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JSP自定义简单标签

程序员文章站 2022-06-09 10:05:44
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1.创建stls.tld文件,放在web项目的WEB-INF目录下

<?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>SimpleTagLibrary</short-name>
    <uri>http://www.stls.com</uri>
    
    
    <tag>
        <name>demo1</name>
		<tag-class>com.tls.web.simpletag.SimpleTagDemo1</tag-class>
		<body-content>scriptless</body-content><!-- 标签体不能使用脚本表达式 -->
    </tag>
    
    <tag>
        <name>demo2</name>
		<tag-class>com.tls.web.simpletag.SimpleTagDemo2</tag-class>
		<body-content>scriptless</body-content>
    </tag>
    
    <tag>
        <name>demo3</name>
		<tag-class>com.tls.web.simpletag.SimpleTagDemo3</tag-class>
		<body-content>scriptless</body-content>
    </tag>
    
    <tag>
        <name>demo4</name>
		<tag-class>com.tls.web.simpletag.SimpleTagDemo4</tag-class>
		<body-content>scriptless</body-content>
    </tag>
    
    <tag>
        <name>demo5</name>
		<tag-class>com.tls.web.simpletag.SimpleTagDemo5</tag-class>
		<body-content>empty</body-content>
    </tag>
    <tag>
        <name>demo6</name>
		<tag-class>com.tls.web.simpletag.SimpleTagDemo6</tag-class>
		<body-content>scriptless</body-content>
		<attribute>
			<name>count</name>
			<required>true</required>
			<rtexprvalue>true</rtexprvalue><!-- 是否可以使用表达式赋值 -->
		</attribute>
		<attribute>
			<name>date</name>
			<required>true</required>
			<rtexprvalue>true</rtexprvalue>
		</attribute>
    </tag>
</taglib>

2.创建简单标签执行类

package com.tls.web.simpletag;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.JspFragment;
import javax.servlet.jsp.tagext.SimpleTagSupport;

//控制标签体是否输出
public class SimpleTagDemo1 extends SimpleTagSupport {
	@Override
	public void doTag() throws JspException, IOException {
		JspFragment jspBody2 = this.getJspBody();
		jspBody2.invoke(this.getJspContext().getOut());
	}
}

package com.tls.web.simpletag;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.JspFragment;
import javax.servlet.jsp.tagext.SimpleTagSupport;

//控制标签体不输出
public class SimpleTagDemo2 extends SimpleTagSupport {
	@Override
	public void doTag() throws JspException, IOException {
		
	}
}

package com.tls.web.simpletag;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.JspFragment;
import javax.servlet.jsp.tagext.SimpleTagSupport;

//控制标签体循环输出
public class SimpleTagDemo3 extends SimpleTagSupport {
	@Override
	public void doTag() throws JspException, IOException {
		JspFragment jspBody2 = this.getJspBody();
		for (int i = 0; i < 5; i++) {
			jspBody2.invoke(null);//相当于jspBody2.invoke(this.getJspContext().getOut());
		}
	}
}

package com.tls.web.simpletag;

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;

//修改标签体后输出
public class SimpleTagDemo4 extends SimpleTagSupport {
	@Override
	public void doTag() throws JspException, IOException {
		JspFragment jf = this.getJspBody();
		StringWriter sw=new StringWriter();
		jf.invoke(sw);
		String content = sw.toString();
		content = content.toUpperCase();
		
		this.getJspContext().getOut().write(content);
	}
}

package com.tls.web.simpletag;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.SkipPageException;
import javax.servlet.jsp.tagext.SimpleTagSupport;

//标签体之后的不输出输出
public class SimpleTagDemo5 extends SimpleTagSupport {
	@Override
	public void doTag() throws JspException, IOException {
		throw new SkipPageException();
	}
}
package com.tls.web.simpletag;


import java.io.IOException;
import java.util.Date;


import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.JspFragment;
import javax.servlet.jsp.tagext.SimpleTagSupport;


//标签体之后的不输出输出
public class SimpleTagDemo6 extends SimpleTagSupport {
	
	private int count;
	
	private Date date;
	
	public void setDate(Date date) {
		this.date = date;
	}
	
	public void setCount(int count) {
		this.count = count;
	}
	@Override
	public void doTag() throws JspException, IOException {
		JspFragment jspBody2 = this.getJspBody();
		this.getJspContext().getOut().write(date.toLocaleString()+"<br />");
		for (int i = 0; i < count; i++) {
			jspBody2.invoke(null);//相当于jspBody2.invoke(this.getJspContext().getOut());
		}
	}
}

3.使用标签

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="http://www.stls.com" prefix="stls" %>


<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>简单标签</title>
</head>
<body>
	标签体输出
	<stls:demo1>
		aaa
	</stls:demo1>
	<br />
	标签体不输出
	<stls:demo2>
		aaa
	</stls:demo2>
	<br />
	标签体循环输出
	<stls:demo3>
		aaa
	</stls:demo3>
	<br />
	标签体修改后输出
	<stls:demo4>
		aaa
	</stls:demo4>
	<br />
	必须要使用脚本表达式传日期,因为标签属性赋值只能转8中基本数据类型,不能转日期类型
	<br /> 
	<stls:demo6 count="9" date="<%=new Date() %>">
		aaa
	</stls:demo6>
	<stls:demo5 />
	aaaa
</body>
</html>