Espressif Systems ESP8266 Beginner's Manual page 27

display it as text instead of interpreting it as HTML and showing it as a button.
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WiFiMulti.h>
#include <ESP8266mDNS.h>
#include <ESP8266WebServer.h>
ESP8266WiFiMulti wifiMulti; // Create an instance of the ESP8266WiFiMulti class, called 'wifiMulti'
ESP8266WebServer server(80); // Create a webserver object that listens for HTTP request on port 80
const int led = 2;
void handleRoot(); // function prototypes for HTTP handlers
void handleLED();
void handleNotFound();
void setup(void){
Serial.begin(115200); // Start the Serial communication to send messages to the computer
delay(10);
Serial.println('\n');
pinMode(led, OUTPUT);
wifiMulti.addAP("ssid_from_AP_1", "your_password_for_AP_1"); // add Wi-Fi networks you want to connect to
wifiMulti.addAP("ssid_from_AP_2", "your_password_for_AP_2");
wifiMulti.addAP("ssid_from_AP_3", "your_password_for_AP_3");
Serial.println("Connecting ...");
int i = 0;
while (wifiMulti.run() != WL_CONNECTED) { // Wait for the Wi-Fi to connect: scan for Wi-Fi networks, and connect to the strongest of
the networks above
delay(250);
Serial.print('.');
}
Serial.println('\n');
Serial.print("Connected to ");
Serial.println(WiFi.SSID()); // Tell us what network we're connected to
Serial.print("IP address:\t");
Serial.println(WiFi.localIP()); // Send the IP address of the ESP8266 to the computer
if (MDNS.begin("esp8266")) { // Start the mDNS responder for esp8266.local
Serial.println("mDNS responder started");
} else {
Serial.println("Error setting up MDNS responder!");
}
server.on("/", HTTP_GET, handleRoot); // Call the 'handleRoot' function when a client requests URI "/"
server.on("/LED", HTTP_POST, handleLED); // Call the 'handleLED' function when a POST request is made to URI "/LED"
server.onNotFound(handleNotFound); // When a client requests an unknown URI (i.e. something other than "/"), call function
"handleNotFound"
server.begin(); // Actually start the server
Serial.println("HTTP server started");
}
void loop(void){
server.handleClient(); // Listen for HTTP requests from clients
}
void handleRoot() { // When URI / is requested, send a web page with a button to toggle the LED
server.send(200, "text/html", "<form action=\"/LED\" method=\"POST\"><input type=\"submit\" value=\"Toggle LED\"></form>");
}
void handleLED() { // If a POST request is made to URI /LED
digitalWrite(led,!digitalRead(led)); // Change the state of the LED
server.sendHeader("Location","/"); // Add a header to respond with a new location for the browser to go to the home page again
server.send(303); // Send it back to the browser with an HTTP status 303 (See Other) to redirect
}
void handleNotFound(){
server.send(404, "text/plain", "404: Not found"); // Send HTTP status 404 (Not Found) when there's no handler for the URI in the
request
}
As you can see, the
server.on
execute.
Connect an LED to GPIO2, and upload the sketch. Then go to http://esp8266.local/ and click the button to turn the LED on or off.
You can open the developer options in Chrome (F12) to check the HTTP request that are made when you click the button: you'll see
that it first send a POST request, and then receives a 303 (See Other) HTTP status as a response. The response also has a Location
header containing the URI "/", so the browser will send a GET request to the URI of this new location:
function now takes three parameters: the URI, the request method (GET or POST) and the function to