Trouble with Struts

[Corey McGlone]

I'm working with the HF book and I've been having some difficulty getting the struts example to work. I'm using Struts 1.1, if that makes any difference. The web.xml and struts-config.xml files are mostly generated via my IDE (WSAD), but the source of those files seems to match what is in the book. Here are the web.xml and struts-config.xml files that I'm currently using:

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" 
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app id="WebApp">
<display-name>Struts</display-name>
<servlet>
<servlet-name>action</servlet-name>
<servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
<init-param>
<param-name>config</param-name>
<param-value>WEB-INF/struts-config.xml</param-value>
</init-param>
<init-param>
<param-name>debug</param-name>
<param-value>2</param-value>
</init-param>
<init-param>
<param-name>detail</param-name>
<param-value>2</param-value>
</init-param>
<init-param>
<param-name>validate</param-name>
<param-value>true</param-value>
</init-param>
<load-on-startup>2</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>action</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<taglib>
<taglib-uri>/WEB-INF/struts-bean.tld</taglib-uri>
<taglib-location>/WEB-INF/struts-bean.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>/WEB-INF/struts-html.tld</taglib-uri>
<taglib-location>/WEB-INF/struts-html.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>/WEB-INF/struts-logic.tld</taglib-uri>
<taglib-location>/WEB-INF/struts-logic.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>/WEB-INF/struts-nested.tld</taglib-uri>
<taglib-location>/WEB-INF/struts-nested.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>/WEB-INF/struts-template.tld</taglib-uri>
<taglib-location>/WEB-INF/struts-template.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>/WEB-INF/struts-tiles.tld</taglib-uri>
<taglib-location>/WEB-INF/struts-tiles.tld</taglib-location>
</taglib>
</web-app>

struts-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.1//EN"
                               "http://jakarta.apache.org/struts/dtds/struts-config_1_1.dtd">
 
<struts-config>
 
<!-- Data Sources -->
<data-sources>
</data-sources>
 
<!-- Form Beans -->
<form-beans>
<form-bean name="selectBeerForm" 
type="edu.mayo.strutstraining.BeerSelectForm">
</form-bean>
</form-beans>
 
<!-- Global Exceptions -->
<global-exceptions>
</global-exceptions>
 
<!-- Global Forwards -->
<global-forwards>
</global-forwards>
 
<!-- Action Mappings -->
<action-mappings>
<action path="/SelectBeer" name="selectBeerForm" scope="request" input="/error.jsp" 
type="edu.mayo.strutstraining.BeerSelectAction" validate="true">
<forward name="suggestedBeer" path="/suggestedBeer.jsp"></forward>
</action>
</action-mappings>
 
<!-- Message Resources -->
<message-resources parameter="edu.mayo.struts.resources.ApplicationResources"/>
 
</struts-config>

Unfortunately, I can get to my index page, index.html, but when I try to submit the form there, which has an action of SelectBeer.do, I get a blank screen. The URL changes to http://localhost:9080/Struts/SelectBeer.do, just as I'd expect, but I don't seem to be executing any of my code.

I even put some simple println statements in my form bean and action objects. None of them print. It's as if the ActionServlet isn't passing on execution to the other classes, at all.

Anyone have any ideas of what I can check?

Thanks,
Corey

[Bryan Basham]

Hi Corey,

I don't trust IDEs, so I would recommend that you do all HFS exercises by hand. It is possible that your IDE has corrupted something.

The only thing that I noticed that looked odd was in the web.xml file:

<init-param>
<param-name>config</param-name>
<param-value>WEB-INF/struts-config.xml</param-value>
</init-param>

This should be:

<init-param>
<param-name>config</param-name>
<param-value>/WEB-INF/struts-config.xml</param-value>
</init-param>

Notice the opening / on the file path. Struts might ignore it but it is something that you can fix easily and test. (unless your IDE prevents you from fixing it

Good luck,
Bryan

[Corey McGlone]

Yeah, I'm not a big fan of IDE's, either, but they do make life easier sometimes. I had already tried adding the slash, but that didn't seem to make any difference.

[Dan Gun]

If you haven't done it, I'll put some debugging statements in the validate method of the form object as you form will be validated with each submission.

