自定义EL函数：小写转大写

时间：2021-12-19 19:41:03

1，定义java静态方法，FunctionDemo，有小写转大写的功能

package com.itheima.domain;

public class FunctionDemo {

	public static String toUpperCase(String string){

		return string.toUpperCase();

	}

}

2，编辑xml文件，扩展名为tld

需要指定类的详细名称，带包名，方法的详细信息，返回值+方法名+参数，和访问路径uri，在页面中导入这个uri才能使用，前缀

<?xml version="1.0" encoding="UTF-8"?>

<taglib xmlns="http://java.sun.com/xml/ns/j2ee"

  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

  xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"

  version="2.0">

  <tlib-version>1.0</tlib-version>

  <short-name>itheima</short-name>

  <uri>http://www.heima.com/jsp/myfun</uri>

  <function>

    <description>

      toUpperCase

    </description>

    <name>toUpperCase</name>

    <function-class>com.itheima.domain.FunctionDemo</function-class>

    <function-signature>java.lang.String toUpperCase(java.lang.String)</function-signature>

    <example>

      <itheima:toUpperCase("aavvavb")>

    </example>

  </function>

</taglib>

3在页面中使用，需要用taglib标签，指定uri和前缀

<%@ page language="java" contentType="text/html; charset=utf-8"

    pageEncoding="utf-8"%>

 <%@taglib uri="http://www.heima.com/jsp/myfun" prefix="itheima" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8">

<title>Insert title here</title>

</head>

<body>

 ${itheima:toUpperCase("adsafjka") }

</body>

</html>

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