Article Title: display the data list in the jsp custom tag Library
Author: javaboy2012
Email: yanek@163.com
Qq: 1046011462
1. Define the tag Library Class UserListTag. java
Package com. yanek. cms. tag;
Import java. io. IOException;
Import java. util. ArrayList;
Import java. util. Iterator;
Import java. util. List;
Import javax. servlet. jsp. JspException;
Import javax. servlet. jsp. tagext. BodyTagSupport;
Import com. yanek. cms. vo. UserInfo;
Public class UserListTag extends BodyTagSupport {
Private String name; // an attribute name
Private Iterator it; // the object to be iterated
Private int cateid; // user category id
@ Override
Public int doEndTag () throws JspException {
Try {
If (bodycontent! = NULL ){
Bodycontent. writeout (bodycontent. getenclosingwriter ());
}
} Catch (ioexception e ){
E. printstacktrace ();
}
Return eval_page;
}
@ Override
Public int dostarttag () throws jspexception {
// Here, different list data is constructed based on the user type, which can be obtained based on the database.
List <userinfo> Users = new arraylist <userinfo> ();
If (cateid = 1 ){
Users. Add (New userinfo ("Michael", 20, "Zhangsan@163.com "));
Users. Add (New userinfo ("Li Si", 30, "Lisi@sina.com "));
} Else {
Users. Add (New userinfo ("Wang Wu", 33, "Wangwu@qq.com "));
Users. Add (New userinfo ("Zhao Liu", 33, "zhaoliu@qq.com "));
}
It = users. iterator ();
If (IT = NULL ){
Return skip_body;
} Else {
Return continuenext ();
}
}
Private int continuenext (){
If (it. hasnext ()){
Pagecontext. setattribute (name, it. Next (), pagecontext. page_scope );
Return eval_body_tag;
} Else {
Return skip_body;
}
}
@ Override
Public int doafterbody (){
Return continuenext ();
}
Public String getName (){
Return name;
}
Public void setName (String name ){
This. name = name;
}
Public int getCateid (){
Return cateid;
}
Public void setCateid (int cateid ){
This. cateid = cateid;
}
}
2. Create the tag library description file my_cms_tag.tld in the WEB-INF directory:
My_cms_tag.tld
<? Xml version = "1.0" encoding = "UTF-8"?>
<! DOCTYPE taglib PUBLIC "-// Sun Microsystems, Inc. // dtd jsp Tag Library 1.1 //" http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd ">
<Taglib>
<Tlibversion> 1.0 </tlibversion>
<Jspversion> 1.0 </jspversion>
<Shortname> cms </shortname>
<Uri> http://www.58tech.cn/mystruts/tags-cms </uri>
<! -- UserListTag start -->
<Tag>
<Name> userListTag </name>
<Tag-class> com. yanek. cms. tag. UserListTag </tag-class>
<Body-content> jsp </body-content>
<Variable>
<! -- <Name-given> user_info </name-given> -->
<Name-from-attribute> name </name-from-attribute>
<Variable-class> com. yanek. cms. vo. UserInfo </variable-class>
<Declare> true </declare>
<Scope> NESTED </scope>
</Variable>
<Attribute>
<Name> name </name>
<Required> true </required>
</Attribute>
<Attribute>
<Name> cateid </name>
<Required> true </required>
</Attribute>
</Tag>
<! -- UserListTag end -->
</Taglib>
3. web. xml configuration
<? Xml version = "1.0" encoding = "UTF-8"?>
<Web-app version = "2.5"
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-app_2_5.xsd>
<Welcome-file-list>
<Welcome-file> index. jsp </welcome-file>
</Welcome-file-list>
<Taglib>
<Taglib-uri>/tags/my-cms </taglib-uri>
<Taglib-location>/WEB-INF/my_cms_tag.tld </taglib-location>
</Taglib>
</Web-app>
4. jsp call
<% @ Page language = "java" import = "java. util. *, com. yanek. cms. vo. *" pageEncoding = "UTF-8" %>
<% @ Taglib uri = "/tags/my-cms" prefix = "myTag" %>
<%
String path = request. getContextPath ();
String basePath = request. getScheme () + ": //" + request. getServerName () + ":" + request. getServerPort () + path + "/";
%>
<! Doctype html public "-// W3C // dtd html 4.01 Transitional // EN">
<Html>
<Head>
<Base href = "<% = basepath %>">
<Title> my JSP 'test. jsp 'starting page </title>
<Meta http-equiv = "Pragma" content = "no-Cache">
<Meta http-equiv = "cache-control" content = "no-Cache">
<Meta http-equiv = "expires" content = "0">
<Meta http-equiv = "keywords" content = "keyword1, keyword2, keyword3">
<Meta http-equiv = "Description" content = "this is my page">
<! --
<LINK rel = "stylesheet" type = "text/CSS" href = "styles.css">
-->
</Head>
<Body>
<Table width = '500px 'border = '1' align = 'center'>
<Tr>
<TD width = '000000'> username </TD>
<TD width = '000000'> age </TD>
<TD> email </TD>
</Tr>
<Mytag: userlisttag name = "user_info1" cateid = "1">
<Tr>
<TD> <% = user_info1.getusername () %> </TD>
<TD> <% = user_info1.getage () %> </TD>
<TD> <% = user_info1.getemail () %>
</TD>
</Tr>
</Mytag: userlisttag>
</Table>
<HR>
<Table width = '500px 'border = '1' align = 'center'>
<Tr>
<TD width = '000000'> username </TD>
<TD width = '000000'> age </TD>
<TD> email </TD>
</Tr>
<MyTag: userListTag name = "user_info2" cateid = "2">
<Tr>
<Td> <% = user_info2.getUserName () %> </td>
<Td> <% = user_info2.getAge () %> </td>
<Td> <% = user_info2.getEmail () %>
</Td>
</Tr>
</MyTag: userListTag>
</Table>
</Body>
</Html>
Object Class Definition
Package com. yanek. cms. vo;
Public class UserInfo {
Private int age;
Private String userName;
Private String email;
Public int getAge (){
Return age;
}
Public void setAge (int age ){
This. age = age;
}
Public String getUserName (){
Return userName;
}
Public void setUserName (String userName ){
This. userName = userName;
}
Public String getEmail (){
Return email;
}
Public void setEmail (String email ){
This. email = email;
}
Public UserInfo (String userName, int age, String email ){
Super ();
This. age = age;
This. userName = userName;
This. email = email;
}
Public UserInfo (){
}
}
Running effect; http: // 127.0.0.1: 8080/TestCMS/page/userlist. jsp
: Http://download.csdn.net/detail/5iasp/5118606 (points not required)
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