Struts for the Complete Beginner (Part 1)

NetBeans IDE 5.0 simplifies Struts. By selecting one single checkbox in the New Web Application wizard, all the Struts libraries are added to your project. In addition, you get the magical struts-config.xml file, which is where you register all the Struts functionality that you want to work with. Wizards are provided for the creation of the two categories of Struts classes—actionform beans and actions. Wizards are also accessible from within struts-config.xml, for the generation of the code used to register the Struts functionality.

Here's a really simple procedure for the creation of a Struts application in NetBeans IDE 5.0. You'll use the Struts framework to create a very simple semi-functioning login form:

All the processing will be done by Struts. (What 'processing' consists of is something you'll discover in the steps below.) You won't learn much conceptually, but through following the steps below you'll familiarize yourself with the Struts framework and the way in which support for this framework has been implemented in NetBeans IDE 5.0.

1. Set Up the Project. Click Ctrl-Shift-N, in the Web category choose web application, click Next, and call it MyVideoStoreApplication. Click Next. Select Struts 1.2.7 and click Add Struts TLDs. Click Finish.

   Here's what you should see, with the most important file (the struts-config.xml file) selected (click to enlarge):

   
   

2. Create the JSP Pages. Right-click the MyVideoStoreApplication project node, choose New > JSP, and call it loginForm. Click Finish. Create another JSP and call it loginSuccessful. In the Source Editor, change the content of the H1 tags in both new JSP files to something meaningful. For example, change the text JSP Page to Login Form and Login Successful!, respectively. Do the same for the text in the TITLE tags.

   Now copy the first two taglib directives from the welcomeStruts.jsp file to the top of your new loginForm.jsp. In loginForm.jsp, below the H1 tags, add the following:

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

   It's handy to know that everything between the <html:form> tags is handled by Struts. Notice that while typing, the IDE helps you by suggesting different ways of completing the code that you're typing. It also provides access to Struts Javadoc (click to enlarge):

   
   

   In the Component Palette on the right side of the Source Editor, expand the HTML section and drag the Table item to just above the <html:submit value="Login" /> line. The Insert Table dialog box pops up. Here, make sure that Rows and Columns are both set to 1, so that we'll create a table consisting of one row and one column. Click OK. 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" />

   
   Add login.name as a key to the ApplicationResource.properties file and add a meaningful message. For example:

   login.name=Name

   The body of loginForm.jsp is now as follows:

   

3. Create the Struts ActionForm Bean. Right-click the MyVideoStoreApplication project node and choose New > File/Folder. In the Web category choose Struts ActionForm Bean and click Next. Select com.myapp.struts in the Package drop-down list and press Finish. The actionform bean opens in the Source Editor. 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>

   Now browse through the actionform bean in the Source Editor and look at the validate method. Notice that a 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. 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, banana brain!

   Now add the following in loginForm.jsp, right above the closing </html:form> tag:

   <html:errors />

4. Create the Struts Action. Right-click the MyVideoStoreApplication project node and choose New > File/Folder. In the Web category choose Struts Action and click Next. Select com.myapp.struts in the Package drop-down list. Type login in the Action Path (the content of Action Path is therefore now /login. Click Next. Notice that the IDE suggests that you associate the action with the actionform bean created in the previous step. In Input Resource browse to your loginForm.jsp page. Click Finish.

   Notice that struts-config.xml 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>

   Browse through the action and look at the execute method. Notice that this action forwards to the output view called success. You need to define the loginSuccessful.jsp as your output view. Open struts-config.xml in the Source Editor, right-click anywhere, and choose Struts > Add Forward. Type success in Forward Name. Browse to loginSuccessful.jsp in Resource File. Click Action. Choose /login from the drop-down list. Click Add. Notice that struts-config.xml now shows the following (the new code is 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>

5. Run the Project. Right-click the MyVideoStoreApplication project node and choose Properties. In the Project Properties dialog box, click the Run node. In Relative URL, type login.do. Click OK.

   Now right-click the MyVideoStoreApplication project node and choose Run Project. The project deploys and displays the loginForm.jsp. You should see the following:

   

   When you enter a name (or anything else, so long as it's not nothing), loginSuccesful.jsp is displayed. One interesting thing to do at this point is to go back to the ApplicationResource.properties file. Change the first four keys to the following:

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

   Now deploy the application again. If loginSuccesful.jsp opens, and you don't want it to, change the scope attribute of the /login path in struts-config.xml from session to request. Deploy again and notice that the error message has been reformatted:

   
   

In future blog entries (and probably in an official NetBeans tutorial), I'll expand on this scenario so that it provides more functionality and so that it becomes a more useful login form. (Update: Click here for Part 2!)