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Better support for @SessionAttributes in clustered environments

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A list of "known" session attributes (listed in @SessionAttributes)
was gradually built as attributes get added to the model. In a
failover scenario that knowledge is lost causing session attributes
to be potentially re-initialized via @ModelAttribute methods.

With this change @SessionAttributes listed by name are immediately
added to he list of "known" session attributes thus this knowledge
is not lost after a failover. Attributes listed by type however
still must be discovered as they get added to the model.
This commit is contained in:
Rossen Stoyanchev
2012-02-03 12:14:36 -05:00
parent 81e25b91c2
commit 871336a8c8
3 changed files with 73 additions and 70 deletions
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90
org.springframework.web/src/main/java/org/springframework/web/method/annotation/SessionAttributesHandler.java
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@@ -1,5 +1,5 @@
/*
* Copyright 2002-2011 the original author or authors.
* Copyright 2002-2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -31,16 +31,16 @@ import org.springframework.web.bind.support.SessionStatus;
import org.springframework.web.context.request.WebRequest;
/**
* Manages controller-specific session attributes declared via
* {@link SessionAttributes @SessionAttributes}. Actual storage is
* performed via {@link SessionAttributeStore}.
*
* <p>When a controller annotated with {@code @SessionAttributes} adds
* attributes to its model, those attributes are checked against names and
* types specified via {@code @SessionAttributes}. Matching model attributes
* are saved in the HTTP session and remain there until the controller calls
* Manages controller-specific session attributes declared via
* {@link SessionAttributes @SessionAttributes}. Actual storage is
* delegated to a {@link SessionAttributeStore} instance.
*
* <p>When a controller annotated with {@code @SessionAttributes} adds
* attributes to its model, those attributes are checked against names and
* types specified via {@code @SessionAttributes}. Matching model attributes
* are saved in the HTTP session and remain there until the controller calls
* {@link SessionStatus#setComplete()}.
*
*
* @author Rossen Stoyanchev
* @since 3.1
*/
@@ -50,51 +50,53 @@ public class SessionAttributesHandler {
private final Set<Class<?>> attributeTypes = new HashSet<Class<?>>();
private final Set<String> resolvedAttributeNames = Collections.synchronizedSet(new HashSet<String>(4));
private final Set<String> knownAttributeNames = Collections.synchronizedSet(new HashSet<String>(4));
private final SessionAttributeStore sessionAttributeStore;
/**
* Creates a new instance for a controller type. Session attribute names/types
* are extracted from a type-level {@code @SessionAttributes} if found.
* Create a new instance for a controller type. Session attribute names and
* types are extracted from the {@code @SessionAttributes} annotation, if
* present, on the given type.
* @param handlerType the controller type
* @param sessionAttributeStore used for session access
*/
public SessionAttributesHandler(Class<?> handlerType, SessionAttributeStore sessionAttributeStore) {
Assert.notNull(sessionAttributeStore, "SessionAttributeStore may not be null.");
this.sessionAttributeStore = sessionAttributeStore;
SessionAttributes annotation = AnnotationUtils.findAnnotation(handlerType, SessionAttributes.class);
if (annotation != null) {
this.attributeNames.addAll(Arrays.asList(annotation.value()));
this.attributeNames.addAll(Arrays.asList(annotation.value()));
this.attributeTypes.addAll(Arrays.<Class<?>>asList(annotation.types()));
}
}
this.knownAttributeNames.addAll(this.attributeNames);
}
/**
* Whether the controller represented by this instance has declared session
* attribute names or types of interest via {@link SessionAttributes}.
* Whether the controller represented by this instance has declared any
* session attributes through an {@link SessionAttributes} annotation.
*/
public boolean hasSessionAttributes() {
return ((this.attributeNames.size() > 0) || (this.attributeTypes.size() > 0));
return ((this.attributeNames.size() > 0) || (this.attributeTypes.size() > 0));
}
/**
* Whether the attribute name and/or type match those specified in the
* controller's {@code @SessionAttributes} annotation.
*
* Whether the attribute name or type match the names and types specified
* via {@code @SessionAttributes} in underlying controller.
*
* <p>Attributes successfully resolved through this method are "remembered"
* and used in {@link #retrieveAttributes(WebRequest)} and
* {@link #cleanupAttributes(WebRequest)}. In other words, retrieval and
* cleanup only affect attributes previously resolved through here.
*
* @param attributeName the attribute name to check; must not be null
* @param attributeType the type for the attribute; or {@code null}
* and subsequently used in {@link #retrieveAttributes(WebRequest)} and
* {@link #cleanupAttributes(WebRequest)}.
*
* @param attributeName the attribute name to check, never {@code null}
* @param attributeType the type for the attribute, possibly {@code null}
*/
public boolean isHandlerSessionAttribute(String attributeName, Class<?> attributeType) {
Assert.notNull(attributeName, "Attribute name must not be null");
if (this.attributeNames.contains(attributeName) || this.attributeTypes.contains(attributeType)) {
this.resolvedAttributeNames.add(attributeName);
this.knownAttributeNames.add(attributeName);
return true;
}
else {
@@ -103,8 +105,8 @@ public class SessionAttributesHandler {
}
/**
* Stores a subset of the given attributes in the session. Attributes not
* declared as session attributes via {@code @SessionAttributes} are ignored.
* Store a subset of the given attributes in the session. Attributes not
* declared as session attributes via {@code @SessionAttributes} are ignored.
* @param request the current request
* @param attributes candidate attributes for session storage
*/
@@ -112,23 +114,23 @@ public class SessionAttributesHandler {
for (String name : attributes.keySet()) {
Object value = attributes.get(name);
Class<?> attrType = (value != null) ? value.getClass() : null;
if (isHandlerSessionAttribute(name, attrType)) {
this.sessionAttributeStore.storeAttribute(request, name, value);
}
}
}
/**
* Retrieve "known" attributes from the session -- i.e. attributes listed
* in {@code @SessionAttributes} and previously stored in the in the model
* at least once.
* Retrieve "known" attributes from the session, i.e. attributes listed
* by name in {@code @SessionAttributes} or attributes previously stored
* in the model that matched by type.
* @param request the current request
* @return a map with handler session attributes; possibly empty.
* @return a map with handler session attributes, possibly empty
*/
public Map<String, Object> retrieveAttributes(WebRequest request) {
Map<String, Object> attributes = new HashMap<String, Object>();
for (String name : this.resolvedAttributeNames) {
for (String name : this.knownAttributeNames) {
Object value = this.sessionAttributeStore.retrieveAttribute(request, name);
if (value != null) {
attributes.put(name, value);
@@ -138,13 +140,13 @@ public class SessionAttributesHandler {
}
/**
* Cleans "known" attributes from the session - i.e. attributes listed
* in {@code @SessionAttributes} and previously stored in the in the model
* at least once.
* Remove "known" attributes from the session, i.e. attributes listed
* by name in {@code @SessionAttributes} or attributes previously stored
* in the model that matched by type.
* @param request the current request
*/
public void cleanupAttributes(WebRequest request) {
for (String attributeName : this.resolvedAttributeNames) {
for (String attributeName : this.knownAttributeNames) {
this.sessionAttributeStore.cleanupAttribute(request, attributeName);
}
}
@@ -158,5 +160,5 @@ public class SessionAttributesHandler {
Object retrieveAttribute(WebRequest request, String attributeName) {
return this.sessionAttributeStore.retrieveAttribute(request, attributeName);
}
}