// Copyright 2007, 2008 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package org.apache.tapestry5.internal.services;
import org.apache.tapestry5.Link;
import org.apache.tapestry5.internal.util.Base64ObjectInputStream;
import org.apache.tapestry5.internal.util.Base64ObjectOutputStream;
import static org.apache.tapestry5.ioc.IOCConstants.PERTHREAD_SCOPE;
import org.apache.tapestry5.ioc.annotations.Scope;
import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
import static org.apache.tapestry5.ioc.internal.util.CollectionFactory.newMap;
import org.apache.tapestry5.ioc.internal.util.InternalUtils;
import org.apache.tapestry5.services.PersistentFieldChange;
import org.apache.tapestry5.services.Request;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
/**
* Manages client-persistent values on behalf of a {@link ClientPersistentFieldStorageImpl}. Some effort is made to
* ensure that we don't uncessarily convert between objects and Base64 (the encoding used to record the value on the
* client).
*/
@Scope(PERTHREAD_SCOPE)
public class ClientPersistentFieldStorageImpl implements ClientPersistentFieldStorage
{
static final String PARAMETER_NAME = "t:state:client";
private static class Key implements Serializable
{
private static final long serialVersionUID = -2741540370081645945L;
private final String pageName;
private final String componentId;
private final String fieldName;
Key(String pageName, String componentId, String fieldName)
{
this.pageName = pageName;
this.componentId = componentId;
this.fieldName = fieldName;
}
public boolean matches(String pageName)
{
return this.pageName.equals(pageName);
}
public PersistentFieldChange toChange(Object value)
{
return new PersistentFieldChangeImpl(componentId == null ? "" : componentId,
fieldName, value);
}
@Override
public int hashCode()
{
final int PRIME = 31;
int result = 1;
result = PRIME * result + ((componentId == null) ? 0 : componentId.hashCode());
// fieldName and pageName are never null
result = PRIME * result + fieldName.hashCode();
result = PRIME * result + pageName.hashCode();
return result;
}
@Override
public boolean equals(Object obj)
{
if (this == obj) return true;
if (obj == null) return false;
if (getClass() != obj.getClass()) return false;
final Key other = (Key) obj;
// fieldName and pageName are never null
if (!fieldName.equals(other.fieldName)) return false;
if (!pageName.equals(other.pageName)) return false;
if (componentId == null)
{
if (other.componentId != null) return false;
}
else if (!componentId.equals(other.componentId)) return false;
return true;
}
}
private final Map<Key, Object> persistedValues = newMap();
private String clientData;
private boolean mapUptoDate = false;
public ClientPersistentFieldStorageImpl(Request request)
{
String value = request.getParameter(PARAMETER_NAME);
// MIME can encode to a '+' character; the browser converts that to a space; we convert it
// back.
clientData = value == null ? null : value.replace(' ', '+');
}
public void updateLink(Link link)
{
refreshClientData();
if (clientData != null) link.addParameter(PARAMETER_NAME, clientData);
}
public Collection<PersistentFieldChange> gatherFieldChanges(String pageName)
{
refreshMap();
if (persistedValues.isEmpty()) return Collections.emptyList();
Collection<PersistentFieldChange> result = CollectionFactory.newList();
for (Map.Entry<Key, Object> e : persistedValues.entrySet())
{
Key key = e.getKey();
if (key.matches(pageName)) result.add(key.toChange(e.getValue()));
}
return result;
}
public void discardChanges(String pageName)
{
refreshMap();
Collection<Key> removedKeys = CollectionFactory.newList();
for (Key key : persistedValues.keySet())
{
if (key.pageName.equals(pageName)) removedKeys.add(key);
}
for (Key key : removedKeys)
{
persistedValues.remove(key);
clientData = null;
}
}
public void postChange(String pageName, String componentId, String fieldName, Object newValue)
{
refreshMap();
Key key = new Key(pageName, componentId, fieldName);
if (newValue == null)
persistedValues.remove(key);
else
{
if (!Serializable.class.isInstance(newValue))
throw new IllegalArgumentException(ServicesMessages
.clientStateMustBeSerializable(newValue));
persistedValues.put(key, newValue);
}
clientData = null;
}
/**
* Refreshes the _persistedValues map if it is not up to date.
*/
@SuppressWarnings("unchecked")
private void refreshMap()
{
if (mapUptoDate) return;
// Parse the client data to form the map.
restoreMapFromClientData();
mapUptoDate = true;
}
/**
* Restores the _persistedValues map from the client data provided in the incoming Request.
*/
private void restoreMapFromClientData()
{
persistedValues.clear();
if (clientData == null) return;
ObjectInputStream in = null;
try
{
in = new Base64ObjectInputStream(clientData);
int count = in.readInt();
for (int i = 0; i < count; i++)
{
Key key = (Key) in.readObject();
Object value = in.readObject();
persistedValues.put(key, value);
}
}
catch (Exception ex)
{
throw new RuntimeException(ServicesMessages.corruptClientState(), ex);
}
finally
{
InternalUtils.close(in);
}
}
private void refreshClientData()
{
// Client data will be null after a change to the map, or if there was no client data in the
// request. In any other case where the client data is non-null, it is by definition
// up-to date (since it is reset to null any time there's a change to the map).
if (clientData != null) return;
// Very typical: we're refreshing the client data but haven't created the map yet, and there
// was no value in the request. Leave it as null.
if (!mapUptoDate) return;
// Null is also appropriate when the persisted values are empty.
if (persistedValues.isEmpty()) return;
// Otherwise, time to update clientData from persistedValues
Base64ObjectOutputStream os = null;
try
{
os = new Base64ObjectOutputStream();
os.writeInt(persistedValues.size());
for (Map.Entry<Key, Object> e : persistedValues.entrySet())
{
os.writeObject(e.getKey());
os.writeObject(e.getValue());
}
}
catch (Exception ex)
{
throw new RuntimeException(ex.getMessage(), ex);
}
finally
{
InternalUtils.close(os);
}
clientData = os.toBase64();
}
}