JAVA高级面试进阶训练营视频教程

admin

前段时间项目用到mqtt的消息推送，整理一下代码，代码的原型是网上找的，具体哪个地址已经忘记了。

代码的实现是新建了一个MyMqttService，全部功能都在里面实现，包括连服务器，断线重连，订阅消息，处理消息，发布消息等基本操作。

首先添加依赖：

dependencies {
    implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.1.0'
    implementation 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'
}
然后编辑AndroidManifest.xml，先添加权限：

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
再注册service：

<service android:name="org.eclipse.paho.android.service.MqttService" />
<service
    android:name=".service.MyMqttService"
    android:enabled="true"
    android:exported="true"/>
接着进入正文MyMqttService.java，功能见注释吧：

 

package com.example.nan.mqtt.service;

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.IBinder;
import android.support.v4.app.NotificationCompat;
import android.util.Log;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

import org.eclipse.paho.android.service.MqttAndroidClient;
import org.eclipse.paho.client.mqttv3.DisconnectedBufferOptions;
import org.eclipse.paho.client.mqttv3.IMqttActionListener;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.IMqttToken;
import org.eclipse.paho.client.mqttv3.MqttCallbackExtended;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.json.JSONObject;

/**
* @author nan
*/
public class MyMqttService extends Service {

private static final String TAG = "nlgMqttService";
private static final String TOPIC_TO_QA = "/s2c/task_quality/";

private static final String publishTopic = "exampleAndroidPublishTopic";

private MqttAndroidClient mqttAndroidClient;
private NotificationManager mNotificationManager;


public MyMqttService() {
}

@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}

@Override
public void onCreate() {
super.onCreate();
Log.d(TAG, "MqttService onCreate executed");
//mqtt服务器的地址
final String serverUri = "tcp://192.168.10.10:1883";
//新建Client,以设备ID作为client ID
mqttAndroidClient = new MqttAndroidClient(MyMqttService.this, serverUri, getIMEI());
mqttAndroidClient.setCallback(new MqttCallbackExtended() {
@Override
public void connectComplete(boolean reconnect, String serverURI) {
//连接成功
if (reconnect) {
Log.d(TAG, "connectComplete: " + serverURI);
// Because Clean Session is true, we need to re-subscribe
subscribeAllTopics();
} else {
Log.d(TAG, "connectComplete: " + serverURI);
}
}

@Override
public void connectionLost(Throwable cause) {
//连接断开
Log.d(TAG, "connectionLost: connection was lost");
}

@Override
public void messageArrived(String topic, MqttMessage message) {
//订阅的消息送达，推送notify
String payload = new String(message.getPayload());
Log.d(TAG, "Topic: " + topic + " ==> Payload: " + payload);
if(mNotificationManager == null) {
mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
}
int roleId = SinSimApp.getApp().getRole();
Gson gson = new Gson();
ServerToClientMsg msg = gson.fromJson(payload, new TypeToken<ServerToClientMsg>(){}.getType());
if(msg != null) {
    //接受消息
    if(topic != null) {
if(topic.equals(TOPIC_TO_QA)) {
Intent intent = new Intent(MyMqttService.this, ProcessToCheckoutActivity.class);
PendingIntent pi = PendingIntent.getActivity(MyMqttService.this, 0, intent, 0);
NotificationCompat.Builder builder = new NotificationCompat.Builder(MyMqttService.this, TOPIC_TO_QA);
Notification notify = builder.setSmallIcon(R.mipmap.to_quality)
.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.to_quality))
.setDefaults(Notification.DEFAULT_SOUND|Notification.DEFAULT_VIBRATE)//响铃震动
.setContentTitle("快递来了")
.setAutoCancel(true)
.setContentIntent(pi)
.setVisibility(Notification.VISIBILITY_PUBLIC)
.setContentText("你的快递单号:" + msg.getOrderNum())
//不设置此项不会悬挂,false 不会出现悬挂
.build();
mNotificationManager.notify(2,notify);
}
}
}
}

