Here it is.
As I mentioned in my initial post: Once I change the name of "pattern" to something else, e.g. "patternString" in the getter/setter methods and in the JSP file the problem is gone.
editVirtualAlias.jsp:
<%@ include file="include.jsp" %>
<%@ taglib prefix="spring" uri="/spring" %>
<html>
<head>
<title><fmt:message key="title"/></title>
</head>
<body>
<c:import url="inc/title.jsp"/>
<h2>Edit Virtual Alias</h2>
<form method="post">
<spring:bind path="virtualAlias.*">
<c:forEach items="${status.errorMessages}" var="error">
Error code: <c:out value="${error}"/><br>
</c:forEach>
</spring:bind>
<p>
Pattern:
<spring:bind path="virtualAlias.pattern">
<input type="text"
name="<c:out value='${status.expression}'/>"
value="<c:out value='${status.value}'/>"/>
</spring:bind>
</p>
<input type="submit" value="OK"/>
</form>
</body>
EditVirtualAliasFormController.java:
package web;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.SimpleFormCont roller;
import org.springframework.web.servlet.view.RedirectView;
import bus.VirtualAlias;
import bus.VirtualAliasManager;
import bus.impl.VirtualAliasImpl;
public class EditVirtualAliasFormController extends SimpleFormController {
private VirtualAliasManager virtualAliasManager;
public ModelAndView onSubmit(Object command) throws ServletException {
VirtualAlias va = (VirtualAlias)command;
virtualAliasManager.updateVirtualAlias(va);
ModelAndView mav = new ModelAndView(new RedirectView(getSuccessView()));
return mav;
}
protected Object formBackingObject(HttpServletRequest request) throws ServletException {
String pattern = request.getParameter("pattern");
VirtualAlias va = virtualAliasManager.getVirtualAliasByPattern(patte rn);
if (va==null) { // create a new virtual alias mapping
logger.info("create new virtual alias");
va = new VirtualAliasImpl();
}
return va;
}
public void setVirtualAliasManager(VirtualAliasManager virtualAliasManager) {
this.virtualAliasManager = virtualAliasManager;
}
public VirtualAliasManager getVirtualAliasManager() {
return virtualAliasManager;
}
}
Bean config from Application Context:
<bean id="editVirtualAliasValidator" class="bus.EditVirtualAliasValidator"/>
<bean id="editVirtualAliasForm" class="web.EditVirtualAliasFormController">
<property name="sessionForm"><value>true</value></property>
<property name="commandName"><value>virtualAlias</value></property>
<property name="commandClass"><value>bus.impl.VirtualAliasImpl</value></property>
<property name="validator"><ref bean="editVirtualAliasValidator"/></property>
<property name="formView"><value>editVirtualAlias</value></property>
<property name="successView"><value>listVirtualAliases.htm</value></property>
<property name="virtualAliasManager">
<ref bean="virtualAliasManager"/>
</property>
</bean>
command class (VirtualAliasImpl.java):
package bus.impl;
import bus.VirtualAlias;
import java.util.LinkedList;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class VirtualAliasImpl implements VirtualAlias {
protected final Log logger = LogFactory.getLog(getClass());
private String pattern;
private LinkedList<String> addresses = new LinkedList<String>();
private String originalPattern;
public String getPattern() {
return pattern;
}
public void setPattern(String newpattern) {
if (this.originalPattern == null) { // initial load
this.originalPattern = newpattern;
}
this.pattern = newpattern;
}
public String[] getAddresses() {
return addresses.toArray(new String[addresses.size()]);
}
public void setAddresses(String[] addresses) {
if (addresses != null) {
this.addresses.clear();
for (int i=0; i<addresses.length; i++) {
this.addresses.add(addresses[i]);
}
}
}
public void addAddress(String address) {
this.addresses.add(address);
}
public void removeAddress(String address) {
this.addresses.remove(address);
}
public boolean equals(Object o) {
return o != null &&
o instanceof VirtualAlias &&
this.pattern.equals(((VirtualAlias)o).getPatternSt ring()) &&
this.addresses.equals(((VirtualAlias)o).getAddress es());
}
public String getOriginalPattern() {
return originalPattern;
}
public String toString() {
return pattern + " " + addresses;
}
}