[Anurag Saksena]

Corey,

What is the Exception you are getting on the console ?

-a.
==========
SCJP 1.4
SCWCD 1.4

[Corey McGlone]

Originally posted by Anurag Saksena:
Corey,

What is the Exception you are getting on the console ?

-a.
==========
SCJP 1.4
SCWCD 1.4

There is no exception being printed to the console - that's part of my problem. There's no error that I can see, but the ActionServlet never seems to forward the request to any other objects, neither my Form Bean nor my Action class. I've put debugging statements into those classes and even put breakpoints in them, but I've hit none of them.

This is what I see...

1. I go to index.html - renders properly
2. I submit the form, which has an action of SelectBeer.do
3. I get a blank screen in my browser (with the URL changed to /SelectBeer.do). There are no errors that I can see, but nothing seems to be happening, either. I do, however, see the following tracing statements in the console:

action: Processing a POST for /SelectBeer
action: Setting locale 'en_US'
action: Looking for ActionForm bean under attribute 'selectBeerForm'
action: Creating new ActionForm instance of class 'edu.mayo.strutstraining.BeerSelectForm'
action: Storing instance under attribute 'selectBeerForm' in scope 'request'
action: Populating bean properties from this request
action: Validating input form properties
action: No errors detected, accepting input
action: Looking for Action instance for class edu.mayo.strutstraining.BeerSelectAction
action: Double checking for Action instance already there
action: Creating new Action instance

From that, it would appear that the ActionServlet is getting the request, but it never seems to make it to my Form Bean or Action Class.

[Nitish Bahadur]

1. In your struts-config.xml under <action-mappings>, write a new action called: <action path="/HelloWorld" forward="/HelloWorld.jsp"/>

2. Create HelloWorld.jsp at the web-root of your Struts Web App.
<html>
<head>
<title>Hello World</title>
</head>
<body>
<h2>Hello World!</h2>
</body>
</html>

3. Stop and start your App Server. (Test Environment in case of WSAD)

4. What do you see when you access http://localhost:9080/Struts/HelloWorld.do thru a browser. (Tells us if Struts Controller is forwarding the request or not)

5. If you still see a blank page, then try accessing the page directly.
http://localhost:9080/Struts/HelloWorld.jsp

[Corey McGlone]

Interesting, Nitish.

I did just what you said and I do see the HelloWorld.jsp file going through the ActionServlet. So, I know that, in this case, at least, the ActionServlet is performing the forward. So what does that tell me about the other case, when I'm going to my own Form Bean and Action Class? Is there error in there? If that's the case, how come I'm not seeing any of the debugging statements and/or hitting and of the breakpoints I have set in those classes?

[Corey McGlone]

Here's a new wrinkle I'll add...

In the console, I'm currently seeing these lines when I try to execute my app:

action:  Looking for ActionForm bean under attribute 'selectBeerForm'
action:  Creating new ActionForm instance of class 'edu.mayo.strutstraining.BeerSelectForm'
action:  Storing instance under attribute 'selectBeerForm' in scope 'request'
action:  Populating bean properties from this request
action:  Validating input form properties
action:   No errors detected, accepting input
action:  Looking for Action instance for class edu.mayo.strutstraining.BeerSelectAction

So, what does that tell us? First of all, I can see that the struts-config file is being read properly and it has located the correct class to do form validation (my Form Bean, 'edu.mayo.strutstraining.BeerSelectForm'). Secondly, it appears that no errors are being found and that it then goes on to try to create an Action instance.

I found this odd simply because I put a breakpoint in my Form Bean so that execution would stop at that point, but I never hit that breakpoint. So, I modifier the code in my Form Bean to look like this:

public class BeerSelectForm extends ActionForm 
{ 
    private String criteria;
    private final static String VALID_CRITERIA = "Light Beer, Dark Beer, Anything from Ireland";
 
    public void setCriteria(String beerSelectionCriteria)
    {
        criteria = beerSelectionCriteria;
    }
 
    public String getCriteria()
    {
        return criteria;
    }
 
    public ActionErrors validation(ActionMapping mapping, HttpServletRequest req) 
    {
        System.out.println(0);
 
        ActionErrors ae = new ActionErrors();
 
        //if (VALID_CRITERIA.indexOf(criteria) == -1)
        //{
            ae.add("color", new ActionError("error.criteriaField.notValid"));
        //}
 
        return ae;
    }
}

You can see that I commented out some code in my validate() method so that I should always have an error with my form parameters. However, when I execute my app again, I get the same output in the console, showing no errors found in the form parameters. This would seem to go along with the fact that I'm not seeing my debugging info and I'm not hitting my breakpoint - this method isn't being invoked.

