[Struts 1] Cambiare tipo di form dinamicamente

[Alcott]

Ciao a tutti.
Ho un problema con Struts 1. Mi è stato chiesto di cambiare il tipo di enctype di una form.
Per varie ragioni (che vi risparmio! :-) ), devo modificare questo valore dinamicamente (è valorizzato di default a "x-www-form-urlencoded").

Il tutto è così strutturato: c'è un template con i tag <html:form ...> e </html:form>, tra i quali viene inclusa la mia JSP.
Ho aggiunto quindi le seguenti righe nella JSP:

var encodingType = document.forms[0].encoding;
alert(encodingType);

document.forms[0].encoding = 'multipart/form-data';

encodingType = document.forms[0].encoding;
alert(encodingType);

e, almeno dagli alert, il tutto sembra funzionare.
Quando premo però sul pulsante per inviare la form, ottengo il seguente errore nel browser (per la prova non ho inserito il tag <html:file>, ma ho lasciato solo gli <html:input> e hidden che erano già presenti nella JSP):

500 Internal Server Error
oracle.classloader.util.AnnotatedNoClassDefFoundError: 

	  Classe mancante: org.apache.commons.beanutils.MethodUtils

	Classe dipendente: org.apache.commons.fileupload.FileUpload
	         Loader: global.libraries:1.0
	    Origine codice: /C:/oc4j/j2ee/home/applib/commons-fileupload.jar
	  Configurazione: <code-source> in /C:/oc4j/j2ee/home/config/server.xml
La classe mancante è disponibile nelle seguenti posizioni:

