(四）esp8266 MDNS域名服务

（实例一）ESP8266 TFT(ST7735)彩屏-web刷图

https://www.arduino.cn/thread-42247-1-1.html

（实例二）自己当AP时建立MDNS域名

https://github.com/esp8266/Arduino/blob/master/libraries/ESP8266mDNS/examples/mDNS_Web_Server/mDNS_Web_Server.ino

/*
  ESP8266 mDNS responder sample
  This is an example of an HTTP server that is accessible
  via http://esp8266.local URL thanks to mDNS responder.
  Instructions:
  - Update WiFi SSID and password as necessary.
  - Flash the sketch to the ESP8266 board
  - Install host software:
    - For Linux, install Avahi (http://avahi.org/).
    - For Windows, install Bonjour (http://www.apple.com/support/bonjour/).
    - For Mac OSX and iOS support is built in through Bonjour already.
  - Point your browser to http://esp8266.local, you should see a response.
*/


#include <ESP8266WiFi.h>
#include <ESP8266mDNS.h>
#include <WiFiClient.h>

#ifndef STASSID
#define STASSID "your-ssid"
#define STAPSK  "your-password"
#endif

const char* ssid = STASSID;
const char* password = STAPSK;

// TCP server at port 80 will respond to HTTP requests
WiFiServer server(80);

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

  // Connect to WiFi network
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  Serial.println("");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  // Set up mDNS responder:
  // - first argument is the domain name, in this example
  //   the fully-qualified domain name is "esp8266.local"
  // - second argument is the IP address to advertise
  //   we send our IP address on the WiFi network
  if (!MDNS.begin("esp8266")) {
    Serial.println("Error setting up MDNS responder!");
    while (1) {
      delay(1000);
    }
  }
  Serial.println("mDNS responder started");

  // Start TCP (HTTP) server
  server.begin();
  Serial.println("TCP server started");

  // Add service to MDNS-SD
  MDNS.addService("http", "tcp", 80);
}

void loop(void) {

  MDNS.update();

  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }
  Serial.println("");
  Serial.println("New client");

  // Wait for data from client to become available
  while (client.connected() && !client.available()) {
    delay(1);
  }

  // Read the first line of HTTP request
  String req = client.readStringUntil('
');

  // First line of HTTP request looks like "GET /path HTTP/1.1"
  // Retrieve the "/path" part by finding the spaces
  int addr_start = req.indexOf(' ');
  int addr_end = req.indexOf(' ', addr_start + 1);
  if (addr_start == -1 || addr_end == -1) {
    Serial.print("Invalid request: ");
    Serial.println(req);
    return;
  }
  req = req.substring(addr_start + 1, addr_end);
  Serial.print("Request: ");
  Serial.println(req);
  client.flush();

  String s;
  if (req == "/") {
    IPAddress ip = WiFi.localIP();
    String ipStr = String(ip[0]) + '.' + String(ip[1]) + '.' + String(ip[2]) + '.' + String(ip[3]);
    s = "HTTP/1.1 200 OK
Content-Type: text/html

<!DOCTYPE HTML>
<html>Hello from ESP8266 at ";
    s += ipStr;
    s += "</html>

";
    Serial.println("Sending 200");
  } else {
    s = "HTTP/1.1 404 Not Found

";
    Serial.println("Sending 404");
  }
  client.print(s);

  Serial.println("Done with client");
}

　　（实例三）自己STA连WIFI

在代码中，我们将包含一个额外的库

# include <ESP8266mDNS.h>

在该库中，我们现在可以访问一个名为 MDNS 响应器的类，我们将使用它来声明一个对象。

MDNSResponder mdns;

　使用此对象，我们可以使用 begin方法创建我们将使用的 Web地址，并将其命名为“esp-01”。此方法需要的第二个参数是我们可以使用Wi-Fi对象的本地IP方法使用的Esp8266的IP地址。

mdns.begin（“esp-01”，Wifi.localIP（））;

添加一个条件语句，当它评估为true时，它会向用户打印一条消息，说 “M DNS 响应者已启动！”。

最后，使用MDNS 内置对象调用Add service 方法

MDNS.addService（ “HTTP”， “TCP”， “80”）;

　　这需要三个参数。牛逼HESE参数描述的类型，我们要在广播服务网络。在这种情况下，我们将在80上使用HTTP over TCP。

#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>

ESP8266WebServer server;

char* ssid = "YOUR_SSID";
char* password = "YOUR_PASSWORD";

MDNSResponder mdns;


void setup()
{
 WiFi.begin(ssid,password);
 Serial.begin(115200);
 while(WiFi.status()!=WL_CONNECTED)
 {
 Serial.print(".");
 delay(500);
 }
 Serial.println("");
 Serial.print("IP Address: ");
 Serial.println(WiFi.localIP());

if (mdns.begin("esp8266-01", WiFi.localIP()))
Serial.println("MDNS responder started");

server.on("/",[](){server.send(200,"text/plain","Hello World!");});
server.begin();

MDNS.addService("http", "tcp", 80);}


void loop()
{
server.handleClient();
}