最近在一家saas企业使用Mqtt开发IM消息推送服务，把开发中的一些问题记录下来，项目仍在商用中，完整的消息服务包括4个模块---协议protocol，信令Signal，规则Rule，状态Status，这个主题主要是协议protocol部分。
主要技术涉及到MongoDB，webservice，httpclient，Mqtt等
protocol分为四个模块类来实现，当然这是为了以后的扩展性比较好
首先看一下我们的主类，主要是mqtt基础方法的一个框架
public class MqttProtocol
{
private static Logger logger = Logger.getLogger(MqttProtocol.class);
public static final String HOST = "tcp://xx.xx.xx.xx:1883";
private static final String CLIENTID = "yyyy";
private MqttClient client;
private MqttConnectOptions options = new MqttConnectOptions();
//private String userName = "admin";
//private String passWord = "public";
public MqttMessage message;
private PushCallback callback;
/**
* 用于初始化mqttclient客户端，设置回调函数，同时连接mqtt服务器
* @throws MqttException
*/
public MqttProtocol() throws MqttException
{
//MemoryPersistence设置clientid的保存形式，默认为以内存保存
client = new MqttClient(HOST, CLIENTID, new MemoryPersistence());
callback = new PushCallback();
client.setCallback(callback);
options = new MqttConnectOptions();
options.setCleanSession(false);
options.setKeepAliveInterval(60);
connect();
}
/**
* 连接mqtt消息服务器，同时设置了断开重连的功能，主要是为了高可用性考虑，在断网服务器崩溃时候我们的程序仍然不会终止
*/
private void connect()
{
SimpleDateFormat sdf= new SimpleDateFormat(Constant.DATE_FORMAT_MDYHMS);
System.out.println(sdf.format(System.currentTimeMillis()));
boolean tryConnecting = true;
while (tryConnecting) {
try {
client.connect(options);
} catch (Exception e1) {
System.out.println("Connection attempt failed with '"+e1.getCause()+
"'. Retrying.");
}
if (client.isConnected()) {
System.out.println("Connected.");
tryConnecting = false;
} else {
pause();
}
}
}
private void pause() {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// Error handling goes here...
}
}
/**
*
* @param topic
* @param qos
* @throws MqttPersistenceException
* @throws MqttException
* 订阅相关主题
*/
public void subscribe(String topic , int qos) throws MqttPersistenceException,
MqttException
{
client.subscribe(topic, qos);
}
/**
*
* @throws MqttPersistenceException
* @throws MqttException
* 断开连接服务器
*/
public void disconnect() throws MqttPersistenceException,
MqttException
{
client.disconnect();
}
/**
*
* @author binshi
*实现mqttcallback接口，主要用于接收消息后的处理方法
*/
private class PushCallback implements MqttCallback {
/**
* 断开后 系统会自动调用这个函数，同时在这个函数里进行重连操作
*/
public void connectionLost(Throwable cause) {
// 连接丢失后，一般在这里面进行重连
System.out.println("连接断开，可以做重连");
connect();
try {
subscribe(Constant.TOPIC_MQTT_PROTOCOL, 2);
} catch (MqttPersistenceException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (MqttException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* 消息成功传送后，系统会自动调用此函数，表明成功向topic发送消息
*/
@Override
public void deliveryComplete(IMqttDeliveryToken arg0) {
// TODO Auto-generated method stub
System.out.println("deliveryComplete---------" + arg0.isComplete());
}
/**
* 连接mongo数据库，返回关于具体collection的Mongocollection
* @param collectionname
* @return
*/
public void messageArrived(String topic, MqttMessage message) throws Exception
{
System.out.println(topic);
SimpleDateFormat sdf= new SimpleDateFormat(Constant.DATE_FORMAT_MDYHMS);
System.out.println(sdf.format(System.currentTimeMillis()));
System.out.println("接收消息主题 : " + topic);
System.out.println("接收消息Qos : " + message.getQos());
System.out.println("接收消息内容 : " + new String(message.getPayload()));
//1 抽取事件信令消息
String messagejudge=new String(message.getPayload());
System.out.println("忽略所有robot消息以及offline离线消息");
JSONObject jo=new JSONObject();
try {
jo=JSONObject.fromObject(messagejudge);
} catch (Exception e) {
