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/*
* Copyright 2000-2018 Vaadin Ltd.
*
* 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 com.vaadin.shared.annotations;
import java.io.Serializable;
import java.lang.annotation.ElementType;
import java.lang.annotation.Target;
import com.vaadin.shared.util.SharedUtil;
/**
* Signals that the property value from a state class should be forwarded to the
* Widget of the corresponding connector instance.
* <p>
* When this annotation is present on a field or on a setter method, the
* framework will call the corresponding setter in the Connector's Widget
* instance with the current state property value whenever it has been changed.
* This is happens after firing
* {@link com.vaadin.client.ConnectorHierarchyChangeEvent}s but before firing
* any {@link com.vaadin.client.communication.StateChangeEvent}.
* <p>
* Take for example a state class looking like this:
*
* <pre>
* public class MyComponentState extends AbstractComponentState {
* @DelegateToWidget
* public String myProperty;
* }
* </pre>
*
* Whenever <code>myProperty</code> is changed, the framework will call code
* like this:
*
* <pre>
* connector.getWidget().setMyProperty(connector.getState().myProperty);
* </pre>
*
* <p>
* By default, the Widget method to call is derived from the property name, but
* {@link #value()} in the annotation can be used to provide a custom method
* name, e.g. {@code @DelegateToWidget("someSpecialName")}.
*
* @since 7.0.0
* @author Vaadin Ltd
*/
@Target({ ElementType.METHOD, ElementType.FIELD })
public @interface DelegateToWidget {
/**
* Defines the name of the Widget method to call when the annotated state
* property has changed. If no value is defined, the method name will be
* derived from the property name, so e.g. a field named
* <code>myProperty</code> will delegate to a method named
* <code>setMyProperty</code>.
*
* @return the name of the method to delegate to, or empty string to use the
* default name
*/
public String value() default "";
/**
* Internal helper for handling default values in a uniform way both at
* runtime and during widgetset compilation.
*/
public static class Helper implements Serializable {
/**
* Gets the name of the method to delegate to for a given property name
* and annotation value.
*
* @param propertyName
* the name of the delegated property
* @param annotationValue
* the {@link DelegateToWidget#value()} of the annotation
* @return the name of the method to delegate to
*/
public static String getDelegateTarget(String propertyName,
String annotationValue) {
String name = annotationValue;
if (name.isEmpty()) {
name = "set" + SharedUtil.capitalize(propertyName);
}
return name;
}
}
}
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