When you are using @SessionAttributes annotaion in your controller and using the same Model Attribute in multiple Request mapping methods in the same controller ; you willrun into issues if you try working in multiple tabs.

What happens is, because Session Attributes stored in SessionAttributeStore are identified by just their name, and when ever a new Object is added with same name to the store the previous one gets overridden.

Very Common scenario could be a simple create and Edit of a page where you have opened a Create new page and before hitting submit you opened an Edit page for some other record in another Tab. This Causes the Edit record Model Attribute overriding the Create new ModelAttribute in the Session Resulting is Error.

In-order to resolve this issue you will have to teach Spring not to store / retrieve the Objects from Session Attribute Store by name but by a unique identification String.

In your  *context.xml you need to define the following beans

<bean id="conversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean" /> <bean id="sessionConversationAttributeStore" class="qld.qsa.edu.au.support.SessionConversationAttributeStore"> <property name="keepAliveConversations" value="10" /> <property name="requestMappingHandlerAdapter"> <ref bean="requestMappingHandlerAdapter" /> </property> </bean> <bean name="requestMappingHandlerAdapter" class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"> <property name="webBindingInitializer"> <bean class="org.springframework.web.bind.support.ConfigurableWebBindingInitializer"> <property name="conversionService" ref="conversionService"></property> <property name="validator"> <bean class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean" /> </property> </bean> </property> <property name="sessionAttributeStore"> <ref bean="sessionConversationAttributeStore" /> </property> <property name="messageConverters"> <list> <bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter" /> <bean class="org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter" /> <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" /> <bean class="org.springframework.http.converter.StringHttpMessageConverter"></bean> <bean class="org.springframework.http.converter.ResourceHttpMessageConverter"></bean> <bean class="org.springframework.http.converter.xml.SourceHttpMessageConverter"></bean> <bean class="org.springframework.http.converter.xml.XmlAwareFormHttpMessageConverter"></bean> </list> </property> </bean> <bean name="handlerMapping" class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"> <property name="useTrailingSlashMatch" value="false"></property> </bean> <bean name="requestDataValueProcessor" class="qld.qsa.edu.au.support.ConversationIdRequestProcessor" /> Now the new beans that we have defined here are

qld.qsa.edu.au.support.SessionConversationAttributeStore

qld.qsa.edu.au.support.ConversationIdRequestProcessor

The purpose of SessionConversationAttributeStore bean is to Override the Spring's SessionAttributeStore and change the way Session Attributes are stored/retrieved/removed from Session Attribute Store. In SessionConversationAttributeStore we will define a '_cId'which will be the unique name of our attributes now.

The Trick here is once you have stored an Attribute with a unique name, that name should always be in the Request so that we can retrieve the same attribute back for Session Store. ConversationIdRequestProcessor adds the unique name of the Attribute as hidden attribute in the form.


