JSP EL 自定义函数
1.编写java类ArticleUtil.JAVA
package com.wangyi.template;public class ArticleUtil {public static String addd(String s, int length) throws Exception{byte[] bytes = s.getBytes("Unicode");int n = 0; // 表示当前的字节数int i = 2; // 要截取的字节数，从第3个字节开始for (; i < bytes.length && n < length; i++){// 奇数位置，如3、5、7等，为UCS2编码中两个字节的第二个字节if (i % 2 == 1){n++; // 在UCS2第二个字节时n加1}else{// 当UCS2编码的第一个字节不等于0时，该UCS2字符为汉字，一个汉字算两个字节if (bytes != 0){n++;}}}// 如果i为奇数时，处理成偶数if (i % 2 == 1){// 该UCS2字符是汉字时，去掉这个截一半的汉字if (bytes != 0){i = i - 1;// 该UCS2字符是字母或数字，则保留该字符}else{i = i + 1;}}return new String(bytes, 0, i, "Unicode");}}
2.编写 wangyifunc.tag放置到WEB-INF下的任何子目录
<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>wangyi template taglib</description> <tlib-version>1.0</tlib-version> <short-name>wy</short-name> <uri>http://template.wangyi.com/article/taglib</uri><function> <description>Reverses the characters in the given String</description> <name>add</name><function-class>com.wangyi.template.ArticleUtil</function-class><function-signature>java.lang.String addd( java.lang.String, int )</function-signature> </function></taglib>
3编写jsp测试页面
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><%@ taglib prefix="wy" uri="http://template.wangyi.com/article/taglib"%><%request.setAttribute("aa","你好1你好2你好3你好4你好5你好6你好7你好8你好9你好0你好1你好2你好3你好4你好5你好6你好7你好8你好9你好0");//request.setAttribute("ints",new Integer(5));%>${wy:add(aa,32)}
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