Struts nested tag Example
The tag library “nested” is included in
Struts 1.1. In this tutorial we are going to explain what are the features of
nested tag library and how you can use it. We can manage nested beans easily
with the help of struts nested tag library.
Nested tags are used in the
nested context. The Nested tags and its supporting classes extends the base struts tags
and making them possible to relate to each other in the nested fashion. In case
of Nested tags the original logic of the tags does not change and all the references to beans and bean properties
is managed in the nested context.
As far as bean is concerned, one is
associated with another internally and access to all the beans are through the
current one. The beans that refers to another is the parent and
the second related to the first one is its child. Here both 'parent' and 'child'
denotes a hierarchical structure of beans.
For example, Take an object which represents a Author. Each author related
to many book .If this case was translated to bean objects,
the author object would have a reference to the book objects he wrote, and each bunch object would hold a reference to
the chapters in the books.
The author object is the parent to the books object, and the books object is a child of the
author object. The books object
is parent to its child chapters objects, and the child chapters objects children of the
books object. The author is higher in
the hierarchy than the books, and the chapters lower in the hierarchy to the
books.
Herbert Schildt
Teach Yourself C++
Java: The Complete Reference, J2SE
Struts: the complete reference
O'Reilly
.NET & XML
ADO.NET in a Nutshell
ADO: ActiveX Data Objects
Create a new struts 1.1 project to to understand nested tags.
Object Class Books
Create a class Books with properties id and name in the
package roseindia.web.common.
Add a getter and setter method for each property.
Also add a constructor that initialize the properties.
Books.java
package roseindia.web.common;
public class Books {
private int id;
private String name;
//constructors
public Books(){}
public Books(int id, String name){
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
|
Object Class Authors
Create a second java class Authors in the same package roseindia.web.common.
Add two properties, id of type int and name of type String and one property
books of type Collection, which holds a list of books.
Add a getter and setter method for each property.
Also add a constructor that initialize the properties.
Authors.java
package roseindia.web.common;
import java.util.*;
public class Authors {
private int id;
private String name;
//books collection
private Collection books;
//constructors
public Authors() {}
public Authors(int id, String name, Collection books){
this.id = id;
this.name = name;
this.books = books;
}
public Collection getBooks() {
return books;
}
public void setBooks(Collection books) {
this.books = books;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
|
Action form class AuthorsBooksForm
Create a java class AuthorsBooksForm in the package roseindia.web.struts.form, which extends the class ActionForm of
struts.
Add a property authors of type Authors .
Add a getter and setter method for the property authors .
Implement the reset() method of the ActionForm class.
AuthorsBooksForm.java
package roseindia.web.struts.form;
import java.util.*;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import roseindia.web.common.Authors;
import roseindia.web.common.Books;
public class AuthorsBooksForm extends ActionForm {
Authors authors;
public void setAuthors(Authors authors) {
this.authors = authors;
}
public Authors getAuthors() {
return authors;
}
public void reset(ActionMapping mapping,HttpServletRequest request) {
//initial a dummy collection of books
Collection books = new ArrayList();
books.add(new Books(1, "Teach Yourself C++"));
books.add(new Books(2, "Java: The Complete Reference, J2SE"));
books.add(new Books(3, "Struts: The Complete Reference"));
//initial a dummy authors
authors = new Authors(1, "Herbert Schildt", books);
}
}
|
Action class AuthorsBooksAction
Create a java class AuthorsBooksAction in the package roseindia.web.struts.action, which extends the class Action of
struts.
Return the forward example.
AuthorsBooksAction.java
package roseindia.web.struts.action;
import roseindia.web.struts.form.AuthorsBooksForm;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.*;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
public class AuthorsBooksAction extends Action {
public ActionForward execute(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) {
AuthorsBooksForm booksForm = (AuthorsBooksForm) form;
return mapping.findForward("books");
}
}
|
The JSP file
Create a new JSP file authorsbooks.jsp.
Add the reference to the tag library nested at the top of the file.
authorsbooks.jsp
<%@ page language="java"%>
<%@ taglib uri="/tags/struts-bean" prefix="bean" %>
<%@ taglib uri="/tags/struts-html" prefix="html" %>
<%@ taglib uri="/tags/struts-logic" prefix="logic" %>
<%@ taglib uri="/tags/struts-nested" prefix="nested"%>
<html>
<head>
<title>Struts nested tag Example</title>
</head>
<body>
<h1>Struts nested tag Example</h1>
<b>Author and his books:</b>
<html:form action="/example" method="post">
<nested:nest property="authors">
<b><nested:write property="name"/> </b>
<nested:iterate property="books">
<ul><li><nested:write property="name"/></li></ul>
</nested:iterate>
</nested:nest>
</html:form>
</body>
</html>
|
Configure the struts-config.xml
Open the struts-config.xml and add the form bean and action mapping.
