JSTL custom label

explain

JSTL Not supported by default LocalDate and LocalDateTime, stay JSP Custom display in LocalDate and LocalDateTime, You need to customize the tag to achieve .

First step ： Create specific tool classes for transformation

• LocalDateTimeFormatter

public class LocalDateTimeFormatter {
    
    public static String formatLocalDateTime(LocalDateTime localDateTime, String pattern) {
    
        return localDateTime.format(DateTimeFormatter.ofPattern(pattern));
    }
}

• LocalDateFormatter

public class LocalDateFormatter {
    
    public static String formatLocalDate(LocalDate localDate, String pattern) {
    
        return localDate.format(DateTimeFormatter.ofPattern(pattern));
    }
}

The second step ： stay WEB-INF Create under directory tld file

<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd" version="2.1">

    <tlib-version>1.0</tlib-version>
    <short-name>Custom_Functions</short-name>
    <uri>http://wego.com/format</uri>

    <function>
        <name>formatLocalDateTime</name>
        <function-class>com.wego.formatter.LocalDateTimeFormatter</function-class>
        <function-signature>java.lang.String formatLocalDateTime(java.time.LocalDateTime, java.lang.String)</function-signature>
    </function>

    <function>
        <name>formatLocalDate</name>
        <function-class>com.wego.formatter.LocalDateFormatter</function-class>
        <function-signature>java.lang.String formatLocalDate(java.time.LocalDate, java.lang.String)</function-signature>
    </function>
</taglib>

The third step ： test

• Server side data

request.setAttribute("localDate", LocalDate.now());
request.setAttribute("localDateTime", LocalDateTime.now());

• Page using

 date ：${
    f:formatLocalDate(localDate, 'yyyy-MM*dd')}
 Date time ：${
    f:formatLocalDateTime(localDateTime, 'yyyy-MM-dd HH:mm:ss')}