org.springframework.boot.context.properties.bind.BindHandler Maven / Gradle / Ivy
/*
* Copyright 2012-2018 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.
* You may obtain a copy of the License at
*
* https://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.springframework.boot.context.properties.bind;
import org.springframework.boot.context.properties.source.ConfigurationPropertyName;
/**
* Callback interface that can be used to handle additional logic during element
* {@link Binder binding}.
*
* @author Phillip Webb
* @author Madhura Bhave
* @since 2.0.0
*/
public interface BindHandler {
/**
* Default no-op bind handler.
*/
BindHandler DEFAULT = new BindHandler() {
};
/**
* Called when binding of an element starts but before any result has been determined.
* @param the bindable source type
* @param name the name of the element being bound
* @param target the item being bound
* @param context the bind context
* @return the actual item that should be used for binding (may be {@code null})
*/
default Bindable onStart(ConfigurationPropertyName name, Bindable target,
BindContext context) {
return target;
}
/**
* Called when binding of an element ends with a successful result. Implementations
* may change the ultimately returned result or perform addition validation.
* @param name the name of the element being bound
* @param target the item being bound
* @param context the bind context
* @param result the bound result (never {@code null})
* @return the actual result that should be used (may be {@code null})
*/
default Object onSuccess(ConfigurationPropertyName name, Bindable target,
BindContext context, Object result) {
return result;
}
/**
* Called when binding fails for any reason (including failures from
* {@link #onSuccess} calls). Implementations may choose to swallow exceptions and
* return an alternative result.
* @param name the name of the element being bound
* @param target the item being bound
* @param context the bind context
* @param error the cause of the error (if the exception stands it may be re-thrown)
* @return the actual result that should be used (may be {@code null}).
* @throws Exception if the binding isn't valid
*/
default Object onFailure(ConfigurationPropertyName name, Bindable target,
BindContext context, Exception error) throws Exception {
throw error;
}
/**
* Called when binding finishes, regardless of whether the property was bound or not.
* @param name the name of the element being bound
* @param target the item being bound
* @param context the bind context
* @param result the bound result (may be {@code null})
* @throws Exception if the binding isn't valid
*/
default void onFinish(ConfigurationPropertyName name, Bindable target,
BindContext context, Object result) throws Exception {
}
}