The following ${} is output as a string in jsp
${requestScope.hello}
is El failure problem
Add at the head of the jsp file
<%@ page isELIgnored="false" %>This configuration means
When isELIgnored is set to true, the jsp will teach the EL expression to be invalid, and will not display the effect of the EL expression on the page, otherwise
When isELIgnored is set to false, jsp can display the corresponding value of the EL expression on the page under the premise that there is no error in the code
In general, it is no problem to use El expression directly on the jsp page, but if the EL expression is invalid, you can try