我想在JSON中执行ESP8266 12E文件（ 15.2KB [（15,601字节）大小）读取和写入。我正在使用
我可以：
HTTPClient。阅读文件并使用以下代码在Serial监视器上打印：
server.on("/read", []() {
myFile = SD.open("commands.txt");
byte thisByte;
if (myFile) {
while (myFile.available()) {
thisByte = myFile.read();
Serial.write(thisByte);
}
}
myFile.close();
server.send(200, "text/html", "File read Success.");
});
我跑了/read 30到40次，效果不错，没有任何错误或ESP的WDT软复位。
我不能：
在String变量中读取文件。代码是
server.on("/read", []() {
myFile = SD.open("commands.txt");
String line = "";
if (myFile) {
while (myFile.available()) {
line = myFile.readString();
}
}
Serial.println(line);
myFile.close();
server.send(200, "text/html", "File read Success.");
});
/read 和/或 /write然后/read ESP重置后。
Soft WDT reset
ctx: cont
sp: 3fff0da0 end: 3fff10d0 offset: 01b0
3fff0f50: 00004e00 3fff0fb0 3fff0fb0 402095c3
3fff0f60: 3fff0054 00004b73 3fff810f 4020a758
3fff0f70: 00000001 3ffe9320 3fff0fd4 40206c54
3fff0f80: 00000001 3ffe9320 3fff0074 4020a789
3fff0f90: 00000001 3ffe9320 3fff0fd4 402092b9
3fff0fa0: 00000001 3ffe9320 3ffefbac 4020245e
3fff0fb0: 00000000 00000000 00000000 402095c3
3fff0fc0: 6d6d6f63 73646e61 7478742e 40209600
3fff0fd0: 3fff2d3c 00000000 00000000 00000000
3fff0fe0: 3fff359c 00004dff 00004df1 4010068c
3fff0ff0: 00000000 00000001 3fff27dc 40206c4a
3fff1000: 3fff27dc 3ffef308 3fff27dc 40206c86
3fff1010: 00000000 00000000 00000000 40209770
3fff1020: 3fff27dc 3ffef308 3ffef2c8 40206d19
3fff1030: 3fff2d24 0000000f 00000005 40205b14
3fff1040: 00000000 00000000 00000000 0000000f
3fff1050: 00000001 3fff00a0 4020a114 3fff00b0
3fff1060: 00000000 00000000 3ffef2c8 3fff00a0
3fff1070: 00000001 3ffef2ec 3ffef2c8 40206f04
3fff1080: 3ffe8d68 00000000 00001388 3fff00b0
3fff1090: 00000000 3fff2c84 000003e8 3fff00a0
3fff10a0: 3fffdad0 00000000 3fff0098 40202367
3fff10b0: 3fffdad0 00000000 3fff0098 4020a160
3fff10c0: feefeffe feefeffe 3fff00b0 4010070c
ets Jan 8 2013,rst cause:2, boot mode:(3,6)
load 0x4010f000, len 1384, room 16
我想将文件数据存储在String变量中，然后逐行处理。
完整代码在这里：
#include <Arduino.h>
#include <SPI.h>
#include <SD.h>
#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>
#include <ESP8266WebServer.h>
#include <ESP8266HTTPClient.h>
IPAddress ip(192, 168, 1, 81); // choose IP address
IPAddress subnet(255, 255, 255, 0);
ESP8266WiFiMulti WiFiMulti;
File myFile;
ESP8266WebServer server(80);
//06519942-652e-11e7-907b-a6006ad3dba0
// SSID, PASSWORD
const char *ssid = "06519942-652e-11e7-907b-a";
const char *password = "password";
void setup() {
Serial.begin(115200); // so you can see debug messages automatically sent by ESP8266
WiFi.mode(WIFI_AP);
WiFi.softAPConfig(ip, ip, subnet); // declared as: bool softAPConfig (IPAddress local_ip, IPAddress gateway, IPAddress subnet)
WiFi.softAP(ssid, password, 7, 0, 1); // network name, network password, wifi channel
IPAddress myIP = WiFi.softAPIP();
Serial.println();
Serial.print("AP IP address: ");
Serial.println(myIP);
delay(1000);
// Serial.setDebugOutput(true);
Serial.print("Initializing SD card...");
if (!SD.begin(16)) {
