First Struts Tutorial (free tools, Struts Console, JBoss IDE)
This tutorial will explain first steps using
the web framework Apache Struts and the development environment
eclipse. We will create a simple example library application using free plugins like the Struts Console and the JBOSS IDE.
General
Autor:
Sebastian Hennebrüder
Sascha Wolski
http://www.laliluna.de/tutorials.html
Datum:
January, 20th 2005
Development
Tools
Eclipse
3.x
Struts
Console
JBOSS
IDE (when using JBOSS)
Sysdeo
Plugin (when using Tomcat)
Source
code:
http://www.laliluna.de/download/first_steps_with_struts.zip
Using the source code.
The
source code does not include any libraries but the sources. Create a
web project, add the libraries manually as explained in the tutorial.
Then extract the sources, we provided, to your project.
The
PDF Version of the tutorial.
http://www.laliluna.de/download/first-steps-with-struts-free-tools-en.pdf
Inhaltsverzeichnis
First
steps tutorial using struts and eclipse 1
Allgemeines 1
Requirements 1
Installation
of the Struts Console 2
Create
a Web Project 2
Adding
Struts Support 2
Create
a default welcome page 4
Global
Action Forwards and Action Mappings 5
Usecase
Book List 6
Usecase
Add, edit and remove the data 15
Changes
to the book list JSP 21
Testen
der Anwendung 22
Requirements
We
require the installation of the JBOSS IDE, when you are using JBOSS
as application server. A Tutorial how to create and deploy web
projects with the JBOSS IDE can you find here.
http://www.laliluna.de/articles/posts/webprojects-eclipse-jbosside-tutorial-en.html
When
you are using Tomcat, you can use the Eclipse Plugin
http://www.sysdeo.com/eclipse/tomcatPlugin.html
as
an alternative.
Installation of the Struts Console
Download the sources from the website
http://www.jamesholmes.com/struts/console/
Unzip the file and copy the
directory
com.jamesholmes.console.struts
to the
path eclipseplugins
Start
Eclipse and that’s it.
Create a Web
Project
The
creation of a web project with the JBOSS IDE is explained in the
tutorial
http://www.laliluna.de/articles/posts/webprojects-eclipse-jbosside-tutorial-en.html
which
was mentioned in the requirements. Explain a web project as explained
there.
Adding Struts Support
For now your
project is a normal J2EE project, so we need to add the struts
capabilities (libraries, xml files, …). The easiest way is to copy
a blanc struts project into your project.
You can download a blanc project here.
http://www.laliluna.de/download/struts-blanc-project-1.2.zip
Unzip the content of the blanc struts project into
your project in the eclipse workspace.
Actualize the project
in the package explorer by clicking on the right mouse button ->
command ?refresh?.
Your project looks
like the following now.
Adding the struts libraries
Now you must add the libraries to your classpath.
Right click on the project and select ?properties? in the context
menu.
Select ?Java Build Path? and ?add jars? in
the Libraries tab.
You
will find the JAR files in Projekt > WebRoot > WEB-INF >
lib. Use SHIFT to select
multiple jar files.
The struts
libraries are now listed in the package explorer.
Create a default welcome page
Ok, now we want to create a default page.
Right click (yes again) on the Folder WebRoot
in the Project and choose New
> JSP. If you cannot
find this option, select ?other? and then JSP.
You must have installed the JBOSS IDE!
Create a new JSP in the directory WebRoot.
You
will find the file index.jsp
in the folder WebRoot of
the project. We must add the Struts Tag Libraries to our JSP. We need
Tag Libraries to use Struts Tags in a JSP. In this case we only need
the Struts logic tab library. Change your JSP content to the
following.
<b><%@page contentType=</b>"text/html"<b> %></b><br><b><%@ page language=</b>"java"<b>%></b><br><br><b><%@ taglib uri=</b>"http://jakarta.apache.org/struts/tags-logic"<b> prefix=</b>"logic"<b> %></b><br><br><br><logic:forward name="welcome"/>
The
logic:forward tag makes Struts look for a forward in the
configuration files. When it cannot find this forward an Exception
will occure. We explain Action Forwards in the next chapter.
Create
a second JSP index.jsp
in the directory /WebRoot/jsp.
Change the JSP to the following:
<%@ page language=“java”%>
<%@ taglib uri=“http://jakarta.apache.org/struts/tags-html” prefix=“html” %>
<!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN”>
<html:html locale=“true”>
<head>
<html:base />
<title>index.jsp</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”>
</head>
<body>
Welcome!
<br>
<html:link action=“bookList”>Show the booklist</html:link>
</body>
</html:html>
Global Action Forwards and
Action Mappings
What
is an action forward?
A
action forward can be used to forward to a jsp or action mapping.
There are two different action forwards. The global action forward
and the local action forward. You can access a global action forward
on each jsp or action class. A local action forward can only be
accessed by the assigned action class.
What
is a action mapping?
The
action mapping is the heart of struts. It managed all actions between
the application and the user. You can define which action will be
executed by creating a action mapping.
The diagram show you, how the application
server manage the request of the index.jsp
or a non existing action
mapping.
In the first
step we create a new action mapping. Open
the struts configuration file struts-config.xml, which is located in
WebRoot/WEB-INF.
The Struts Console is opened. (If not, right click on the
struts-config.xml and select ?open with?.
Click on Action Mappings and select Add.
Input /default as path and select the Action
Type Forward. As Forward
Path we will use our welcome page /jsp/default.jsp
In the next step we will create the Global
Action Forward. Click on ?Global Forwards?, select ?add?.
Choose /default.do as path, wich is the
action we specified above.
Usecase Book List
A Struts Action does always some kind of
business logic and saves the result in a class of type ActionForm.
The data from the ActionForm can be displayed in a JSP.
Our
Action will read data from the database, save it in the action form.
The JSP will display our data.
Create a object class ?book?
Create a new class Book
in the package de.laliluna.tutorial.library.
The Class Book
represents a book with the properties id, author, title and
available.
Create four variables.
Create a getter and setter for each
variable. Right click in your class, Source
> Generate Getters and Setters
Choose Select
All and insertion point Last
method.
Add two constructors to the class to set the
properties on initialisation of the class.
// Contructor<br>public Book(){}<br><br>// Contructor to initial the properties<br>public Book(long id, String author, String title, boolean available) {<br> this.id = id;<br> this.author = author;<br> this.title = title;<br> this.available = available;<br>}<br>
Thats all for our book class!
Create a form bean, action form and jsp
Create a new sub
class of ActionForm. The ActionForm will hold our books to display
them in the JSP.
Open the
struts-config.xml and add
a new form bean with the struts console. The type is our just created
class.
Change the source code of the action form class.
Open
the file BookListForm.java and change the source code:
public class BookListForm extends ActionForm {<br><br> private Collection books;<br><br> /* lalinuna.de 02.11.2004<br> * get the collection books<br> */<br> public Collection getBooks() {<br> return books;<br> }<br><br> /* lalinuna.de 02.11.2004<br> * set the collection books<br> */<br> public void setBooks(Collection books) {<br> this.books = books;<br> }<br><br> /* lalinuna.de 02.11.2004<br> * reset the collection books<br> */<br> public void reset(ActionMapping arg0, HttpServletRequest arg1) {<br> books = new ArrayList();<br> }<br>}
In our class we have defined a collection
books and the access
methods (getters and setters).The method reset
is called by struts each time a form is initialized. When your scope
is request, this is at each request.
Create an action mapping and an action class.
Create a class BookListAction. This class
loads the books from the database and saves it in the BookListForm.
Change the source code of the action class.
Open the class bookListAction
and implement the methode execute
from the super class ActionForm.
The following call
mapping.findForward(“showList”)
looks for a forward with the
name ?showList? in the action mapping declaration and forwards to
it.
/** <br> * Method execute<br> * @param mapping<br> * @param form<br> * @param request<br> * @param response<br> * @return ActionForward<br> */<br> public ActionForward execute(<br> ActionMapping mapping,<br> ActionForm form,<br> HttpServletRequest request,<br> HttpServletResponse response) {<br> BookListForm bookListForm = (BookListForm) form;<br><br><br> /* lalinuna.de 03.11.2004<br> * init SimulateDB class and set some dummy data<br> */<br> SimulateDB simulateDB = new SimulateDB();<br> bookListForm.setBooks(simulateDB.getAllBooks(request.getSession()));<br><br><br> return mapping.findForward("showList");<br> }
Database simulation class
We will not use a real database in this
tutorial but a database simulation. Copy the file SimulateDB.java
from the source code which we provided as a download above to the
package de.laliluna.tutorial.library.
