在本教程中，您将学习如何使用带有 Arduino IDE 的 ESP8266 NodeMCU 板发出 HTTP GET 和 HTTP POST 请求。我们将介绍有关如何获取值、发布 JSON 对象、URL 编码请求等的示例。
推荐：ESP32 HTTP GET 和 HTTP POST，带 Arduino IDE（JSON、URL 编码、文本）
目录
HTTP 请求方法：GET 与 POST
超文本传输协议 （HTTP） 用作客户端和服务器之间的请求-响应协议。下面是一个示例：
- ESP8266（客户端）向运行 Node-RED（服务器）的 Raspberry Pi 提交 HTTP 请求;
- 服务器向ESP8266（客户端）返回响应;
- 最后，响应包含有关请求的状态信息，也可能包含请求的内容。
HTTP 获取
GET 用于从指定资源请求数据。它通常用于从 API 获取值。
例如，您可以拥有：
GET /update-sensor?temperature=value1请注意，查询字符串（name = temperature 和 value = value1）在 HTTP GET 请求的 URL 中发送。
或者，您可以使用简单的请求来返回值或 JSON 对象，例如：
GET /get-sensor（使用 HTTP GET，数据对 URL 请求中的每个人都可见。
HTTP POST
POST 用于将数据发送到服务器以创建/更新资源。例如，将传感器读数发布到服务器。
使用 POST 发送到服务器的数据存储在 HTTP 请求的请求正文中：
POST /update-sensor HTTP/1.1
Host: example.com
api_key=api&sensor_name=name&temperature=value1&humidity=value2&pressure=value3
Content-Type: application/x-www-form-urlencoded在正文请求中，还可以发送 JSON 对象：
POST /update-sensor HTTP/1.1
Host: example.com
{api_key: "api", sensor_name: "name", temperature: value1, humidity: value2, pressure: value3}
Content-Type: application/json（使用 HTTP POST 时，数据在 URL 请求中不可见。但是，如果它未加密，它仍然在请求正文中可见。
带有ESP8266的 HTTP GET/POST
在本教程中，我们将探讨以下方案：
- ESP8266 HTTP GET：URL 中的值或查询
- ESP8266 HTTP GET：JSON 数据对象或纯文本
- ESP8266 HTTP POST：URL 编码、JSON 数据对象、纯文本
先决条件
在继续学习本教程之前，请确保完成以下先决条件。
Arduino集成开发环境
我们将使用 Arduino IDE 对 ESP8266 NodeMCU 板进行编程，因此请确保您已安装 ESP8266 插件。
Arduino_JSON库
您还需要安装 Arduino_JSON 库。您可以在 Arduino IDE 库管理器中安装此库。只需转到“程序”>“包含库”>“管理库”，然后搜索库名称，如下所示：
所需零件
在本教程中，您需要以下部分：
- ESP8266
- Raspberry Pi 板
- MicroSD 卡 – 16GB Class10
- Raspberry Pi 电源 （5V 2.5A）
- 连接线
- 面包板
准备 Node-RED（可选）
例如，我们将使用 Raspberry Pi 和 Node-RED 创建一个 Web 服务，以充当 Web 服务（如 API）。基本上，您将向 Raspberry Pi 发出 HTTP GET 和 HTTP POST 请求以获取值或更新它们。您可以使用任何其他 Web 服务。
如果您尚未安装 Node-RED，请按照以下教程操作：
- Raspberry Pi 上的 Node-RED 入门
- Node-RED Dashboard 的安装和入门
在 Raspberry Pi 上运行 Node-RED，转到 Raspberry Pi IP 地址，然后转到 ：1880。
http://raspberry-pi-ip-address:1880Node-RED 接口应打开。您可以简单地导入最终流程：
转到“导入”>菜单，并将以下内容复制到剪贴板以创建 Node-RED 流程。
[{"id":"599740b7.efde9","type":"http response","z":"b01416d3.f69f38","name":"","statusCode":"200","headers":{},"x":420,"y":689,"wires":[]},{"id":"1618a829.76f638","type":"json","z":"b01416d3.f69f38","name":"","property":"payload","action":"obj","pretty":true,"x":410,"y":809,"wires":[["d0089cc7.d25ac"]]},{"id":"c7410fa2.1c2fa","type":"debug","z":"b01416d3.f69f38","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":850,"y":709,"wires":[]},{"id":"75a22f74.f1aba","type":"ui_text","z":"b01416d3.f69f38","group":"2b7ac01b.fc984","order":1,"width":0,"height":0,"name":"","label":"Sensor