Class DefaultBeanFactory
- All Implemented Interfaces:
BeanFactory
The default implementation of the BeanFactory
interface.
This class creates beans of arbitrary types using reflection. Each time the createBean()
method is invoked, a
new bean instance is created. A default bean class is not supported.
For data type conversions (which may be needed before invoking methods through reflection to ensure that the current
parameters match their declared types) a ConversionHandler
object is used. An instance of this class can be
passed to the constructor. Alternatively, a default ConversionHandler
instance is used.
An instance of this factory class will be set as the default bean factory for the BeanHelper
class. This
means that if not bean factory is specified in a BeanDeclaration
, this default instance will be used.
- Since:
- 1.3
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate final ConversionHandler
The conversion handler used by this instance.private static final String
A format string for generating error messages for constructor matching.static final DefaultBeanFactory
Stores the default instance of this class. -
Constructor Summary
ConstructorsConstructorDescriptionConstructs a new instance ofDefaultBeanFactory
using a defaultConversionHandler
.DefaultBeanFactory
(ConversionHandler convHandler) Constructs a new instance ofDefaultBeanFactory
using the specifiedConversionHandler
for data type conversions. -
Method Summary
Modifier and TypeMethodDescriptionprivate static <T> void
checkSingleMatchingConstructor
(Class<T> beanClass, BeanDeclaration data, List<Constructor<T>> matchingConstructors) Checks whether exactly one matching constructor was found.private static ConfigurationRuntimeException
constructorMatchingException
(Class<?> beanClass, BeanDeclaration data, String msg) Constructs an exception if no single matching constructor was found with a meaningful error message.Creates a new bean instance.protected Object
Creates the bean instance.private Object[]
fetchConstructorArgs
(Constructor<?> ctor, BeanCreationContext bcc) Obtains the arguments for a constructor call to create a bean.protected static <T> Constructor
<T> findMatchingConstructor
(Class<T> beanClass, BeanDeclaration data) Evaluates constructor arguments in the specifiedBeanDeclaration
and tries to find a unique matching constructor.private static <T> List
<Constructor<T>> findMatchingConstructors
(Class<T> beanClass, BeanDeclaration data) Returns a list with all constructors which are compatible with the constructor arguments specified by the givenBeanDeclaration
.private static Collection
<ConstructorArg> Gets constructor arguments from a bean declaration.Gets theConversionHandler
used by this object.Class
<?> Gets the default bean class used by this factory.protected void
initBeanInstance
(Object bean, BeanCreationContext bcc) Initializes the newly created bean instance.private static boolean
matchesConstructor
(Constructor<?> ctor, Collection<ConstructorArg> args) Checks whether the given constructor is compatible with the given list of arguments.private static Collection
<ConstructorArg> Fetches constructor arguments from the given bean declaration.
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Field Details
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INSTANCE
Stores the default instance of this class. -
FMT_CTOR_ERROR
A format string for generating error messages for constructor matching.- See Also:
-
conversionHandler
The conversion handler used by this instance.
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Constructor Details
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DefaultBeanFactory
public DefaultBeanFactory()Constructs a new instance ofDefaultBeanFactory
using a defaultConversionHandler
. -
DefaultBeanFactory
Constructs a new instance ofDefaultBeanFactory
using the specifiedConversionHandler
for data type conversions.- Parameters:
convHandler
- theConversionHandler
; can be null, then a default handler is used- Since:
- 2.0
-
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Method Details
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getConversionHandler
Gets theConversionHandler
used by this object.- Returns:
- the
ConversionHandler
- Since:
- 2.0
-
createBean
Creates a new bean instance. This implementation delegates to the protected methodscreateBeanInstance()
andinitBeanInstance()
for creating and initializing the bean. This makes it easier for derived classes that need to change specific functionality of the base class.- Specified by:
createBean
in interfaceBeanFactory
- Parameters:
bcc
- the context object defining the bean to be created- Returns:
- the new bean instance
- Throws:
Exception
- if an error occurs
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getDefaultBeanClass
Gets the default bean class used by this factory. This is always null for this implementation.- Specified by:
getDefaultBeanClass
in interfaceBeanFactory
- Returns:
- the default bean class
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createBeanInstance
Creates the bean instance. This method is called bycreateBean()
. It uses reflection to create a new instance of the specified class.- Parameters:
bcc
- the context object defining the bean to be created- Returns:
- the new bean instance
- Throws:
Exception
- if an error occurs
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initBeanInstance
Initializes the newly created bean instance. This method is called bycreateBean()
. It calls theinitBean()
method of the context object for performing the initialization.- Parameters:
bean
- the newly created bean instancebcc
- the context object defining the bean to be created- Throws:
Exception
- if an error occurs
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findMatchingConstructor
protected static <T> Constructor<T> findMatchingConstructor(Class<T> beanClass, BeanDeclaration data) Evaluates constructor arguments in the specifiedBeanDeclaration
and tries to find a unique matching constructor. If this is not possible, an exception is thrown. Note: This method is intended to be used by concreteBeanFactory
implementations and not by client code.- Type Parameters:
T
- the type of the bean to be created- Parameters:
beanClass
- the class of the bean to be createddata
- the currentBeanDeclaration
- Returns:
- the single matching constructor
- Throws:
ConfigurationRuntimeException
- if no single matching constructor can be foundNullPointerException
- if the bean class or bean declaration are null
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fetchConstructorArgs
Obtains the arguments for a constructor call to create a bean. This method resolves nested bean declarations and performs necessary type conversions.- Parameters:
ctor
- the constructor to be invokedbcc
- the context object defining the bean to be created- Returns:
- an array with constructor arguments
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nullSafeConstructorArgs
Fetches constructor arguments from the given bean declaration. Handles null values safely.- Parameters:
data
- the bean declaration- Returns:
- the collection with constructor arguments (never null)
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findMatchingConstructors
private static <T> List<Constructor<T>> findMatchingConstructors(Class<T> beanClass, BeanDeclaration data) Returns a list with all constructors which are compatible with the constructor arguments specified by the givenBeanDeclaration
.- Parameters:
beanClass
- the bean class to be instantiateddata
- the currentBeanDeclaration
- Returns:
- a list with all matching constructors
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matchesConstructor
Checks whether the given constructor is compatible with the given list of arguments.- Parameters:
ctor
- the constructor to be checkedargs
- the collection of constructor arguments- Returns:
- a flag whether this constructor is compatible with the given arguments
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getConstructorArgs
Gets constructor arguments from a bean declaration. Deals with null values.- Parameters:
data
- the bean declaration- Returns:
- the collection with constructor arguments (never null)
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checkSingleMatchingConstructor
private static <T> void checkSingleMatchingConstructor(Class<T> beanClass, BeanDeclaration data, List<Constructor<T>> matchingConstructors) Checks whether exactly one matching constructor was found. Throws a meaningful exception if there is not a single matching constructor.- Parameters:
beanClass
- the bean classdata
- the bean declarationmatchingConstructors
- the list with matching constructors- Throws:
ConfigurationRuntimeException
- if there is not exactly one match
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constructorMatchingException
private static ConfigurationRuntimeException constructorMatchingException(Class<?> beanClass, BeanDeclaration data, String msg) Constructs an exception if no single matching constructor was found with a meaningful error message.- Parameters:
beanClass
- the affected bean classdata
- the bean declarationmsg
- an error message- Returns:
- the exception with the error message
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