File content as of revision 97:d87239079f29:

/* WiFi Example
 * Copyright (c) 2016 ARM Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "mbed.h"
#include "MQTTNetwork.h"    
#include "MQTTmbed.h"
#include "MQTTClient.h"
#include "ESP8266Interface.h"

const char* hostname = "172.20.16.92"; //修改服务器IP及端口号
int port = 1883;


WiFiInterface *wifi;

const char *sec2str(nsapi_security_t sec)
{
    switch (sec) {
        case NSAPI_SECURITY_NONE:
            return "None";
        case NSAPI_SECURITY_WEP:
            return "WEP";
        case NSAPI_SECURITY_WPA:
            return "WPA";
        case NSAPI_SECURITY_WPA2:
            return "WPA2";
        case NSAPI_SECURITY_WPA_WPA2:
            return "WPA/WPA2";
        case NSAPI_SECURITY_UNKNOWN:
        default:
            return "Unknown";
    }
}

int scan_demo(WiFiInterface *wifi)
{
    WiFiAccessPoint *ap;

    printf("Scan:\n");

    int count = wifi->scan(NULL,0);

    if (count <= 0) {
        printf("scan() failed with return value: %d\n", count);
        return 0;
    }

    /* Limit number of network arbitrary to 15 */
    count = count < 15 ? count : 15;

    ap = new WiFiAccessPoint[count];
    count = wifi->scan(ap, count);

    if (count <= 0) {
        printf("scan() failed with return value: %d\n", count);
        return 0;
    }

    for (int i = 0; i < count; i++) {
        printf("Network: %s secured: %s BSSID: %hhX:%hhX:%hhX:%hhx:%hhx:%hhx RSSI: %hhd Ch: %hhd\n", ap[i].get_ssid(),
               sec2str(ap[i].get_security()), ap[i].get_bssid()[0], ap[i].get_bssid()[1], ap[i].get_bssid()[2],
               ap[i].get_bssid()[3], ap[i].get_bssid()[4], ap[i].get_bssid()[5], ap[i].get_rssi(), ap[i].get_channel());
    }
    printf("%d networks available.\n", count);

    delete[] ap;
    return count;
}

int main()
{
    printf("WiFi example\n");

#ifdef MBED_MAJOR_VERSION
    printf("Mbed OS version %d.%d.%d\n\n", MBED_MAJOR_VERSION, MBED_MINOR_VERSION, MBED_PATCH_VERSION);
#endif

    wifi = WiFiInterface::get_default_instance();
    if (!wifi) {
        printf("ERROR: No WiFiInterface found.\n");
        return -1;
    }

    int count = scan_demo(wifi);
    if (count == 0) {
        printf("No WIFI APs found - can't continue further.\n");
        return -1;
    }

    printf("\nConnecting to %s...\n", MBED_CONF_APP_WIFI_SSID);
    int ret = wifi->connect("OPPO_R11s", "12345678", NSAPI_SECURITY_WPA_WPA2);
    if (ret != 0) {
        printf("\nConnection error: %d\n", ret);
        return -1;
    }

    printf("Success\n\n");
    printf("MAC: %s\n", wifi->get_mac_address());
    printf("IP: %s\n", wifi->get_ip_address());
    printf("Netmask: %s\n", wifi->get_netmask());
    printf("Gateway: %s\n", wifi->get_gateway());
    printf("RSSI: %d\n\n", wifi->get_rssi());

    wifi->disconnect();

    printf("\nDone\n");
     MQTTNetwork mqttNetwork(network);
MQTT::Client<MQTTNetwork, Countdown> client(mqttNetwork);

int rc = mqttNetwork.connect(hostname, port);

    MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
    data.MQTTVersion = 3;
    data.clientID.cstring = "mbed-sample";
    data.username.cstring = "testuser";
    data.password.cstring = "testpassword";
    if ((rc = client.connect(data)) != 0)
        printf("rc from MQTT connect is %d\r\n", rc);
        
if ((rc = client.subscribe(“sensor”, MQTT::QOS2, messageArrived)) != 0) //订阅消息
        printf("rc from MQTT subscribe is %d\r\n", rc);
while(true){
    client.yield(100);  //在循环中一直等待接收消息
}
void messageArrived(MQTT::MessageData& md)  //消息接收回调函数
{
    MQTT::Message &message = md.message;
    if(((char*)message.payload)[0] == '0')  //解析服务器消息
    {
        led = 0;                //处理消息开关灯，可在此修改为其他控制指令
    }
    else
{   
led = 1;
    }
}
}