在ESP8266上，可以使用基于Websocket的MQTT和直接MQTT两种方式进行通信。下面是包含代码示例的解决方法。

1. 使用基于Websocket的MQTT： 首先，需要安装PubSubClient库。在Arduino IDE中，选择“工具”->“管理库”，搜索“PubSubClient”并安装。

示例代码如下：

#include 
#include 
#include 

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
const char* mqttServer = "your_MQTT_SERVER";
const int mqttPort = 1883;
const char* mqttUser = "your_MQTT_USER";
const char* mqttPassword = "your_MQTT_PASSWORD";

WiFiClient wifiClient;
WebSocketsClient webSocket;
PubSubClient mqttClient(wifiClient);

void setup() {
  Serial.begin(115200);

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }

  webSocket.begin(mqttServer, mqttPort, "/mqtt");
  webSocket.setAuthorization(mqttUser, mqttPassword);

  mqttClient.setServer(mqttServer, mqttPort);
  mqttClient.setCallback(callback);

  while (!mqttClient.connected()) {
    if (mqttClient.connect("ESP8266Client", mqttUser, mqttPassword)) {
      Serial.println("Connected to MQTT server");
      mqttClient.subscribe("topic");
    } else {
      Serial.print("Failed to connect to MQTT server, rc=");
      Serial.print(mqttClient.state());
      delay(2000);
    }
  }
}

void loop() {
  webSocket.loop();
  mqttClient.loop();
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Received message: ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}

2. 使用直接MQTT： 同样需要安装PubSubClient库。

示例代码如下：

#include 
#include 

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
const char* mqttServer = "your_MQTT_SERVER";
const int mqttPort = 1883;
const char* mqttUser = "your_MQTT_USER";
const char* mqttPassword = "your_MQTT_PASSWORD";

WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);

void setup() {
  Serial.begin(115200);

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }

  mqttClient.setServer(mqttServer, mqttPort);
  mqttClient.setCallback(callback);

  while (!mqttClient.connected()) {
    if (mqttClient.connect("ESP8266Client", mqttUser, mqttPassword)) {
      Serial.println("Connected to MQTT server");
      mqttClient.subscribe("topic");
    } else {
      Serial.print("Failed to connect to MQTT server, rc=");
      Serial.print(mqttClient.state());
      delay(2000);
    }
  }
}

void loop() {
  mqttClient.loop();
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Received message: ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}

注意：以上示例中的代码仅包含连接到MQTT服务器和订阅主题的部分，你可以根据自己的需求，添加其他功能和逻辑。另外，需要替换示例代码中的"your_SSID"、"your_PASSWORD"等参数为你自己的网络和MQTT服务器信息。