Java custom simple tag instances

The following will take the control of permissions as an example to customize a label:
One, label type

<wxt:per uri="${pageContext.request.contextPath }/privilege/list"></wxt:per>

Steps:
1. Custom PerssionTag class inherits SimpleTagSupport (custom tags typically inherit from this class)

package cn.com.liveuc.privilege.tag;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.SimpleTagSupport;
import cn.com.liveuc.privilege.model.Privilege;
import cn.com.liveuc.privilege.model.Resource;
import cn.com.liveuc.privilege.model.Role;
import cn.com.liveuc.privilege.model.User;

public class PerssionTag extends SimpleTagSupport {

 //Custom tag properties for tag passing parameters
 private String uri;

 //Receive the parameters passed in by the label
 public void setUri(String uri) {
  this.uri = uri;
 }
 @Override
 public void doTag() throws JspException, IOException {
  //Gets the Session saved after the user logs in
  PageContext page = (PageContext) this.getJspContext();
  User user = (User) page.getSession().getAttribute("login");
  //If the user logs in
  if(user != null) {
   //User login to determine user permissions
   List<String> list = new ArrayList<String>();
   //Gets the user's role
   Set<Role> role = user.getRole();
   for(Role r:role) {
    //Gets the permissions for the role
    Set<Privilege> privilege = r.getPrivilege();
    for(Privilege p:privilege) {
     //Gets the resource corresponding to the permission
     Set<Resource> res = p.getResource();
     for(Resource re:res) {
      list.add(re.getUri());
     }
    }
   }
   for(String ur:list) {
    //Determine the user's permissions
    if(ur.equals(uri)) {
     this.getJspBody().invoke(null); //Has permission to output the tag body content
    }
   }
  }
 }
}

2. Create the TLD file description label under web-inf.

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 version="2.0"
 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd">
 <description><![CDATA["To make it easier to access dynamic data;
                    the Apache Struts framework includes a library of custom tags.
                    The tags interact with the framework's validation and internationalization features;
                    to ensure that input is correct and output is localized.
                    The Struts Tags can be used with JSP FreeMarker or Velocity."]]></description>
 <display-name>"Struts Tags"</display-name>
 <tlib-version>2.2.3</tlib-version>
 <short-name>s</short-name>
 <uri>/wxt</uri>
 <tag>
  <name>per</name><!--  Tag name  -->
  <tag-class>cn.com.liveuc.privilege.tag.PerssionTag</tag-class>
  <body-content>scriptless</body-content>
  <!--  Tag attributes  -->
  <attribute>
   <name>uri</name><!--  The attribute name  -->
   <required>true</required><!--  Whether must  -->
   <rtexprvalue>true</rtexprvalue><!--  Is it a dynamic tag  -->
  </attribute>
 </tag>
</taglib>

Use labels
Import the tag in the Jsp page:
< A href="mailto:%@taglib prefix=' WXT 'uri='/ WXT' %"> % @ taglib prefix = "WXT" uri = "/ WXT" % < / A>
Use of labels:
< WXT: per uri = "${pageContext. Request. ContextPath} / user/list" >
          < A href = "${pageContext. Request. ContextPath} / user/list" target = "reight >" User management < / a>
< / WXT: per>
User permissions that contain uri resources will output label content.