Android客户端实现消息推送无外乎以下几种方式：
1、轮询：客户端通过定时机制往服务端获取消息，这种方式太傻逼，不算真正的推送，费流量。
2、客户端和服务端建立长久连接：这种方式才是真正的推送，由服务端通过连接的通道主动推送给客户端，常用的有xmpp和mqtt协议。
MQTT协议
MQTT协议是由IBM提出的基于发布／订阅模型的消息传输协议，相比于XMPP，它显得非常轻量小巧，协议内容包括固定头部+可变头部+消息体，最下的情况下头部只需要两个字节，在传输开销上有着巨大的优势，可以节省流量和电量。
MQTT可以保证消息的可靠性，它包括三种不同的服务质量（最多只传一次、最少被传一次、一次且只传一次），如果客户端意外掉线，可以使用“遗愿”发布一条消息，同时支持持久订阅。
“至多一次”
消息根据底层因特网协议网络尽最大努力进行传递。 可能会丢失消息。
例如，将此服务质量与通信环境传感器数据一起使用。 对于是否丢失个别读取或是否稍后立即发布新的读取并不重要。
“至少一次”
保证消息抵达，但可能会出现重复。
“刚好一次”
确保只收到一次消息
MQTT服务器搭建
这个请自行百度，这里我们不加以详述。
MQTT Android客户端实现
在使用之前，配置android端的mqtt需要下面这些参数：
Topic：订阅的事件。在图一中，也就是“主题”
URI：MQTT服务器的地址。
username & password：账户与密码
ClientId：客户端的ID，可以自定义，必须保证唯一性，否则连接服务器的时候会导致服务器断开
1、添加依赖
implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.1.0'
implementation 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'
2、配置客户端相关参数
public static final String MQTT_IP="192.168.0.207";//服务器地址
public static final String MQTT_PORT="1883";//服务器端口
public static final String MQTT_TOPIC="mqtt";//订阅主题
public static final String MQTT_USERNAME="Test11";//用户名
public static final String MQTT_USERID="12";//用户id
3、连接mqtt服务器
public class MqttConfig {
private String TAG = "mqtt";
/**MQTT配置参数**/
private static String host = Constants.MQTT_IP;
private static String port = Constants.MQTT_PORT;
private static String userID = "";
private static String passWord = "";
private static String clientID = MqttAppState.getInstance().getIMEI();
private int mqttRetryCount=0;
/**MQTT状态信息**/
private boolean isConnect = false;
/**MQTT支持类**/
private MqttAsyncClient mqttClient=null;
private MqttListener mMqttListener;//mqtt回调函数
private Handler mHandler=new Handler(new Handler.Callback() {
@Override
public boolean handleMessage(Message message) {
switch (message.arg1) {
case MqttTag.MQTT_STATE_CONNECTED:
if (BuildConfig.DEBUG) Log.d(TAG, "handleMessage: connected");
mMqttListener.onConnected();
mqttRetryCount=0;
break;
case MqttTag.MQTT_STATE_FAIL:
if (BuildConfig.DEBUG) Log.d(TAG, "handleMessage: fail");
mMqttListener.onFail();
break;
case MqttTag.MQTT_STATE_LOST:
if (BuildConfig.DEBUG) Log.d(TAG, "handleMessage: lost");
mMqttListener.onLost();
break;
case MqttTag.MQTT_STATE_RECEIVE:
if (BuildConfig.DEBUG) Log.d(TAG, "handleMessage: receive");
MqttObject object= (MqttObject) message.obj;
mMqttListener.onReceive(object.getTopic(),object.getMessage());
break;
case MqttTag.MQTT_STATE_SEND_SUCC:
if (BuildConfig.DEBUG) Log.d(TAG, "handleMessage: send");
mMqttListener.onSendSucc();
break;
}
return true;
}
});
/**
* 自带的监听类，判断Mqtt活动变化
*/
private IMqttActionListener mIMqttActionListener=new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
isConnect=true;
Message msg=new Message();
msg.arg1=MqttTag.MQTT_STATE_CONNECTED;
mHandler.sendMessage(msg);
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
isConnect=false;
Message msg=new Message();
msg.arg1=MqttTag.MQTT_STATE_FAIL;
mHandler.sendMessage(msg);
}
};
/**
* 自带的监听回传类
*/
private MqttCallback mMqttCallback=new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {
isConnect=false;
Message msg=new Message();
msg.arg1=MqttTag.MQTT_STATE_LOST;
mHandler.sendMessage(msg);
}
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
Message msg=new Message();
msg.arg1=MqttTag.MQTT_STATE_RECEIVE;
String content=new String(message.getPayload());
MqttObject object=new MqttObject();
object.setTopic(topic);
object.setMessage(content);
msg.obj=object;
mHandler.sendMessage(msg);
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
Message msg=new Message();
msg.arg1=MqttTag.MQTT_STATE_SEND_SUCC;
mHandler.sendMessage(msg);
}
};
public MqttConfig(MqttListener lis){
mMqttListener=lis;
}
public static void setMqttSetting(String host, String port, String userID, String passWord, String clientID){
MqttConfig.host = host;
MqttConfig.port = port;
MqttConfig.userID = userID;
MqttConfig.passWord = passWord;
MqttConfig.clientID = clientID;
}
/**
* 进行Mqtt连接
*/
public void connectMqtt(){
try {
mqttClient=new MqttAsyncClient("tcp://"+this.host+":"+this.port ,
