目标需求
利用esp32的WebServer功能，展示一个网页，对里面的参数进行配置，并以json文本格式保存到flash里面。
1、定义HTML
const char index_html[] PROGMEM = R"rawliteral(
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no"><title>采集器配置</title><link rel="stylesheet" href="http://www.kanzz.net/res/eve.css">
</head>
<body>
<form id="config-form" autocomplete="off"><div class="form-item"><label for="versioin">软件版本:</label><input type="text" id="versioin" name="versioin" value="%VERSION%" value="1.0"></div><div class="form-item"><label for="sn">编号:</label><input type="text" id="sn" name="sn" value="%SN%" required></div><div class="form-item"><label for="ip">IP 地址：</label><input type="text" id="ip" name="ip" value="%MYIP%" required></div><div class="form-item"><label for="mask">子网掩码：</label><input type="text" id="mask" name="mask" value="%MYMASK%" required></div><div class="form-item"><label for="gateway">网关：</label><input type="text" id="gateway" name="gateway" value="%GATEWAY%" required></div><div class="form-item"><label for="ssid">WiFi SSID:</label><input type="text" id="ssid" name="ssid" value="%SSID%" required></div><div class="form-item"><label for="wifipwd">WiFi Password:</label><input type="text" id="wifipwd" name="wifipwd" value="%WIFIPWD%"></div><div class="form-item"><label for="waittime">拉取时间(秒):</label><input type="text" id="waittime" name="waittime" value="%WAITTIME%"></div><div class="form-item"><label for="apiurl">推送接⼝:</label><input type="text" id="apiurl" name="apiurl" value="%APIURL%"></div><div class="form-item"><label for="appid">AppID:</label><input type="text" id="appid" name="appid" value="%APPID%"></div><div class="form-item"><label for="secret">Secret:</label><input type="text" id="secret" name="secret" value="%SECRET%"></div><div class="form-item"><button type="submit">保存配置</button></div></form>
</body>
</html>
)rawliteral";const char info_html[] PROGMEM = R"rawliteral(<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no"><title>采集器配置</title><link rel="stylesheet" href="http://www.kanzz.net/res/eve.css"></head><body><div style="margin:100px auto;width:400px;"><div style="color: #060;font-size: 16px;line-height: 30px;margin: 20px 0;">修改完成!</div><div class="button"><button id="back" style="width: 160px;height: 40px;line-height: 30px;border: 1px solid #999;color: #fff;background-color: #5cd6b2;border: none;border-radius: 4px;box-shadow: 4px 4px 4px #999;cursor: pointer;">返回</button></div></div><script> document.getElementById('back').addEventListener('click', function(event) {location.href = '/';})</script></body></html>
)rawliteral";其中定义了一些变量，展示页面的时候会用变量来替代，如：
<div class="form-item"><label for="ssid">WiFi SSID:</label><input type="text" id="ssid" name="ssid" value="%SSID%" required>
</div>代码中的 value="%SSID%"
2、安装ESPAsyncWebServer
3、定义JSON字符串
String jsonStr = "{\"version\": \"1.1\", \"sn\":\"2021\", \"mask\":\"255.255.255.0\", \"gateway\":\"192.168.0.1\", \"waittime\":\"0.5\", \"apiurl\":\"https://\", \"appid\":\"appid12345\", \"secret\":\"secret\"}";4、读取Flash中的JSON文件
String readJsonFile()
{File configFile = SPIFFS.open("/config.json", FILE_READ);if (!configFile) {Serial.println("Failed to open config file");return "";}if(configFile.available()){String line = configFile.readString();configFile.close();return line;}
}5、保存JSON文件到Flash中
void saveJsonFile()
{File configFile = SPIFFS.open("/config.json", "w");if (!configFile) {Serial.println("Failed to open config file for writing");return;}configFile.println(jsonStr);configFile.close();Serial.println("Config file saved");
}6、处理HTML模板中的变量
String processor(const String& var)
{jsonConfig config = transTojson();if (var == "VERSION"){return config.version;}if (var == "SN"){return config.sn;}if (var == "MYIP"){return ip;}if (var == "MYMASK"){return config.mask;}if (var == "GATEWAY"){return config.gateway;}if (var == "SSID"){return ssid;}if (var == "WIFIPWD"){return password;}if (var == "WAITTIME"){return config.waittime;}if (var == "APIURL"){return config.apiurl;}if (var == "APPID"){return config.appid;}if (var == "SECRET"){return config.secret;}return String();
}7、WebServer的监听
server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){request->send_P(200, "text/html", index_html, processor);});server.on("/save", HTTP_POST, [](AsyncWebServerRequest *request){String version, sn, mask, gateway, waittime, apiurl, appid, secret;if (request->hasParam("version", true)) {version = request->getParam("version", true)->value();} else {version = "-";}if (request->hasParam("sn", true)) {sn = request->getParam("sn", true)->value();} else {sn = "-";}if (request->hasParam("mask", true)) {mask = request->getParam("mask", true)->value();} else {mask = "-";}if (request->hasParam("gateway", true)) {gateway = request->getParam("gateway", true)->value();} else {gateway = "-";}if (request->hasParam("waittime", true)) {waittime = request->getParam("waittime", true)->value();} else {waittime = "-";}if (request->hasParam("apiurl", true)) {apiurl = request->getParam("apiurl", true)->value();} else {apiurl = "-";}if (request->hasParam("appid", true)) {appid = request->getParam("appid", true)->value();} else {appid = "-";}if (request->hasParam("secret", true)) {secret = request->getParam("secret", true)->value();} else {secret = "-";}jsonStr = "{\"version\": \"" + version + "\", \"sn\":\"" + sn + "\", \"mask\":\"" + mask + "\", \"gateway\":\"" + gateway + "\", \"waittime\":\"" + waittime + "\", \"apiurl\":\"" + apiurl + "\", \"appid\":\"" + appid + "\", \"secret\":\"" + secret + "\"}";saveJsonFile();delay(100);request->send_P(200, "text/html", info_html);});根据逻辑整合起来后，测试成功！
