Arduino C＆＃x2B;＆＃x2B;将HTTP客户端初始化移至函数

Question

我正在研究ESP-01（ESP8266板）项目，并提出一些HTTP请求。我正在尝试重构代码以保持干燥，但是我坚持如何将HTTP客户端初始化提取到功能上。

这是我工作的PUT请求函数：

void httpPut(const char* url, const char* data) {
  WiFiClient client;
  HTTPClient http;

  http.begin(client, url);
  http.addHeader("Content-Type", "application/json");
  http.PUT(data);

  http.end();
}

我的想法是制作这样的函数：

HTTPClient prepareRequest(const char* url) {
  WiFiClient client;
  HTTPClient http;

  http.begin(client, url);
  http.addHeader("Content-Type", "application/json");
  return http;
}

并在我的所有请求函数中使用它：

void httpGet(const char* url) {
  HTTPClient http = prepareRequest(url);
  http.GET();
  http.end();
}

我遇到了此编译器错误，但我不确定它的含义（提到的第90行是返回http;）：

/home/<user>/Code/Micro/mittari-micro/src/mittari.ino: In function 'HTTPClient prepareRequest(const char*)':
/home/<user>/Code/Micro/mittari-micro/src/mittari.ino:90:10: error: use of deleted function 'HTTPClient::HTTPClient(const HTTPClient&)'
   90 |   return http;
      |          ^~~~
In file included from /home/<user>/Code/Micro/mittari-micro/src/mittari.ino:2:
/home/<user>/.platformio/packages/framework-arduinoespressif8266/libraries/ESP8266HTTPClient/src/ESP8266HTTPClient.h:151:7: note: 'HTTPClient::HTTPClient(const HTTPClient&)' is implicitly deleted because the default definition would be ill-formed:
  151 | class HTTPClient
      |       ^~~~~~~~~~
/home/<user>/.platformio/packages/framework-arduinoespressif8266/libraries/ESP8266HTTPClient/src/ESP8266HTTPClient.h:151:7: error: use of deleted function 'std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with _Tp = StreamString; _Dp = std::default_delete<StreamString>]'
In file included from /home/<user>/.platformio/packages/toolchain-xtensa/xtensa-lx106-elf/include/c++/10.3.0/memory:83,
                 from /home/<user>/.platformio/packages/framework-arduinoespressif8266/libraries/ESP8266WiFi/src/ESP8266WiFiGeneric.h:28,
                 from /home/<user>/.platformio/packages/framework-arduinoespressif8266/libraries/ESP8266WiFi/src/ESP8266WiFiSTA.h:28,
                 from /home/<user>/.platformio/packages/framework-arduinoespressif8266/libraries/ESP8266WiFi/src/ESP8266WiFi.h:34,
                 from /home/<user>/Code/Micro/mittari-micro/src/mittari.ino:1:
/home/<user>/.platformio/packages/toolchain-xtensa/xtensa-lx106-elf/include/c++/10.3.0/bits/unique_ptr.h:468:7: note: declared here
  468 |       unique_ptr(const unique_ptr&) = delete;
      |       ^~~~~~~~~~

是否可以将共同功能提取到功能？我该怎么做？

Answer 1

您正在尝试在PrepareRequest函数结束时通过Value 返回httpclient对象（HTTP）。这意味着在这种情况下复制构造，并且编译器告诉您，该课程故意禁用复制构造。 （可能有很多原因。）

在Arduino环境中进行此操作的习惯是将您的“ WificLient客户端”和“ HTTPCLCLIENT HTTP”移至全局范围。然后将您的初始化代码写入“设置”函数，最后您可以在喜欢的任何功能中使用它们。这样，您可以将URL和标头的设置分离为“ PrepareRequest”功能，实际上HTTP进入了“ HTTPGET”功能，而无需它们返回任何内容。

有更复杂的解决方案，带有const参考，指针等……但是，除非您特别想走那条路，否则我会选择上面提到的解决方案。

Answer 2

我将有效的和httpclient放在全球范围内，然后将准备方法更改为这样的空隙：

WiFiClient client;
HTTPClient http;

void prepareRequest(const char* url) {
  http.end(); // In case previous request did not call end for some reason.
  http.begin(client, url);
  http.addHeader("Content-Type", "application/json");
}

void httpGet(const char* url) {
  prepareRequest(url);
  http.GET();
  http.end();
}

到目前为止，它似乎很好。