org.springframework.beans.factory.InjectionPoint Maven / Gradle / Ivy
/*
* Copyright 2002-2019 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.beans.factory;
import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Field;
import java.lang.reflect.Member;
import org.springframework.core.MethodParameter;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
/**
* A simple descriptor for an injection point, pointing to a method/constructor
* parameter or a field. Exposed by {@link UnsatisfiedDependencyException}.
* Also available as an argument for factory methods, reacting to the
* requesting injection point for building a customized bean instance.
*
* @author Juergen Hoeller
* @since 4.3
* @see UnsatisfiedDependencyException#getInjectionPoint()
* @see org.springframework.beans.factory.config.DependencyDescriptor
*/
public class InjectionPoint {
@Nullable
protected MethodParameter methodParameter;
@Nullable
protected Field field;
@Nullable
private volatile Annotation[] fieldAnnotations;
/**
* Create an injection point descriptor for a method or constructor parameter.
* @param methodParameter the MethodParameter to wrap
*/
public InjectionPoint(MethodParameter methodParameter) {
Assert.notNull(methodParameter, "MethodParameter must not be null");
this.methodParameter = methodParameter;
}
/**
* Create an injection point descriptor for a field.
* @param field the field to wrap
*/
public InjectionPoint(Field field) {
Assert.notNull(field, "Field must not be null");
this.field = field;
}
/**
* Copy constructor.
* @param original the original descriptor to create a copy from
*/
protected InjectionPoint(InjectionPoint original) {
this.methodParameter = (original.methodParameter != null ?
new MethodParameter(original.methodParameter) : null);
this.field = original.field;
this.fieldAnnotations = original.fieldAnnotations;
}
/**
* Just available for serialization purposes in subclasses.
*/
protected InjectionPoint() {
}
/**
* Return the wrapped MethodParameter, if any.
* Note: Either MethodParameter or Field is available.
* @return the MethodParameter, or {@code null} if none
*/
@Nullable
public MethodParameter getMethodParameter() {
return this.methodParameter;
}
/**
* Return the wrapped Field, if any.
*
Note: Either MethodParameter or Field is available.
* @return the Field, or {@code null} if none
*/
@Nullable
public Field getField() {
return this.field;
}
/**
* Return the wrapped MethodParameter, assuming it is present.
* @return the MethodParameter (never {@code null})
* @throws IllegalStateException if no MethodParameter is available
* @since 5.0
*/
protected final MethodParameter obtainMethodParameter() {
Assert.state(this.methodParameter != null, "Neither Field nor MethodParameter");
return this.methodParameter;
}
/**
* Obtain the annotations associated with the wrapped field or method/constructor parameter.
*/
public Annotation[] getAnnotations() {
if (this.field != null) {
Annotation[] fieldAnnotations = this.fieldAnnotations;
if (fieldAnnotations == null) {
fieldAnnotations = this.field.getAnnotations();
this.fieldAnnotations = fieldAnnotations;
}
return fieldAnnotations;
}
else {
return obtainMethodParameter().getParameterAnnotations();
}
}
/**
* Retrieve a field/parameter annotation of the given type, if any.
* @param annotationType the annotation type to retrieve
* @return the annotation instance, or {@code null} if none found
* @since 4.3.9
*/
@Nullable
public A getAnnotation(Class annotationType) {
return (this.field != null ? this.field.getAnnotation(annotationType) :
obtainMethodParameter().getParameterAnnotation(annotationType));
}
/**
* Return the type declared by the underlying field or method/constructor parameter,
* indicating the injection type.
*/
public Class getDeclaredType() {
return (this.field != null ? this.field.getType() : obtainMethodParameter().getParameterType());
}
/**
* Returns the wrapped member, containing the injection point.
* @return the Field / Method / Constructor as Member
*/
public Member getMember() {
return (this.field != null ? this.field : obtainMethodParameter().getMember());
}
/**
* Return the wrapped annotated element.
* Note: In case of a method/constructor parameter, this exposes
* the annotations declared on the method or constructor itself
* (i.e. at the method/constructor level, not at the parameter level).
* Use {@link #getAnnotations()} to obtain parameter-level annotations in
* such a scenario, transparently with corresponding field annotations.
* @return the Field / Method / Constructor as AnnotatedElement
*/
public AnnotatedElement getAnnotatedElement() {
return (this.field != null ? this.field : obtainMethodParameter().getAnnotatedElement());
}
@Override
public boolean equals(@Nullable Object other) {
if (this == other) {
return true;
}
if (other == null || getClass() != other.getClass()) {
return false;
}
InjectionPoint otherPoint = (InjectionPoint) other;
return (ObjectUtils.nullSafeEquals(this.field, otherPoint.field) &&
ObjectUtils.nullSafeEquals(this.methodParameter, otherPoint.methodParameter));
}
@Override
public int hashCode() {
return (this.field != null ? this.field.hashCode() : ObjectUtils.nullSafeHashCode(this.methodParameter));
}
@Override
public String toString() {
return (this.field != null ? "field '" + this.field.getName() + "'" : String.valueOf(this.methodParameter));
}
}