如何编写一个标签函数？

Question

<?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 web-jsptaglibrary_2_0.xsd"
    version="2.0">  <description>JSTL 1.1 core library</description>
  <display-name>JSTL core</display-name>
  <tlib-version>1.1</tlib-version>
  <short-name>c</short-name>
  <uri>http://java.sun.com/jsp/jstl/core</uri>  <validator>
    <description>
        Provides core validation features for JSTL tags.
    </description>
    <validator-class>
        org.apache.taglibs.standard.tlv.JstlCoreTLV
    </validator-class>
  </validator>  <tag>
    <description>
        Catches any Throwable that occurs in its body and optionally
        exposes it.
    </description>
    <name>catch</name>
    <tag-class>org.apache.taglibs.standard.tag.common.core.CatchTag</tag-class>
    <body-content>JSP</body-content>
    <attribute>
        <description>
Name of the exported scoped variable for the
exception thrown from a nested action. The type of the
scoped variable is the type of the exception thrown.
        </description>
        <name>var</name>
        <required>false</required>
        <rtexprvalue>false</rtexprvalue>
    </attribute>
  </tag>
</taglib>

Answer 1

我看到楼上些的代码里没有<function></function>标签
只是一个标准的标签文件，我想在jsp页面里使用标签函数。

Answer 2

要在lib中导入一个jar包，然后就可以使用
<?xml version="1.0" encoding="ISO-8859-1" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
//就是这个
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee web-jsptaglibrary_2_0.xsd"
    version="2.0">
  <tlib-version>1.0</tlib-version>
  <jsp-version>1.2</jsp-version>
  <short-name>function</short-name>
  <uri>http://hellking.com/function</uri>
  <display-name>JSTL sql RT</display-name>
  <description>my function</description>  
  <function>
  <name>add</name>
  <function-class>com.jspdev.ch16.Function</function-class>
  <function-signature>int add(int,int)</function-signature>
  </function> 
  <function>
  <name>trans</name>
  <function-class>com.jspdev.ch16.Function</function-class>
  <function-signature>java.lang.String trans(java.lang.String)</function-signature>
  </function> 
<function>
  <name>formatPer</name>
  <function-class>com.jspdev.ch16.PerUtil</function-class>
  <function-signature>java.lang.String formatPer(float)</function-signature>
  </function> 
</taglib>
JSP应用开发详解（第二版）上有

Answer 3

to:IBug008()
在lib中导入那个jar包呢？
我的项目下已经导入了JSTL标签库

Answer 4

导入jstl，standard包（Jbuilder上有）：
1。建立类Function package eldemo;import java.io.*;public class Function {
     //中文转换
    public static String tarns(String chi)
    {
       String result=null;
       byte temp[];        try {
            temp = chi.getBytes("iso-8859-1");
            result = new String(temp);
        } catch (UnsupportedEncodingException ex) {
            ex.printStackTrace();
        }
        return result;
    }
       //测试用
    public static int add(int x,int y)
    {
       return x+y;
    }
}
2。 建立func.tld,源码如下：
<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>function</short-name>
    <uri>http://wq.com/function</uri>
    <display-name>JSTL sql RT</display-name>
    <description>my function</description>    <function>
        <name>add</name>
        <function-class>eldemo.Function</function-class>
        <function-signature>int add(int,int)</function-signature>
    </function>    <function>
         <name>trans</name>
         <function-class>eldemo.Function</function-class>
         <function-signature>java.lang.String trans(java.lang.String)</function-signature>
    </function>
</taglib>3。然后再web.xml上配置
<?xml version="1.0" encoding="UTF-8"?>
<web-app 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-app_2_4.xsd" version="2.4">
  <display-name>Demo</display-name>
  <jsp-config>
    <taglib>
      <taglib-uri>http://wq.com/function</taglib-uri>
      <taglib-location>/WEB-INF/func.tld</taglib-location>
    </taglib>
  </jsp-config>
</web-app>4。可以直接调用（fun.jsp）
<%@ page contentType="text/html; charset=GBK" %>
<%@ taglib prefix="my" uri="http://wq.com/function" %>
<html>
<head>
<title>
MyFun
</title>
</head>
<body bgcolor="#ffffff">
<h1>
${my:add(10,20)}
</h1>
</body>
</html>