吴裕雄--天生自然JAVA开发JSP-Servlet学习笔记：自定义标签-以页面片段作为属性的标签

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package lee;

import javax.servlet.jsp.tagext.*;
import javax.servlet.jsp.*;
import java.io.*;

/**
 *
 * @author Administrator
 */
public class FragmentTag extends SimpleTagSupport {

    private JspFragment fragment;

    // fragment的setter和getter方法
    public void setFragment(JspFragment fragment) {
        this.fragment = fragment;
    }

    public JspFragment getFragment() {
        return this.fragment;
    }

    @Override
    public void doTag() throws JspException, IOException {
        JspWriter out = getJspContext().getOut();
        out.println("<div style='padding:10px;border:1px solid black;"
                + ";border-radius:20px'>");
        out.println("<h3>下面是动态传入的JSP片段</h3>");
        // 调用、输出“页面片段”
        fragment.invoke(null);
        out.println("</div");
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<taglib version="2.1" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd">
    <tlib-version>1.0</tlib-version>
    <short-name>mytaglib</short-name>
    <uri>/WEB-INF/tlds/mytaglib</uri>
    <!-- A validator verifies that the tags are used correctly at JSP
          translation time. Validator entries look like this: 
       <validator>
           <validator-class>com.mycompany.TagLibValidator</validator-class>
           <init-param>
              <param-name>parameter</param-name>
              <param-value>value</param-value>
           </init-param>
       </validator>
    -->
    <!-- A tag library can register Servlet Context event listeners in
         case it needs to react to such events. Listener entries look
         like this: 
      <listener>
          <listener-class>com.mycompany.TagLibListener</listener-class> 
      </listener>
    -->
    <!-- 定义第一个标签 -->
    <!-- 定义第一个标签 -->
    <tag>
        <!-- 定义标签名 -->
        <name>helloWorld</name>
        <!-- 定义标签处理类 -->
        <tag-class>lee.HelloWorldTag</tag-class>
        <!-- 定义标签体为空 -->
        <body-content>empty</body-content>
    </tag>

    <!-- 定义第二个标签 -->
    <tag>
        <!-- 定义标签名 -->
        <name>query</name>
        <!-- 定义标签处理类 -->
        <tag-class>lee.QueryTag</tag-class>
        <!-- 定义标签体为空 -->
        <body-content>empty</body-content>
        <!-- 配置标签属性:driver -->
        <attribute>
            <name>driver</name> 
            <required>true</required>
            <fragment>true</fragment>
        </attribute>
        <!-- 配置标签属性:url -->
        <attribute>
            <name>url</name> 
            <required>true</required>
            <fragment>true</fragment>
        </attribute>
        <!-- 配置标签属性:user -->
        <attribute>
            <name>user</name> 
            <required>true</required>
            <fragment>true</fragment>
        </attribute>
        <!-- 配置标签属性:pass -->
        <attribute>
            <name>pass</name> 
            <required>true</required>
            <fragment>true</fragment>
        </attribute>
        <!-- 配置标签属性:sql -->
        <attribute>
            <name>sql</name> 
            <required>true</required>
            <fragment>true</fragment>
        </attribute>
    </tag>

    <!-- 定义第三个标签 -->
    <tag>
        <!-- 定义标签名 -->
        <name>iterator</name>
        <!-- 定义标签处理类 -->
        <tag-class>lee.IteratorTag</tag-class>
        <!-- 定义标签体不允许出现JSP脚本 -->
        <body-content>scriptless</body-content>
        <!-- 配置标签属性:collection -->
        <attribute>
            <name>collection</name> 
            <required>true</required>
            <fragment>true</fragment>
        </attribute>
        <!-- 配置标签属性:item -->
        <attribute>
            <name>item</name> 
            <required>true</required>
            <fragment>true</fragment>
        </attribute>
    </tag>
    <tag>
        <!-- 定义标签名 -->
        <name>fragment</name>
        <!-- 定义标签处理类 -->
        <tag-class>lee.FragmentTag</tag-class>
        <!-- 指定该标签不支持标签体 -->
        <body-content>empty</body-content>
        <!-- 定义标签属性：fragment -->
        <attribute>
            <name>fragment</name>
            <required>true</required>
            <fragment>true</fragment>
        </attribute>
    </tag>
    <!-- 定义接受动态属性的标签 -->
    <tag>
        <name>dynaAttr</name>
        <tag-class>lee.DynaAttributesTag</tag-class>
        <body-content>empty</body-content>
        <!-- 指定支持动态属性 -->
        <dynamic-attributes>true</dynamic-attributes>
    </tag>
</taglib>

<%-- 
    Document   : fragmentTag
    Created on : 2020-5-4, 23:43:14
    Author     : Administrator
--%>

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@ page import="java.util.*"%>
<%@ taglib uri= "/WEB-INF/tlds/mytaglib" prefix="mytag"%>

<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>自定义标签示范</title>
    </head>
    <body bgcolor="#ffffc0">
        <h2>下面显示的是自定义标签中的内容</h2>
    <mytag:fragment>
        <jsp:attribute name="fragment">
            <%-- 下面是动态的JSP页面片段 --%>
            <mytag:helloWorld/>
        </jsp:attribute>
    </mytag:fragment>
    <br/>
    <mytag:fragment>
        <jsp:attribute name="fragment">
            <%-- 下面是动态的JSP页面片段 --%>
            ${pageContext.request.remoteAddr}
        </jsp:attribute>
    </mytag:fragment>
</body>
</html>

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package lee;

import javax.servlet.jsp.tagext.*;
import javax.servlet.jsp.*;
import java.io.*;

/**
 *
 * @author Administrator
 */
public class HelloWorldTag extends SimpleTagSupport {
    // 重写doTag()方法，该方法为标签生成页面内容

    public void doTag() throws JspException,
            IOException {
        // 获取页面输出流，并输出字符串
        getJspContext().getOut().write("Hello World "
                + new java.util.Date());
    }
}