So, if that's the case, what is getting invoked? Anything?

[Nitish Bahadur]

1. BeerSelectForm.java
(a.) change import org.apache.struts.action.ActionError to import org.apache.struts.action.ActionMessage;
(b.) Add the following method:
public ActionErrors validate(ActionMapping mapping, HttpServletRequest request) {
return validation(mapping, request);
}

(c.) validation should look like this:
public ActionErrors validation(ActionMapping mapping, HttpServletRequest req) {
System.out.println(0);
ActionErrors ae = new ActionErrors();
if (VALID_CRITERIA.indexOf(criteria) == -1)
{
ae.add("color", new ActionMessage("error.criteriaField.notValid")); // changed
}
return ae;
}

2. beerSelection.jsp
I removed the JSTL declaration at the top. (not being used in the version you sent me)

3. BeerSelectAction.java
(a.) Add public ActionForward execute(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) {
return actionForward(mapping, form, request, response);
}

These might be related to the differences between Struts 1.0, 1.1 and 1.2. It works in my Tomcat.

[Corey McGlone]

Woohoo! It works! Thanks, Nitish.

I think my problem was that the methods invoked by ActionServlet have changed from version to version in Struts. I believe I was using signatures from Struts 1.2 and/or 1.1 when my ActionServer is from 1.0. I didn't make the exact changes you specified (the method in the Action class is actually called "perform"), but your suggestions certainly got me going in the right direction.

Thanks for the help, Nitish.

Corey

[Juhan Voolaid]

Originally posted by Nitish Bahadur:
1. In your struts-config.xml under <action-mappings>, write a new action called: <action path="/HelloWorld" forward="/HelloWorld.jsp"/>

2. Create HelloWorld.jsp at the web-root of your Struts Web App.
<html>
<head>
<title>Hello World</title>
</head>
<body>
<h2>Hello World!</h2>
</body>
</html>

3. Stop and start your App Server. (Test Environment in case of WSAD)

4. What do you see when you access http://localhost:9080/Struts/HelloWorld.do thru a browser. (Tells us if Struts Controller is forwarding the request or not)

5. If you still see a blank page, then try accessing the page directly.
http://localhost:9080/Struts/HelloWorld.jsp

I am having problems with the very same beer-app struts example. My problem is that I get HTTP Status 404 - Servlet FrontController is not available
So I tried the advice above and got the same error with http://localhost/~juhan/HelloWorld.do while .../HelloWorld.jsp is displayed fine.

I think the problem may be in my xml conf files so I add them here allso.
web.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
        version="2.4">
 
    <servlet>
        <servlet-name>FrontController</servlet-name>
        <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
 
        <init-param>
            <param-name>config</param-name>
            <param-value>/WEB-INF/struts-config.xml</param-value>
        </init-param>
 
        <load-on-startup>1</load-on-startup>
    </servlet>
 

    <servlet-mapping>
        <servlet-name>FrontController</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>
</web-app>

struts-config.xml

<?xml version="1.0" encoding="ISO-8859-1" ?>
 
<!DOCTYPE struts-config
  PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.1//EN"
  "http://jakarta.apache.org/struts/dtds/struts-config_1_1.dtd">
 
<struts-config>
 
    <form-beans>
        <form-bean name="selectBeerForm" type="test.web.SelectBeerForm" />
    </form-beans>
 

    <action-mappings>
        <action
            path="/SelectBeer"
            type="test.web.BeerSelectAction"
            name="selectBeerForm"
            scope="request"
            validate="true"
            input="/form.jsp">
            <forward name="show_results" path="/result.jsp"/>
        </action>
        <action path="/HelloWorld" forward="/HelloWorld.jsp"/>
    </action-mappings>
    <!-- dunno -->
    <message-resources parameter="ApplicationResources" null="false">
</struts-config>