Serial.println("initialization failed!");
return;
}
Serial.println("initialization done.");
Serial.println();
Serial.println();
Serial.println();
for (uint8_t t = 4; t > 0; t--) {
Serial.printf("[SETUP] WAIT %d...\n", t);
Serial.flush();
delay(1000);
}
WiFiMulti.addAP("SSID", "PASSWORD"); // Change it with yours
delay(1000);
server.on("/", []() {
server.send(200, "text/html", "Welcome");
});
server.on("/read", []() {
myFile = SD.open("commands.txt");
byte thisByte;
if (myFile) {
while (myFile.available()) {
thisByte = myFile.read();
Serial.write(thisByte);
}
}
myFile.close();
server.send(200, "text/html", "File read Success.");
});
server.on("/write", []() {
HTTPClient http;
Serial.print("[HTTP] begin...\n");
if (SD.exists("commands.txt")) {
SD.remove("commands.txt");
Serial.println("commands.txt removed.");
}
// configure server and url
http.begin("http://controlxapi.azurewebsites.net/download");
Serial.print("[HTTP] GET...\n");
// start connection and send HTTP header
int httpCode = http.GET();
if (httpCode > 0) {
// HTTP header has been send and Server response header has been handled
Serial.printf("[HTTP] GET... code: %d\n", httpCode);
// file found at server
if (httpCode == HTTP_CODE_OK) {
Serial.println("Creating commands.txt...");
myFile = SD.open("commands.txt", FILE_WRITE);
// get lenght of document (is -1 when Server sends no Content-Length header)
int len = http.getSize();
Serial.println(len);
// create buffer for read
uint8_t buff[128] = { 0 };
// get tcp stream
WiFiClient * stream = http.getStreamPtr();
// read all data from server
while (http.connected() && (len > 0 || len == -1)) {
// get available data size
size_t size = stream->available();
if (size) {
// read up to 128 byte
int c = stream->readBytes(buff, ((size > sizeof(buff)) ? sizeof(buff) : size));
// write it to Serial
//Serial.write(buff, c);
myFile.write(buff, c);
if (len > 0) {
len -= c;
}
}
delay(1);
}
stream->flush();
myFile.close();
Serial.println();
Serial.print("[HTTP] connection closed. File write end.\n");
}
}
else {
Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str());
}
http.end();
http.~HTTPClient();
server.send(200, "text/html", "File write Success.");
});
//Start the server
server.begin();
Serial.println("HTTP server(local) started");
}
void loop() {
server.handleClient();
//delay(100);
if (WiFiMulti.run() != WL_CONNECTED) {
Serial.print(".");
delay(1000);
}
else {
}
}
答案 0 :(得分：0)
问题的根源在于
String line = "";
请不要使用String类来获得可靠的性能。 原因-这会刺穿您的堆并导致内存泄漏->崩溃并重置
用于阅读以html，js，bmp等形式发送到浏览器的方法：
const char* path = "\myfolder\myfile.html";
FILE_SYSTEM can be either SD, SPIFFS, LittleFS
File dataFile = FILE_SYSTEM.open(path, "r");
... do all sorts of checking if needed
// e.g. contentType = F("text/html"); -> determined by a function analysing the
file extension
if (server.streamFile(dataFile, contentType) != dataFile.size()) {
} // sends the file tothe browser
仅用于下载到PC机
contentType = F("application/octet-stream")
Avr开发技巧。摆脱String类并坚持使用c-char数组。刚开始时辛苦，但最后却付出了。