安卓连接Mqtt服务器「建议收藏」

handler = new Handler() { 
   
            @SuppressLint("SetTextI18n")
            public void handleMessage(Message msg) { 
   
                super.handleMessage(msg);
                switch (msg.what) { 
   
                    case 1: //开机校验更新回传
                        break;
                    case 2:  // 反馈回传

                        break;
                    case 3:  //MQTT 收到消息回传 UTF8Buffer msg=new UTF8Buffer(object.toString());
                        Toast.makeText(MainActivity.this, msg.obj.toString(), Toast.LENGTH_SHORT).show();
                        text_test.setText(msg.obj.toString());
                        break;
                    case 30:  //连接失败
                        Toast.makeText(MainActivity.this, "连接失败", Toast.LENGTH_SHORT).show();
                        break;
                    case 31:   //连接成功
                        Toast.makeText(MainActivity.this, "连接成功", Toast.LENGTH_SHORT).show();
                        try { 
   
                            client.subscribe(mqtt_sub_topic, 1);
                        } catch (MqttException e) { 
   
                            e.printStackTrace();
                        }
                        break;
                    default:
                        break;
                }
            }
        };
    }
        private void Mqtt_init() { 
   
            try { 
   
                //host为主机名，test为clientid即连接MQTT的客户端ID，一般以客户端唯一标识符表示，MemoryPersistence设置clientid的保存形式，默认为以内存保存
                client = new MqttClient(host, "*****",
                        new MemoryPersistence());
                //MQTT的连接设置
                options = new MqttConnectOptions();
                //设置是否清空session,这里如果设置为false表示服务器会保留客户端的连接记录，这里设置为true表示每次连接到服务器都以新的身份连接
                options.setCleanSession(false);
                //设置连接的用户名
                options.setUserName(userName);
                //设置连接的密码
                options.setPassword(passWord.toCharArray());
                // 设置超时时间 单位为秒
                options.setConnectionTimeout(10);
                // 设置会话心跳时间 单位为秒 服务器会每隔1.5*20秒的时间向客户端发送个消息判断客户端是否在线，但这个方法并没有重连的机制
                options.setKeepAliveInterval(20);
                //设置回调
                client.setCallback(new MqttCallback() { 
   
                    @Override
                    public void connectionLost(Throwable cause) { 
   
                        //连接丢失后，一般在这里面进行重连
                        System.out.println("connectionLost----------");
                        //startReconnect();
                    }

                    @Override
                    public void deliveryComplete(IMqttDeliveryToken token) { 
   
                        //publish后会执行到这里
                        System.out.println("deliveryComplete---------"
                                + token.isComplete());
                    }

                    @Override
                    public void messageArrived(String topicName, MqttMessage message)
                            throws Exception { 
   
                        //subscribe后得到的消息会执行到这里面
                        System.out.println("messageArrived----------");
                        Message msg = new Message();
                        msg.what = 3;   //收到消息标志位
                        msg.obj = topicName + "---" + message.toString();
                        handler.sendMessage(msg);    // hander 回传
                    }
                });
            } catch (Exception e) { 
   
                e.printStackTrace();
            }
        }
        private void Mqtt_connect () { 
   
            new Thread(new Runnable() { 
   
                @Override
                public void run() { 
   
                    try { 
   
                        if (!(client.isConnected()))  //如果还未连接
                        { 
   
                            client.connect(options);
                            Message msg = new Message();
                            msg.what = 31;
                            handler.sendMessage(msg);
                        }
                    } catch (Exception e) { 
   
                        e.printStackTrace();
                        Message msg = new Message();
                        msg.what = 30;
                        handler.sendMessage(msg);
                    }
                }
            }).start();
        }
        private void startReconnect(){ 
   
            scheduler = Executors.newSingleThreadScheduledExecutor();
            scheduler.scheduleAtFixedRate(new Runnable() { 
   
                @Override
                public void run() { 
   
                    if (!client.isConnected()) { 
   
                        Mqtt_connect();
                    }
                }
            }, 0 * 1000, 10 * 1000, TimeUnit.MILLISECONDS);
        }
    }

Mqtt_init()
Mqtt_connect()
startReconnect()

Handler()

<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.demo.mqtt_project">
    <!--允许程序打开网络套接字-->
    <uses-permission android:name="android.permission.INTERNET" />
    <!--允许程序获取网络状态-->
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />