Using Struts Custom Tag Libraries in a JSP Page

Many web applications use JavaServer Pages (JSP) for the view in the MVC paradigm, so Struts provides custom tag libraries which facilitate interaction with HTML forms. These can be very easily and smoothly set up and used in a JSP page in the IDE.

1. Right-click the LoginPage project node, choose New > JSP, and name the new JSP page loginForm. Click Finish.
2. In the Source Editor, change the content of the <h2> tags to Login Form and do the same for the text in the <title> tags.
3. Copy these first two taglib directives from the welcomeStruts.jsp file to the top of your new loginForm.jsp file:

   <%@ taglib uri="http://jakarta.apache.org/struts/tags-bean" prefix="bean" %>
   <%@ taglib uri="http://jakarta.apache.org/struts/tags-html" prefix="html" %>

4. In loginForm.jsp, below the <h2> tags, add the following:

   <html:form action="login">
   
      <html:submit value="Login" />
   
   </html:form>

   
   Notice that when you type in the Source Editor, the IDE provides you with code completion for Struts tags, as well as the Struts Javadoc:
   
   Whenever you finish typing in the Source Editor, you can neaten the code by right-clicking and choosing Format (Alt-Shift-F).
5. In the Component Palette (Ctrl-Shift-8) on the right side of the Source Editor, within the HTML section, drag the Table item to just above the <html:submit value="Login" /> line. The Insert Table dialog box pops up. Set both the rows and Ccolumns to 1, so that you will create a table consisting of one row and one column. Click OK. The loginForm.jsp now looks as follows:

   <html:form action="login">
       <table border="1">
           <thead>
               <tr>
                   <th></th>
               </tr>
           </thead>
           <tbody>
               <tr>
                   <td></td>
               </tr>
           </tbody>
       </table>
   
       <html:submit value="Login" />
   
   </html:form>

6. In between the <th> tags, type the following:

   <bean:message key="login.name" />

   
   In between the <td> tags, type the following:

   <html:text property="name" />

   
   The body of loginForm.jsp is now as follows:
   
7. In the Projects window, expand the Source Packages node, expand the com.myapp.struts node, and double-click the ApplicationResource.properties file so that it opens in the Source Editor. Add login.name as a key, anywhere in the ApplicationResource.properties file, and add a meaningful message. For example:

   login.name=Name

Using Struts to Validate a Field in a JSP Page

A Struts actionform bean represents data shared between the view (in this case, a JSP page) and the Struts action class. An actionform bean is available both for populating the view and for providing input to an action class. An actionform bean also has a validate method to allow input mapped from the view to be verified.

1. Right-click the LoginPage project node and choose New > Other. In the Struts category choose Struts ActionForm Bean and click Next. Notice that your actionform bean is named "NewStrutsActionForm". Leave the default name for purposes of this tutorial. Select com.myapp.struts in the Package drop-down list and click Finish.
   
   The actionform bean opens in the Source Editor. By default, the IDE provides it with a String called name and an int called number. Both fields also have getters and setters defined for them.
2. Open struts-config.xml in the Source Editor and note that it contains, among other things, the following:

   <form-beans>
       <form-bean name="NewStrutsActionForm" type="com.myapp.struts.NewStrutsActionForm" />
   </form-beans>

   Hold down the Ctrl key and move your mouse over the actionform bean's fully qualified class name:
   
   A hyperlink appears. Click it to navigate to the actionform bean.
3. Now browse through the actionform bean in the Source Editor. Look at the validate method that the IDE created for you:

   public ActionErrors validate(ActionMapping mapping, HttpServletRequest request) {
       ActionErrors errors = new ActionErrors();
       if (getName() == null || getName().length() < 1) {
           errors.add("name", new ActionMessage("error.name.required"));
           // TODO: add 'error.name.required' key to your resources
       }
       return errors;
   }

   Notice that the field called name is validated by default. If validation fails, which happens when no name is entered in the JSP page, a message that is identified by error.name.required is returned.
4. Following the TODO instruction that the IDE put in the validate method for you, add error.name.required as a key to the ApplicationResource.properties file and add a meaningful message. For example:

   error.name.required=Enter a name!

   At the top of the file, to customize the formatting of your error message, change the first four keys to the following:

   errors.header=
   errors.prefix=<span style="color: red" >
   errors.suffix=</span>
   errors.footer=

5. Specify where you want the error message to be rendered, by adding the following line in loginForm.jsp, right above the closing </html:form> tag:

   <html:errors />

Using Struts to Navigate between JSP Pages

A Struts action class is executed in response to a user request and commonly interacts with the model through a business delegate. The responsibility of an action class is to provide navigation and forward control to the appropriate view.

1. Right-click the LoginPage project node and choose New > Other. In the Struts category choose Struts Action and click Next.
2. In the Name and Location panel, notice that your action class is called "NewStrutsAction". Leave the default name for purposes of this tutorial.
3. Select com.myapp.struts in the Package drop-down list.
4. Type login in Action Path (the content of Action Path is therefore now /login). Click Next.
5. In ActionForm Bean, Parameter, notice that the IDE suggests that you associate the action class with the actionform bean that you created in the previous step. In Input Resource, browse to your loginForm.jsp page. Click Finish.
6. Open struts-config.xml in the Source Editor and note that it contains, among other things, the following:

   <action-mappings>
       <action input="/loginForm.jsp"
           name="NewStrutsActionForm"
           path="/login"
           scope="session"
           type="com.myapp.struts.NewStrutsAction" />
       <action path="/Welcome"
           forward="/welcomeStruts.jsp" />
   </action-mappings>

   If you want the action class to function per request, instead of per session, put the cursor in the scope attribute and press Ctrl-Space:
   
   Choose Request.
7. Hold down the Ctrl key and move your mouse over the action class's fully qualified class name:
   
   A hyperlink appears. Click it to navigate to the action class.
8. Browse through the action class and look at the execute method:

   public ActionForward execute(ActionMapping mapping, ActionForm  form,
       HttpServletRequest request, HttpServletResponse response)
       throws Exception {
   
       return mapping.findForward(SUCCESS);}

   Notice the definition of SUCCESS, at the top of the NewStrutsAction:

   private final static String SUCCESS = "success";

   The SUCCESS string declaration specifies that this action class forwards to the output view called success.
9. You need to define a page that will be displayed when the output view above is called. So, create another JSP in the same location as loginForm.jsp and call it loginSuccessful. In the Source Editor, change the default content of the <h2> tags in the new JSP files to Login Successful! and do the same for the text in the <title> tags.
10. Open struts-config.xml in the Source Editor, right-click anywhere in the /login action mapping, and choose Struts > Add Forward. The Add Forward dialog box opens. Type success in Forward Name. Browse to loginSuccessful.jsp in Resource File. The dialog box should now look as follows:
    
    Click Add. Notice that struts-config.xml now shows the following (new code in bold):

    <action-mappings>
    
        <action input="/loginForm.jsp"
            name="NewStrutsActionForm"
            path="/login"
            scope="session"
            type="com.myapp.struts.NewStrutsAction">
            <forward name="success"
                path="/loginSuccessful.jsp"/>
        </action>
    
        <action path="/Welcome"
            forward="/welcomeStruts.jsp"/>
    
    </action-mappings>

Using Struts to Add "Cancel" Functionality

In this section, we add Cancel functionality, which is handled by Struts.

1. In loginForm.jsp, below the <html:submit> line, create the Cancel button by adding the following:

   <html:cancel />

2. Add these lines to the execute method in org.myapp.struts.NewStrutsAction:

   if (isCancelled(request)) {
       return mapping.findForward(CANCEL);
   }

   Press Ctrl-Space within the isCancelled method and then read the Javadoc to understand the method:
   
   Declare the definition of CANCEL at the top of the NewStrutsAction class, right below the definition of SUCCESS:

   private final static String CANCEL = "cancel";

3. You need to define a page that will be displayed when CANCEL is called. So, create another JSP in the same location as loginForm.jsp and call it loginCancel. In the Source Editor, change the default content of the <h2> tags in the new JSP files to Login Cancelled! and do the same for the text in the <TITLE> tags.
4. Open struts-config.xml in the Source Editor, right-click anywhere in the /login action mapping, and choose Struts > Add Forward. The Add Forward dialog box opens. Type cancel in Forward Name. Browse to loginCancel.jsp in Resource File. The dialog box should now look as follows:
   
5. Click Add. Notice that struts-config.xml now shows the following (new code in bold):

   <action-mappings>
   
       <action input="/loginForm.jsp"
           name="NewStrutsActionForm"
           path="/login"
           scope="session"
           type="com.myapp.struts.NewStrutsAction">
           <forward name="success"
               path="/loginSuccessful.jsp"/>
           <forward name="cancel"
               path="/loginCancel.jsp"/>
       </action>
   
       <action path="/Welcome"
           forward="/welcomeStruts.jsp"/>
   
   </action-mappings>

6. In Struts 1.2.9 and 1.3, note that there are changes in cancellation functionality, as described here. As a result, you need to add the line below (in bold):

   <action-mappings>
   
       <action input="/loginForm.jsp"
           name="NewStrutsActionForm"
           path="/login"
           scope="session"
           type="com.myapp.struts.NewStrutsAction">
           <forward name="success"
               path="/loginSuccessful.jsp"/>
           <forward name="cancel"
               path="/loginCancel.jsp"/>
           <set-property property="cancellable" value="true"/>
       </action>
   
       <action path="/Welcome"
           forward="/welcomeStruts.jsp"/>
   
   </action-mappings>

7. Run the application again and notice the new Cancel button:
   
   Click it and notice that the new loginCancel.jsp page is opened in the browser.

Using Struts to Add "Logout" Functionality

1. In loginForm.jsp, below the <h2> tags, create the Logout link by adding the following:

   <html:link action="/logout">Logout</html:link>

2. You need to define a page that will be displayed when the Logout link is clicked. So, create another JSP in the same location as loginForm.jsp and call it loginOut. In the Source Editor, change the default content of the <h2> tags in the new JSP files to Have a Nice Day! and do the same for the text in the <title> tags.
3. Open struts-config.xml in the Source Editor, right-click anywhere, and choose Struts > Add Forward/Include Action. The Add Forward/Include Action dialog box opens.
4. Type logout in Action Path. Browse to loginOut.jsp in Resource File. The dialog box should now look as follows:
   
5. Click Add. Notice that struts-config.xml now shows the following (new code in bold):

   <action-mappings>
   
       <action input="/loginForm.jsp"
           name="NewStrutsActionForm"
           path="/login"
           scope="session"
           type="com.myapp.struts.NewStrutsAction">
           <forward name="success"
               path="/loginSuccessful.jsp"/>
           <forward name="cancel"
               path="/loginCancel.jsp"/>
       </action>
   
       <action forward="/loginOut.jsp"
           path="/logout"/>
   
       <action path="/Welcome"
           forward="/welcomeStruts.jsp"/>
   
   </action-mappings>

6. Run the application again and notice the new Logout link:
   
   Click it and notice that the new loginOut.jsp page is opened in the browser.

Using Struts to Add "Reset" Functionality

1. In loginForm.jsp, between the Submit and Cancel buttons, create the Reset button by adding the following:

   <html:reset />

2. Run the application again and notice the new Reset button:
   
   Type something in the Name row, click Reset, and notice that Struts empties the table.