接下来，我们继续实验示例代码中的Wifi"高级web服务器"，配置相关的无线密码后，开始实验
#include <WiFi.h>
#include <WiFiClient.h>
#include <WebServer.h>
#include <ESPmDNS.h>
const char *ssid = "XIAOFEIYU";
const char *password = "XIAOFEIU666";
WebServer server(80);
const int led = 13;
void handleRoot() {
digitalWrite(led, 1);
char temp[400];
int sec = millis() / 1000;
int min = sec / 60;
int hr = min / 60;
snprintf(temp, 400,
"<html>\
<head>\
<meta http-equiv='refresh' content='5'/>\
<title>ESP32 Demo</title>\
<style>\
body { background-color: #cccccc; font-family: Arial, Helvetica, Sans-Serif; Color: #000088; }\
</style>\
</head>\
<body>\
<h1>Hello from ESP32!</h1>\
<p>Uptime: %02d:%02d:%02d</p>\
<img src=\"/test.svg\" />\
</body>\
</html>",
hr, min % 60, sec % 60
);
server.send(200, "text/html", temp);
digitalWrite(led, 0);
}
void handleNotFound() {
digitalWrite(led, 1);
String message = "File Not Found\n\n";
message += "URI: ";
message += server.uri();
message += "\nMethod: ";
message += (server.method() == HTTP_GET) ? "GET" : "POST";
message += "\nArguments: ";
message += server.args();
message += "\n";
for (uint8_t i = 0; i < server.args(); i++) {
message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
}
server.send(404, "text/plain", message);
digitalWrite(led, 0);
}
void setup(void) {
pinMode(led, OUTPUT);
digitalWrite(led, 0);
Serial.begin(9600);
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());
if (MDNS.begin("esp32")) {
Serial.println("MDNS responder started");
}
server.on("/", handleRoot);
server.on("/test.svg", drawGraph);
server.on("/inline", []() {
server.send(200, "text/plain", "this works as well");
});
server.onNotFound(handleNotFound);
server.begin();
Serial.println("HTTP server started");
}
void loop(void) {
server.handleClient();
delay(2);
}
void drawGraph() {
String out = "";
char temp[100];
out += "<svg xmlns=\"http://www.w3.org/2000/svg\" version=\"1.1\" width=\"400\" height=\"150\">\n";
out += "<rect width=\"400\" height=\"150\" fill=\"rgb(250, 230, 210)\" stroke-width=\"1\" stroke=\"rgb(0, 0, 0)\" />\n";
out += "<g stroke=\"black\">\n";
int y = rand() % 130;
for (int x = 10; x < 390; x += 10) {
int y2 = rand() % 130;
sprintf(temp, "<line x1=\"%d\" y1=\"%d\" x2=\"%d\" y2=\"%d\" stroke-width=\"1\" />\n", x, 140 - y, x + 10, 140 - y2);
out += temp;
y = y2;
}
out += "</g>\n</svg>\n";
server.send(200, "image/svg+xml", out);
}
从串口监视器查看获取的ip地址，使用浏览器打开这个服务器，可以看到下面的图形会定时更新切换。
这个例子给了我们一个可以生成实时图表的思路，使用硬件获取数据后可以直接以web图形的形式进行输出，直接作为服务器使用，这样的系统更为稳定，不用单独再配置计算机来进行数据的展示。