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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.wicket;
import org.apache.wicket.behavior.AbstractBehavior;
import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.parser.XmlTag;
import org.apache.wicket.model.IComponentAssignedModel;
import org.apache.wicket.model.IModel;
import org.apache.wicket.protocol.http.portlet.PortletRequestContext;
import org.apache.wicket.util.value.IValueMap;
/**
* This class allows a tag attribute of a component to be modified dynamically with a value obtained
* from a model object. This concept can be used to programmatically alter the attributes of
* components, overriding the values specified in the markup. The two primary uses of this class are
* to allow overriding of markup attributes based on business logic and to support dynamic
* localization. The replacement occurs as the component tag is rendered to the response.
*
* The attribute whose value is to be modified must be given on construction of the instance of this
* class along with the model containing the value to replace with. Optionally a pattern can be
* supplied that is a regular expression that the existing value must match before the replacement
* can be carried out.
*
* If an attribute is not in the markup, this modifier will add an attribute to the tag only if
* addAttributeIfNotPresent is true and the replacement value is not null.
*
*
* Instances of this class should be added to components via the
* {@link org.apache.wicket.Component#add(AttributeModifier)} method after the component has been
* constructed.
*
* It is possible to create new subclasses of AttributeModifier by overriding the newValue(String,
* String) method. For example, you could create an AttributeModifier subclass which appends the
* replacement value like this:
* new AttributeModifier("myAttribute", model)
* {
* protected String newValue(final String currentValue, final String replacementValue)
* {
* return currentValue + replacementValue;
* }
* };
*
*
* @author Chris Turner
* @author Eelco Hillenius
* @author Jonathan Locke
* @author Martijn Dashorst
* @author Ralf Ebert
*/
public class AttributeModifier extends AbstractBehavior implements IClusterable
{
/** Marker value to have an attribute without a value added. */
public static final String VALUELESS_ATTRIBUTE_ADD = "VA_ADD";
/** Marker value to have an attribute without a value removed. */
public static final String VALUELESS_ATTRIBUTE_REMOVE = "VA_REMOVE";
private static final long serialVersionUID = 1L;
/** Whether to add the attribute if it is not an attribute in the markup. */
private final boolean addAttributeIfNotPresent;
/** Attribute specification. */
private final String attribute;
/** Modification information. */
private boolean enabled;
/** The pattern. */
private final String pattern;
/** The model that is to be used for the replacement. */
private final IModel replaceModel;
/**
* Create a new attribute modifier with the given attribute name and model to replace with. The
* additional boolean flag specifies whether to add the attribute if it is not present.
*
* @param attribute
* The attribute name to replace the value for
* @param addAttributeIfNotPresent
* Whether to add the attribute if it is not present
* @param replaceModel
* The model to replace the value with
*/
public AttributeModifier(final String attribute, final boolean addAttributeIfNotPresent,
final IModel replaceModel)
{
this(attribute, null, addAttributeIfNotPresent, replaceModel);
}
/**
* Create a new attribute modifier with the given attribute name and model to replace with. The
* attribute will not be added if it is not present.
*
* @param attribute
* The attribute name to replace the value for
* @param replaceModel
* The model to replace the value with
*/
public AttributeModifier(final String attribute, final IModel replaceModel)
{
this(attribute, null, false, replaceModel);
}
/**
* Create a new attribute modifier with the given attribute name and expected pattern to match
* plus the model to replace with. A null pattern will match the attribute regardless of its
* value. The additional boolean flag specifies whether to add the attribute if it is not
* present.
*
* @param attribute
* The attribute name to replace the value for
* @param pattern
* The pattern of the current attribute value to match
* @param addAttributeIfNotPresent
* Whether to add the attribute if it is not present and the replacement value is not
* null
* @param replaceModel
* The model to replace the value with
*/
public AttributeModifier(final String attribute, final String pattern,
final boolean addAttributeIfNotPresent, final IModel replaceModel)
{
if (attribute == null)
{
throw new IllegalArgumentException("Attribute parameter cannot be null");
}
this.attribute = attribute;
this.pattern = pattern;
enabled = true;
this.addAttributeIfNotPresent = addAttributeIfNotPresent;
this.replaceModel = replaceModel;
}
/**
* Create a new attribute modifier with the given attribute name and expected pattern to match
* plus the model to replace with. A null pattern will match the attribute regardless of its
* value. The attribute will not be added if it is not present.
*
* @param attribute
* The attribute name to replace the value for
* @param pattern
* The pattern of the current attribute value to match
* @param replaceModel
* The model to replace the value with
*/
public AttributeModifier(final String attribute, final String pattern,
final IModel replaceModel)
{
this(attribute, pattern, false, replaceModel);
}
/**
* Detach the model if it was a IDetachableModel Internal method. shouldn't be called from the
* outside. If the attribute modifier is shared, the detach method will be called multiple
* times.