Struts configuration for the book list
Create
a new action mapping with the Struts Console. The path must begin
with a slash, the typoe is the action we have just created.
Click on the Action Mapping in the Struts
console to access the advanced settings.
Create a Forward for the Action Mapping of
the JSP with the name showList
Create the book list JSP
Create a new JSP in the directory /jsp/ ,
name it bookList.jsp .
<%@ page language="java"%><br><%@ taglib uri="http://jakarta.apache.org/struts/tags-bean" prefix="bean"%><br><%@ taglib uri="http://jakarta.apache.org/struts/tags-html" prefix="html"%><br><%@ taglib uri="http://jakarta.apache.org/struts/tags-logic" prefix="logic"%><br><html><br><head><br><title>Show book list</title><br></head><br><body><br><table border="1"><br> <tbody><br> <%-- set the header --%><br> <tr><br> <td>Author</td><br> <td>Book name</td><br> <td>Available</td><br> <td>&nbsp;</td><br> <td>&nbsp;</td><br> </tr><br> <%-- check if book exists and display message or iterate over books --%><br> <logic:empty name="bookListForm" property="books"><br> <tr><br> <td colspan="5">No books available</td><br> </tr><br> </logic:empty><br> <logic:notEmpty name="bookListForm" property="books"><br> <logic:iterate name="bookListForm" property="books" id="book"><br> <tr><br> <%-- print out the book informations --%><br> <td><bean:write name="book" property="author" /></td><br> <td><bean:write name="book" property="title" /></td><br> <td><html:checkbox disabled="true" name="book" property="available" /><br> </td><br> <%-- print out the edit and delete link for each book --%><br> <td><html:link action="bookEdit.do?do=editBook" paramName="book"<br> paramProperty="id" paramId="id">Edit</html:link></td><br> <td><html:link action="bookEdit.do?do=deleteBook" paramName="book"<br> paramProperty="id" paramId="id">Delete</html:link></td><br> </tr><br> </logic:iterate><br> </logic:notEmpty><br> <br> <%-- end interate --%><br> </tbody><br></table><br></body><br></html>
The tag
<logic:iterate> loops over the collection books
of the form bean bookListForm
Within
the tag <logic:iterate>
you have access to the properties of the book. The tag <bean:write>
prints out a property (author, title) on the current position.
<html:checkbox>
creates a checkbox.
Es ist
geschafft puhhhh, wir haben unser Form Bean mit Action Form Klasse,
unser Action Mapping mit Action Klasse und unsere JSP, die uns zur
Anzeige dient, angelegt.
Very good. We
have create an action class which saves the data in an action form.
To display the book list we have created a JSP which uses the data in
the action form. Easy, isn’t it.
If you like
you do a first test of your application right here. Have a look at
the end of the tutorial, to see how to test.
Usecase Add, edit and remove the data
In the next section we add the functionality
to add, edit and remove the data. The process is the same:
-
Action
-
ActionForm
-
Struts Konfiguration
New
form bean
Create a new class as action form in the
package de.laliluna.tutorial.library.form . Call it BookEditForm.
Add a new
instance of book.
Book book = new Book();
Generate the getters and setters.
Then delegate all methods from the class Book.
The source
code should look like:
public class BookEditForm extends ActionForm {
Book book = new Book();
public Book getBook() {
return book;
}
public void setBook(Book book) {
this.book = book;
}
public boolean equals(Object arg0) {
return book.equals(arg0);
}
public String getAuthor() {
return book.getAuthor();
}
public long getId() {
return book.getId();
}
public String getTitle() {
return book.getTitle();
}
public int hashCode() {
return book.hashCode();
}
public boolean isAvailable() {
return book.isAvailable();
}
public void setAuthor(String author) {
book.setAuthor(author);
}
public void setAvailable(boolean available) {
book.setAvailable(available);
}
public void setId(long id) {
book.setId(id);
}
public void setTitle(String title) {
book.setTitle(title);
}
public String toString() {
return book.toString();
}
}
Now we can access the attributes of book
later in the action form.
Create the action class
Create a new class. This time the class is not a
sub class of Action but of org.apache.struts.DispatchAction.
