jstl learning

java custom tag library - JSTL

reason:It is forbidden to write a line of Java code in the Jsp page

Function: remove java code in Jsp page

Steps:
1. Write a Java class that implements the Tag interface, overwrite the doStartTag method, and write the java code in the jsp page into the doStartTag method.

2. Write a tag library descriptor (tld) file in Web-Inf, and describe the custom tag in the tld file.

For details, please refer to: https://www.cnblogs.com/kuangwong/p/6393794.html