Name","format":"msg.payload","layout":"row-spread","x":860,"y":769,"wires":[]},{"id":"1c8f9093.8bc2bf","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"2b7ac01b.fc984","order":2,"width":0,"height":0,"gtype":"gage","title":"Temperature","label":"ºC","format":"value","min":0,"max":"38","colors":["#00b500","#e6e600","#ca3838"],"seg1":"","seg2":"","x":850,"y":829,"wires":[]},{"id":"a5bd2706.54e108","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"2b7ac01b.fc984","order":3,"width":0,"height":0,"gtype":"gage","title":"Humidity","label":"%","format":"value","min":0,"max":"100","colors":["#0080ff","#0062c4","#002f5e"],"seg1":"","seg2":"","x":840,"y":889,"wires":[]},{"id":"105ac2cc.7b3cfd","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"2b7ac01b.fc984","order":4,"width":0,"height":0,"gtype":"gage","title":"Pressure","label":"hPa","format":"value","min":0,"max":"1200","colors":["#b366ff","#8000ff","#440088"],"seg1":"","seg2":"","x":840,"y":949,"wires":[]},{"id":"d0089cc7.d25ac","type":"function","z":"b01416d3.f69f38","name":"JSON or URL Encoded","func":"var msg0 = { payload: msg.payload.api_key };nvar msg1 = { payload: msg.payload.sensor };nvar msg2 = { payload: msg.payload.value1 };nvar msg3 = { payload: msg.payload.value2 };nvar msg4 = { payload: msg.payload.value3 };nnreturn [msg0, msg1, msg2, msg3, msg4];","outputs":5,"noerr":0,"x":610,"y":809,"wires":[["c7410fa2.1c2fa"],["75a22f74.f1aba"],["1c8f9093.8bc2bf"],["a5bd2706.54e108"],["105ac2cc.7b3cfd"]]},{"id":"5d9ab0d2.66b92","type":"http in","z":"b01416d3.f69f38","name":"","url":"update-sensor","method":"post","upload":false,"swaggerDoc":"","x":200,"y":740,"wires":[["599740b7.efde9","c7410fa2.1c2fa","1618a829.76f638"]]},{"id":"7f5cf345.63f56c","type":"http response","z":"b01416d3.f69f38","name":"","statusCode":"200","headers":{},"x":540,"y":420,"wires":[]},{"id":"6530621.95b429c","type":"http in","z":"b01416d3.f69f38","name":"","url":"/get-sensor","method":"get","upload":false,"swaggerDoc":"","x":180,"y":600,"wires":[["9471d1a0.68588"]]},{"id":"5ddc9f47.4b555","type":"http response","z":"b01416d3.f69f38","name":"","statusCode":"200","headers":{},"x":540,"y":560,"wires":[]},{"id":"9471d1a0.68588","type":"function","z":"b01416d3.f69f38","name":"","func":"msg.payload = {"value1":24.25, "value2":49.54, "value3":1005.14};nreturn msg;","outputs":1,"noerr":0,"x":350,"y":600,"wires":[["5ddc9f47.4b555","13aea59.7430e5a"]]},{"id":"13aea59.7430e5a","type":"debug","z":"b01416d3.f69f38","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":550,"y":628,"wires":[]},{"id":"e71c7a7d.e7c598","type":"debug","z":"b01416d3.f69f38","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":550,"y":500,"wires":[]},{"id":"c7807102.3f433","type":"http in","z":"b01416d3.f69f38","name":"","url":"/update-sensor","method":"get","upload":false,"swaggerDoc":"","x":190,"y":460,"wires":[["60410cde.562a34"]]},{"id":"60410cde.562a34","type":"function","z":"b01416d3.f69f38","name":"","func":"msg.payload = msg.payload.temperature;nreturn msg;","outputs":1,"noerr":0,"x":390,"y":460,"wires":[["e71c7a7d.e7c598","7f5cf345.63f56c"]]},{"id":"2b7ac01b.fc984","type":"ui_group","z":"","name":"SENSORS","tab":"99ab8dc5.f435c","disp":true,"width":"6","collapse":false},{"id":"99ab8dc5.f435c","type":"ui_tab","z":"","name":"HTTP","icon":"dashboard","order":1,"disabled":false,"hidden":false}]
