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// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// MIT License
//
// This example shows how to store your project configuration in a file.
// It uses the SD library but can be easily modified for any other file-system.
//
// The file contains a JSON document with the following content:
// {
// "hostname": "examples.com",
// "port": 2731
// }
//
// To run this program, you need an SD card connected to the SPI bus as follows:
// * MOSI <-> pin 11
// * MISO <-> pin 12
// * CLK <-> pin 13
// * CS <-> pin 4
//
// https://arduinojson.org/v6/example/config/
#include <ArduinoJson.h>
#include <SD.h>
#include <SPI.h>
// Our configuration structure.
//
// Never use a JsonDocument to store the configuration!
// A JsonDocument is *not* a permanent storage; it's only a temporary storage
// used during the serialization phase. See:
// https://arduinojson.org/v6/faq/why-must-i-create-a-separate-config-object/
struct Config {
char hostname[64];
int port;
};
const char *filename = "/config.txt"; // <- SD library uses 8.3 filenames
Config config; // <- global configuration object
// Loads the configuration from a file
void loadConfiguration(const char *filename, Config &config) {
// Open file for reading
File file = SD.open(filename);
// Allocate a temporary JsonDocument
// Don't forget to change the capacity to match your requirements.
// Use https://arduinojson.org/v6/assistant to compute the capacity.
StaticJsonDocument<512> doc;
// Deserialize the JSON document
DeserializationError error = deserializeJson(doc, file);
if (error)
Serial.println(F("Failed to read file, using default configuration"));
// Copy values from the JsonDocument to the Config
config.port = doc["port"] | 2731;
strlcpy(config.hostname, // <- destination
doc["hostname"] | "example.com", // <- source
sizeof(config.hostname)); // <- destination's capacity
// Close the file (Curiously, File's destructor doesn't close the file)
file.close();
}
// Saves the configuration to a file
void saveConfiguration(const char *filename, const Config &config) {
// Delete existing file, otherwise the configuration is appended to the file
SD.remove(filename);
// Open file for writing
File file = SD.open(filename, FILE_WRITE);
if (!file) {
Serial.println(F("Failed to create file"));
return;
}
// Allocate a temporary JsonDocument
// Don't forget to change the capacity to match your requirements.
// Use https://arduinojson.org/assistant to compute the capacity.
StaticJsonDocument<256> doc;
// Set the values in the document
doc["hostname"] = config.hostname;
doc["port"] = config.port;
// Serialize JSON to file
if (serializeJson(doc, file) == 0) {
Serial.println(F("Failed to write to file"));
}
// Close the file
file.close();
}
// Prints the content of a file to the Serial
void printFile(const char *filename) {
// Open file for reading
File file = SD.open(filename);
if (!file) {
Serial.println(F("Failed to read file"));
return;
}
// Extract each characters by one by one
while (file.available()) {
Serial.print((char)file.read());
}
Serial.println();
// Close the file
file.close();
}
void setup() {
// Initialize serial port
Serial.begin(9600);
while (!Serial) continue;
// Initialize SD library
const int chipSelect = 4;
while (!SD.begin(chipSelect)) {
Serial.println(F("Failed to initialize SD library"));
delay(1000);
}
// Should load default config if run for the first time
Serial.println(F("Loading configuration..."));
loadConfiguration(filename, config);
// Create configuration file
Serial.println(F("Saving configuration..."));
saveConfiguration(filename, config);
// Dump config file
Serial.println(F("Print config file..."));
printFile(filename);
}
void loop() {
// not used in this example
}
// Performance issue?
// ------------------
//
// File is an unbuffered stream, which is not optimal for ArduinoJson.
// See: https://arduinojson.org/v6/how-to/improve-speed/
// See also
// --------
//
// https://arduinojson.org/ contains the documentation for all the functions
// used above. It also includes an FAQ that will help you solve any
// serialization or deserialization problem.
//
// The book "Mastering ArduinoJson" contains a case study of a project that has
// a complex configuration with nested members.
// Contrary to this example, the project in the book uses the SPIFFS filesystem.
