我的个人网站 http://www.cheese.ren/
博客来源 http://www.cheese.ren/blog/blog/334
欢迎交换友链 :-)
最近查看了一下阿里云物联网平台的文档，发现使用mqtt的连接方法并没有写的很清楚，就来稍微归纳一下
相关网站
MQTT：https://mqtt.org/ （物联网消息传递标准）
Eventbus：https://github.com/greenrobot/EventBus （Android和Java的发布/订阅事件总线）
在build.gradle中添加下列依赖
//MQTT
implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.1.0'
implementation 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'
//Eventbus
implementation 'org.greenrobot:eventbus:3.0.0'
implementation 'org.greenrobot:eventbus:3.1.1'重新Make Project一下即可
创建IoT.java
package com.example.fackunlocking;
import android.content.Context;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.MqttTopic;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
import org.greenrobot.eventbus.EventBus;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
public class IoT {
private String productKey, deviceName, deviceSecret, regionId, topic; //基础配置
private MqttClient mqttClient;
public IoT(String productKey, String deviceName, String deviceSecret, String regionId) {
this.productKey = productKey;
this.deviceName = deviceName;
this.deviceSecret = deviceSecret;
this.regionId = regionId; //这里设置的是物联网平台的区域，例如“华东2（上海）”的值为“cn-shanghai”，具体地区对应的值请查看阿里云的文档
topic = "/" + productKey + "/" + deviceName;
}
//连接
public boolean connect() {
try {
//配置 服务器地址 客户端id 用户名 密码
String clientId = "java" + System.currentTimeMillis();
String timestamp = String.valueOf(System.currentTimeMillis());
Map<String, String> params = new HashMap<>(16);
params.put("productKey", productKey);
params.put("deviceName", deviceName);
params.put("clientId", clientId);
params.put("timestamp", timestamp);
String targetServer = "tcp://" + productKey + ".iot-as-mqtt." + regionId + ".aliyuncs.com:1883";
String mqttClientId = clientId + "|securemode=3,signmethod=hmacsha1,timestamp=" + timestamp + "|";
String mqttUsername = deviceName + "&" + productKey;
String mqttPassword = sign(params, deviceSecret, "hmacsha1"); //获取密码
//使用MQTT进行连接
MemoryPersistence persistence = new MemoryPersistence();
mqttClient = new MqttClient(targetServer, mqttClientId, persistence);
MqttConnectOptions connectOptions = new MqttConnectOptions();
connectOptions.setMqttVersion(4);
connectOptions.setCleanSession(false);
connectOptions.setAutomaticReconnect(false);
connectOptions.setUserName(mqttUsername);
connectOptions.setPassword(mqttPassword.toCharArray());
connectOptions.setKeepAliveInterval(60);
mqttClient.connect(connectOptions);
}
catch (Exception e) {
e.printStackTrace();
return false;
}
return true;
}
//发布 topic是要发布的topic地址，只需补全剩下的地址即可 payload或许有一定的格式，可以在类中定义格式，本例子偷懒不写了=W=
public boolean publish(String topic, String payload) {
try {
MqttMessage message = new MqttMessage(payload.getBytes("utf-8"));
/*
这里出现了Qos，稍微科普一下，后面就不再重复了
参数0代表Sender发送的一条消息，Receiver最多能收到一次，也就是说Sender尽力向Receiver发送消息，如果发送失败，也就算了
参数1代表Sender发送的一条消息，Receiver至少能收到一次，也就是说Sender向Receiver发送消息，如果发送失败，会继续重试，直到Receiver收到消息为止，但是因为重传的原因，Receiver有可能会收到重复的消息
参数2代表Sender发送的一条消息，Receiver确保能收到而且只收到一次，也就是说Sender尽力向Receiver发送消息，如果发送失败，会继续重试，直到Receiver收到消息为止，同时保证Receiver不会因为消息重传而收到重复的消息
*/
message.setQos(1);
mqttClient.publish(topic, message);
}
catch (Exception e) {
e.printStackTrace();
return false;
}
return true;
}
//订阅
public boolean listen(Context context, String topic) {
try {
//注册广播
EventBus.getDefault().register(this.connect());
mqttClient.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {
}
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
String str = new String(message.getPayload());
EventBus.getDefault().post(new MessageEvent(str));
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
}
});
MqttTopic mqttTopic = mqttClient.getTopic(topic);
mqttClient.subscribe(topic, 1);
}
catch (Exception e) {
e.printStackTrace();
return false;
}
return true;
}
//关闭连接
public boolean close(Context context) {
try {
EventBus.getDefault().unregister(context);//注销广播
mqttClient.disconnect();
}
catch (Exception e) {
e.printStackTrace();
return false;
}
return true;
}
private String sign(Map<String, String> params, String deviceSecret, String signMethod) {
String[] sortedKeys = params.keySet().toArray(new String[]{});
Arrays.sort(sortedKeys);
StringBuilder canonicalizedQueryString = new StringBuilder();
for (String key : sortedKeys) {
if ("sign".equalsIgnoreCase(key)) {
continue;
}
canonicalizedQueryString.append(key).append(params.get(key));
}
try {
String key = deviceSecret;
return encryptHMAC(signMethod, canonicalizedQueryString.toString(), key);
}
catch (Exception e) {
throw new RuntimeException(e);
}
}
private String encryptHMAC(String signMethod, String content, String key) throws Exception {
SecretKey secretKey = new SecretKeySpec(key.getBytes("utf-8"), signMethod);
Mac mac = Mac.getInstance(secretKey.getAlgorithm());
mac.init(secretKey);
byte[] data = mac.doFinal(content.getBytes("utf-8"));
return bytesToHexString(data);
}
private String bytesToHexString(byte[] bArray) {
StringBuffer sb = new StringBuffer(bArray.length);
String sTemp;
for (int i=0; i<bArray.length; i++) {
sTemp = Integer.toHexString(0xFF & bArray[i]);
if (sTemp.length() < 2) {
sb.append(0);
}
sb.append(sTemp.toUpperCase());
}
return sb.toString();
}
}发布消息的步骤
IoT iot = new IoT("productKey", "deviceName", "deviceSecret", "regionId")
iot.connect();
iot.publish("topic", "payload");
//用完请关掉！养成良好习惯！
//iot.close(Activity.this);订阅消息的步骤
IoT iot = new IoT("productKey", "deviceName", "deviceSecret", "regionId")
iot.connect();
//订阅的方法
@RequiresApi(api = Build.VERSION_CODES.M)
@Subscribe(threadMode = ThreadMode.MAIN)
public void listenWay(MessageEvent messageEvent) {
System.out.println(messageEvent.getMessage());
}
iot.listen(Activity.this, "topic");
//用完请关掉！养成良好习惯！
//iot.close(Activity.this);当消息赶来时就会调用listenWay这个方法，很方便！
这样一个连接阿里云物联网平台的类就封装完成啦！或许有些地方不太准确，但大致意思是没错了的，更多的使用方法可以自行探索。
