Jstl自定义标签

Posted 2020-10-25 with-lj

第一步：在web-inf下创建一个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">  
    <description>  
    <![CDATA[security Tags]]>  
    </description>  
    <tlib-version>1.0</tlib-version>  
    <short-name>security</short-name>  
    <uri>http://www.springsecurity.org/jsp</uri>
    <tag>  
        <description>  
        <![CDATA[authorize Tag]]>  
        </description>  
        <name>authorize</name>  
        <tag-class>  
           cn.tms.util.AuthorizeTag
        </tag-class>  
        <body-content>JSP</body-content>  
        <attribute>  
            <name>URL</name>  
            <required>false</required>  
            <rtexprvalue>true</rtexprvalue>  
            <type>java.lang.String</type>  
        </attribute>  
    </tag>  
</taglib>  

authorize.tld

第二步：创建一个类继承BodyTagSupport

package cn.tms.util;

import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.tagext.BodyTagSupport;

import cn.tms.dao.IPrivilegeDAO;
import cn.tms.dao.IRoleDAO;
import cn.tms.entity.Privilege;
import cn.tms.entity.UserInfo;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
//标签
public class AuthorizeTag  extends BodyTagSupport {
    //你提供一个用户名字，我给一个用户拥有的权限集合，并且操作是在权限的DAO中
        private IPrivilegeDAO privilegeDAO;
        private String URL;
        public String getURL() {  
            return URL;  
        }  
        public void setURL(String uRL) {
            URL = uRL;  
        }  
        @Override  
        public int doStartTag() {
            // 如果URL不空就显示URL，否则就不显  
            if (null != URL) {
                getUserDao();
                HttpServletRequest request = (HttpServletRequest)pageContext.getRequest();
                UserInfo info=(UserInfo)request.getSession().getAttribute("userinfo");
                List<Privilege> list = privilegeDAO.findAllPrivilegeByUserId(info.getUserid());
                System.out.println(list.size());
                
                for (Privilege item : list) {

                    System.out.println(URL+"==========================");
                    if(item.getUrl().equals(URL)){
                          //正确渲染该标签
                          return EVAL_BODY_INCLUDE;  
                    }
                }
              
            }  
            return this.SKIP_BODY;  
        }
        public void getUserDao() {
              WebApplicationContext applicationContext = WebApplicationContextUtils.getWebApplicationContext(pageContext.getServletContext());
            privilegeDAO=(IPrivilegeDAO)applicationContext.getBean("IPrivilegeDAO");
        }

}

AuthorizeTag

第三步: 在页面上使用之前在页面上添加

<%@taglib prefix="Authorize" uri="http://www.springsecurity.org/jsp" %>
*注意：这里的URi的地址和web-inf里面配的地址保持一致
最后使用：


这里Authorize是你自己定义的

URL是传入到Authorize里的，然后和后台取到的url进行对比，如果一致就在页面上渲染此标签，不一致就不渲染此标签