH
                + json.getString(MsgKeys.userId) + "_"
                + System.currentTimeMillis() + ".amr";
        FileTools.getInstance().saveMultyFile(voicePath, moMsg.msgBytes);
        json.put(MsgKeys.voicePath, voicePath);
        break;
    case iMoMoMsgTypes.ADD_FRIEND:

// String headPath = StaticValues.HEAD_P_PATH
// + json.getString(MsgKeys.userId) + “.png”;
// json.put(MsgKeys.imagePath, headPath);
break;

    case iMoMoMsgTypes.RESET_HEAD:
        String headPath = StaticValues.MSG_CACHE_IMA_P_PATH
        + json.getString(MsgKeys.userId) + "_"
        + System.currentTimeMillis() + ".png";
        FileTools.getInstance().saveMultyFile(headPath, moMsg.msgBytes);
        json.put(MsgKeys.imagePath, headPath);
        break;

    }
    msgDb.msgType = msgtype;
    msgDb.msgJson = json.toJSONString();
    return msgDb;
}

}

然后是转发离线消息:
/**
* 转发离线消息
*
* @param session
* @param userId
* @param model
*/
private void sendCacheMsg(IoSession session, String userId, SqlModel model) {
if (model.isTableExists(“mc_” + userId)) {
if (model.getMsgCount(userId) > 0) {
// 说明有离线消息
List list = model.getCacheMsgs(userId);
for (MsgDb msgDb : list) {
iMoMoMsg moMsg = MsgTranceUtil.getInstance().Trance_Db2Net(
msgDb);

                session.write(moMsg);
            }
            // 清空数据库离线文件
            model.clearMsgCache(userId);
        }
    }
}