Java自定义简单标签实例

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

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;
/**
 *
 * @说明   自定义标签
 */
public class perssiontag extends simpletagsupport {

 //自定义标签属性，用于标签传入参数
 private string uri;

 //接收标签传入的参数
 public void seturi(string uri) {
  this.uri = uri;
 }
 @override
 public void dotag() throws jspexception, ioexception {
  //获取用户登陆后保存的session
  pagecontext page = (pagecontext) this.getjspcontext();
  user user = (user) page.getsession().getattribute("login");
  //如果用户登陆
  if(user != null) {
   //用户登陆判断用户权限
   list<string> list = new arraylist<string>();
   //获取用户的角色
   set<role> role = user.getrole();
   for(role r:role) {
    //获取角色对应的权限
    set<privilege> privilege = r.getprivilege();
    for(privilege p:privilege) {
     //获取权限对应的资源
     set<resource> res = p.getresource();
     for(resource re:res) {
      list.add(re.geturi());
     }
    }
   }
   for(string ur:list) {
    //判断用户的权限
    if(ur.equals(uri)) {
     this.getjspbody().invoke(null); //有权限输出标签体内容
    }
   }
  }
 }
}

<?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><!-- 标签名 -->
  <tag-class>cn.com.liveuc.privilege.tag.perssiontag</tag-class>
  <body-content>scriptless</body-content>
  <!-- 标签属性 -->
  <attribute>
   <name>uri</name><!-- 属性名称 -->
   <required>true</required><!-- 是否必须 -->
   <rtexprvalue>true</rtexprvalue><!-- 是否为动态标签 -->
  </attribute>
 </tag>
</taglib>