// Learn more at https://arduinojson.org/book/
// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤

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// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// MIT License
//
// This example shows how to use DeserializationOption::Filter
//
// https://arduinojson.org/v6/example/filter/
#include <ArduinoJson.h>
void setup() {
// Initialize serial port
Serial.begin(9600);
while (!Serial) continue;
// The huge input: an extract from OpenWeatherMap response
auto input_json = F(
"{\"cod\":\"200\",\"message\":0,\"list\":[{\"dt\":1581498000,\"main\":{"
"\"temp\":3.23,\"feels_like\":-3.63,\"temp_min\":3.23,\"temp_max\":4.62,"
"\"pressure\":1014,\"sea_level\":1014,\"grnd_level\":1010,\"humidity\":"
"58,\"temp_kf\":-1.39},\"weather\":[{\"id\":800,\"main\":\"Clear\","
"\"description\":\"clear "
"sky\",\"icon\":\"01d\"}],\"clouds\":{\"all\":0},\"wind\":{\"speed\":6."
"19,\"deg\":266},\"sys\":{\"pod\":\"d\"},\"dt_txt\":\"2020-02-12 "
"09:00:00\"},{\"dt\":1581508800,\"main\":{\"temp\":6.09,\"feels_like\":-"
"1.07,\"temp_min\":6.09,\"temp_max\":7.13,\"pressure\":1015,\"sea_"
"level\":1015,\"grnd_level\":1011,\"humidity\":48,\"temp_kf\":-1.04},"
"\"weather\":[{\"id\":800,\"main\":\"Clear\",\"description\":\"clear "
"sky\",\"icon\":\"01d\"}],\"clouds\":{\"all\":9},\"wind\":{\"speed\":6."
"64,\"deg\":268},\"sys\":{\"pod\":\"d\"},\"dt_txt\":\"2020-02-12 "
"12:00:00\"}],\"city\":{\"id\":2643743,\"name\":\"London\",\"coord\":{"
"\"lat\":51.5085,\"lon\":-0.1257},\"country\":\"GB\",\"population\":"
"1000000,\"timezone\":0,\"sunrise\":1581492085,\"sunset\":1581527294}}");
// The filter: it contains "true" for each value we want to keep
StaticJsonDocument<200> filter;
filter["list"][0]["dt"] = true;
filter["list"][0]["main"]["temp"] = true;
// Deserialize the document
StaticJsonDocument<400> doc;
deserializeJson(doc, input_json, DeserializationOption::Filter(filter));
// Print the result
serializeJsonPretty(doc, Serial);
}
void loop() {
// not used in this example
}
// See also
// --------
//
// https://arduinojson.org/ contains the documentation for all the functions
// used above. It also includes an FAQ that will help you solve any
// deserialization problem.
//
// The book "Mastering ArduinoJson" contains a tutorial on deserialization.
// It begins with a simple example, like the one above, and then adds more
// features like deserializing directly from a file or an HTTP request.
// Learn more at https://arduinojson.org/book/
// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤

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// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// MIT License
//
// This example shows how to generate a JSON document with ArduinoJson.
//
// https://arduinojson.org/v6/example/generator/
#include <ArduinoJson.h>
void setup() {
// Initialize Serial port
Serial.begin(9600);
while (!Serial) continue;
// Allocate the JSON document
//
// Inside the brackets, 200 is the RAM allocated to this document.
// Don't forget to change this value to match your requirement.
// Use https://arduinojson.org/v6/assistant to compute the capacity.
StaticJsonDocument<200> doc;
// StaticJsonObject allocates memory on the stack, it can be
// replaced by DynamicJsonDocument which allocates in the heap.
//
// DynamicJsonDocument doc(200);
// Add values in the document
//
doc["sensor"] = "gps";
doc["time"] = 1351824120;
// Add an array.
//
JsonArray data = doc.createNestedArray("data");
data.add(48.756080);
data.add(2.302038);
// Generate the minified JSON and send it to the Serial port.
//
serializeJson(doc, Serial);
// The above line prints:
// {"sensor":"gps","time":1351824120,"data":[48.756080,2.302038]}
// Start a new line
Serial.println();
// Generate the prettified JSON and send it to the Serial port.
//
serializeJsonPretty(doc, Serial);
// The above line prints:
// {
// "sensor": "gps",
// "time": 1351824120,
// "data": [
// 48.756080,
// 2.302038
// ]
// }
}
void loop() {
// not used in this example
}
// See also
// --------
//
// https://arduinojson.org/ contains the documentation for all the functions
// used above. It also includes an FAQ that will help you solve any
// serialization problem.
