1 Question
For APPsocketAfter writing the server, the PC sends the request to the APP, there is a cross-domain problem.
2 Solutions
Add the following key code in the APP return header using socket server
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header="Content-Type: "+ JSON_TYPE + "; charset=utf-8 \r\n"
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+ "Connection: close\r\n"
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+ "Access-Control-Allow-Origin: " + Request.origin + "\r\n"
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+ "Access-Control-Allow-Headers: *\r\n"
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+ "Access-Control-Allow-Credentials: true\r\n"
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+ "Access-Control-Allow-Methods: GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS\r\n"
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+ "Access-Control-Max-Age: 86400\r\n"
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+"Content-length: "+ length +" \r\n\r\n";
1) Access-Control-Allow-Origin
Its value is either requestedOriginThe value of the field, or a *, means accepting requests from any domain name
2) Access-Control-Allow-Headers
Supportable request header name. The request header lists all supported headers, separated by commas.
Note that the following specific headers are always allowed: {{HTTPHeader("Accept")}}, {{HTTPHeader("Accept-Language")}}, {{HTTPHeader("Content-Language")}}, {{HTTPHeader("Content-Type")}} (but only if its value belongs to one of the MIME type application/x-www-form-urlencoded, multipart/form-data or text/plain). These are called {{Glossary("simple headers")}}, and you don't need to declare them specifically.
3) Access-Control-Allow-Credentials
Set to true, which means the server explicitly allows it. Cookies can be included in the request and sent to the server together. If the server does not send cookies by the browser, just delete this field.
If you want to send cookies, Access-Control-Allow-Origin cannot be set as an asterisk. You must specify an explicit domain name that is consistent with the requested webpage.
4) Access-Control-Allow-Methods
This field is required, and its value is a comma-separated string indicating all cross-domain request methods supported by the server. Note that all supported methods are returned, not just the one requested by the browser. This is to avoid multiple "preflight" requests.