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我正在爲我的最終大學工作做一個項目。 我想做一個Android應用程序，使用MQTT協議與我的覆盆子pi溝通。 爲此，我使用了一個mosquitto broker，但是當我使用Eclipse Paho使用Java MQTT客戶端在代理中發佈消息時，我的應用程序發佈了相同的消息5次，並且我不知道錯誤是否屬於我的發佈消息的類，或者我的android類的on_create（）類。如何僅使用Eclipse發佈使用Java MQTT客戶端的一條消息Paho
我的代碼如下：
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
EditText distanceCondition;
EditText timeCondition;
EditText countCondition;
String distance;
String time;
String count;
String topic;
int notificationID = 1;
int functionality;
int ok = 1;
public void mqttconnect(final String topic, final String message){
final MqttAndroidClient mqttAndroidClient = new MqttAndroidClient(this.getApplicationContext(), "tcp://192.168.1.36", "androidSampleClient");
mqttAndroidClient.setCallback(new MqttCallback() { //iot.eclipse.org:1883
@Override
public void connectionLost(Throwable cause) {
System.out.println("Connection was lost!");
}
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
System.out.println("Message Arrived!: " + topic + ": " + new String(message.getPayload()));
//displayNotification("DETECT MOVEMENT! visit LCESS app now.");
JSONObject inf = new JSONObject(Arrays.toString(message.getPayload()));
try {
if (inf.optString("Functionality").equals(6)) {
if (inf.optString("ok").equals(1)) {
displayNotification("DETECT MOVEMENT! visit LCESS app now.");
}
}
if (inf.optString("Functionality").equals(7)) {
if (inf.optString("ok").equals(1)) {
displayNotification("DETECT MOVEMENT IN" + inf.optString("Distance") + " CM! visit LCESS app now.");
}
}
if (inf.optString("Functionality").equals(8)) {
if (inf.optString("ok").equals(1)) {
displayNotification("DETECT MOVEMENT IN" + inf.optString("Time") + " HOURS! visit LCESS app now.");
}
}
if (inf.optString("Functionality").equals(9)) {
if (inf.optString("ok").equals(1)) {
displayNotification("DETECT MOVEMENT IN" + inf.optString("Distance") + " CM and in " + inf.optString("Time") + " HOURS! visit LCESS app now.");
}
}
if (inf.optString("Functionality").equals(10)) {
if (inf.optString("ok").equals(1)) {
displayNotification("DETECT " + inf.optString("Count") + " OBJECTS/PERSONS! visit LCESS app now.");
}
}
}
catch (Exception functionality){
}
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
System.out.println("Delivery Complete!");
}
});
try {
mqttAndroidClient.connect(null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
System.out.println("Connection Success!");
try {
System.out.println("Subscribing to: "+ topic);
mqttAndroidClient.subscribe(topic, 0);
System.out.println("Subscribed to: "+ topic);
System.out.println("Publishing message..");
mqttAndroidClient.publish(topic, new MqttMessage(message.getBytes()));
} catch (MqttException ex) {
}
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
System.out.println("Connection Failure!");
}
});
} catch (MqttException ex) {
}
}
public JSONObject sendJSONmessage() {
topic = "Mesurement";
distance = distanceCondition.getText().toString();
time = timeCondition.getText().toString();
count = countCondition.getText().toString();
JSONObject post_dict = new JSONObject();
try {
post_dict.put("Topic", topic);
post_dict.put("ok" ,ok);
post_dict.put("Functionality", functionality);
post_dict.put("Distance", distance);
post_dict.put("Time", time);
post_dict.put("Count", count);
} catch (JSONException e) {
e.printStackTrace();
}
if (post_dict.length() > 0) {
System.out.println(post_dict);
}
return post_dict;
}
protected void displayNotification(CharSequence contentText){
Intent i = new Intent(this, NotificationActivity.class);
i.putExtra("notificationID", notificationID);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, i, 0);
NotificationManager nm = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
CharSequence ticker ="Notification in LCESS";
CharSequence contentTitle = "LCESS";
Notification noti = new NotificationCompat.Builder(this)
.setContentIntent(pendingIntent)
.setTicker(ticker)
.setContentTitle(contentTitle)
.setContentText(contentText)
.setSmallIcon(R.drawable.lcess)
.addAction(R.drawable.lcess, ticker, pendingIntent)
.setVibrate(new long[] {100, 250, 100, 500})
.build();
nm.notify(notificationID, noti);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
distanceCondition = (EditText) findViewById(R.id.edit_detectDistanceCondition);
timeCondition = (EditText) findViewById(R.id.edit_detectTimeCondition);
countCondition = (EditText) findViewById(R.id.edit_countDetects);
Button button_detectDistance = (Button) findViewById(R.id.button_detectDistance);
Button button_detectDistanceCondition = (Button) findViewById(R.id.button_detectDistanceCondition);
Button button_detectTimeCondition = (Button) findViewById(R.id.button_detectTimeCondition);
Button button_detectIfAllCondition = (Button) findViewById(R.id.button_detectIfAllCondition);
Button button_count = (Button) findViewById(R.id.button_count);
assert button_detectDistance != null;
/*button_detectDistance.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
functionality = 1;
mqttconnect("Device1/Detect", sendJSONmessage().toString());
}
});*/
button_detectDistance.setOnClickListener(this);
assert button_detectDistanceCondition != null;
button_detectDistanceCondition.setOnClickListener(this);
assert button_detectTimeCondition != null;
button_detectTimeCondition.setOnClickListener(this);
assert button_detectIfAllCondition != null;
button_detectIfAllCondition.setOnClickListener(this);
assert button_count != null;
button_count.setOnClickListener(this);
}
public void onClick(View v){
if (R.id.button_detectDistance==v.getId()){
functionality = 1;
mqttconnect("Mesurement", sendJSONmessage().toString());
}
else if (R.id.button_detectDistanceCondition==v.getId()){
functionality = 2;
mqttconnect(sendJSONmessage().optString(topic), sendJSONmessage().toString());
}
else if (R.id.button_detectTimeCondition==v.getId()){
functionality = 3;
mqttconnect(sendJSONmessage().optString(topic), sendJSONmessage().toString());
}
else if (R.id.button_detectIfAllCondition==v.getId()){
functionality = 4;
mqttconnect("Device1/Detect1", sendJSONmessage().toString());
}
else if (R.id.button_count==v.getId()){
functionality = 5;
mqttconnect("Device1/Detect1", sendJSONmessage().toString());
}
}
}
首先，我創建了MQTT類來發布和訂閱的話題，之後，該類發佈，我需要在JSON消息格式。
下一課我用它來顯示通知。 最後，onCreate（）和onClick類聲明瞭我的按鈕，edittext ...以及在哪裏放置條件來發布消息。 更有意思的是，當按下按鈕時，我用JSON格式發佈消息。
該應用程序運行良好。但問題是： 如何在經紀人中只發布一條消息？
在下圖中，您可以看到按下按鈕時如何發佈5條消息。 In red you can see the message published 5 or 6 times
