1. Function of the EL expressions
Role of EL expressions can be divided into three categories
Access Bean attributes.
Simple calculation result output.
Get request parameter values.
2. The role of JSP tags? How to define?
JSP tags can separate content and logic JSP pages, business logic, developers can create custom labels, packaging business logic, reusable and easy to maintain, easy to modify by hand, the tool is easy to maintain and provide a concise syntax.
JSP tag definitions:
Write tag handler
Write tld file
The tag processor and tld files into the same package
The JSP pages and tag library configuration deployed together
3. Talk about familiar JSTL tags.
Commonly used labels: <c: out>, <c: remove>, <c: catch>, <c: set>
Iteration tag: <c: foreach>
条件标签：<c:if>、<c:when>、<c:choose>、<c:otherwise>
URL标签：<c:import>、<c:redirect>、<c:url>