//
// The book "Mastering ArduinoJson" contains a tutorial on serialization.
// It begins with a simple example, like the one above, and then adds more
// features like serializing directly to a file or an HTTP request.
// Learn more at https://arduinojson.org/book/
// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤

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// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// 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 https://arduinojson.org/example.json
// Here is the expected response:
// {
// "sensor": "gps",
// "time": 1351824120,
// "data": [
// 48.756080,
// 2.302038
// ]
// }
//
// https://arduinojson.org/v6/example/http-client/
#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"));
client.stop();
return;
}
// Check HTTP status
char status[32] = {0};
client.readBytesUntil('\r', status, sizeof(status));
// It should be "HTTP/1.0 200 OK" or "HTTP/1.1 200 OK"
if (strcmp(status + 9, "200 OK") != 0) {
Serial.print(F("Unexpected response: "));
Serial.println(status);
client.stop();
return;
}
// Skip HTTP headers
char endOfHeaders[] = "\r\n\r\n";
if (!client.find(endOfHeaders)) {
Serial.println(F("Invalid response"));
client.stop();
return;
}
// Allocate the JSON document
// Use https://arduinojson.org/v6/assistant to compute the capacity.
const size_t capacity = JSON_OBJECT_SIZE(3) + JSON_ARRAY_SIZE(2) + 60;
DynamicJsonDocument doc(capacity);
// Parse JSON object
DeserializationError error = deserializeJson(doc, client);
if (error) {
Serial.print(F("deserializeJson() failed: "));
Serial.println(error.f_str());
client.stop();
return;
}
// Extract values
Serial.println(F("Response:"));
Serial.println(doc["sensor"].as<const char*>());
Serial.println(doc["time"].as<long>());
Serial.println(doc["data"][0].as<float>(), 6);
Serial.println(doc["data"][1].as<float>(), 6);
// Disconnect
client.stop();
}
void loop() {
// not used in this example
}
// Performance issue?
// ------------------
//
// EthernetClient is an unbuffered stream, which is not optimal for ArduinoJson.
// See: https://arduinojson.org/v6/how-to/improve-speed/
// See also
// --------
//
// https://arduinojson.org/ contains the documentation for all the functions
// used above. It also includes an FAQ that will help you solve any
// serialization problem.
//
// The book "Mastering ArduinoJson" contains a tutorial on deserialization
// showing how to parse the response from GitHub's API. In the last chapter,
// it shows how to parse the huge documents from OpenWeatherMap
// and Reddit.
// Learn more at https://arduinojson.org/book/
// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤

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// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// MIT License
//
// This example shows how to deserialize a JSON document with ArduinoJson.
//
// https://arduinojson.org/v6/example/parser/
#include <ArduinoJson.h>
void setup() {
// Initialize serial port
Serial.begin(9600);
while (!Serial) continue;
// Allocate the JSON document
//
// Inside the brackets, 200 is the capacity of the memory pool in bytes.
// Don't forget to change this value to match your JSON document.
// Use https://arduinojson.org/v6/assistant to compute the capacity.
StaticJsonDocument<200> doc;
// StaticJsonDocument<N> allocates memory on the stack, it can be
// replaced by DynamicJsonDocument which allocates in the heap.
//
// DynamicJsonDocument doc(200);
// JSON input string.
//
// Using a char[], as shown here, enables the "zero-copy" mode. This mode uses
// the minimal amount of memory because the JsonDocument stores pointers to
// the input buffer.
// If you use another type of input, ArduinoJson must copy the strings from
// the input to the JsonDocument, so you need to increase the capacity of the
// JsonDocument.
char json[] =
"{\"sensor\":\"gps\",\"time\":1351824120,\"data\":[48.756080,2.302038]}";
// Deserialize the JSON document
DeserializationError error = deserializeJson(doc, json);
// Test if parsing succeeds.
if (error) {
Serial.print(F("deserializeJson() failed: "));
Serial.println(error.f_str());
return;
}
// Fetch values.
//
// Most of the time, you can rely on the implicit casts.
// In other case, you can do doc["time"].as<long>();
const char* sensor = doc["sensor"];
long time = doc["time"];
double latitude = doc["data"][0];
double longitude = doc["data"][1];
// Print values.
