infra.beans.factory.config.DependencyDescriptor Maven / Gradle / Ivy
/*
* Copyright 2017 - 2024 the original author or authors.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see [https://www.gnu.org/licenses/]
*/
package infra.beans.factory.config;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.Serial;
import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.Map;
import java.util.Optional;
import infra.beans.BeansException;
import infra.beans.factory.BeanFactory;
import infra.beans.factory.InjectionPoint;
import infra.beans.factory.NoUniqueBeanDefinitionException;
import infra.beans.factory.annotation.NonOrdered;
import infra.beans.factory.support.AutowireCandidateResolver;
import infra.core.MethodParameter;
import infra.core.ParameterNameDiscoverer;
import infra.core.ResolvableType;
import infra.core.TypeDescriptor;
import infra.lang.Nullable;
import infra.util.ObjectUtils;
/**
* Descriptor for a specific dependency that is about to be injected.
* Wraps a constructor parameter, a method parameter or a field,
* allowing unified access to their metadata.
*
* @author Juergen Hoeller
* @author Harry Yang
* @since 4.0 2021/12/22 21:32
*/
public class DependencyDescriptor extends InjectionPoint implements Serializable {
@Serial
private static final long serialVersionUID = 1L;
private final Class declaringClass;
@Nullable
private String methodName;
@Nullable
private Class[] parameterTypes;
private int parameterIndex;
@Nullable
private String fieldName;
private final boolean required;
private final boolean eager;
private int nestingLevel = 1;
@Nullable
private Class containingClass;
@Nullable
private transient volatile ResolvableType resolvableType;
@Nullable
private transient volatile TypeDescriptor typeDescriptor;
private volatile Boolean ordered;
/**
* Create a new descriptor for a method or constructor parameter.
* Considers the dependency as 'eager'.
*
* @param methodParameter the MethodParameter to wrap
* @param required whether the dependency is required
*/
public DependencyDescriptor(MethodParameter methodParameter, boolean required) {
this(methodParameter, required, true);
}
/**
* Create a new descriptor for a method or constructor parameter.
*
* @param methodParameter the MethodParameter to wrap
* @param required whether the dependency is required
* @param eager whether this dependency is 'eager' in the sense of
* eagerly resolving potential target beans for type matching
*/
public DependencyDescriptor(MethodParameter methodParameter, boolean required, boolean eager) {
super(methodParameter);
this.declaringClass = methodParameter.getDeclaringClass();
if (methodParameter.getMethod() != null) {
this.methodName = methodParameter.getMethod().getName();
}
this.parameterTypes = methodParameter.getExecutable().getParameterTypes();
this.parameterIndex = methodParameter.getParameterIndex();
this.containingClass = methodParameter.getContainingClass();
this.required = required;
this.eager = eager;
}
/**
* Create a new descriptor for a field.
* Considers the dependency as 'eager'.
*
* @param field the field to wrap
* @param required whether the dependency is required
*/
public DependencyDescriptor(Field field, boolean required) {
this(field, required, true);
}
/**
* Create a new descriptor for a field.
*
* @param field the field to wrap
* @param required whether the dependency is required
* @param eager whether this dependency is 'eager' in the sense of
* eagerly resolving potential target beans for type matching
*/
public DependencyDescriptor(Field field, boolean required, boolean eager) {
super(field);
this.declaringClass = field.getDeclaringClass();
this.fieldName = field.getName();
this.required = required;
this.eager = eager;
}
/**
* Copy constructor.
*
* @param original the original descriptor to create a copy from
*/
public DependencyDescriptor(DependencyDescriptor original) {
super(original);
this.declaringClass = original.declaringClass;
this.methodName = original.methodName;
this.parameterTypes = original.parameterTypes;
this.parameterIndex = original.parameterIndex;
this.fieldName = original.fieldName;
this.containingClass = original.containingClass;
this.required = original.required;
this.eager = original.eager;
this.nestingLevel = original.nestingLevel;
}
/**
* Return whether this dependency is required.
* Optional semantics are derived from Java 8's {@link java.util.Optional},
* any variant of a parameter-level {@code Nullable} annotation (such as from
* JSR-305 or the FindBugs set of annotations), or a language-level nullable
* type declaration in Kotlin.
