ArduinoJson/examples/JsonHttpClient/JsonHttpClient.ino

// ArduinoJson - arduinojson.org
// Copyright Benoit Blanchon 2014-2017
// MIT License
//
// This example shows how to parse a JSON document in an HTTP response.
// It uses the Ethernet library, but can be easily adapted for Wifi.
//
// It performs a GET resquest on arduinojson.org/example.json
// Here is the expected response:
// {
//   "sensor": "gps",
//   "time": 1351824120,
//   "data": [
//     48.756080,
//     2.302038
//   ]
// }

#include <ArduinoJson.h>
#include <Ethernet.h>
#include <SPI.h>

void setup() {
  // Initialize Serial port
  Serial.begin(9600);
  while (!Serial) continue;

  // Initialize Ethernet library
  byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
  if (!Ethernet.begin(mac)) {
    Serial.println(F("Failed to configure Ethernet"));
    return;
  }
  delay(1000);

  Serial.println(F("Connecting..."));

  // Connect to HTTP server
  EthernetClient client;
  client.setTimeout(10000);
  if (!client.connect("arduinojson.org", 80)) {
    Serial.println(F("Connection failed"));
    return;
  }

  Serial.println(F("Connected!"));

  // Send HTTP request
  client.println(F("GET /example.json HTTP/1.0"));
  client.println(F("Host: arduinojson.org"));
  client.println(F("Connection: close"));
  if (client.println() == 0) {
    Serial.println(F("Failed to send request"));
    return;
  }

  // Check HTTP status
  char status[32] = {0};
  client.readBytesUntil('\r', status, sizeof(status));
  if (strcmp(status, "HTTP/1.1 200 OK") != 0) {
    Serial.print(F("Unexpected response: "));
    Serial.println(status);
    return;
  }

  // Skip HTTP headers
  char endOfHeaders[] = "\r\n\r\n";
  if (!client.find(endOfHeaders)) {
    Serial.println(F("Invalid response"));
    return;
  }

  // Allocate JsonBuffer
  // Use arduinojson.org/assistant to compute the capacity.
  const size_t capacity = JSON_OBJECT_SIZE(3) + JSON_ARRAY_SIZE(2) + 60;
  DynamicJsonBuffer jsonBuffer(capacity);

  // Parse JSON object
  JsonObject& root = jsonBuffer.parseObject(client);
  if (!root.success()) {
    Serial.println(F("Parsing failed!"));
    return;
  }

  // Extract values
  Serial.println(F("Response:"));
  Serial.println(root["sensor"].as<char*>());
  Serial.println(root["time"].as<char*>());
  Serial.println(root["data"][0].as<char*>());
  Serial.println(root["data"][1].as<char*>());

  // Disconnect
  client.stop();
}

void loop() {
  // not used in this example
}

// See also
// --------
//
// The website arduinojson.org contains the documentation for all the functions
// used above. It also includes an FAQ that will help you solve any
// serialization  problem.
// Please check it out at: https://arduinojson.org/
//
// The book "Mastering ArduinoJson" contains a tutorial on deserialization
// showing how to parse the response from Yahoo Weather. In the last chapter,
// it shows how to parse the huge documents from OpenWeatherMap
// and Weather Underground.
// Please check it out at: https://leanpub.com/arduinojson/