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- // Sample Arduino Json Web Client
- // Downloads and parse http://jsonplaceholder.typicode.com/users/1
- //
- // Copyright Benoit Blanchon 2014-2017
- // MIT License
- //
- // Arduino JSON library
- // https://bblanchon.github.io/ArduinoJson/
- // If you like this project, please add a star!
- #include <ArduinoJson.h>
- #include <Ethernet.h>
- #include <SPI.h>
- EthernetClient client;
- const char* server = "jsonplaceholder.typicode.com"; // server's address
- const char* resource = "/users/1"; // http resource
- const unsigned long BAUD_RATE = 9600; // serial connection speed
- const unsigned long HTTP_TIMEOUT = 10000; // max respone time from server
- const size_t MAX_CONTENT_SIZE = 512; // max size of the HTTP response
- // The type of data that we want to extract from the page
- struct UserData {
- char name[32];
- char company[32];
- };
- // ARDUINO entry point #1: runs once when you press reset or power the board
- void setup() {
- initSerial();
- initEthernet();
- }
- // ARDUINO entry point #2: runs over and over again forever
- void loop() {
- if (connect(server)) {
- if (sendRequest(server, resource) && skipResponseHeaders()) {
- UserData userData;
- if (readReponseContent(&userData)) {
- printUserData(&userData);
- }
- }
- }
- disconnect();
- wait();
- }
- // Initialize Serial port
- void initSerial() {
- Serial.begin(BAUD_RATE);
- while (!Serial) {
- ; // wait for serial port to initialize
- }
- Serial.println("Serial ready");
- }
- // Initialize Ethernet library
- void initEthernet() {
- byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
- if (!Ethernet.begin(mac)) {
- Serial.println("Failed to configure Ethernet");
- return;
- }
- Serial.println("Ethernet ready");
- delay(1000);
- }
- // Open connection to the HTTP server
- bool connect(const char* hostName) {
- Serial.print("Connect to ");
- Serial.println(hostName);
- bool ok = client.connect(hostName, 80);
- Serial.println(ok ? "Connected" : "Connection Failed!");
- return ok;
- }
- // Send the HTTP GET request to the server
- bool sendRequest(const char* host, const char* resource) {
- Serial.print("GET ");
- Serial.println(resource);
- client.print("GET ");
- client.print(resource);
- client.println(" HTTP/1.0");
- client.print("Host: ");
- client.println(host);
- client.println("Connection: close");
- client.println();
- return true;
- }
- // Skip HTTP headers so that we are at the beginning of the response's body
- bool skipResponseHeaders() {
- // HTTP headers end with an empty line
- char endOfHeaders[] = "\r\n\r\n";
- client.setTimeout(HTTP_TIMEOUT);
- bool ok = client.find(endOfHeaders);
- if (!ok) {
- Serial.println("No response or invalid response!");
- }
- return ok;
- }
- // Parse the JSON from the input string and extract the interesting values
- // Here is the JSON we need to parse
- // {
- // "id": 1,
- // "name": "Leanne Graham",
- // "username": "Bret",
- // "email": "Sincere@april.biz",
- // "address": {
- // "street": "Kulas Light",
- // "suite": "Apt. 556",
- // "city": "Gwenborough",
- // "zipcode": "92998-3874",
- // "geo": {
- // "lat": "-37.3159",
- // "lng": "81.1496"
- // }
- // },
- // "phone": "1-770-736-8031 x56442",
- // "website": "hildegard.org",
- // "company": {
- // "name": "Romaguera-Crona",
- // "catchPhrase": "Multi-layered client-server neural-net",
- // "bs": "harness real-time e-markets"
- // }
- // }
- bool readReponseContent(struct UserData* userData) {
- // Compute optimal size of the JSON buffer according to what we need to parse.
- // See https://bblanchon.github.io/ArduinoJson/assistant/
- const size_t BUFFER_SIZE =
- JSON_OBJECT_SIZE(8) // the root object has 8 elements
- + JSON_OBJECT_SIZE(5) // the "address" object has 5 elements
- + JSON_OBJECT_SIZE(2) // the "geo" object has 2 elements
- + JSON_OBJECT_SIZE(3) // the "company" object has 3 elements
- + MAX_CONTENT_SIZE; // additional space for strings
- // Allocate a temporary memory pool
- DynamicJsonBuffer jsonBuffer(BUFFER_SIZE);
- JsonObject& root = jsonBuffer.parseObject(client);
- if (!root.success()) {
- Serial.println("JSON parsing failed!");
- return false;
- }
- // Here were copy the strings we're interested in
- strcpy(userData->name, root["name"]);
- strcpy(userData->company, root["company"]["name"]);
- // It's not mandatory to make a copy, you could just use the pointers
- // Since, they are pointing inside the "content" buffer, so you need to make
- // sure it's still in memory when you read the string
- return true;
- }
- // Print the data extracted from the JSON
- void printUserData(const struct UserData* userData) {
- Serial.print("Name = ");
- Serial.println(userData->name);
- Serial.print("Company = ");
- Serial.println(userData->company);
- }
- // Close the connection with the HTTP server
- void disconnect() {
- Serial.println("Disconnect");
- client.stop();
- }
- // Pause for a 1 minute
- void wait() {
- Serial.println("Wait 60 seconds");
- delay(60000);
- }
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