其他 Web 服务或 API
在本教程中，ESP8266 对 Node-RED 执行 HTTP 请求，但您可以将这些示例与其他服务一起使用，例如 ThingSpeak、IFTTT.com（Web Hooks 服务）、OpenWeatherMap.org、PHP 服务器等……本教程中提供的所有示例也适用于其他 API。
总之，要使本教程与任何服务兼容，您需要搜索服务 API 文档。然后，您需要服务器名称（URL 或 IP 地址）和要在请求中发送的参数（URL 路径或请求正文）。最后，修改我们的示例以与您要使用的任何 API 集成。
1. ESP8266 HTTP GET：URL 中的值或查询
在第一个示例中，ESP8266将发出 HTTP GET 请求以更新服务中的读数。这种类型的请求还可用于筛选值、请求值或返回 JSON 对象。
使用 Arduino IDE ESP8266 HTTP GET 的代码
安装必要的板附加组件和库后，将以下代码复制到 Arduino IDE，但不要上传。您需要进行一些更改才能使其适合您。
/*
更多Arduino/ESP8266/ESP32等教程请访问： https://www.qutaojiao.com
(see in Tools > Boards > Boards Manager > ESP8266)
*/
#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClient.h>
const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";
//Your Domain name with URL path or IP address with path
String serverName = "http://192.168.1.106:1880/update-sensor";
// the following variables are unsigned longs because the time, measured in
// milliseconds, will quickly become a bigger number than can be stored in an int.
unsigned long lastTime = 0;
// Timer set to 10 minutes (600000)
//unsigned long timerDelay = 600000;
// Set timer to 5 seconds (5000)
unsigned long timerDelay = 5000;
void setup() {
Serial.begin(115200);
WiFi.begin(ssid, password);
Serial.println("Connecting");
while(WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.print("Connected to WiFi network with IP Address: ");
Serial.println(WiFi.localIP());
Serial.println("Timer set to 5 seconds (timerDelay variable), it will take 5 seconds before publishing the first reading.");
}
void loop() {
// Send an HTTP POST request depending on timerDelay
if ((millis() - lastTime) > timerDelay) {
//Check WiFi connection status
if(WiFi.status()== WL_CONNECTED){
WiFiClient client;
HTTPClient http;
String serverPath = serverName + "?temperature=24.37";
// Your Domain name with URL path or IP address with path
http.begin(client, serverPath.c_str());
// If you need Node-RED/server authentication, insert user and password below
//http.setAuthorization("REPLACE_WITH_SERVER_USERNAME", "REPLACE_WITH_SERVER_PASSWORD");
// Send HTTP GET request
int httpResponseCode = http.GET();
if (httpResponseCode>0) {
Serial.print("HTTP Response code: ");
Serial.println(httpResponseCode);
String payload = http.getString();
Serial.println(payload);
}
else {
Serial.print("Error code: ");
Serial.println(httpResponseCode);
}
// Free resources
http.end();
}
else {
Serial.println("WiFi Disconnected");
}
lastTime = millis();
}
}
设置网络凭据
使用您的网络凭据修改下一行：SSID 和密码。该代码对您应该在何处进行更改进行了很好的注释。
// Replace with your network credentials
const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";设置 serverName
您还需要键入您的域名或 Node-RED IP 地址，以便 ESP 将读数发布到您自己的服务器。
String serverName = "http://192.168.1.106:1880/update-sensor";现在，将代码上传到您的开发板，它应该可以立即工作。
如果您想了解如何发出 HTTP GET 请求，请阅读下一节。