"ClientID"+this.clientID, new MemoryPersistence());
mqttClient.connect(getOptions(), null, mIMqttActionListener);
mqttClient.setCallback(mMqttCallback);
} catch (MqttException e) {
Log.e("yaolinnan","e:",e);
// e.printStackTrace();
}
}
/**
* 断开Mqtt连接重新连接
*/
public void reStartMqtt(){
if(mqttRetryCount<5) {
disConnectMqtt();
connectMqtt();
mqttRetryCount++;
}else {
Log.i(TAG,"mqtt server reconnect error!");
}
}
/**
* 断开Mqtt连接
*/
public void disConnectMqtt(){
try {
mqttClient.disconnect();
mqttClient = null;
isConnect = false;
} catch (MqttException e) {
e.printStackTrace();
}
}
/**
* 向Mqtt服务器发送数据
*/
public void pubMsg(String Topic, String Msg, int Qos){
if(!isConnect){
Log.d(TAG,"Mqtt连接未打开");
return;
}
try {
/** Topic,Msg,Qos,Retained**/
mqttClient.publish(Topic,Msg.getBytes(),Qos,false);
} catch (MqttException e) {
e.printStackTrace();
}
}
/**
* 向Mqtt服务器发送数据
*/
public void pubMsg(String Topic, byte[] Msg, int Qos){
if(!isConnect){
Log.d(TAG,"Mqtt连接未打开");
return;
}
try {
/** Topic,Msg,Qos,Retained**/
mqttClient.publish(Topic,Msg,Qos,false);
} catch (MqttException e) {
e.printStackTrace();
}
}
/**
* 向Mqtt服务器订阅某一个Topic
*/
public void subTopic(String Topic, int Qos){
if(!isConnect){
Log.d(TAG,"Mqtt连接未打开");
return;
}
try {
mqttClient.subscribe(Topic,Qos);
} catch (MqttException e) {
e.printStackTrace();
}
}
public void subTopic(String[] Topic, int[] Qos){
if(!isConnect){
Log.d(TAG,"Mqtt连接未打开");
return;
}
try {
mqttClient.subscribe(Topic,Qos);
} catch (MqttException e) {
e.printStackTrace();
}
}
/**
* 设置Mqtt的连接信息
*/
private MqttConnectOptions getOptions(){
MqttConnectOptions options = new MqttConnectOptions();
options.setCleanSession(true);//重连不保持状态
if(this.userID!=null&&this.userID.length()>0&&this.passWord!=null&&this.passWord.length()>0){
options.setUserName(this.userID);//设置服务器账号密码
options.setPassword(this.passWord.toCharArray());
}
options.setConnectionTimeout(10);//设置连接超时时间
options.setKeepAliveInterval(20);//设置保持活动时间，超过时间没有消息收发将会触发ping消息确认
// options.setAutomaticReconnect(true);
// options.setCleanSession(false);
return options;
}
public boolean isConnect() {
return isConnect;
}
public static String getClientID() {
return clientID;
}
class MqttObject{
String topic;
String message;
public String getTopic() {
return topic;
}
public void setTopic(String topic) {
this.topic = topic;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
}
4、通过service后台服务管理mqtt的连接、消息的接收和发送
public class MqttService extends Service implements MqttListener{
private static final int MESSAGE_CHECK=0;
private static MqttConfig mqttConfig;
private static List<MqttListener> mMqttListenerList=new ArrayList<>();
private CheckMqttThread myThread;
private Timer timer=new Timer(true);
private Handler mHandler=new Handler(){
@Override
public void handleMessage(Message msg) {
if(msg.what==MESSAGE_CHECK){
if(mqttConfig!=null&&!mqttConfig.isConnect()){
mqttConfig.connectMqtt();
}
}
}
};
@Override
public void onCreate() {
super.onCreate();
mqttConfig=new MqttConfig(this);
mqttConfig.connectMqtt();
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
if(myThread==null){
myThread=new CheckMqttThread();//定时检查mqtt服务是否连接
timer.scheduleAtFixedRate(myThread,2000,10000);
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {//启动前台服务
startForeground(1, getNotification());
}
return Service.START_STICKY;
}
private Notification getNotification() {
Notification notification=null;
NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
//设置Notification的ChannelID,否则不能正常显示
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationChannel mChannel = new NotificationChannel("mqtt", getResources().getString(R.string.app_name), NotificationManager.IMPORTANCE_HIGH);
notificationManager.createNotificationChannel(mChannel);
notification = new Notification.Builder(getApplicationContext(), "mqtt").build();
}else {
Notification.Builder builder = new Notification.Builder(this)
.setSmallIcon(R.mipmap.ic_launcher)
.setContentTitle(getResources().getString(R.string.app_name))
.setContentText("");
notification = builder.build();
