一，jsp自定义标签
1）在jsp中会遇到现有标签不能解决的问题，而自定义标签就是一个很好的选择
二，定义步骤
1）决定要实现的功能以及格式，例如 <control : if code="1">要展示的内容</control : if>
2）编写tld文件，放在WEB-INF下
3）编写处理类
三，实现功能
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@taglib prefix="control" uri="WEB-INF/control.tld"%>
<!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>控制</title>
</head>
<body>
<control:if code="1">
<a href="http://www.baidu.com">百度</a>
</control:if>
<a href="http://www.jd.com">京东</a>
<a href="http://www.taobao.com">淘宝</a>
</body>
</html>
四，编写tld文件
<?xml version="1.0" encoding="UTF-8"?>
<taglib
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"
version="2.1"
>
<tlib-version>1.0</tlib-version>
<short-name>control</short-name>
<tag>
<name>if</name>
<tag-class>com.****.utli.UserCode</tag-class>
<body-content>scriptless</body-content>
//body-content可以参考https://www.cnblogs.com/keyi/p/7127685.html
<attribute>
<description>权限码</description>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
<name>code</name>
</attribute>
</tag>
</taglib>
五，处理类
public class UserCode extends SimpleTagSupport{
private String code;
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
@Override
public void doTag() throws JspException, IOException {
// 获取请求对象
HttpServletRequest request = (HttpServletRequest) ((PageContext) this.getJspContext()).getRequest();
// 获取 session域
HttpSession session = request.getSession();
if("1".equals(code)) {
JspFragment body = this.getJspBody();
body.invoke(null);
}
}
}