Serial.println(sensor);
Serial.println(time);
Serial.println(latitude, 6);
Serial.println(longitude, 6);
}
void loop() {
// not used in this example
}
// See also
// --------
//
// https://arduinojson.org/ contains the documentation for all the functions
// used above. It also includes an FAQ that will help you solve any
// deserialization problem.
//
// The book "Mastering ArduinoJson" contains a tutorial on deserialization.
// It begins with a simple example, like the one above, and then adds more
// features like deserializing directly from a file or an HTTP request.
// Learn more at https://arduinojson.org/book/
// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤

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// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// MIT License
//
// This example shows how to implement an HTTP server that sends a JSON document
// in the response.
// It uses the Ethernet library but can be easily adapted for Wifi.
//
// The JSON document contains the values of the analog and digital pins.
// It looks like that:
// {
// "analog": [0, 76, 123, 158, 192, 205],
// "digital": [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0]
// }
//
// https://arduinojson.org/v6/example/http-server/
#include <ArduinoJson.h>
#include <Ethernet.h>
#include <SPI.h>
byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
EthernetServer server(80);
void setup() {
// Initialize serial port
Serial.begin(9600);
while (!Serial) continue;
// Initialize Ethernet libary
if (!Ethernet.begin(mac)) {
Serial.println(F("Failed to initialize Ethernet library"));
return;
}
// Start to listen
server.begin();
Serial.println(F("Server is ready."));
Serial.print(F("Please connect to http://"));
Serial.println(Ethernet.localIP());
}
void loop() {
// Wait for an incomming connection
EthernetClient client = server.available();
// Do we have a client?
if (!client)
return;
Serial.println(F("New client"));
// Read the request (we ignore the content in this example)
while (client.available()) client.read();
// Allocate a temporary JsonDocument
// Use https://arduinojson.org/v6/assistant to compute the capacity.
StaticJsonDocument<500> doc;
// Create the "analog" array
JsonArray analogValues = doc.createNestedArray("analog");
for (int pin = 0; pin < 6; pin++) {
// Read the analog input
int value = analogRead(pin);
// Add the value at the end of the array
analogValues.add(value);
}
// Create the "digital" array
JsonArray digitalValues = doc.createNestedArray("digital");
for (int pin = 0; pin < 14; pin++) {
// Read the digital input
int value = digitalRead(pin);
// Add the value at the end of the array
digitalValues.add(value);
}
Serial.print(F("Sending: "));
serializeJson(doc, Serial);
Serial.println();
// Write response headers
client.println(F("HTTP/1.0 200 OK"));
client.println(F("Content-Type: application/json"));
client.println(F("Connection: close"));
client.print(F("Content-Length: "));
client.println(measureJsonPretty(doc));
client.println();
// Write JSON document
serializeJsonPretty(doc, client);
// Disconnect
client.stop();
}
// Performance issue?
// ------------------
//
// EthernetClient is an unbuffered stream, which is not optimal for ArduinoJson.
// See: https://arduinojson.org/v6/how-to/improve-speed/
// See also
// --------
//
// https://arduinojson.org/ contains the documentation for all the functions
// used above. It also includes an FAQ that will help you solve any
// serialization problem.
//
// The book "Mastering ArduinoJson" contains a tutorial on serialization.
// It begins with a simple example, then adds more features like serializing
// directly to a file or an HTTP client.
// Learn more at https://arduinojson.org/book/
// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤

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// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// MIT License
//
// This example shows how to send a JSON document to a UDP socket.
// At regular interval, it sends a UDP packet that contains the status of
// analog and digital pins.
// It looks like that:
// {
// "analog": [0, 76, 123, 158, 192, 205],
// "digital": [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0]
// }
//
// If you want to test this program, you need to be able to receive the UDP
// packets.
