Struts errors and messages from action

I had a problem today when developing a login system to learn struts. How to transfer easily the error and messages from action, and show them on jsp pages.

It seems Struts 2’s ActionError and ActionMessage class is the a very good choice.

So in my login action, I just call directly addActionMessage() and addActionError() to add the messages I want:

	@Override
    public String execute() throws Exception {

        UserService userService = new UserService();
        user = userService.getUserByName(username);

        // To check weather the password is correct
        if(user != null && password.equals(user.getPassword())) {
        	addActionMessage("Login successfully");
            return SUCCESS; // With my configuration, it will go to info.jsp
        }else{
            addActionError("Password or username is wrong or not existing");
            return ERROR; // With my configuration, it will stay on the same page login.jsp.
        }
    }

In info.jsp:

<s:if test="hasActionMessages()">
    <s:actionmessage/>
</s:if>

Obviously, hasActionMessages() here will return true when we called addActionMessages() in our action. If it’s true, all contents in s:if will be shown. s:actionmessage will be replaced by the messages we just set in action.

In login.jsp:

<s:if test="hasActionErrors()">
    <s:actionerror/>
</s:if>

So it’s the same. hasActionErrors() will return true when we called addActionError() in our action. If it’s true, all contents in s:if will be shown. s:actionerror will be replaced by the messages we just set in action.

Ref

• Struts 2 ActionError & ActionMessage Example