*
* @param component
* the model that initiates the detachment
*/
@Override
public final void detach(Component component)
{
if (replaceModel != null)
{
replaceModel.detach();
}
}
/**
* @return whether to add the attribute if it is not an attribute in the markup
*/
public final boolean getAddAttributeIfNotPresent()
{
return addAttributeIfNotPresent;
}
/**
* @return the attribute name to replace the value for
*/
public final String getAttribute()
{
return attribute;
}
/**
* @return the pattern of the current attribute value to match
*/
public final String getPattern()
{
return pattern;
}
/**
* Checks whether this attribute modifier is enabled or not.
*
* @return Whether enabled or not
* @deprecated
*/
@Deprecated
public final boolean isEnabled()
{
return enabled;
}
/**
* Made final to support the parameterless variant.
*
* @see org.apache.wicket.behavior.AbstractBehavior#isEnabled(org.apache.wicket.Component)
*/
@Override
public boolean isEnabled(Component component)
{
return enabled;
}
/**
* @see org.apache.wicket.behavior.IBehavior#onComponentTag(org.apache.wicket.Component,
* org.apache.wicket.markup.ComponentTag)
*/
@Override
public final void onComponentTag(Component component, ComponentTag tag)
{
if (tag.getType() != XmlTag.CLOSE)
{
replaceAttributeValue(component, tag);
}
}
/**
* Checks the given component tag for an instance of the attribute to modify and if all criteria
* are met then replace the value of this attribute with the value of the contained model
* object.
*
* @param component
* The component
* @param tag
* The tag to replace the attribute value for
*
* @deprecated see {@link #replaceAttributeValue(Component, ComponentTag)}
*/
@Deprecated
public void replaceAttibuteValue(final Component component, final ComponentTag tag)
{
replaceAttributeValue(component, tag);
}
/**
* Checks the given component tag for an instance of the attribute to modify and if all criteria
* are met then replace the value of this attribute with the value of the contained model
* object.
*
* @param component
* The component
* @param tag
* The tag to replace the attribute value for
*/
public final void replaceAttributeValue(final Component component, final ComponentTag tag)
{
if (isEnabled(component))
{
final IValueMap attributes = tag.getAttributes();
final Object replacementValue = getReplacementOrNull(component);
if (VALUELESS_ATTRIBUTE_ADD.equals(replacementValue))
{
attributes.put(attribute, null);
}
else if (VALUELESS_ATTRIBUTE_REMOVE.equals(replacementValue))
{
attributes.remove(attribute);
}
else
{
if (attributes.containsKey(attribute))
{
final String value = toStringOrNull(attributes.get(attribute));
if (pattern == null || value.matches(pattern))
{
final String newValue = newValue(value, toStringOrNull(replacementValue));
if (newValue != null)
{
attributes.put(attribute, getContextRelativeValue(newValue));
}
}
}
else if (addAttributeIfNotPresent)
{
final String newValue = newValue(null, toStringOrNull(replacementValue));
if (newValue != null)
{
attributes.put(attribute, getContextRelativeValue(newValue));
}
}
}
}
}
/**
* Checks if value represents a path and if it does transforms it into a relative
* path
*
* @param value
* @return value as a relative path or untouched if not a path
*/
protected String getContextRelativeValue(String value)
{
if ("href".equals(attribute) || "src".equals(attribute))
{
RequestContext rc = RequestContext.get();
if (rc.isPortletRequest() &&
!(value.startsWith("http://") || value.startsWith("https://")))
{
if ("href".equals(attribute))
{
value = ((PortletRequestContext)rc).encodeRenderURL(value).toString();
}
else
{
value = ((PortletRequestContext)rc).encodeSharedResourceURL(value).toString();
}
}
}
return value;
}
/**
* Sets whether this attribute modifier is enabled or not.
*
* @param enabled
* Whether enabled or not
*/
public final void setEnabled(final boolean enabled)
{
this.enabled = enabled;
}
/**
* @see java.lang.Object#toString()
*/
@Override
public String toString()
{
return "[AttributeModifier attribute=" + attribute + ", enabled=" + enabled + ", pattern=" +
pattern + ", replacementModel=" + replaceModel + "]";
}
/**
* gets replacement with null check.
*
* @param component
* @return replacement value
*/
private Object getReplacementOrNull(final Component component)
{
IModel model = replaceModel;
if (model instanceof IComponentAssignedModel)
{
model = ((IComponentAssignedModel)model).wrapOnAssignment(component);
}
return (model != null) ? model.getObject() : null;
}
/**
* gets replacement as a string with null check.
*
* @param replacementValue
* @return replacement value as a string
*/
private String toStringOrNull(final Object replacementValue)
{
return (replacementValue != null) ? replacementValue.toString() : null;
}
/**
* Gets the replacement model. Allows subclasses access to replace model.
*
* @return the replace model of this attribute modifier
*/
protected final IModel getReplaceModel()
{
return replaceModel;
}
/**
* Gets the value that should replace the current attribute value. This gives users the ultimate
* means to customize what will be used as the attribute value. For instance, you might decide
* to append the replacement value to the current instead of just replacing it as is Wicket's
* default.
*
* @param currentValue
* The current attribute value. This value might be null!
* @param replacementValue
* The replacement value. This value might be null!
* @return The value that should replace the current attribute value
*/
protected String newValue(final String currentValue, final String replacementValue)
{
return replacementValue;
}
}