通过继承BodyTagSupport实现自定义标签

最新推荐文章于 2022-07-26 11:09:39 发布

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最新推荐文章于 2022-07-26 11:09:39 发布

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分类专栏：自定义标签文章标签： tag

本文链接：https://blog.csdn.net/tao_ssh/article/details/53580762

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1 篇文章

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一、实现类

package com.want.mytag;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyContent;
import javax.servlet.jsp.tagext.BodyTagSupport;
import java.io.IOException;

/**
 * Created by want on 2016/12/12.
 */
public class MyBodyTag extends BodyTagSupport {

    private String name;
    private String tel;

    public void setName(String name) {
        System.out.println("[setName]name = " + name);
        this.name = name;
    }

    public void setTel(String tel) {
        System.out.println("[setTel]tel = " + tel);
        this.tel = tel;
    }

    public String getName() {
        System.out.println("[getName]");
        return name;
    }

    public String getTel() {
        System.out.println("[getTel]");
        return tel;
    }

    public MyBodyTag() {
        super();
        System.out.println("MyBodyTag构造方法");
    }

    @Override
    public int doEndTag() throws JspException {
        System.out.println("doEndTag()");
        return super.doEndTag();
    }

    @Override
    public void doInitBody() throws JspException {
        //如果标签没有内容将不执行，<body-content>empty</body-content>此时会出现空指针异常
        System.out.println("doInitBody()");
        super.doInitBody();
    }

    @Override
    public int doStartTag() throws JspException {
        System.out.println("doStartTag()");
        return super.doStartTag();
    }

    public int doAfterBody() throws JspException {
        try {
            BodyContent bodycontent = getBodyContent();
            System.out.println("bodycontent" + bodycontent);
            String body = bodycontent.getString();
            body+=":"+getName()+":"+getTel();
            System.out.println("body" + body);
            JspWriter out = bodycontent.getEnclosingWriter();
            System.out.println("out" + out);
            if (body != null) {
                out.print(body.toUpperCase());
            }
        } catch (IOException ioe) {
            throw new JspException("Error:" + ioe.getMessage());
        }
        return SKIP_BODY;
    }
}

二、.tld文件

<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XML Spy v4.1 U (http://www.xmlspy.com) by À¼ÌØ (LanTe) -->
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"
        "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
<!-- template test -->

<taglib>
    <tlib-version>1.0</tlib-version>
    <jsp-version>1.2</jsp-version>
    <short-name>want</short-name>
    <tag>
        <name>btag</name>
        <tag-class>com.want.mytag.MyBodyTag</tag-class>

        <!--empty：空标记，即起始标记和结束标记之间没有内容。-->
        <!--<body-content>empty</body-content>-->

        <!--JSP：接受所有JSP语法，如定制的或内部的tag、scripts、静态HTML、脚本元素、JSP指令和动作。-->
        <body-content>JSP</body-content>

        <!--tagdependent：标签体内容直接被写入BodyContent，由自定义标签类来进行处理，而不被JSP容器解释，-->
        <!-- <body-content>tagdependent</body-content>-->

        <!--scriptless：接受文本、EL和JSP动作-->
        <!-- <body-content>scriptless</body-content>-->
        <attribute>
            <name>name</name>
            <required>true</required>
        </attribute>
        <attribute>
            <name>tel</name>
            <required>true</required>
        </attribute>
    </tag>
</taglib>

三、jsp页面

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="tt" uri="/WEB-INF/mybodytag.tld" %>
<html>
<head>
    <title>标签2</title>
</head>
<body>
标签:<br>
<tt:btag name="小王" tel="123456780">标签A</tt:btag><br>
<tt:btag name="小李" tel="6542130">标签B</tt:btag><br>
<tt:btag name="空的" tel="0000"></tt:btag><br>
</body>
</html>

四、显示效果