To refer to the relevant tags in this article, you need to refer to the corresponding tag library

<%--Import formatted action label Library--%>
<%@taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>

Format action label

1. Reference to formatNumber tag

formatNumber tag
    Syntax format
        <fmt:formatNumber
            value='<string>'
            type ='<string>'
            var = '<string>'
            scope = "<string>"
            />
    Common attributes:
            Valuethe value to format
            Type the type to format
            percent percentage type
            Currency currency type
            var restricted variable name is used to receive formatted results
            scope var attribute range (page|request|session|application)

        Note: 1. If the var attribute is used, the label will not output the result, which needs to be obtained through the el expression
           2. The default value of type {type} is number
Example code:

<fmt:formatNumber value="10" type="number" var="num" />${num} <br>
<fmt:formatNumber value="1" type="percent"/><br>
<fmt:formatNumber value="10" type="currency" /><br>
<fmt:setLocale value="en_US"/>
<fmt:formatNumber value="10" type="currency"/><br>

2. Reference to formatDate tag

formatDate tag
Converts Date data into a string in the specified format
Syntax format:
    <fmt:formatDate
    Value = "< string >" date to be formatted
    Type = "< string >" formatted type date date date date type year month day time time type hour minute second both time date type
    Datestyle = "< string >" date format: FULL LONG MEDIUM SHORT DEFAULT
    Timestyle = "< string >" time format: FULL LONG MEDIUM SHORT DEFAULT
    Pattern = "< string >" custom mode y M d H m s
    Timezone = "< string >" displays the time zone of the date
    Var = "< string >" the variable name that stores the formatted date
    Scope = "< string >" stores the range of formatted log variables
    />
Example code:
　　

<%--format date--%>
    <%
        request.setAttribute("myDate",new Date());
    %>
    ${myDate}<br>
    <fmt:formatDate value="${myDate}"/><br>
    <fmt:formatDate value="${myDate}" type="date"/> <br>
    <fmt:formatDate value="${myDate}" type="time"/> <br>
    <fmt:formatDate value="${myDate}" type="both"/> <br>
    <fmt:formatDate value="${myDate}" type="both" dateStyle="FULL"/> <br>
    <fmt:formatDate value="${myDate}" type="both" timeStyle="short"/><br>
    <fmt:formatDate value="${myDate}" pattern="yyyy-MM-dd"/><br>
    <hr>

3. Reference to parseNumber tag

parseNumber tag
    Converts a string in the specified format to numeric
Syntax format:
    <fmt:parseNumber
    value="<string>"
    type="<string>"
    var="<string>"
    scope="<string>"
    />

Example code:
　　

    <fmt:setLocale value="zh_CN"/>
    <fmt:parseNumber value="100"/> <br>
    <fmt:parseNumber value="100" type="number"/> <br>
    <fmt:parseNumber value="100%" type="percent" /> <br>
    <fmt:parseNumber value="￥10.00" type="currency"/><br>

Error record here:

code:

 <fmt:parseNumber value="100"/> <br>
    <fmt:parseNumber value="100" type="number"/> <br>
    <fmt:parseNumber value="100%" type="percent" /> <br>
    <fmt:parseNumber value="￥10.00" type="currency"/><br>

Error display:

Cause of error:

The display format here is still the U.S. display format set by the above agent < FMT: setlocale value = "en_us" / > so the '￥' character cannot be recognized,

Therefore, change the display format to < FMT: setlocale value = "zh_cn" / > to correct the error

4. Reference to parseDate tag

parseDate tag
    Converts a Date string to a Date string
<fmt:parseDate
    Value = "< string >" date to be formatted
    Type = "< string >" formatted type date date date date type year month day time time type hour minute second both time date type
    Datestyle = "< string >" date format: FULL LONG MEDIUM SHORT DEFAULT
    Timestyle = "< string >" time format: FULL LONG MEDIUM SHORT DEFAULT
    Pattern = "< string >" custom mode y M d H m s
    Timezone = "< string >" displays the time zone of the date
    Var = "< string >" the variable name that stores the formatted date
    Scope = "< string >" stores the range of formatted log variables
    />
Example code:
　　

<fmt:parseDate value="2021-01-11" type="date"/> <br>
<fmt:parseDate value="2021/01/11" pattern="yyyy/MM/dd" /><br>