A DispatchAction calls not the
execute method but can call different methods depending on a
parameter. With the parameter we can decide if the create/edit/delete
method is called.
Source code of the DispatchAction class
Open the file
bookEditAction.java.
Add the methods:
/** <br> * Method editBook<br> * @param mapping<br> * @param form<br> * @param request<br> * @param response<br> * @return ActionForward<br> */<br>public ActionForward editBook(<br> ActionMapping mapping,<br> ActionForm form,<br> HttpServletRequest request,<br> HttpServletResponse response) {<br> BookEditForm bookEditForm = (BookEditForm) form;<br><br> /* lalinuna.de 04.11.2004<br> * get id of the book from request<br> */<br> long id = Long.parseLong(request.getParameter("id"));<br><br> /* lalinuna.de 04.11.2004<br> * init SimulateDB class and get book by id<br> */<br> SimulateDB simulateDB = new SimulateDB();<br> bookEditForm.setBook(simulateDB.loadBookById(id, request.getSession()));<br><br> return mapping.findForward("showEdit");<br><br>}
The method editBook get
the parameter id of the
request and reads the book
by id from the simulated database. The forward showEdit
refres to the edit page bookEdit.jsp
/** <br> * Method deleteBook<br> * @param mapping<br> * @param form<br> * @param request<br> * @param response<br> * @return ActionForward<br> */<br>public ActionForward deleteBook(<br> ActionMapping mapping,<br> ActionForm form,<br> HttpServletRequest request,<br> HttpServletResponse response) {<br> BookEditForm bookEditForm = (BookEditForm) form;<br><br> /* lalinuna.de 04.11.2004<br> * get id of the book from request<br> */<br> long id = Long.parseLong(request.getParameter("id"));<br><br> /* lalinuna.de 04.11.2004<br> * init SimulateDB class and delete book by id<br> */<br> SimulateDB simulateDB = new SimulateDB();<br> simulateDB.deleteBookById(id, request.getSession());<br><br> return mapping.findForward("showList");<br><br>}<br>
The method deleteBook get
the parameter id of the
request and remove the
book by id from the simulated database. The forward showList
refres to the book listing page bookList.jsp
/*
* Method addBook
* @param mapping
* @param form
* @param request
* @param response
* @return ActionForward
*/
public ActionForward addBook(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) {
BookEditForm bookEditForm = (BookEditForm) form;
return mapping.findForward(“showAdd”);
}
The method addBook
forwards on the add page bookAdd.jsp
/*
* Method saveBook
*param mapping<br> * @param form<br> * @param request<br> * @param response<br> * @return ActionForward<br> */<br>public ActionForward saveBook(<br> ActionMapping mapping,<br> ActionForm form,<br> HttpServletRequest request,<br> HttpServletResponse response) {<br> BookEditForm bookEditForm = (BookEditForm) form;<br><br> /* lalinuna.de 04.11.2004<br> * init SimulateDB class and get data by id<br> */<br> SimulateDB simulateDB = new SimulateDB();<br> simulateDB.saveToDB(bookEditForm.getBook(), request.getSession());<br><br> return mapping.findForward("showList");<br><br>}</pre> <p> The last method get the book of the form bean bookEditForm and save it in the simulated Database. Then the application forwards to the book list.</p> <h2>Struts configuration</h2> <p>Create a new form bean with the Struts Console.</p> <p><img width="389" height="135" border="0" align="left" name="grafik57" src="/images/articles/first-steps-using-struts-tutorial/cons-bookedit-mapping1.gif"><br clear="left"><br><br></p> <p>Create a new action mapping. As parameter specify do. This parameter is needed by the DispatchAction.</p> <p><img width="476" height="256" border="0" align="left" name="grafik58" src="/images/articles/first-steps-using-struts-tutorial/cons-bookedit-mapping2.gif"><br clear="left"><br><br></p> <p align="left">Change theAction.</p> <p align="left"><img width="577" height="280" border="0" align="left" name="grafik59" src="/images/articles/first-steps-using-struts-tutorial/cons-bookedit-mapping3.gif"><br clear="left"><br><br></p> <p>Create three forwards in the ?forward tab?. One for the JSP to edit, one for the JSP to add and one which forwards to the book list.