// For example, you can run netcat on your computer
// $ ncat -ulp 8888
// See https://nmap.org/ncat/
//
// https://arduinojson.org/v6/example/udp-beacon/
#include <ArduinoJson.h>
#include <Ethernet.h>
#include <SPI.h>
byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
IPAddress remoteIp(192, 168, 0, 108); // <- EDIT!!!!
unsigned short remotePort = 8888;
unsigned short localPort = 8888;
EthernetUDP udp;
void setup() {
// Initialize serial port
Serial.begin(9600);
while (!Serial) continue;
// Initialize Ethernet libary
if (!Ethernet.begin(mac)) {
Serial.println(F("Failed to initialize Ethernet library"));
return;
}
// Enable UDP
udp.begin(localPort);
}
void loop() {
// Allocate a temporary JsonDocument
// Use https://arduinojson.org/v6/assistant to compute the capacity.
StaticJsonDocument<500> doc;
// Create the "analog" array
JsonArray analogValues = doc.createNestedArray("analog");
for (int pin = 0; pin < 6; pin++) {
// Read the analog input
int value = analogRead(pin);
// Add the value at the end of the array
analogValues.add(value);
}
// Create the "digital" array
JsonArray digitalValues = doc.createNestedArray("digital");
for (int pin = 0; pin < 14; pin++) {
// Read the digital input
int value = digitalRead(pin);
// Add the value at the end of the array
digitalValues.add(value);
}
// Log
Serial.print(F("Sending to "));
Serial.print(remoteIp);
Serial.print(F(" on port "));
Serial.println(remotePort);
serializeJson(doc, Serial);
// Send UDP packet
udp.beginPacket(remoteIp, remotePort);
serializeJson(doc, udp);
udp.println();
udp.endPacket();
// Wait
delay(10000);
}
// Performance issue?
// ------------------
//
// EthernetUDP is an unbuffered stream, which is not optimal for ArduinoJson.
// See: https://arduinojson.org/v6/how-to/improve-speed/
// See also
// --------
//
// https://arduinojson.org/ contains the documentation for all the functions
// used above. It also includes an FAQ that will help you solve any
// serialization problem.
//
// The book "Mastering ArduinoJson" contains a tutorial on serialization.
// It begins with a simple example, then adds more features like serializing
// directly to a file or any stream.
// Learn more at https://arduinojson.org/book/
// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤

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// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// MIT License
//
// This example shows how to deserialize a MessagePack document with
// ArduinoJson.
//
// https://arduinojson.org/v6/example/msgpack-parser/
#include <ArduinoJson.h>
void setup() {
// Initialize serial port
Serial.begin(9600);
while (!Serial) continue;
// Allocate the JSON document
//
// Inside the brackets, 200 is the capacity of the memory pool in bytes.
// Don't forget to change this value to match your JSON document.
// Use https://arduinojson.org/v6/assistant to compute the capacity.
StaticJsonDocument<200> doc;
// StaticJsonObject allocates memory on the stack, it can be
// replaced by DynamicJsonObject which allocates in the heap.
//
// DynamicJsonObject doc(200);
// MessagePack input string.
//
// Using a char[], as shown here, enables the "zero-copy" mode. This mode uses
// the minimal amount of memory because the JsonDocument stores pointers to
// the input buffer.
// If you use another type of input, ArduinoJson must copy the strings from
// the input to the JsonDocument, so you need to increase the capacity of the
// JsonDocument.
uint8_t input[] = {131, 166, 115, 101, 110, 115, 111, 114, 163, 103, 112, 115,
164, 116, 105, 109, 101, 206, 80, 147, 50, 248, 164, 100,
97, 116, 97, 146, 203, 64, 72, 96, 199, 58, 188, 148,
112, 203, 64, 2, 106, 146, 230, 33, 49, 169};
// This MessagePack document contains:
// {
// "sensor": "gps",
// "time": 1351824120,
// "data": [48.75608, 2.302038]
// }
DeserializationError error = deserializeMsgPack(doc, input);
// Test if parsing succeeded.
if (error) {
Serial.print("deserializeMsgPack() failed: ");
Serial.println(error.f_str());
return;
}
// Fetch values.
//
// Most of the time, you can rely on the implicit casts.
// In other case, you can do doc["time"].as<long>();
const char* sensor = doc["sensor"];
long time = doc["time"];
double latitude = doc["data"][0];
double longitude = doc["data"][1];
// Print values.
Serial.println(sensor);
Serial.println(time);
Serial.println(latitude, 6);
Serial.println(longitude, 6);
}
void loop() {
// not used in this example
}

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// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// MIT License
//
// This example shows the different ways you can use Flash strings with
// ArduinoJson.