e.printStackTrace();
}
String from=jo.getString("from");
System.out.println("获得from"+from);
System.out.println("确定消息是否包含offline，如果包含取得offline，为1就不处理");
String offline=null;
if(messagejudge.contains("offline"))
{
offline=jo.getString("offline");
}
if((offline==null)&&(!from.contains("robot")))
{
System.out.println("处理非系统消息和非离线消息");
String type=jo.getString("type");
System.out.println("获得type"+type);
if(type.equals("shakehand"))
{
System.out.println("处理shakehand消息");
String admin="doyounkowwhy";
if(jo.toString().contains("admin"))
{
admin=jo.getString("admin");
}
System.out.println("取得admin 如果为1定义为客服，否则为普通用户 admin为"+admin);
if(admin.equals("1"))
{
System.out.println("处理客服握手消息");
System.out.println("发送握手成功消息");
MqttTopic retopic=client.getTopic(topic);
MsgOperation.sendSysMsgToClient(from,"0", "1005", "握手成功", null,retopic);
System.out.println("向客户端发送离线未接收的消息");
String convid=jo.getString("convid");
String database="dolina";
String collection="messages";
MongoDBDao.getMongoDBDaoInstance().sendOfflineMsgToClient(from, convid,retopic,database,collection);
}
else
{
System.out.println("处理普通用户的握手消息");
String appid=jo.getString("appid");
String pageid=jo.getString("pageid");
String convid=jo.getString("convid");
MqttTopic retopic=client.getTopic(topic);
MsgOperation.sendShakeHandInfo(from,convid,appid,pageid,retopic);
}
}
else if(type.equals("text")||type.equals("image"))
{
System.out.println("处理图片和文字消息");
String tmpindex=jo.getString("tmpindex");
String convid=jo.getString("convid");
MqttTopic retopic=client.getTopic(topic);
MsgOperation.getTextMsg( tmpindex, from, convid, retopic);
System.out.println("保存图片文字消息");
String database="dolina";
String collection="messages";
MongoDBDao.getMongoDBDaoInstance().saveTextMsg(database,collection,jo);
}
else if(type.equals("ack"))
{
System.out.println("处理ack消息");
String tmpindex=jo.getString("tmpindex");
String convid=jo.getString("convid");
String database="dolina";
String collection="messages";
MongoDBDao.getMongoDBDaoInstance().getAck(tmpindex,convid,from,database,collection);
}
}
}
}
/**
*
* @param args
* @throws MqttException
* 整个工程从这里开始执行，生成可执行jar包，这个设置为主类。
*/
public static void main(String[] args) throws MqttException
{
MqttProtocol signal = new MqttProtocol();
signal.message = new MqttMessage();
/**
server.message.setQos(2);
server.message.setRetained(false);
server.message.setPayload("给客户端124推送的信息".getBytes());
server.subscribe("/engyne/1/7/169573fcbc96a816281192222", 2);
*/
signal.subscribe(Constant.TOPIC_MQTT_PROTOCOL, 2);
System.out.println(signal.message.isRetained() + "------ratained状态");
}
}
接下来使我们的远程连接模块，主要是通过给定的url调用远程接口
public class RemoteOperation
{
private static Logger logger = Logger.getLogger(MqttProtocol.class);
public static JSONObject remoteCall(String url) throws HttpException, IOException
{
HttpClient httpClient = new HttpClient();
GetMethod method =null ;
method=new GetMethod(url);
int retcode = httpClient.executeMethod(method);
if (retcode != HttpStatus.SC_OK)
{// 发送不成功
logger.info("远程调用出错");
return null;
}
else
{
String body = method.getResponseBodyAsString();
logger.info(body+"远程调用php成功");
JSONObject jsonObject=new JSONObject();
try {
jsonObject=JSONObject.fromObject(body);
} catch (Exception e) {
e.printStackTrace();
}
if (method != null)
{
method.releaseConnection();
}
return jsonObject;
}
}
}
下面是Mongo数据库的相关操作的一个封装，设计为单例模式，相当于每次都使用同一个client打开连接，类似于连接池的概念，当然业务逻辑部分可以更换
public class MongoDBDao
{
private static Logger logger = Logger.getLogger(MongoDBDao.class);
