org.springframework.beans.factory.config

Class DependencyDescriptor

java.lang.Object

org.springframework.beans.factory.InjectionPoint

org.springframework.beans.factory.config.DependencyDescriptor

All Implemented Interfaces:

java.io.Serializable

public class DependencyDescriptor
extends InjectionPoint
implements java.io.Serializable

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.

Since:

2.5

Author:

Juergen Hoeller

See Also:

Serialized Form

Field Summary

Fields inherited from class org.springframework.beans.factory.InjectionPoint

field, methodParameter

Constructor Summary

Constructors

Constructor and Description
DependencyDescriptor(DependencyDescriptor original) Copy constructor.
DependencyDescriptor(java.lang.reflect.Field field, boolean required) Create a new descriptor for a field.
DependencyDescriptor(java.lang.reflect.Field field, boolean required, boolean eager) Create a new descriptor for a field.
DependencyDescriptor(org.springframework.core.MethodParameter methodParameter, boolean required) Create a new descriptor for a method or constructor parameter.
DependencyDescriptor(org.springframework.core.MethodParameter methodParameter, boolean required, boolean eager) Create a new descriptor for a method or constructor parameter.

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object other)
boolean	fallbackMatchAllowed() Return whether a fallback match is allowed.
DependencyDescriptor	forFallbackMatch() Return a variant of this descriptor that is intended for a fallback match.
java.lang.String	getDependencyName() Determine the name of the wrapped parameter/field.
java.lang.Class<?>	getDependencyType() Determine the declared (non-generic) type of the wrapped parameter/field.
org.springframework.core.ResolvableType	getResolvableType() Build a ResolvableType object for the wrapped parameter/field.
int	hashCode()
void	increaseNestingLevel() Increase this descriptor's nesting level.
void	initParameterNameDiscovery(org.springframework.core.ParameterNameDiscoverer parameterNameDiscoverer) Initialize parameter name discovery for the underlying method parameter, if any.
boolean	isEager() Return whether this dependency is 'eager' in the sense of eagerly resolving potential target beans for type matching.
boolean	isRequired() Return whether this dependency is required.
boolean	isStreamAccess() Return whether this descriptor allows for stream-style access to result instances.
java.lang.Object	resolveCandidate(java.lang.String beanName, java.lang.Class<?> requiredType, BeanFactory beanFactory) Resolve the specified bean name, as a candidate result of the matching algorithm for this dependency, to a bean instance from the given factory.
java.lang.Object	resolveNotUnique(java.lang.Class<?> type, java.util.Map<java.lang.String,java.lang.Object> matchingBeans) Deprecated. as of 5.1, in favor of resolveNotUnique(ResolvableType, Map)
java.lang.Object	resolveNotUnique(org.springframework.core.ResolvableType type, java.util.Map<java.lang.String,java.lang.Object> matchingBeans) Resolve the specified not-unique scenario: by default, throwing a NoUniqueBeanDefinitionException.
java.lang.Object	resolveShortcut(BeanFactory beanFactory) Resolve a shortcut for this dependency against the given factory, for example taking some pre-resolved information into account.
void	setContainingClass(java.lang.Class<?> containingClass) Optionally set the concrete class that contains this dependency.

Methods inherited from class org.springframework.beans.factory.InjectionPoint

getAnnotatedElement, getAnnotation, getAnnotations, getDeclaredType, getField, getMember, getMethodParameter, obtainMethodParameter, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

DependencyDescriptor

public DependencyDescriptor(org.springframework.core.MethodParameter methodParameter,
                            boolean required)

Create a new descriptor for a method or constructor parameter. Considers the dependency as 'eager'.

Parameters:

methodParameter - the MethodParameter to wrap

required - whether the dependency is required

DependencyDescriptor

public DependencyDescriptor(org.springframework.core.MethodParameter methodParameter,
                            boolean required,
                            boolean eager)

Create a new descriptor for a method or constructor parameter.

Parameters:

methodParameter - the MethodParameter to wrap

required - whether the dependency is required

eager - whether this dependency is 'eager' in the sense of eagerly resolving potential target beans for type matching

DependencyDescriptor

public DependencyDescriptor(java.lang.reflect.Field field,
                            boolean required)

Create a new descriptor for a field. Considers the dependency as 'eager'.

Parameters:

field - the field to wrap

required - whether the dependency is required

DependencyDescriptor

public DependencyDescriptor(java.lang.reflect.Field field,
                            boolean required,
                            boolean eager)

Create a new descriptor for a field.

Parameters:

field - the field to wrap

required - whether the dependency is required

eager - whether this dependency is 'eager' in the sense of eagerly resolving potential target beans for type matching

DependencyDescriptor

public DependencyDescriptor(DependencyDescriptor original)

Copy constructor.

Parameters:

original - the original descriptor to create a copy from

Method Detail

isRequired

public boolean isRequired()

Return whether this dependency is required.

