How can I get the content type from the HttpServletRequest without reading the request body?
When I use the following, I get null:
request.getContentType()
When I try to read the JSON data that comes in the request body using the following:
StringBuilder jsonsb = new StringBuilder();
BufferedReader jsonbr = request.getReader();
The request.getReader() throws
Caused by: java.lang.NullPointerException: null
at java.io.ByteArrayInputStream.<init>(ByteArrayInputStream.java:106)
I even tried using the following and was able to get the content type but, still getting the same NullPointerException while getting the reader from request after this statement.
request.getHeader("Accept")
Are you handling a GET request. That might not contain a Content-Types header and therefore you are seeing a null there.
来源：https://stackoverflow.com/questions/30049094/how-to-determine-content-type-of-a-http-servlet-request