@Override
public void deliveryComplete(IMqttDeliveryToken token) {
//即服务器成功delivery消息
}
});
//新建连接设置
MqttConnectOptions mqttConnectOptions = new MqttConnectOptions();
//断开后，是否自动连接
mqttConnectOptions.setAutomaticReconnect(true);
//是否清空客户端的连接记录。若为true，则断开后，broker将自动清除该客户端连接信息
mqttConnectOptions.setCleanSession(false);
//设置超时时间，单位为秒
//mqttConnectOptions.setConnectionTimeout(2);
//心跳时间，单位为秒。即多长时间确认一次Client端是否在线
//mqttConnectOptions.setKeepAliveInterval(2);
//允许同时发送几条消息（未收到broker确认信息）
//mqttConnectOptions.setMaxInflight(10);
//选择MQTT版本
mqttConnectOptions.setMqttVersion(MqttConnectOptions.MQTT_VERSION_3_1_1);
try {
Log.d(TAG, "onCreate: Connecting to " + serverUri);
    //开始连接
mqttAndroidClient.connect(mqttConnectOptions, null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
Log.d(TAG, "onSuccess: Success to connect to " + serverUri);
DisconnectedBufferOptions disconnectedBufferOptions = new DisconnectedBufferOptions();
disconnectedBufferOptions.setBufferEnabled(true);
disconnectedBufferOptions.setBufferSize(100);
disconnectedBufferOptions.setPersistBuffer(false);
disconnectedBufferOptions.setDeleteOldestMessages(false);
mqttAndroidClient.setBufferOpts(disconnectedBufferOptions);
    //成功连接以后开始订阅
subscribeAllTopics();
}

@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
//连接失败
    Log.d(TAG, "onFailure: Failed to connect to " + serverUri);
exception.printStackTrace();
}
});
} catch (MqttException ex) {
ex.printStackTrace();
}

//service绑定notification
Intent intent = new Intent(this, SplashActivity.class);
intent.putExtra(SinSimApp.FROM_NOTIFICATION, true);
//这边设置“FLAG_UPDATE_CURRENT”是为了让后面的Activity接收pendingIntent中Extra的数据
PendingIntent pi = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
Notification notification = new NotificationCompat.Builder(this)
.setContentTitle("mqtt快递")
.setContentText("mqtt快递管理系统")
.setWhen(System.currentTimeMillis())
.setSmallIcon(R.mipmap.ic_launcher)
.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))
.setContentIntent(pi)
.build();
startForeground(1, notification);
}

//订阅所有消息
    private void subscribeAllTopics() {
subscribeToTopic(TOPIC_TO_QA);
}

/**
* 订阅消息
*/
public void subscribeToTopic(String subscriptionTopic) {
try {
mqttAndroidClient.subscribe(subscriptionTopic, 2, null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
Log.d(TAG, "onSuccess: Success to Subscribed!");
}

@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
Log.d(TAG, "onFailure: Failed to subscribe");
}
});
} catch (MqttException ex) {
Log.d(TAG, "subscribeToTopic: Exception whilst subscribing");
ex.printStackTrace();
}
}

/**
* 发布消息
*/
public void publishMessage(String msg) {
try {
MqttMessage message = new MqttMessage();
message.setPayload(msg.getBytes());
mqttAndroidClient.publish(publishTopic, message);
Log.d(TAG, "publishMessage: Message Published: " + msg);
} catch (MqttException e) {
Log.d(TAG, "publishMessage: Error Publishing: " + e.getMessage());
e.printStackTrace();
}
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "MqttService onStartCommand executed");
return super.onStartCommand(intent, flags, startId);
}

@Override
public void onDestroy() {
super.onDestroy();
try {
if(mqttAndroidClient!=null){
//服务退出时client断开连接
mqttAndroidClient.disconnect();
}
} catch (MqttException e) {
e.printStackTrace();
}
Log.d(TAG, "MqttService onDestroy executed");
}
}

调试过程中出现过一个小插曲：服务在有些时候会不停的断线重连。断线重连的设置是开了的：
mqttConnectOptions.setAutomaticReconnect(true);
但是断开的原因找不到，当时还没有重写onDestory方法，就算退出应用也还在重连，一度怀疑service的开启与关闭的问题，还系统的重新学习了一下service的使用，学完以后也没有啥进展，然后重学mqtt的调用流程发挥了效果，在onDestory里面调用了disconnect()方法，完了以后在退出应用以后就不会重连了，但是重新开还是继续不停重连。到了晚上，奇怪的事情发生了，当夜深人静，独自加班的时候，居然再也复现不了了。为什么呢，心想可能平时给八阿哥上的香起了效果，那就开心的回家吧。下班的路上虽然开心的吃了块鸡排，但心里的结还是没有打开，为什么呢，是道德的沦丧还是人性的扭曲，让我独自加班还不饿给我复现问题。突然灵光一现，想到今天特么加班就我一个人，也就是一个人玩就是好的，玩的人多就会有问题，那么答案就来了，跟唯一性有关的只有clientID了，特么老子把clientID设置成用户id了，测试用的用户id就注册了3个，好几个人来回切着用，不出问题才怪。于是我默默的把clientID改成了设备id，困扰2天的问题就这么解决了。
---------------------
作者：邦德总管
来源：CSDN
原文：https://blog.csdn.net/a5nan/article/details/79975488
版权声明：本文为博主原创文章，转载请附上博文链接！