HTTP GET 请求
在 loop() 中，您实际上每 5 秒使用示例数据发出一次 HTTP GET 请求：
String serverPath = serverName + "?temperature=24.37";
// Your Domain name with URL path or IP address with path
http.begin(client, serverPath.c_str());
// If you need Node-RED/server authentication, insert user and password below
//http.setAuthorization("REPLACE_WITH_SERVER_USERNAME", "REPLACE_WITH_SERVER_PASSWORD");
// Send HTTP GET request
int httpResponseCode = http.GET();注意：如果 Node-RED 需要身份验证，请取消注释以下行并插入 Node-RED 用户名和密码。
// If you need Node-RED/server authentication, insert user and password below
//http.setAuthorization("REPLACE_WITH_SERVER_USERNAME", "REPLACE_WITH_SERVER_PASSWORD");ESP8266在以下 URL 中发出新请求，以使用新温度更新传感器字段。
http://192.168.1.106:1880/update-sensor?temperature=24.37然后，以下代码行保存来自服务器的 HTTP 响应。
if (httpResponseCode>0) {
Serial.print("HTTP Response code: ");
Serial.println(httpResponseCode);
String payload = http.getString();
Serial.println(payload);
}
else {
Serial.print("Error code: ");
Serial.println(httpResponseCode);
}示范
在开发板运行新程序的情况下，打开 Node-RED 调试窗口。您将看到示例值已成功打印 （24.37）。
2. ESP8266 HTTP GET：JSON 数据对象或纯文本
下一个示例演示如何发出 HTTP GET 请求以获取 JSON 对象并使用 ESP8266对其进行解码。许多 API 以 JSON 格式返回数据。
将下一个程序复制到Arduino IDE（键入SSID和密码）：
设置 serverName
输入您的域名或 Node-RED IP 地址，以便 ESP 请求将在 JSON 对象中检索的传感器读数。
String serverName = "http://192.168.1.106:1880/get-sensor";现在，将代码上传到您的看板。
HTTP GET 请求（JSON 对象）
在 loop() 中，调用 httpGETRequest() 函数以发出 HTTP GET 请求：
sensorReadings = httpGETRequest(serverName);httpGETRequest() 函数向 Node-RED 地址 http://192.168.1.106:1880/get-sensor 发出请求，并检索带有 JSON 对象的字符串。
String httpGETRequest(const char* serverName) {
WiFiClient client;
HTTPClient http;
// Your IP address with path or Domain name with URL path
http.begin(client, serverName);
// If you need Node-RED/server authentication, insert user and password below
//http.setAuthorization("REPLACE_WITH_SERVER_USERNAME", "REPLACE_WITH_SERVER_PASSWORD");
// Send HTTP POST request
int httpResponseCode = http.GET();
String payload = "{}";
if (httpResponseCode>0) {
Serial.print("HTTP Response code: ");
Serial.println(httpResponseCode);
payload = http.getString();
}
else {
Serial.print("Error code: ");
Serial.println(httpResponseCode);
}
// Free resources
http.end();
return payload;
}注意：如果 Node-RED 需要身份验证，请取消注释以下行并插入 Node-RED 用户名和密码。
// If you need Node-RED/server authentication, insert user and password below
//http.setAuthorization("REPLACE_WITH_SERVER_USERNAME", "REPLACE_WITH_SERVER_PASSWORD");解码 JSON 对象
若要访问这些值，请解码 JSON 对象并将所有值存储在 sensorReadingsArr 数组中。
JSONVar myObject = JSON.parse(sensorReadings);
// JSON.typeof(jsonVar) can be used to get the type of the var
if (JSON.typeof(myObject) == "undefined") {
Serial.println("Parsing input failed!");
return;
}
Serial.print("JSON object = ");
Serial.println(myObject);
// myObject.keys() can be used to get an array of all the keys in the object
JSONVar keys = myObject.keys();