Code for SessionConversationAttributeStore package qld.qsa.edu.au.support; import java.util.HashMap; import java.util.LinkedHashMap; import java.util.Map; import java.util.UUID; import org.apache.log4j.Logger; import org.springframework.beans.factory.InitializingBean; import org.springframework.util.Assert; import org.springframework.web.bind.support.SessionAttributeStore; import org.springframework.web.context.request.WebRequest; import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter; /** * This class handles how session scoped model attributes are stored and * retrieved from the HttpSession. This implementation uses a UUId.randomUUID * to distinguish multiple command objects of the same type. This is needed * for users editing the same entity on multiple tabs of a browser. * @author msin * @version May 5, 2014 * */ public class SessionConversationAttributeStore implements SessionAttributeStore,InitializingBean { private Logger logger = Logger.getLogger(SessionConversationAttributeStore.class.getName()); // private int _numConversationsToKeep = 10; private RequestMappingHandlerAdapter requestMappingHandlerAdapter; public RequestMappingHandlerAdapter getRequestMappingHandlerAdapter() { return requestMappingHandlerAdapter; } public void setRequestMappingHandlerAdapter(RequestMappingHandlerAdapter requestMappingHandlerAdapter) { this.requestMappingHandlerAdapter = requestMappingHandlerAdapter; } private int keepAliveConversations = 10; public final static String CID_FIELD = "_cid"; public final static String SESSION_MAP = "sessionConversationMap"; @Override public void storeAttribute(WebRequest request, String attributeName, Object attributeValue) { Assert.notNull(request, "WebRequest must not be null"); Assert.notNull(attributeName, "Attribute name must not be null"); Assert.notNull(attributeValue, "Attribute value must not be null"); String cId = getConversationId(request); if (cId == null || cId.trim().length() == 0) { cId = UUID.randomUUID().toString(); } request.setAttribute(CID_FIELD, cId, WebRequest.SCOPE_REQUEST); logger.debug("storeAttribute - storing bean reference for (" + attributeName + ")."); store(request, attributeName, attributeValue, cId); } @Override public Object retrieveAttribute(WebRequest request, String attributeName) { Assert.notNull(request, "WebRequest must not be null"); Assert.notNull(attributeName, "Attribute name must not be null"); if (getConversationId(request) != null) { if (logger.isDebugEnabled()) { logger.debug("retrieveAttribute - retrieving bean reference for (" + attributeName + ") for conversation (" + getConversationId(request) + ")."); } return getConversationStore(request, getConversationId(request)).get(attributeName); } else { return null; } } @Override public void cleanupAttribute(WebRequest request, String attributeName) { Assert.notNull(request, "WebRequest must not be null"); Assert.notNull(attributeName, "Attribute name must not be null"); if (logger.isDebugEnabled()) { logger.debug("cleanupAttribute - removing bean reference for (" + attributeName + ") from conversation (" + getConversationId(request) + ")."); } Map<String, Object> conversationStore = getConversationStore(request, getConversationId(request)); conversationStore.remove(attributeName); // Delete the conversation store from the session if empty if (conversationStore.isEmpty()) { getSessionConversationsMap(request).remove(getConversationId(request)); } } /** * Retrieve a specific conversation's map of objects from the session. Will * create the conversation map if it does not exist. * * The conversation map is stored inside a session map - which is a map of * maps. If this does not exist yet- it will be created too. * * @param request * - the incoming request * @param conversationId * - the conversation id we are dealing with * @return - the conversation's map */ private Map<String, Object> getConversationStore(WebRequest request, String conversationId) { Map<String, Object> conversationMap = getSessionConversationsMap(request).get(conversationId); if (conversationId != null && conversationMap == null) { conversationMap = new HashMap<String, Object>(); getSessionConversationsMap(request).put(conversationId, conversationMap); } return conversationMap; } /** * Get the session's conversations map. * * @param request * - the request * @return - LinkedHashMap of all the conversations and their maps */ private LinkedHashMap<String, Map<String, Object>> getSessionConversationsMap(WebRequest request) { @SuppressWarnings("unchecked") LinkedHashMap<String, Map<String, Object>> sessionMap = (LinkedHashMap<String, Map<String, Object>>) request.getAttribute( SESSION_MAP, WebRequest.SCOPE_SESSION); if (sessionMap == null) { sessionMap = new LinkedHashMap<String, Map<String, Object>>(); request.setAttribute(SESSION_MAP, sessionMap, WebRequest.SCOPE_SESSION); } return sessionMap; } /** * Store an object on the session. If the configured maximum number of live * conversations to keep is reached - clear out the oldest conversation. (If * max number is configured as 0 - no removal will happen) * * @param request * - the web request * @param attributeName * - the name of the attribute (from @SessionAttributes) * @param attributeValue * - the value to store */ private void store(WebRequest request, String attributeName, Object attributeValue, String cId) { LinkedHashMap<String, Map<String, Object>> sessionConversationsMap = getSessionConversationsMap(request); if (keepAliveConversations > 0 && sessionConversationsMap.size() >= keepAliveConversations && !sessionConversationsMap.containsKey(cId)) { // clear oldest conversation String key = sessionConversationsMap.keySet().iterator().next(); sessionConversationsMap.remove(key); } getConversationStore(request, cId).put(attributeName, attributeValue); } public int getKeepAliveConversations() { return keepAliveConversations; } public void setKeepAliveConversations(int numConversationsToKeep) { keepAliveConversations = numConversationsToKeep; } /** * Helper method to get conversation id from the web request * * @param request * - Incoming request * @return - the conversationId (note that this is a request parameter, and * only gets there on form submit) */ private String getConversationId(WebRequest request) { String cid = request.getParameter(CID_FIELD); if (cid == null) { cid = (String) request.getAttribute(CID_FIELD, WebRequest.SCOPE_REQUEST); } return cid; } /** * Required for wiring the RequestMappingHandlerAdapter */ @Override public void afterPropertiesSet() throws Exception { requestMappingHandlerAdapter.setSessionAttributeStore(this); } }

Code for ConversationIdRequestProcessor package qld.qsa.edu.au.support; import java.util.HashMap; import java.util.Map; import javax.servlet.http.HttpServletRequest; import org.springframework.web.servlet.support.RequestDataValueProcessor; /** * This processor is used to add the conversation id as a hidden field on the * form If the conversation id exists on the request. * * @author msin * */ public class ConversationIdRequestProcessor implements RequestDataValueProcessor { @Override public String processAction(HttpServletRequest request, String action) { return action; } @Override public String processFormFieldValue(HttpServletRequest request, String name, String value, String type) { return value; } @Override public Map<String, String> getExtraHiddenFields(HttpServletRequest request) { Map<String, String> hiddenFields = new HashMap<String, String>(); if (request.getAttribute(SessionConversationAttributeStore.CID_FIELD) != null) { hiddenFields.put(SessionConversationAttributeStore.CID_FIELD, request.getAttribute(SessionConversationAttributeStore.CID_FIELD).toString()); } return hiddenFields; } @Override public String processUrl(HttpServletRequest request, String url) { return url; } }

Make sure you remove from your context.xml You should be able to see some thing like

In your source of the page.