Optional semantics are derived from Java 8's Optional, any variant of a parameter-level Nullable annotation (such as from JSR-305 or the FindBugs set of annotations), or a language-level nullable type declaration in Kotlin.

isEager

public boolean isEager()

Return whether this dependency is 'eager' in the sense of eagerly resolving potential target beans for type matching.

isStreamAccess

public boolean isStreamAccess()

Return whether this descriptor allows for stream-style access to result instances.

By default, dependencies are strictly resolved to the declaration of the injection point and therefore only resolve multiple entries if the injection point is declared as an array, collection or map. This is indicated by returning false here.

Overriding this method to return true indicates that the injection point declares the bean type but the resolution is meant to end up in a Stream for the declared bean type, with the caller handling the multi-instance case for the injection point.

Since:

5.1

resolveNotUnique

@Nullable
public java.lang.Object resolveNotUnique(org.springframework.core.ResolvableType type,
                                                   java.util.Map<java.lang.String,java.lang.Object> matchingBeans)
                                            throws BeansException

Resolve the specified not-unique scenario: by default, throwing a NoUniqueBeanDefinitionException.

Subclasses may override this to select one of the instances or to opt out with no result at all through returning null.

Parameters:

type - the requested bean type

matchingBeans - a map of bean names and corresponding bean instances which have been pre-selected for the given type (qualifiers etc already applied)

Returns:

a bean instance to proceed with, or null for none

Throws:

BeansException - in case of the not-unique scenario being fatal

Since:

5.1

resolveNotUnique

@Deprecated
 @Nullable
public java.lang.Object resolveNotUnique(java.lang.Class<?> type,
                                                                java.util.Map<java.lang.String,java.lang.Object> matchingBeans)
                                                         throws BeansException

Deprecated. as of 5.1, in favor of resolveNotUnique(ResolvableType, Map)

Resolve the specified not-unique scenario: by default, throwing a NoUniqueBeanDefinitionException.

Subclasses may override this to select one of the instances or to opt out with no result at all through returning null.

Parameters:

type - the requested bean type

matchingBeans - a map of bean names and corresponding bean instances which have been pre-selected for the given type (qualifiers etc already applied)

Returns:

a bean instance to proceed with, or null for none

Throws:

BeansException - in case of the not-unique scenario being fatal

Since:

4.3

resolveShortcut

@Nullable
public java.lang.Object resolveShortcut(BeanFactory beanFactory)
                                           throws BeansException

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 InjectionPoint exposure etc.

Parameters:

beanFactory - the associated factory

Returns:

the shortcut result if any, or null if none

Throws:

BeansException - if the shortcut could not be obtained

Since:

4.3.1

resolveCandidate

public java.lang.Object resolveCandidate(java.lang.String beanName,
                                         java.lang.Class<?> requiredType,
                                         BeanFactory beanFactory)
                                  throws BeansException

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 BeanFactory.getBean(String). Subclasses may provide additional arguments or other customizations.

Parameters:

beanName - the bean name, as a candidate result for this dependency

requiredType - the expected type of the bean (as an assertion)

beanFactory - the associated factory

Returns:

the bean instance (never null)

Throws:

BeansException - if the bean could not be obtained

Since:

4.3.2

See Also:

BeanFactory.getBean(String)

increaseNestingLevel

public void increaseNestingLevel()

Increase this descriptor's nesting level.

See Also:

MethodParameter.increaseNestingLevel()

setContainingClass

public void setContainingClass(java.lang.Class<?> containingClass)

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.

Since:

4.0

getResolvableType

public org.springframework.core.ResolvableType getResolvableType()

Build a ResolvableType object for the wrapped parameter/field.

Since:

4.0

fallbackMatchAllowed

public boolean fallbackMatchAllowed()

Return whether a fallback match is allowed.

This is false by default but may be overridden to return true in order to suggest to an AutowireCandidateResolver that a fallback match is acceptable as well.

Since:

4.0

forFallbackMatch

public DependencyDescriptor forFallbackMatch()

Return a variant of this descriptor that is intended for a fallback match.

Since:

4.0

See Also:

fallbackMatchAllowed()

initParameterNameDiscovery

public void initParameterNameDiscovery(@Nullable
                                       org.springframework.core.ParameterNameDiscoverer parameterNameDiscoverer)

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 getDependencyName() (if ever).

getDependencyName

@Nullable
public java.lang.String getDependencyName()

Determine the name of the wrapped parameter/field.

Returns:

the declared name (never null)

getDependencyType

public java.lang.Class<?> getDependencyType()

Determine the declared (non-generic) type of the wrapped parameter/field.

Returns:

the declared type (never null)

equals

public boolean equals(java.lang.Object other)

Overrides:

equals in class InjectionPoint

hashCode

public int hashCode()

Overrides:

hashCode in class InjectionPoint