for (int i = 0; i < keys.length(); i++) {
JSONVar value = myObject[keys[i]];
Serial.print(keys[i]);
Serial.print(" = ");
Serial.println(value);
sensorReadingsArr[i] = double(value);
}
Serial.print("1 = ");
Serial.println(sensorReadingsArr[0]);
Serial.print("2 = ");
Serial.println(sensorReadingsArr[1]);
Serial.print("3 = ");
Serial.println(sensorReadingsArr[2]);HTTP GET 演示
上传代码后，打开 Arduino IDE，您将看到它正在接收以下 JSON 数据：
{"value1":24.25,"value2":49.54,"value3":1005.14}然后，在 Arduino IDE 串行监视器中打印解码的 JSON 对象。
出于调试目的，请求的信息也会打印在 Node-RED 调试窗口中。
3. ESP8266 HTTP POST：URL 编码、JSON 数据对象、纯文本
最后，您将学习如何使用ESP8266发出 HTTP POST 请求。
在此示例中，ESP8266可以使用三种不同类型的正文请求发出 HTTP POST 请求：URL 编码、JSON 对象或纯文本。这些是最常见的方法，应与大多数 API 或 Web 服务集成。
将下一个程序复制到Arduino IDE（键入SSID和密码）：
设置 serverName
输入您的域名或 Node-RED IP 地址，以便 ESP 发布示例传感器读数。
String serverName = "http://192.168.1.106:1880/update-sensor";现在，将代码上传到您的看板。
HTTP POST URL 编码
发出 URL 编码类型的 HTTP POST 请求，如下所示
POST /update-sensor HTTP/1.1
Host: 192.168.1.106:1880
api_key=tPmAT5Ab3j7F9&sensor=BME280&value1=24.25&value2=49.54&value3=1005.14
Content-Type: application/x-www-form-urlencoded您需要在Arduino代码中运行以下内容：
// Your Domain name with URL path or IP address with path
http.begin(client, serverName);
// If you need Node-RED/server authentication, insert user and password below
//http.setAuthorization("REPLACE_WITH_SERVER_USERNAME", "REPLACE_WITH_SERVER_PASSWORD");
// Specify content-type header
http.addHeader("Content-Type", "application/x-www-form-urlencoded");
// Data to send with HTTP POST
String httpRequestData = "api_key=tPmAT5Ab3j7F9&sensor=BME280&value1=24.25&value2=49.54&value3=1005.14";
// Send HTTP POST request
int httpResponseCode = http.POST(httpRequestData);注意：如果 Node-RED 需要身份验证，请取消注释以下行并插入 Node-RED 用户名和密码。
// If you need Node-RED/server authentication, insert user and password below
//http.setAuthorization("REPLACE_WITH_SERVER_USERNAME", "REPLACE_WITH_SERVER_PASSWORD");HTTP POST JSON 对象
或者，如果您更喜欢使用 JSON 对象发出 HTTP POST 请求：
POST /update-sensor HTTP/1.1
Host: example.com
{api_key: "tPmAT5Ab3j7F9", sensor_name: "BME280", temperature: 24.25; humidity: 49.54; pressure: 1005.14}
Content-Type: application/json使用下一个代码片段：
http.addHeader("Content-Type", "application/json");
int httpResponseCode = http.POST("{"api_key":"tPmAT5Ab3j7F9","sensor":"BME280","value1":"24.25","value2":"49.54","value3":"1005.14"}");HTTP 纯文本
如果要发送纯文本或值，请使用以下命令：
http.addHeader("Content-Type", "text/plain");
int httpResponseCode = http.POST("Hello, World!");注意：我们使用的 Node-RED 流程（Web 服务）未设置为接收纯文本，但如果您计划集成的 API 仅接受纯文本或值，则可以使用前面的代码段。
HTTP POST 演示
在 Node-RED 调试窗口中，您可以查看 ESP 每 5 秒发出一次 HTTP POST 请求。
在此示例中，这些值也会发送到 3 个仪表，并显示在 Node-RED 仪表板中：
http://raspberry-pi-ip-address:1880/ui
总结
在本教程中，你学习了如何使用 HTTP GET 和 HTTP POST 请求将 ESP8266 与联机服务集成。
HTTP GET 和 HTTP POST 通常用于大多数 Web 服务和 API。这些在您的项目中很有用：将您的传感器读数发布到 IFTTT、ThingSpeak 等 Web 服务;到 ESP8266 或 Raspberry Pi Web 服务器或您自己的服务器;从 Internet 或数据库请求数据，等等。
讲得很好，赞！