	1. Origine codice: /C:/viewstore/andrea.iampieri_view/WMC_DEV/Project/WebApp/WMC/WEB-INF/lib/commons-beanutils.jar (from WEB-INF/lib/ directory in C:\viewstore\andrea.iampieri_view\WMC_DEV\Project\WebApp\WMC\WEB-INF\lib)
 	   Questa origine codice è disponibile nel loader wmc.web.WMC:0.0.0. 
	at oracle.classloader.PolicyClassLoader.handleClassNotFound (PolicyClassLoader.java:2068) [/C:/oc4j/j2ee/home/lib/pcl.jar (from system property java.class.path), by sun.misc.Launcher$AppClassLoader@10469011]	at oracle.classloader.PolicyClassLoader.internalLoadClass (PolicyClassLoader.java:1679) [/C:/oc4j/j2ee/home/lib/pcl.jar (from system property java.class.path), by sun.misc.Launcher$AppClassLoader@10469011]	at oracle.classloader.PolicyClassLoader.loadClass (PolicyClassLoader.java:1635) [/C:/oc4j/j2ee/home/lib/pcl.jar (from system property java.class.path), by sun.misc.Launcher$AppClassLoader@10469011]	at oracle.classloader.PolicyClassLoader.loadClass (PolicyClassLoader.java:1620) [/C:/oc4j/j2ee/home/lib/pcl.jar (from system property java.class.path), by sun.misc.Launcher$AppClassLoader@10469011]	at java.lang.ClassLoader.loadClassInternal (ClassLoader.java:319) [jre bootstrap, by jre.bootstrap:1.5.0_06]	at org.apache.commons.fileupload.FileUpload.getNewInstanceMethod (FileUpload.java:612) [/C:/oc4j/j2ee/home/applib/commons-fileupload.jar (from <code-source> in /C:/oc4j/j2ee/home/config/server.xml), by global.libraries:1.0]	at org.apache.commons.fileupload.FileUpload.createItem (FileUpload.java:543) [/C:/oc4j/j2ee/home/applib/commons-fileupload.jar (from <code-source> in /C:/oc4j/j2ee/home/config/server.xml), by global.libraries:1.0]	at org.apache.commons.fileupload.FileUpload.parseRequest (FileUpload.java:433) [/C:/oc4j/j2ee/home/applib/commons-fileupload.jar (from <code-source> in /C:/oc4j/j2ee/home/config/server.xml), by global.libraries:1.0]	at org.apache.commons.fileupload.FileUpload.parseRequest (FileUpload.java:304) [/C:/oc4j/j2ee/home/applib/commons-fileupload.jar (from <code-source> in /C:/oc4j/j2ee/home/config/server.xml), by global.libraries:1.0]	at org.apache.struts.upload.CommonsMultipartRequestHandler.handleRequest (CommonsMultipartRequestHandler.java:234) [/C:/viewstore/andrea.iampieri_view/WMC_DEV/Project/WebApp/WMC/WEB-INF/lib/struts.jar (from WEB-INF/lib/ directory in C:\viewstore\andrea.iampieri_view\WMC_DEV\Project\WebApp\WMC\WEB-INF\lib), by wmc.web.WMC:0.0.0]	at org.apache.struts.util.RequestUtils.populate (RequestUtils.java:934) [/C:/viewstore/andrea.iampieri_view/WMC_DEV/Project/WebApp/WMC/WEB-INF/lib/struts.jar (from WEB-INF/lib/ directory in C:\viewstore\andrea.iampieri_view\WMC_DEV\Project\WebApp\WMC\WEB-INF\lib), by wmc.web.WMC:0.0.0]	at org.apache.struts.action.RequestProcessor.processPopulate (RequestProcessor.java:779) [/C:/viewstore/andrea.iampieri_view/WMC_DEV/Project/WebApp/WMC/WEB-INF/lib/struts.jar (from WEB-INF/lib/ directory in C:\viewstore\andrea.iampieri_view\WMC_DEV\Project\WebApp\WMC\WEB-INF\lib), by wmc.web.WMC:0.0.0]	at org.apache.struts.action.RequestProcessor.process (RequestProcessor.java:246) [/C:/viewstore/andrea.iampieri_view/WMC_DEV/Project/WebApp/WMC/WEB-INF/lib/struts.jar (from WEB-INF/lib/ directory in C:\viewstore\andrea.iampieri_view\WMC_DEV\Project\WebApp\WMC\WEB-INF\lib), by wmc.web.WMC:0.0.0]	at org.apache.struts.action.ActionServlet.process (ActionServlet.java:1292) [/C:/viewstore/andrea.iampieri_view/WMC_DEV/Project/WebApp/WMC/WEB-INF/lib/struts.jar (from WEB-INF/lib/ directory in C:\viewstore\andrea.iampieri_view\WMC_DEV\Project\WebApp\WMC\WEB-INF\lib), by wmc.web.WMC:0.0.0]	at org.apache.struts.action.ActionServlet.doPost (ActionServlet.java:510) [/C:/viewstore/andrea.iampieri_view/WMC_DEV/Project/WebApp/WMC/WEB-INF/lib/struts.jar (from WEB-INF/lib/ directory in C:\viewstore\andrea.iampieri_view\WMC_DEV\Project\WebApp\WMC\WEB-INF\lib), by wmc.web.WMC:0.0.0]	at javax.servlet.http.HttpServlet.service (HttpServlet.java:763) [/C:/oc4j/j2ee/home/lib/servlet.jar (from <code-source> (ignore manifest Class-Path) in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by api:1.4.0]	at javax.servlet.http.HttpServlet.service (HttpServlet.java:856) [/C:/oc4j/j2ee/home/lib/servlet.jar (from <code-source> (ignore manifest Class-Path) in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by api:1.4.0]	at com.evermind[Oracle Containers for J2EE 10g (10.1.3.3.0) ].server.http.ServletRequestDispatcher.invoke (ServletRequestDispatcher.java:713) [/C:/oc4j/j2ee/home/lib/oc4j-internal.jar (from <code-source> in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by oc4j:10.1.3]	at com.evermind[Oracle Containers for J2EE 10g (10.1.3.3.0) ].server.http.ServletRequestDispatcher.forwardInternal (ServletRequestDispatcher.java:370) [/C:/oc4j/j2ee/home/lib/oc4j-internal.jar (from <code-source> in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by oc4j:10.1.3]	at com.evermind[Oracle Containers for J2EE 10g (10.1.3.3.0) ].server.http.HttpRequestHandler.doProcessRequest (HttpRequestHandler.java:871) [/C:/oc4j/j2ee/home/lib/oc4j-internal.jar (from <code-source> in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by oc4j:10.1.3]	at com.evermind[Oracle Containers for J2EE 10g (10.1.3.3.0) ].server.http.HttpRequestHandler.processRequest (HttpRequestHandler.java:453) [/C:/oc4j/j2ee/home/lib/oc4j-internal.jar (from <code-source> in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by oc4j:10.1.3]	at com.evermind[Oracle Containers for J2EE 10g (10.1.3.3.0) ].server.http.HttpRequestHandler.serveOneRequest (HttpRequestHandler.java:221) [/C:/oc4j/j2ee/home/lib/oc4j-internal.jar (from <code-source> in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by oc4j:10.1.3]	at com.evermind[Oracle Containers for J2EE 10g (10.1.3.3.0) ].server.http.HttpRequestHandler.run (HttpRequestHandler.java:122) [/C:/oc4j/j2ee/home/lib/oc4j-internal.jar (from <code-source> in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by oc4j:10.1.3]	at com.evermind[Oracle Containers for J2EE 10g (10.1.3.3.0) ].server.http.HttpRequestHandler.run (HttpRequestHandler.java:111) [/C:/oc4j/j2ee/home/lib/oc4j-internal.jar (from <code-source> in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by oc4j:10.1.3]	at oracle.oc4j.network.ServerSocketReadHandler$SafeRunnable.run (ServerSocketReadHandler.java:260) [/C:/oc4j/j2ee/home/lib/oc4j-internal.jar (from <code-source> in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by oc4j:10.1.3]	at com.evermind[Oracle Containers for J2EE 10g (10.1.3.3.0) ].util.ReleasableResourcePooledExecutor$MyWorker.run (ReleasableResourcePooledExecutor.java:303) [/C:/oc4j/j2ee/home/lib/oc4j-internal.jar (from <code-source> in META-INF/boot.xml in C:\oc4j\j2ee\home\oc4j.jar), by oc4j:10.1.3]	at java.lang.Thread.run (Thread.java:595) [jre bootstrap, by jre.bootstrap:1.5.0_06]

Avete qualche consiglio da darmi?
Grazie come sempre!

[manu1980]

Sembra che ti manchi la libreria commons-beanutils.jar. Oppure il web-server non riesce a trovarla. Verifica i path.