自定义jstl标签
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2022-06-08 18:09:36
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1.新建一个tld文件，内容如下：
<?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>/test</uri> <!--为该标签配一个uri-->
<tag>
<name>viewIP</name> <!-- 为标签处理器类配一个标签名 -->
<tag-class>demo.spring.mvc.common.ViewIPTag</tag-class>
<body-content>empty</body-content>
</tag>
</taglib> 其中 uri 对应jsp中引用的<%@ taglib uri="/test" >
tag-class 对应的是具体实体类的内容，具体这个标签的内容是在后台生成的。
2.新建a.jsp，引入刚才声明的taglib,内容如下：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<jsp:include page="../com/com.jsp"></jsp:include>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="/test" prefix="testIp"%>
<!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>Insert title here</title>
<c:set var="ct" value="${pageContext.request.contextPath}"></c:set>
<script src="../js/jquery.min.js"></script>
<script src="${ct}/js/aa.js" type="text/javascript"></script>
<script src="${ctx}/js/bb.js" type="text/javascript"></script>
<!-- <script type="text/javascript">
alert(222);
</script> -->
</head>
<body>
you and me!
<div style="position: relative;"> 11111111</div>
<div style="position: absolute;">您的IP是：<testIp:viewIP/></div>
</body>
</html>3.具体的ViewIPTag类实现的 Tag 接口，复写其中的doTag方法，内容如下：
package demo.spring.mvc.common;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.Tag;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
public class ViewIPTag implements Tag{
private PageContext pageContext;
@Override
public int doEndTag() throws JspException {
HttpServletRequest request2 = ((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getRequest();
HttpServletResponse response = ((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getResponse();
String ip = request2.getRemoteAddr(); //通过request获取客户机的ip
try {
PrintWriter out2=response.getWriter();
out2.write("<div style='color:red' position:relation>"+ip+"</div>");
} catch (IOException e1) {
e1.printStackTrace();
}
return 0;
}
@Override
public int doStartTag() throws JspException {
// TODO Auto-generated method stub
return 0;
}
@Override
public Tag getParent() {
// TODO Auto-generated method stub
return null;
}
@Override
public void release() {
// TODO Auto-generated method stub
}
@Override
public void setPageContext(PageContext arg0) {
// TODO Auto-generated method stub
}
@Override
public void setParent(Tag arg0) {
// TODO Auto-generated method stub
}
}