struts-config.xml
<form-beans>
<form-bean name="AuthorsBooksForm"
type="roseindia.web.struts.form.AuthorsBooksForm" />
</form-beans>
<action-mappings>
<action
path="/example"
type="roseindia.web.struts.action.AuthorsBooksAction"
input="/pages/user/authorsbooks.jsp"
name="AuthorsBooksForm"
scope="request"
validate="false">
<forward name="example" path="/pages/user/authorsbooks.jsp" />
</action>
</action-mappings>
|
Output:
To view the output run the authorsbooks.jsp from the browser.
|
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Current Comments
7 comments so far (post your own) View All Comments Latest 10 Comments:java.lang.ClassNotFoundException: org.apache.struts.taglib.nested.NestedWriteNestingTei
Hi all,
The reason for this ugly stack is because
the of incompatibility between struts.jar
and TAG library definition.
Your TAG library version is 1.2
but your struts.jar Specification-Version: 1.1
The tomact by going through your struts-nested.tld
of version 1.2 figured out that it has to load
"org.apache.struts.taglib.nested.NestedWriteNestingTei"
which is not there in struts.jar of version 1.1
Good Luck :)
Posted by Sudhakar KV on Thursday, 06.5.08 @ 16:29pm | #62188
Very nice tutorial! It has been very helpful.
Posted by Nikos on Wednesday, 11.21.07 @ 17:03pm | #38175
please restart ur server, check ur jsp contaier,library finles
Posted by nani on Wednesday, 05.30.07 @ 15:54pm | #17730
This is good one, but an example ofsome runtime data entry from the user side should be there...
Posted by Indubhusan on Friday, 04.13.07 @ 09:16am | #14042
i try to run the above program.but the following error is occured
please reply to my mail
HTTP Status 500 -
--------------------------------------------------------------------------------
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: Failed to load or instantiate TagExtraInfo class: org.apache.struts.taglib.nested.NestedWriteNestingTei
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:50)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:407)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:279)
org.apache.jasper.compiler.TagLibraryInfoImpl.createTagInfo(TagLibraryInfoImpl.java:422)
org.apache.jasper.compiler.TagLibraryInfoImpl.parseTLD(TagLibraryInfoImpl.java:248)
org.apache.jasper.compiler.TagLibraryInfoImpl.<init>(TagLibraryInfoImpl.java:162)
org.apache.jasper.compiler.Parser.parseTaglibDirective(Parser.java:418)
org.apache.jasper.compiler.Parser.parseDirective(Parser.java:483)
org.apache.jasper.compiler.Parser.parseElements(Parser.java:1543)
org.apache.jasper.compiler.Parser.parse(Parser.java:126)
org.apache.jasper.compiler.ParserController.doParse(ParserController.java:211)
org.apache.jasper.compiler.ParserController.parse(ParserController.java:100)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:146)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:286)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:267)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:255)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:556)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:293)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause
java.lang.ClassNotFoundException: org.apache.struts.taglib.nested.NestedWriteNestingTei
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1332)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1181)
org.apache.jasper.compiler.TagLibraryInfoImpl.createTagInfo(TagLibraryInfoImpl.java:419)
org.apache.jasper.compiler.TagLibraryInfoImpl.parseTLD(TagLibraryInfoImpl.java:248)
org.apache.jasper.compiler.TagLibraryInfoImpl.<init>(TagLibraryInfoImpl.java:162)
org.apache.jasper.compiler.Parser.parseTaglibDirective(Parser.java:418)
org.apache.jasper.compiler.Parser.parseDirective(Parser.java:483)
org.apache.jasper.compiler.Parser.parseElements(Parser.java:1543)
org.apache.jasper.compiler.Parser.parse(Parser.java:126)
org.apache.jasper.compiler.ParserController.doParse(ParserController.java:211)
org.apache.jasper.compiler.ParserController.parse(ParserController.java:100)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:146)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:286)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:267)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:255)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:556)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:293)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.9 logs.
--------------------------------------------------------------------------------
Apache Tomcat/5.5.9
Posted by kokul on Saturday, 03.10.07 @ 11:03am | #11304
this tutorils is very nice for a beginer,who have some litle knowledge in struts,the author has done a great job.......
Posted by ravishankar on Wednesday, 03.7.07 @ 14:25pm | #10973
how to use nested tags with dynaactionforms .
can you send me a tutorial for the same
Posted by vidyadhar on Wednesday, 02.28.07 @ 13:04pm | #9939