https://blog.csdn.net/fjj2397194209?type=blog互三兄弟们

[_Return_My_Offer_]

https://blog.csdn.net/fjj2397194209?type=blog%E4%BA%92%E4%B8%89%E5%85%84%E5%BC%9F%E4%BB%AC

[小余努力变优秀]

您好本人在校大学生想用Android studio连接到阿里云上并获取数据以下代码没报错运行在app上是显示连接错误，麻烦您可以帮我看一下吗谢谢：
package com.example.smarthome;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.os.Bundle;
import android.os.Message;
import android.util.Log;
import android.view.MenuItem;
import android.os.Handler;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.google.android.material.navigation.NavigationBarView;

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.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

//mqtt

public class HomeActivity extends AppCompatActivity {
private MqttClient client;
private MqttConnectOptions options;
private Handler handler;
private ScheduledExecutorService scheduler;

private String productKey="k08o5pYygtP";
private String deviceName="mqtt_stm32";
private String deviceSecret="c698a4a26bbf16231e2134a3affd1342";

//MQTT发布的主题
private final String pub_topic= "/sys/k08o5pYygtP/app_dev/thing/event/property/post";
//MQTT订阅的主题
private final String sub_topic = "/sys/k08o5pYygtP/app_dev/thing/service/property/set";

private int temperature=0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);
    //TextView
    TextView tv_temp=findViewById(R.id.TV_temp);

    //home
    BottomNavigationView bottomNavigationView=(findViewById(R.id.button_navigation));
    bottomNavigationView.setSelectedItemId(R.id.home);
    bottomNavigationView.setOnItemSelectedListener(new NavigationBarView.OnItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem menuitem) {

            if (menuitem.getItemId()==R.id.about)
            {
                startActivity(new Intent(getApplicationContext(), AboutActivity2.class));
                overridePendingTransition(0,0);
                return true;
            }
            if(menuitem.getItemId()==R.id.home)
            {
                return  true;
            }

            return false;
        }
    });
    mqtt_init();
    start_reconnect();

//MQTT数据订阅

    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());
                    String message = msg.obj.toString();
                    Log.d("nicecode", "handleMessage: "+ message);
                    try {
                        JSONObject jsonObjectALL = null;
                        jsonObjectALL = new JSONObject(message);
                        JSONObject items = jsonObjectALL.getJSONObject("items");

                        JSONObject obj_temp = items.getJSONObject("temp");
                       // JSONObject obj_humi = items.getJSONObject("humi");

                        temperature = obj_temp.getInt("value");
                        //humidity = obj_humi.getInt("value");

                        tv_temp.setText(temperature + "");
                       // tv_humi.setText(humidity + "");
                        Log.d("nicecode", "temp: "+ temperature);
                       // Log.d("nicecode", "humi: "+ humidity);
                    } catch (JSONException e) {
                        e.printStackTrace();
                        break;
                    }
                    break;
                case 30:  //连接失败
                    Toast.makeText(HomeActivity.this, "连接失败", Toast.LENGTH_SHORT).show();
                    break;
                case 31:   //连接成功
                    Toast.makeText(HomeActivity.this, "连接成功", Toast.LENGTH_SHORT).show();
                    try {
                        client.subscribe(sub_topic, 1);
                    } catch (MqttException e) {
                        e.printStackTrace();
                    }
                    break;
                default:
                    break;
            }
        }
    };



}

//MQTT初始化
private void mqtt_init() {
try {

        String clientId = "k08o5pYygtP.mqtt_stm32";
        Map<String, String> params = new HashMap<String, String>(16);

        params.put("productKey", productKey);
        params.put("deviceName", deviceName);
        params.put("clientId", clientId);
        String timestamp = String.valueOf(System.currentTimeMillis());
        params.put("timestamp", timestamp);
        // cn-shanghai
        String host_url ="tcp://"+ productKey + ".iot-as-mqtt.cn-shanghai.aliyuncs.com:1883";
        String client_id = clientId + "|securemode=2,signmethod=hmacsha256,timestamp=" +timestamp+  "|";
        String user_name = deviceName + "&" + productKey;
        String password = com.example.smarthome.AliyunIoTSignUtil.sign(params, deviceSecret, "hmacsha1");

        //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
        System.out.println(">>>" + host_url);
        System.out.println(">>>" + client_id);

        //connectMqtt(targetServer, mqttclientId, mqttUsername, mqttPassword);

        client = new MqttClient(host_url, client_id, 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(user_name);
        //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(60);
        //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----------");
            }

            @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();
                //封装message包
                msg.what = 3;   //收到消息标志位
                msg.obj =message.toString();
                //发送messge到handler
                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;
                    // 没有用到obj字段
                    handler.sendMessage(msg);
                }
            } catch (Exception e) {
                e.printStackTrace();
                Message msg = new Message();
                msg.what = 30;
                // 没有用到obj字段
                handler.sendMessage(msg);
            }
        }
    }).start();
}




//MQTT的连接
private void start_reconnect() {
    scheduler = Executors.newSingleThreadScheduledExecutor();
    scheduler.scheduleAtFixedRate(new Runnable() {
        @Override
        public void run() {
            if (!client.isConnected()) {
                mqtt_connect();
            }
        }
    }, 0 * 1000, 10 * 1000, TimeUnit.MILLISECONDS);
}

}