如何将对象从JSP表单传递到Struts2中的Action类而不将所有表单字段定义为类属性？

Question

To make the question clear I make an example:

1. consider theSubscriber form defined bellow in first.jsp :

    <s:form id="theSubscriber" name="theSubscriber" method="post" action="next.action"> <s:bean name="my.hibernate.actors.Subscriber" var="user"> <s:hidden name="id" key="id" value="%{user.id}" /> <s:textfield id="subscriberForename" name="forename" key="forename" value="%{user.forename}" label="Forename" /> <s:textfield id="subscriberSurname" name="surname" key="surname" value="%{user.surname}" label="Surname" /> </s:bean> </s:form> 

2. consider the following action class for the next.action

    public class NextAction extends ActionSupport { private Subscriber user = new Subscriber(); private String forename; public String getForename() { return forename; } public void setForename(String forename) { this.forename = forename; } public ManageSubscriber() { // TODO Auto-generated constructor stub } public ManageSubscriber(Subscriber user) { this.user = user; } public Subscriber getUser() { return user; } public void setUser(Subscriber user) { this.user = user; } public String execute() { System.out.println(getUser());//This prints out null System.out.println(getForename());//This prints out the posted forename return SUCCESS; } } 

3. The question is: I know that defining all the form fields as action class properties let the class fill them correctly. But I want to make it fill the relevant fields in another class which contains all necessary properties. The user/subscriber class is like this:

    public class User { private long id; private String username; private String password; private UserLevel userLevel; private String forename; private String surname; private String email; private String phoneNumber; private String address; private Date birthday; private Date registrationDate; } 

I have defined all accessor methods. In fact the problem is that it looks very annoying and redundant to define all these fields for the nextAction class and then evaluate the instance of user in that class.

How should I solve this problem?

Answer 1

It is easier than you think.

You are very close, and you've already done it for value attribute (used to pre-set the value for the item on the page): now just do it for name attribute (used to send the value to the Action), like this:

<s:hidden name="user.id" key="id" value="%{user.id}"  />
<s:textfield id="subscriberForename" name="user.forename"
    value="%{user.forename}" label="Forename" />
<s:textfield id="subscriberSurname" name="user.surname" 
    value="%{user.surname}" label="Surname" />

( Key attribute was not necessary here)

Note that for this to work, you will need a bean with a no-args constructor (as you have).

Avoid initializating it yourself too.

Change this:

private Subscriber user = new Subscriber();

to this

private Subscriber user;

Answer 2

I think you are asking how you can persist in memory a User object that will be used across multiple actions.

You have a couple of options if I understand your question correctly.

One option, which is not very Struts like, would be to add the User object to a session variable. You can access the session variable as described here .

Another option, which I would recommend if you plan on maintaining the object in your session for a specific set of actions (or steps, such as a 'wizard' portion of your app) is the ScopeInterceptor. You can read about that here and here .

Hope that helps.