Part IV: Putting It All Together in Java

Creating QR Code in Java Part IV: Putting It All Together

Listing 14-5 (continued)

ModuleException me = new ModuleException( errordbsql ); throw me; } } finally { finally code omitted } return user; }

When a user tries to join, three possibilities can occur As a result, there are three possible directions to take from the JoinAction If a user account gets created, go to the welcomejsp page If a user account fails to be created, return to the joinjsp page If the user cancels the registration process, go back to the homejsp page Make sure to turn on validation by setting the validation attribute to true Here is the action mapping for JoinAction:

<action path= /join type= dummiesstrutsmusicJoinAction name= joinForm scope= request input= /joinjsp validate= true > <forward name= cancel path= /homejsp /> <forward name= failure path= /joinjsp /> <forward name= success path= /welcomejsp /> </action>

The Welcome page is displayed after the user successfully creates an account This page presents a personalized welcome message along with a link to take the user to the main music display page Figure 14-6 shows the Welcome page

When a user has logged on, the application retrieves the user s album infor mation from the database and displays it in a list From this page, the user can create, edit, or delete an album There is also a Logoff button for the user to invalidate the user s session

On the MusicList page, we ll be displaying a collection of items, namely albums This means we need to dig a little deeper into the JSTL tag library to discover some of the iterative tags For each album displayed, we will show the following information: A number representing the row number of the album in the current list The album name, which is also a link to the entire album record for edit ing and viewing The individual or group who recorded the album The year the album was released A delete link that enables the user to delete the album from the collection In addition, the page has two buttons, as shown in Figure 14-7 The first is used to add a new album to the list, and the second is used to log off MusicCollectioncom Clicking the Add an Album button results in

MusicListAction forwarding the request to AlbumAction For the Logoff button, the MusicListAction redirects the request to LogoffAction

Because the MusicList page has no input fields, you might conclude that no form is necessary However, several functions can be used from the page, namely creating a new album and logging off (You can also edit and delete an album, but these actions are handled directly by AlbumAction, not MusicListAction) Therefore, you need to have a way of specifying the par ticular action to MusicListAction To do so, you can create a hidden field named action that specifies the requested action When the page is submitted, the value in the action field determines what function needs to be performed The two actions are new, to create a new album, and logoff, to invalidate the user s session Here is the form definition in the struts-config file:

<form-bean name= musiclistForm type= orgapachestrutsactionDynaActionForm > <form-property name= action type= javalangString initial= /> </form-bean>

MusicListAction needs to handle three situations that can arise from a user s action The first is displaying the user s list of albums When MusicListAction is called, the action form variable determines what action should be per formed If action is null or empty, the request displays all the user s albums MusicListBean does all the work to retrieve the album list MusicListAction

just needs to instantiate the bean and pass it the user object The bean returns the list of albums in a Collection, which MusicListAction puts into the ses sion for use by the MusicList page for display If the action form variable s value is add, the user is requesting to create an album AlbumAction handles the creation of the new album Therefore, con trol is forwarded to newalbum ActionForward The third possibility is when the action form variable equals logoff, which indicates that the user wants to log off the MusicCollectioncom Web site Control is forwarded to logoff ActionForward, which is the LogoffAction class Listing 14-6 lists the code for MusicListAction

Listing 14-6