}
return notification;
}
private class CheckMqttThread extends TimerTask {
@Override
public void run() {
mHandler.sendEmptyMessage(MESSAGE_CHECK);
}
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
public static void addMqttListener(MqttListener listener){
if (!mMqttListenerList.contains(listener)) {
mMqttListenerList.add(listener);
}
}
public static void removeMqttListener(MqttListener listener){
mMqttListenerList.remove(listener);
}
public static MqttConfig getMqttConfig(){
return mqttConfig;
}
@Override
public void onConnected() {
Log.i("mqtt","mqttserver connnected");
if(mqttConfig!=null){
mqttConfig.subTopic(Constants.MQTT_TOPIC,0);
}
for (MqttListener mqttListener : mMqttListenerList) {
mqttListener.onConnected();
}
}
@Override
public void onFail() {
Log.i("mqtt","mqttserver fail");
if(mqttConfig!=null) {
mqttConfig.reStartMqtt();
}
for (MqttListener mqttListener : mMqttListenerList) {
mqttListener.onFail();
}
}
@Override
public void onLost() {
Log.i("mqtt","mqttserver lost");
if(mqttConfig!=null) {
mqttConfig.reStartMqtt();
}
for (MqttListener mqttListener : mMqttListenerList) {
mqttListener.onLost();
}
}
@Override
public void onReceive(String topic, String message) {
Log.i("mqtt","mqttserver receive message:"+message);
for (MqttListener mqttListener : mMqttListenerList) {
mqttListener.onReceive(topic,message);
}
}
@Override
public void onSendSucc() {
Log.i("mqtt","mqttserver send success!");
for (MqttListener mqttListener : mMqttListenerList) {
mqttListener.onSendSucc();
}
}
}
5、编写聊天界面
public class MainActivity extends AppCompatActivity implements MqttListener{
private RecyclerView mMessageRV;
private EditText mMessageET;
private Button mSendBtn;
private Gson gson=new Gson();
private List<MqttMessage> messageList=new ArrayList<>();
private MqttAdapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MqttService.addMqttListener(this);
Intent intent=new Intent(this, MqttService.class);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
startForegroundService(intent);
}else {
startService(intent);
}
mMessageRV=findViewById(R.id.swipe_target);
mMessageET=findViewById(R.id.send_edit);
mSendBtn=findViewById(R.id.send_button);
mSendBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String message=mMessageET.getText().toString().trim();
if(!TextUtils.isEmpty(message)){
MqttMessage mqttMessage=new MqttMessage();
mqttMessage.setUserid(Constants.MQTT_USERID);
mqttMessage.setMessage(message);
mqttMessage.setUsername(Constants.MQTT_USERNAME);
mqttMessage.setSendTime(new SimpleDateFormat("yyyy-MM-dd HH:mm").format(new Date()));
MqttService.getMqttConfig().pubMsg(Constants.MQTT_TOPIC,gson.toJson(mqttMessage),0);
}else {
MqttAppState.getInstance().showToast("不可发送为空的消息");
}
}
});
LinearLayoutManager layoutManager = new LinearLayoutManager(this) {
@Override
public RecyclerView.LayoutParams generateDefaultLayoutParams() {
return new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}
};
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mMessageRV.setLayoutManager(layoutManager);
layoutManager.setReverseLayout(true);//倒序显示
layoutManager.setStackFromEnd(true);
mAdapter=new MqttAdapter(this,messageList);
mMessageRV.setAdapter(mAdapter);
}
@Override
protected void onDestroy() {
super.onDestroy();
MqttService.removeMqttListener(this);
}
@Override
public void onConnected() {
}
@Override
public void onFail() {
}
@Override
public void onLost() {
}
@Override
public void onReceive(String topic, String message) {
if(topic.equals(Constants.MQTT_TOPIC)){
MqttMessage mqttMessage=gson.fromJson(message,MqttMessage.class);
if(messageList.size()>0)
messageList.add(0,mqttMessage);
else
messageList.add(mqttMessage);
mAdapter.setList(messageList);
mMessageRV.scrollToPosition(0);
}
}
@Override
public void onSendSucc() {
MqttAppState.getInstance().showToast("消息发送成功");
mMessageET.setText("");
mMessageET.clearFocus();
}
}
6、效果示意图
这样基本上就完成了通过mqtt协议聊天的功能！
完整代码：https://github.com/ylnJohn/MqttDemo
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