The request encoding is the character encoding in which parameters in an incoming request are interpreted. Currently, many browsers do not send a request encoding qualifier with the Content-Type header. In such cases, a web container will use the default encoding, ISO-8859-1, to parse request data.
If the client hasn’t set character encoding and the request data is encoded with a different encoding from the default, the data won’t be interpreted correctly. To remedy this situation, you can use the ServletRequest.setCharacterEncoding(String enc) method to override the character encoding supplied by the container. To control the request encoding from JSP pages, you can use the JSTL fmt:requestEncoding tag. You must call the method or tag before parsing any request parameters or reading any input from the request. Calling the method or tag once data has been read will not affect the encoding.