Java custom simple tags can easily output information on the page, and the control of permissions, and for JSP tags and servlet code separation has a good role
The following will take control of permissions as an example to customize a label:
One, label type
Copy Code code as follows:
<wxt:per uri= "${pagecontext.request.contextpath}/privilege/list" ></wxt:per>
steps:
1. Customize a Class Perssiontag inheritance Simpletagsupport (custom tags will generally inherit this class)
Copy Code code as follows:
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;
/**
*
* Description Custom Label
*/
public class Perssiontag extends Simpletagsupport {
//Custom label properties, for label incoming parameters
private String URI;
//Receive label incoming parameters
public void Seturi (String uri) {
This.uri = URI;
}
@Override
public void Dotag () throws Jspexception, IOException {
//Get user Login Save session
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 rights
list<string> List = new arraylist<string> ();
//Get the user's role
set<role> role = User.getrole ();
for (role r:role) {
//Get the role's corresponding permissions
set<privilege> privilege = R.getprivilege ();
for (privilege P:privilege) {
//Get the resources corresponding to the permissions
set<resource> res = P.getresource ();
for (Resource re:res) {
List.add (Re.geturi ());
}
}
}
for (String ur:list) {
Judge the permissions of a user
if (Ur.equals (URI)) {
this.getjspbody (). Invoke (null); have permission to output tag body content
}
}
}
}
}
2. Create a TLD file description tag under Web-inf.
Copy Code code as follows:
<?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 the input is correct and the 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>
<!--label Properties-->
<attribute>
<name>uri</name><!--Property name-->
<required>true</required><!--must be-->
<rtexprvalue>true</rtexprvalue><!--is a dynamic label-->
</attribute>
</tag>
</taglib>
3. Use tags
import tags in jsp page:
<a href= "mailto:% @taglib prefix= ' wxt ' uri= '/wxt '%" >%@ Taglib prefix= "Wxt" uri= "/wxt"%</A>
uses tags:
<wxt:per uri= "${" PageContext.request.contextPath}/user/list "
<a href=" ${ PageContext.request.contextPath}/user/list "target=" reight "> User management </a>
</wxt:per>
User rights that contain URI resources will output the label content.