*/
public boolean isRequired() {
if (!this.required) {
return false;
}
if (this.field != null) {
return !(this.field.getType() == Optional.class || hasNullableAnnotation());
}
else {
return !obtainMethodParameter().isOptional();
}
}
/**
* Check whether the underlying field is annotated with any variant of a
* {@code Nullable} annotation, e.g. {@code jakarta.annotation.Nullable} or
* {@code edu.umd.cs.findbugs.annotations.Nullable}.
*
* @see Nullable
*/
private boolean hasNullableAnnotation() {
for (Annotation annotation : getAnnotations()) {
if ("Nullable".equals(annotation.annotationType().getSimpleName())) {
return true;
}
}
return false;
}
/**
* Return whether this dependency is 'eager' in the sense of
* eagerly resolving potential target beans for type matching.
*/
public boolean isEager() {
return this.eager;
}
/**
* is required order
*/
public boolean isOrdered() {
Boolean ordered = this.ordered;
if (ordered == null) {
ordered = getAnnotation(NonOrdered.class) == null;
this.ordered = ordered;
}
return ordered;
}
/**
* Resolve the specified not-unique scenario: by default,
* throwing a {@link NoUniqueBeanDefinitionException}.
*
Subclasses may override this to select one of the instances or
* to opt out with no result at all through returning {@code null}.
*
* @param type the requested bean type
* @param matchingBeans a map of bean names and corresponding bean
* instances which have been pre-selected for the given type
* (qualifiers etc already applied)
* @return a bean instance to proceed with, or {@code null} for none
* @throws BeansException in case of the not-unique scenario being fatal
*/
@Nullable
public Object resolveNotUnique(ResolvableType type, Map matchingBeans) throws BeansException {
throw new NoUniqueBeanDefinitionException(type, matchingBeans.keySet());
}
/**
* Resolve a shortcut for this dependency against the given factory, for example
* taking some pre-resolved information into account.
* The resolution algorithm will first attempt to resolve a shortcut through this
* method before going into the regular type matching algorithm across all beans.
* Subclasses may override this method to improve resolution performance based on
* pre-cached information while still receiving {@link InjectionPoint} exposure etc.
*
* @param beanFactory the associated factory
* @return the shortcut result if any, or {@code null} if none
* @throws BeansException if the shortcut could not be obtained
*/
@Nullable
public Object resolveShortcut(BeanFactory beanFactory) throws BeansException {
return null;
}
/**
* Resolve the specified bean name, as a candidate result of the matching
* algorithm for this dependency, to a bean instance from the given factory.
*
The default implementation calls {@link BeanFactory#getBean(String)}.
* Subclasses may provide additional arguments or other customizations.
*
* @param beanName the bean name, as a candidate result for this dependency
* @param requiredType the expected type of the bean (as an assertion)
* @param beanFactory the associated factory
* @return the bean instance
* @throws BeansException if the bean could not be obtained
* @see BeanFactory#getBean(String)
*/
@Nullable
public Object resolveCandidate(
String beanName, Class requiredType, BeanFactory beanFactory) throws BeansException {
return beanFactory.getBean(beanName);
}
/**
* Increase this descriptor's nesting level.
*/
public void increaseNestingLevel() {
this.nestingLevel++;
this.resolvableType = null;
if (this.methodParameter != null) {
this.methodParameter = this.methodParameter.nested();
}
}
/**
* Optionally set the concrete class that contains this dependency.
* This may differ from the class that declares the parameter/field in that
* it may be a subclass thereof, potentially substituting type variables.
*/
public void setContainingClass(Class containingClass) {
this.containingClass = containingClass;
this.resolvableType = null;
if (this.methodParameter != null) {
this.methodParameter = this.methodParameter.withContainingClass(containingClass);
}
}
/**
* Build a {@link ResolvableType} object for the wrapped parameter/field.
*/
public ResolvableType getResolvableType() {
ResolvableType resolvableType = this.resolvableType;
if (resolvableType == null) {
resolvableType = (this.field != null ?
ResolvableType.forField(this.field, this.nestingLevel, this.containingClass) :
ResolvableType.forMethodParameter(obtainMethodParameter()));
this.resolvableType = resolvableType;
}
return resolvableType;
}
/**
* Build a {@link TypeDescriptor} object for the wrapped parameter/field.
