EL表达式（2）

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1、访问作用域范围的隐含对象

pageScope,requestScope,sessionScope,applicationScope

2、定义使用EL函数

建个.java，方法为静态方法、在web-inf中创建.tld然后就可以调用静态方法了

java

package com.gaint.el;

public class KindMethod {

//字符串翻转
public static String reverse(String text){
System.out.println("-----------字符串翻转text-------"+text);
String result = new StringBuffer(text).reverse().toString();
System.out.println("-----------字符串翻转-------"+result);
return result;
}
//转化为大写字母
public static String cape(String text){
System.out.println("-----------字符串翻转转化为大写字母text-------"+text);
String result = new String(text).toUpperCase();
System.out.println("-----------字符串翻转转化为大写字母-------"+result);
return result;

}

}
.tld

<?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">  <description>library</description>  <display-name>functions</display-name>  <tlib-version>1.1</tlib-version>  <short-name>fn</short-name>  <function>    <description>reverse</description>    <name>reverse</name>    <function-class>com.gaint.el.KindMethod</function-class>    <function-signature>java.lang.String reverse( java.lang.String )</function-signature>  </function>   <function>    <description>cape</description>    <name>cape</name>    <function-class>com.gaint.el.KindMethod</function-class>    <function-signature>java.lang.String cape( java.lang.String )</function-signature>  </function></taglib>

index

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%@ taglib prefix="fn" uri="/WEB-INF/funcation.tld" %><%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'index.jsp' starting page</title><meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page">  </head>    <body>    <form action="index.jsp">    <table>       <tr>        <td>          <input type="text" name="foo" value="${param.foo}"></input>            <input type="submit" name="Sumit" value="提交"></input>         </td>       </tr>     </table>    </form>         <table>     <tr>       <td>说明</td>       <td>输出结果</td>          </tr>        <td>将输入内容翻转输出</td>        <td>${fn:reverse(param.foo)}</td>          <tr>           </tr>        <td>将输入内容转化为大写字母</td>        <td>${fn:cape(param.foo)}</td>          <tr>          </tr>          </table>        escapeXML属性为true是：       <c:out value="水平标记<hr>" escapeXml="true"></c:out>       <br>        escapeXML属性为false是：       <c:out value="水平标记<hr>" escapeXml="false"></c:out>    </body></html>

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