/*
* Copyright 2012-2020 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.data.util;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.FieldCallback;
A FieldCallback
that will inspect each field for a given annotation. This field's type can then be accessed afterwards. Author: Oliver Gierke, Christoph Strobl
/**
* A {@link FieldCallback} that will inspect each field for a given annotation. This field's type can then be accessed
* afterwards.
*
* @author Oliver Gierke
* @author Christoph Strobl
*/
public class AnnotationDetectionFieldCallback implements FieldCallback {
private final Class<? extends Annotation> annotationType;
private @Nullable Field field;
Creates a new AnnotationDetectionFieldCallback
scanning for an annotation of the given type. Params: - annotationType – must not be null.
/**
* Creates a new {@link AnnotationDetectionFieldCallback} scanning for an annotation of the given type.
*
* @param annotationType must not be {@literal null}.
*/
public AnnotationDetectionFieldCallback(Class<? extends Annotation> annotationType) {
Assert.notNull(annotationType, "AnnotationType must not be null!");
this.annotationType = annotationType;
}
/*
* (non-Javadoc)
* @see org.springframework.util.ReflectionUtils.FieldCallback#doWith(java.lang.reflect.Field)
*/
public void doWith(Field field) throws IllegalArgumentException, IllegalAccessException {
if (this.field != null) {
return;
}
if (AnnotatedElementUtils.findMergedAnnotation(field, annotationType) != null) {
ReflectionUtils.makeAccessible(field);
this.field = field;
}
}
Returns the detected field.
Returns: the field
/**
* Returns the detected field.
*
* @return the field
*/
@Nullable
public Field getField() {
return field;
}
Returns the field that was detected.
Throws: - IllegalStateException – in case no field with the configured annotation was found.
Returns:
/**
* Returns the field that was detected.
*
* @return
* @throws IllegalStateException in case no field with the configured annotation was found.
*/
public Field getRequiredField() {
Field field = this.field;
if (field == null) {
throw new IllegalStateException(String.format("No field found for annotation %s!", annotationType));
}
return field;
}
Returns the type of the field.
Returns:
/**
* Returns the type of the field.
*
* @return
*/
@Nullable
public Class<?> getType() {
Field field = this.field;
return field == null ? null : field.getType();
}
Returns the type of the field or throws an IllegalArgumentException
if no field could be found. Throws: - IllegalStateException – in case no field with the configured annotation was found.
Returns:
/**
* Returns the type of the field or throws an {@link IllegalArgumentException} if no field could be found.
*
* @return
* @throws IllegalStateException in case no field with the configured annotation was found.
*/
public Class<?> getRequiredType() {
return getRequiredField().getType();
}
Retrieves the value of the field by reflection.
Params: - source – must not be null.
Returns:
/**
* Retrieves the value of the field by reflection.
*
* @param source must not be {@literal null}.
* @return
*/
@Nullable
@SuppressWarnings("unchecked")
public <T> T getValue(Object source) {
Assert.notNull(source, "Source object must not be null!");
Field field = this.field;
if (field == null) {
return null;
}
return (T) ReflectionUtils.getField(field, source);
}
}