*/
public TypeDescriptor getTypeDescriptor() {
TypeDescriptor typeDescriptor = this.typeDescriptor;
if (typeDescriptor == null) {
typeDescriptor = this.field != null
? new TypeDescriptor(getResolvableType(), getDependencyType(), field)
: new TypeDescriptor(obtainMethodParameter());
this.typeDescriptor = typeDescriptor;
}
return typeDescriptor;
}
/**
* Return whether a fallback match is allowed.
*
This is {@code false} by default but may be overridden to return {@code true} in order
* to suggest to an {@link AutowireCandidateResolver}
* that a fallback match is acceptable as well.
*/
public boolean fallbackMatchAllowed() {
return false;
}
/**
* Return a variant of this descriptor that is intended for a fallback match.
*
* @see #fallbackMatchAllowed()
*/
public DependencyDescriptor forFallbackMatch() {
return new DependencyDescriptor(this) {
@Override
public boolean fallbackMatchAllowed() {
return true;
}
@Override
public boolean usesStandardBeanLookup() {
return true;
}
};
}
/**
* Initialize parameter name discovery for the underlying method parameter, if any.
*
This method does not actually try to retrieve the parameter name at
* this point; it just allows discovery to happen when the application calls
* {@link #getDependencyName()} (if ever).
*/
public void initParameterNameDiscovery(@Nullable ParameterNameDiscoverer parameterNameDiscoverer) {
if (this.methodParameter != null) {
this.methodParameter.initParameterNameDiscovery(parameterNameDiscoverer);
}
}
/**
* Determine the name of the wrapped parameter/field.
*
* @return the declared name (may be {@code null} if unresolvable)
*/
@Nullable
public String getDependencyName() {
return (this.field != null ? this.field.getName() : obtainMethodParameter().getParameterName());
}
/**
* Determine the declared (non-generic) type of the wrapped parameter/field.
*
* @return the declared type (never {@code null})
*/
public Class getDependencyType() {
if (this.field != null) {
if (this.nestingLevel > 1) {
Class clazz = getResolvableType().getRawClass();
return (clazz != null ? clazz : Object.class);
}
else {
return this.field.getType();
}
}
else {
return obtainMethodParameter().getNestedParameterType();
}
}
/**
* Determine whether this dependency supports lazy resolution,
* e.g. through extra proxying. The default is {@code true}.
*
* @see AutowireCandidateResolver#getLazyResolutionProxyIfNecessary
*/
public boolean supportsLazyResolution() {
return true;
}
/**
* Determine whether this descriptor uses a standard bean lookup
* in {@link #resolveCandidate(String, Class, BeanFactory)} and
* therefore qualifies for factory-level shortcut resolution.
*
By default, the {@code DependencyDescriptor} class itself
* uses a standard bean lookup but subclasses may override this.
* If a subclass overrides other methods but preserves a standard
* bean lookup, it may override this method to return {@code true}.
*
* @see #resolveCandidate(String, Class, BeanFactory)
*/
public boolean usesStandardBeanLookup() {
return (getClass() == DependencyDescriptor.class);
}
@Override
public boolean equals(@Nullable Object other) {
if (this == other) {
return true;
}
if (!super.equals(other)) {
return false;
}
DependencyDescriptor otherDesc = (DependencyDescriptor) other;
return (this.required == otherDesc.required && this.eager == otherDesc.eager &&
this.nestingLevel == otherDesc.nestingLevel && this.containingClass == otherDesc.containingClass);
}
@Override
public int hashCode() {
return (31 * super.hashCode() + ObjectUtils.nullSafeHashCode(this.containingClass));
}
//---------------------------------------------------------------------
// Serialization support
//---------------------------------------------------------------------
@Serial
private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
// Rely on default serialization; just initialize state after deserialization.
ois.defaultReadObject();
// Restore reflective handles (which are unfortunately not serializable)
try {
if (this.fieldName != null) {
this.field = this.declaringClass.getDeclaredField(this.fieldName);
}
else {
if (this.methodName != null) {
this.methodParameter = new MethodParameter(
this.declaringClass.getDeclaredMethod(this.methodName, this.parameterTypes), this.parameterIndex);
}
else {
this.methodParameter = new MethodParameter(
this.declaringClass.getDeclaredConstructor(this.parameterTypes), this.parameterIndex);
}
for (int i = 1; i < this.nestingLevel; i++) {
this.methodParameter = this.methodParameter.nested();
}
}
}
catch (Throwable ex) {
throw new IllegalStateException("Could not find original class structure", ex);
}
}
}