org.springframework.test.context.junit.jupiter

Class ParameterAutowireUtils

java.lang.Object

org.springframework.test.context.junit.jupiter.ParameterAutowireUtils

abstract class ParameterAutowireUtils
extends java.lang.Object

Collection of utilities related to autowiring of individual method parameters.

Since:

5.0

Author:

Sam Brannen

See Also:

isAutowirable(java.lang.reflect.Parameter, int), resolveDependency(java.lang.reflect.Parameter, int, java.lang.Class<?>, org.springframework.context.ApplicationContext)

Field Summary

Fields

Modifier and Type	Field and Description
private static java.lang.reflect.AnnotatedElement	EMPTY_ANNOTATED_ELEMENT

Constructor Summary

Constructors

Constructor and Description
ParameterAutowireUtils()

Method Summary

Modifier and Type	Method and Description
private static java.lang.reflect.AnnotatedElement	getEffectiveAnnotatedParameter(java.lang.reflect.Parameter parameter, int index) Due to a bug in javac on JDK versions prior to JDK 9, looking up annotations directly on a Parameter will fail for inner class constructors.
(package private) static boolean	isAutowirable(java.lang.reflect.Parameter parameter, int parameterIndex) Determine if the supplied Parameter can potentially be autowired from an ApplicationContext.
(package private) static java.lang.Object	resolveDependency(java.lang.reflect.Parameter parameter, int parameterIndex, java.lang.Class<?> containingClass, ApplicationContext applicationContext) Resolve the dependency for the supplied Parameter from the supplied ApplicationContext.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

EMPTY_ANNOTATED_ELEMENT

private static final java.lang.reflect.AnnotatedElement EMPTY_ANNOTATED_ELEMENT

Constructor Detail

ParameterAutowireUtils

ParameterAutowireUtils()

Method Detail

isAutowirable

static boolean isAutowirable(java.lang.reflect.Parameter parameter,
                             int parameterIndex)

Determine if the supplied Parameter can potentially be autowired from an ApplicationContext.

Returns true if the supplied parameter is of type ApplicationContext (or a sub-type thereof) or is annotated or meta-annotated with @Autowired, @Qualifier, or @Value.

Parameters:

parameter - the parameter whose dependency should be autowired

parameterIndex - the index of the parameter

See Also:

resolveDependency(java.lang.reflect.Parameter, int, java.lang.Class<?>, org.springframework.context.ApplicationContext)

resolveDependency

@Nullable
static java.lang.Object resolveDependency(java.lang.reflect.Parameter parameter,
                                                    int parameterIndex,
                                                    java.lang.Class<?> containingClass,
                                                    ApplicationContext applicationContext)

Resolve the dependency for the supplied Parameter from the supplied ApplicationContext.

Provides comprehensive autowiring support for individual method parameters on par with Spring's dependency injection facilities for autowired fields and methods, including support for @Autowired, @Qualifier, and @Value with support for property placeholders and SpEL expressions in @Value declarations.

The dependency is required unless the parameter is annotated with @Autowired with the required flag set to false.

If an explicit qualifier is not declared, the name of the parameter will be used as the qualifier for resolving ambiguities.

Parameters:

parameter - the parameter whose dependency should be resolved

parameterIndex - the index of the parameter

containingClass - the concrete class that contains the parameter; this may differ from the class that declares the parameter in that it may be a subclass thereof, potentially substituting type variables

applicationContext - the application context from which to resolve the dependency

Returns:

the resolved object, or null if none found

Throws:

BeansException - if dependency resolution failed

See Also:

isAutowirable(java.lang.reflect.Parameter, int), Autowired.required(), SynthesizingMethodParameter.forParameter(Parameter), AutowireCapableBeanFactory.resolveDependency(DependencyDescriptor, String)

getEffectiveAnnotatedParameter

private static java.lang.reflect.AnnotatedElement getEffectiveAnnotatedParameter(java.lang.reflect.Parameter parameter,
                                                                                 int index)

Due to a bug in javac on JDK versions prior to JDK 9, looking up annotations directly on a Parameter will fail for inner class constructors.

Bug in javac in JDK < 9

The parameter annotations array in the compiled byte code excludes an entry for the implicit enclosing instance parameter for an inner class constructor.

Workaround

This method provides a workaround for this off-by-one error by allowing the caller to access annotations on the preceding Parameter object (i.e., index - 1). If the supplied index is zero, this method returns an empty AnnotatedElement.

WARNING

The AnnotatedElement returned by this method should never be cast and treated as a Parameter since the metadata (e.g., Parameter.getName(), Parameter.getType(), etc.) will not match those for the declared parameter at the given index in an inner class constructor.

Returns:

the supplied parameter or the effective Parameter if the aforementioned bug is in effect