Class ReflectivePropertyAccessor
java.lang.Object
org.springframework.expression.spel.support.ReflectivePropertyAccessor
- All Implemented Interfaces:
PropertyAccessor
- Direct Known Subclasses:
DataBindingPropertyAccessor
A powerful
PropertyAccessor
that uses reflection to access properties
for reading and possibly also for writing on a target instance.
A property can be referenced through a public getter method (when being read) or a public setter method (when being written), and also as a public field.
- Since:
- 3.0
- Author:
- Andy Clement, Juergen Hoeller, Phillip Webb, Sam Brannen, Sebastien Deleuze
- See Also:
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Nested Class Summary
Modifier and TypeClassDescriptionstatic class
An optimized form of a PropertyAccessor that will use reflection but only knows how to access a particular property on a particular class. -
Constructor Summary
ConstructorDescriptionCreate a new property accessor for reading as well writing.ReflectivePropertyAccessor
(boolean allowWrite) Create a new property accessor for reading and possibly also writing. -
Method Summary
Modifier and TypeMethodDescriptionboolean
canRead
(EvaluationContext context, Object target, String name) Called to determine if a resolver instance is able to access a specified property on a specified target object.boolean
canWrite
(EvaluationContext context, Object target, String name) Called to determine if a resolver instance is able to write to a specified property on a specified target object.createOptimalAccessor
(EvaluationContext context, Object target, String name) Attempt to create an optimized property accessor tailored for a property of a particular name on a particular class.protected Field
Find a field of a certain name on a specified class.protected Method
findGetterForProperty
(String propertyName, Class<?> clazz, boolean mustBeStatic) Find a getter method for the specified property.protected Method
findSetterForProperty
(String propertyName, Class<?> clazz, boolean mustBeStatic) Find a setter method for the specified property.protected String
getPropertyMethodSuffix
(String propertyName) Return the method suffix for a given property name.protected String[]
getPropertyMethodSuffixes
(String propertyName) Return the method suffixes for a given property name.Class<?>[]
Returnsnull
which means this is a general purpose accessor.protected boolean
isCandidateForProperty
(Method method, Class<?> targetClass) Determine whether the givenMethod
is a candidate for property access on an instance of the given target class.read
(EvaluationContext context, Object target, String name) Called to read a property from a specified target object.void
write
(EvaluationContext context, Object target, String name, Object newValue) Called to write to a property on a specified target object.
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Constructor Details
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ReflectivePropertyAccessor
public ReflectivePropertyAccessor()Create a new property accessor for reading as well writing.- See Also:
-
ReflectivePropertyAccessor
public ReflectivePropertyAccessor(boolean allowWrite) Create a new property accessor for reading and possibly also writing.- Parameters:
allowWrite
- whether to allow write operations on a target instance- Since:
- 4.3.15
- See Also:
-
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Method Details
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getSpecificTargetClasses
Returnsnull
which means this is a general purpose accessor.- Specified by:
getSpecificTargetClasses
in interfacePropertyAccessor
- Returns:
- an array of classes that this resolver is suitable for
(or
null
if a general resolver)
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canRead
public boolean canRead(EvaluationContext context, @Nullable Object target, String name) throws AccessException Description copied from interface:PropertyAccessor
Called to determine if a resolver instance is able to access a specified property on a specified target object.- Specified by:
canRead
in interfacePropertyAccessor
- Parameters:
context
- the evaluation context in which the access is being attemptedtarget
- the target object upon which the property is being accessedname
- the name of the property being accessed- Returns:
- true if this resolver is able to read the property
- Throws:
AccessException
- if there is any problem determining whether the property can be read
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read
public TypedValue read(EvaluationContext context, @Nullable Object target, String name) throws AccessException Description copied from interface:PropertyAccessor
Called to read a property from a specified target object. Should only succeed ifPropertyAccessor.canRead(org.springframework.expression.EvaluationContext, java.lang.Object, java.lang.String)
also returnstrue
.- Specified by:
read
in interfacePropertyAccessor
- Parameters:
context
- the evaluation context in which the access is being attemptedtarget
- the target object upon which the property is being accessedname
- the name of the property being accessed- Returns:
- a TypedValue object wrapping the property value read and a type descriptor for it
- Throws:
AccessException
- if there is any problem accessing the property value
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canWrite
public boolean canWrite(EvaluationContext context, @Nullable Object target, String name) throws AccessException Description copied from interface:PropertyAccessor
Called to determine if a resolver instance is able to write to a specified property on a specified target object.- Specified by:
canWrite
in interfacePropertyAccessor
- Parameters:
context
- the evaluation context in which the access is being attemptedtarget
- the target object upon which the property is being accessedname
- the name of the property being accessed- Returns:
- true if this resolver is able to write to the property
- Throws:
AccessException
- if there is any problem determining whether the property can be written to
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write
public void write(EvaluationContext context, @Nullable Object target, String name, @Nullable Object newValue) throws AccessException Description copied from interface:PropertyAccessor
Called to write to a property on a specified target object. Should only succeed ifPropertyAccessor.canWrite(org.springframework.expression.EvaluationContext, java.lang.Object, java.lang.String)
also returnstrue
.- Specified by:
write
in interfacePropertyAccessor
- Parameters:
context
- the evaluation context in which the access is being attemptedtarget
- the target object upon which the property is being accessedname
- the name of the property being accessednewValue
- the new value for the property- Throws:
AccessException
- if there is any problem writing to the property value
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findGetterForProperty
@Nullable protected Method findGetterForProperty(String propertyName, Class<?> clazz, boolean mustBeStatic) Find a getter method for the specified property. -
findSetterForProperty
@Nullable protected Method findSetterForProperty(String propertyName, Class<?> clazz, boolean mustBeStatic) Find a setter method for the specified property. -
isCandidateForProperty
Determine whether the givenMethod
is a candidate for property access on an instance of the given target class.The default implementation considers any method as a candidate, even for non-user-declared properties on the
Object
base class.- Parameters:
method
- the Method to evaluatetargetClass
- the concrete target class that is being introspected- Since:
- 4.3.15
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getPropertyMethodSuffixes
Return the method suffixes for a given property name. The default implementation uses JavaBean conventions with additional support for properties of the form 'xY' where the method 'getXY()' is used in preference to the JavaBean convention of 'getxY()'. -
getPropertyMethodSuffix
Return the method suffix for a given property name. The default implementation uses JavaBean conventions. -
findField
Find a field of a certain name on a specified class. -
createOptimalAccessor
public PropertyAccessor createOptimalAccessor(EvaluationContext context, @Nullable Object target, String name) Attempt to create an optimized property accessor tailored for a property of a particular name on a particular class. The general ReflectivePropertyAccessor will always work but is not optimal due to the need to lookup which reflective member (method/field) to use each time read() is called. This method will just return the ReflectivePropertyAccessor instance if it is unable to build a more optimal accessor.Note: An optimal accessor is currently only usable for read attempts. Do not call this method if you need a read-write accessor.
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