/**
* MongoClient的实例代表数据库连接池，是线程安全的，可以被多线程共享，客户端在多线程条件下仅维持一个实例即可
* Mongo是非线程安全的，目前mongodb API中已经建议用MongoClient替代Mongo
*/
private MongoClient mongoClient = null;
/**
*
* 私有的构造函数
* 作者：shibin
*/
private MongoDBDao(){
if(mongoClient == null){
String url = Constant.MONGO_MQTT_URL;
String user = Constant.MONGO_MQTT_USER;
String password = Constant.MONGO_MQTT_PASSWORD;
String database = Constant.MONGO_MQTT_DATABASE;
int port = 27017;
ServerAddress serverAddress = new ServerAddress(url, port);
ListserverAddresses = new ArrayList();
serverAddresses.add(serverAddress);
MongoCredential credential = MongoCredential.createCredential(user, database, password.toCharArray());
Listcredentials = new ArrayList();
credentials.add(credential);
mongoClient = new MongoClient(serverAddresses, credentials);
System.out.println(mongoClient);
System.out.println("初始化client完成");
}
}
/********单例模式声明开始，采用饿汉式方式生成，保证线程安全********************/
//类初始化时，自行实例化，饿汉式单例模式
private static final MongoDBDao mongoDBDao = new MongoDBDao();
/**
*
* 方法名：getMongoDBDaoImplInstance
* 作者：shibin
*
* 描述：单例的静态工厂方法
* @return
*/
public static MongoDBDao getMongoDBDaoInstance(){
return mongoDBDao;
}
public void sendOfflineMsgToClient(String from, String convid,MqttTopic retopic,String database,String collection) throws MqttPersistenceException, MqttException
{
System.out.println("获得message的连接");
MongoDatabase mongoDatabase = mongoClient.getDatabase(database);
MongoCollection mongoCollection = mongoDatabase.getCollection(collection);
System.out.println("取得convid所对应的msg列表");
BasicDBObject query = new BasicDBObject();
query.put("_id", convid);
FindIterableiterable=null;
iterable = mongoCollection.find(query);
if(iterable.first()!=null)
{
System.out.println(iterable.first());
String res= iterable.first().toJson();
JSONObject jo=new JSONObject();
try {
jo=JSONObject.fromObject(res);
} catch (Exception e) {
e.printStackTrace();
}
JSONArray jsonArray=jo.getJSONArray("msg");
for(int i=0;i
doc.put("read", read);
Document tdoc = new Document();
tdoc.put("msg", doc);
UpdateOptions updateOptions=new UpdateOptions();
updateOptions.upsert(true);
mongoCollection.updateOne(filter, new Document("$addToSet", tdoc), updateOptions);
iterable = mongoCollection.find(query);
System.out.println("更新message之后的值"+iterable.first());
}
public void getAck(String tmpindex,String convid,String from,String database,String collection)
{
System.out.println("接收到ack消息后更新message中的read字段");
MongoDatabase mongoDatabase = mongoClient.getDatabase(database);
MongoCollection mongoCollection = mongoDatabase.getCollection(collection);
BasicDBObject query = new BasicDBObject();
query.put("_id", convid);
query.put("msg.tmpindex", tmpindex);
BasicDBObject query1 = new BasicDBObject();
query1.put("_id", convid);
FindIterable iterable;
FindIterable iterable2;
iterable = mongoCollection.find(query1);
iterable2 = mongoCollection.find(query);
System.out.println("更新message满足id过滤条件之前的值"+iterable.first());
System.out.println("更新message满足id和tmpindex过滤条件之前的值"+iterable2.first());
if(iterable2.first()!=null)
{
Document doc = new Document();
doc.put("msg.$.read", from);
UpdateOptions updateOptions=new UpdateOptions();
updateOptions.upsert(true);
mongoCollection.updateOne(query, new Document("$addToSet", doc), updateOptions);
}
iterable = mongoCollection.find(query1);
System.out.println("更新messages之后的值"+iterable.first());
}
}
剩下的关于业务逻辑方面的就不多说了，主要是关于mqtt高可用性断开重连的功能以及mongo相关的操作
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