</p> <p><br><br></p> <p>The lost forward does not forward to a JSP but to another action.</p> <p><img width="464" height="197" border="0" align="left" name="grafik60" src="/images/articles/first-steps-using-struts-tutorial/cons-bookedit-mapping4.gif"><br clear="left"><br><br></p> <p>Create a JSP bookAdd.jsp in the directory /WebRoot/jsp. The forward showAdd forwards to this page.</p> <h2>Change the source code of the JSP</h2> <p>Open the file bookAdd.jsp and add the following source code.</p> <p> </p> <pre><%page language=“java”%>
<%@ taglib uri=“http://jakarta.apache.org/struts/tags-bean” prefix=“bean”%>
<%@ taglib uri=“http://jakarta.apache.org/struts/tags-html” prefix=“html”%>
<%@ taglib uri=“http://jakarta.apache.org/struts/tags-logic” prefix=“logic” >
<html>
<head>
<title>Add a book</title>
</head>
<body>
<— create a html form-%>- print out the form data
<html:form action=“bookEdit”>
<%-%>- set the parameter for the dispatch action —%>
<table border=“1”>
<tr>
<td>Author:</td>
<td><html:text property=“author” /></td>
</tr>
<tr>
<td>Title:</td>
<td><html:text property=“title” /></td>
</tr>
<tr>
<td>Available:</td>
<td><html:checkbox property=“available” /></td>
</tr>
<tr>
<td colspan=“2”>
<html:submit>Save</html:submit>
</td>
</tr>
</table>
<%
<html:hidden property=“do” value=“saveBook” />
</html:form>
</body>
</html>
The tag <html:form>
creates a new HTML form and refers with the parameter
action=?bookEdit? to
the action mapping. The Tag <html:text>
creates a text field with the property author of the
book.
<html:hidden>
is a hidden form field with the name do. We need this hidden field,
because it tells the dispatch action class which method will called.
Open the file bookEdit.jsp.
You can use the source code of the of the file bookAdd.jsp
and change the following lines.
<title>Edit a book</title>
Add the following line above <html:hidden
property=“do” value=“saveBook” />
<%— hidden field that contains the id of the book-%>
<html:hidden property=“id” />
Changes to the book list JSP
Open the file bookList.jsp
and change the source code:
<%@ page language=“java”%>
<%@ taglib uri=“http://jakarta.apache.org/struts/tags-bean” prefix=“bean”%>
<%@ taglib uri=“http://jakarta.apache.org/struts/tags-html” prefix=“html”%>
<%@ taglib uri=“http://jakarta.apache.org/struts/tags-logic” prefix=“logic”%>
<html>
<head>
<title>Show book list</title>
</head>
<body>
<table border=“1”>
<tbody>
<%- set the header-%>- check if book exists and display message or iterate over books
<tr>
<td>Author</td>
<td>Book name</td>
<td>Available</td>
<td> </td>
<td> </td>
</tr>
<%-%>- print out the book informations
<logic:empty name=“bookListForm” property=“books”>
<tr>
<td colspan=“5”>No books available</td>
</tr>
</logic:empty>
<logic:notEmpty name=“bookListForm” property=“books”>
<logic:iterate name=“bookListForm” property=“books” id=“book”>
<tr>
<%-%>- print out the edit and delete link for each book
<td><bean:write name=“book” property=“author” /></td>
<td><bean:write name=“book” property=“title” /></td>
<td><html:checkbox disabled=“true” name=“book” property=“available” />
</td>
<%-%>- print out the add link
<td><html:link action=“bookEdit.do?do=editBook” paramName=“book”
paramProperty=“id” paramId=“id”>Edit</html:link></td>
<td><html:link action=“bookEdit.do?do=deleteBook” paramName=“book”
paramProperty=“id” paramId=“id”>Delete</html:link></td>
</tr>
</logic:iterate>
</logic:notEmpty>
<%-%>- end interate
<tr>
<td colspan=“5”><html:link action=“bookEdit.do?do=addBook”>Add a new book</html:link>
</td>
</tr>
<%-%>
</tbody>
</table>
</body>
</html>
Now, you have finished all the coding and
can test your application.
Testen der Anwendung
Start
the jboss and deploy the project as package archiv. (We have
explained this in the JBOSS IDE Webproject tutorial, mentioned
above.)
Call
the project in your favorite web browser.
http://localhost:8080/LibraryWeb/
Gratulation, you are close to be a struts
expert. ;)