//
// Use Flash strings sparingly, because ArduinoJson duplicates them in the
// JsonDocument. Prefer plain old char*, as they are more efficient in term of
// code size, speed, and memory usage.
//
// https://arduinojson.org/v6/example/progmem/
#include <ArduinoJson.h>
void setup() {
DynamicJsonDocument doc(1024);
// You can use a Flash String as your JSON input.
// WARNING: the strings in the input will be duplicated in the JsonDocument.
deserializeJson(doc, F("{\"sensor\":\"gps\",\"time\":1351824120,"
"\"data\":[48.756080,2.302038]}"));
// You can use a Flash String as a key to get a member from JsonDocument
// No duplication is done.
long time = doc[F("time")];
// You can use a Flash String as a key to set a member of a JsonDocument
// WARNING: the content of the Flash String will be duplicated in the
// JsonDocument.
doc[F("time")] = time;
// You can set a Flash String as the content of a JsonVariant
// WARNING: the content of the Flash String will be duplicated in the
// JsonDocument.
doc["sensor"] = F("gps");
// It works with serialized() too:
doc["sensor"] = serialized(F("\"gps\""));
doc["sensor"] = serialized(F("\xA3gps"), 3);
// You can compare the content of a JsonVariant to a Flash String
if (doc["sensor"] == F("gps")) {
// ...
}
}
void loop() {
// not used in this example
}
// See also
// --------
//
// https://arduinojson.org/ contains the documentation for all the functions
// used above. It also includes an FAQ that will help you solve any memory
// problem.
//
// The book "Mastering ArduinoJson" contains a quick C++ course that explains
// how your microcontroller stores strings in memory. It also tells why you
// should not abuse Flash strings with ArduinoJson.
// Learn more at https://arduinojson.org/book/
// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤

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@ -0,0 +1,77 @@
// ArduinoJson - https://arduinojson.org
// Copyright © 2014-2023, Benoit BLANCHON
// MIT License
//
// This example shows the different ways you can use String with ArduinoJson.
//
// Use String objects sparingly, because ArduinoJson duplicates them in the
// JsonDocument. Prefer plain old char[], as they are more efficient in term of
// code size, speed, and memory usage.
//
// https://arduinojson.org/v6/example/string/
#include <ArduinoJson.h>
void setup() {
DynamicJsonDocument doc(1024);
// You can use a String as your JSON input.
// WARNING: the string in the input will be duplicated in the JsonDocument.
String input =
"{\"sensor\":\"gps\",\"time\":1351824120,\"data\":[48.756080,2.302038]}";
deserializeJson(doc, input);
// You can use a String as a key to get a member from JsonDocument
// No duplication is done.
long time = doc[String("time")];
// You can use a String as a key to set a member of a JsonDocument
// WARNING: the content of the String will be duplicated in the JsonDocument.
doc[String("time")] = time;
// You can get the content of a JsonVariant as a String
// No duplication is done, at least not in the JsonDocument.
String sensor = doc["sensor"];
// Unfortunately, the following doesn't work (issue #118):
// sensor = doc["sensor"]; // <- error "ambiguous overload for 'operator='"
// As a workaround, you need to replace by:
sensor = doc["sensor"].as<String>();
// You can set a String as the content of a JsonVariant
// WARNING: the content of the String will be duplicated in the JsonDocument.
doc["sensor"] = sensor;
// It works with serialized() too:
doc["sensor"] = serialized(sensor);
// You can also concatenate strings
// WARNING: the content of the String will be duplicated in the JsonDocument.
doc[String("sen") + "sor"] = String("gp") + "s";
// You can compare the content of a JsonObject with a String
if (doc["sensor"] == sensor) {
// ...
}
// Lastly, you can print the resulting JSON to a String
// WARNING: it doesn't replace the content but appends to it
String output;
serializeJson(doc, output);
}
void loop() {
// not used in this example
}
// See also
// --------
//
// https://arduinojson.org/ contains the documentation for all the functions
// used above. It also includes an FAQ that will help you solve any problem.
//
// The book "Mastering ArduinoJson" contains a quick C++ course that explains
// how your microcontroller stores strings in memory. On several occasions, it
// shows how you can avoid String in your program.
// Learn more at https://arduinojson.org/book/
// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