javaweb之自定义标签库——转义标签

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<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib uri="/example" prefix="c" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <title>开发转义标签（修改标签体案例）</title>    <%-- 转义技术用在：论坛 --%>  </head>    <body>  <c:htmlfilter>  <a href="">超链接</a>  </c:htmlfilter>  </body></html>

package cn.itcast.web.tag.example;import java.io.IOException;import java.io.StringWriter;import javax.servlet.jsp.JspException;import javax.servlet.jsp.tagext.JspFragment;import javax.servlet.jsp.tagext.SimpleTagSupport;//开发转义标签//输出到一个缓冲区将数据转义public class HtmlFilterTag extends SimpleTagSupport {@Overridepublic void doTag() throws JspException, IOException {StringWriter sw = new StringWriter();JspFragment jf = this.getJspBody();jf.invoke(sw);String count = sw.getBuffer().toString();//<是<  >是>//apache中有转义代码apache-tomcat-7.0.41\\webapps\\examples\\WEB-INF\\classes\\util\\HTMLFilter.java的filter方法，//将static修饰符去掉，做工具类不用去掉static修饰count = filter(count);this.getJspContext().getOut().write(count);} public  String filter(String message) {        if (message == null)            return (null);        char content[] = new char[message.length()];        message.getChars(0, message.length(), content, 0);        StringBuilder result = new StringBuilder(content.length + 50);        for (int i = 0; i < content.length; i++) {            switch (content[i]) {            case '<':                result.append("<");                break;            case '>':                result.append(">");                break;            case '&':                result.append("&");                break;            case '"':                result.append(""");                break;            default:                result.append(content[i]);            }        }        return (result.toString());    }}

<?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>A tag library exercising SimpleTag handlers.</description>    <tlib-version>1.0</tlib-version>    <short-name>example</short-name><!-- 描述文件的名称 -->    <uri>/example</uri><!-- 描述文件的uri -->            <tag>        <name>referer</name>        <tag-class>cn.itcast.web.tag.example.RefererTag</tag-class>        <body-content>empty</body-content>        <attribute>        <name>site</name>        <required>true</required>        <rtexprvalue>true</rtexprvalue>        </attribute>                <attribute>        <name>page</name>        <required>true</required>        <rtexprvalue>true</rtexprvalue>        </attribute>    </tag>        <tag>        <name>if</name>        <tag-class>cn.itcast.web.tag.example.IfTag</tag-class>        <body-content>scriptless</body-content>        <attribute>        <name>test</name>        <required>true</required>        <rtexprvalue>true</rtexprvalue>        </attribute>    </tag>        <tag>        <name>choose</name>        <tag-class>cn.itcast.web.tag.example.ChooseTag</tag-class>        <body-content>scriptless</body-content>    </tag>        <tag>        <name>when</name>        <tag-class>cn.itcast.web.tag.example.WhenTag</tag-class>        <body-content>scriptless</body-content>        <attribute>        <name>test</name>        <required>true</required>        <rtexprvalue>true</rtexprvalue>        </attribute>    </tag>         <tag>        <name>otherwise</name>        <tag-class>cn.itcast.web.tag.example.OtherWiseTag</tag-class>        <body-content>scriptless</body-content>    </tag>        <tag>        <name>foreach</name>        <tag-class>cn.itcast.web.tag.example.ForeachTag</tag-class>        <body-content>scriptless</body-content>        <attribute>        <name>items</name>        <required>true</required>        <rtexprvalue>true</rtexprvalue>        </attribute>                 <attribute>        <name>var</name>        <required>true</required>        <rtexprvalue>false</rtexprvalue>        </attribute>    </tag>         <tag>        <name>foreach2</name>        <tag-class>cn.itcast.web.tag.example.ForeachTag2</tag-class>        <body-content>scriptless</body-content>        <attribute>        <name>items</name>        <required>true</required>        <rtexprvalue>true</rtexprvalue>        </attribute>                 <attribute>        <name>var</name>        <required>true</required>        <rtexprvalue>false</rtexprvalue>        </attribute>    </tag>        <tag>        <name>htmlfilter</name>        <tag-class>cn.itcast.web.tag.example.HtmlFilterTag</tag-class>        <body-content>scriptless</body-content>    </tag>   </taglib>

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