org.springframework.expression.spel.support

Class ReflectivePropertyAccessor

java.lang.Object

org.springframework.expression.spel.support.ReflectivePropertyAccessor

All Implemented Interfaces:

PropertyAccessor

Direct Known Subclasses:

DataBindingPropertyAccessor

public class ReflectivePropertyAccessor
extends Object
implements PropertyAccessor

A powerful PropertyAccessor that uses reflection to access properties for reading and possibly also for writing.

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

See Also:

StandardEvaluationContext, SimpleEvaluationContext, DataBindingPropertyAccessor

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ReflectivePropertyAccessor.OptimalPropertyAccessor 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

Constructors

Constructor and Description
ReflectivePropertyAccessor() Create a new property accessor for reading as well writing.
ReflectivePropertyAccessor(boolean allowWrite) Create a new property accessor for reading and possibly writing.

Method Summary

Modifier and Type	Method and Description
boolean	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.
PropertyAccessor	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	findField(String name, Class<?> clazz, boolean mustBeStatic) 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.
Member	getLastReadInvokerPair() Deprecated. as of 4.3.15 since it is not used within the framework anymore
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<?>[]	getSpecificTargetClasses() Returns null which means this is a general purpose accessor.
protected boolean	isCandidateForProperty(Method method, Class<?> targetClass) Determine whether the given Method is a candidate for property access on an instance of the given target class.
TypedValue	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.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReflectivePropertyAccessor

public ReflectivePropertyAccessor()

Create a new property accessor for reading as well writing.

See Also:

ReflectivePropertyAccessor(boolean)

ReflectivePropertyAccessor

public ReflectivePropertyAccessor(boolean allowWrite)

Create a new property accessor for reading and possibly writing.

Parameters:

allowWrite - whether to also allow for write operations

Since:

4.3.15

See Also:

canWrite(org.springframework.expression.EvaluationContext, java.lang.Object, java.lang.String)

Method Detail

getSpecificTargetClasses

@Nullable
public Class<?>[] getSpecificTargetClasses()

Returns null which means this is a general purpose accessor.

Specified by:

getSpecificTargetClasses in interface PropertyAccessor

Returns:

an array of classes that this resolver is suitable for (or null if a general resolver)

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 interface PropertyAccessor

Parameters:

context - the evaluation context in which the access is being attempted

target - the target object upon which the property is being accessed

name - 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

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 if PropertyAccessor.canRead(org.springframework.expression.EvaluationContext, java.lang.Object, java.lang.String) also returns true.

Specified by:

read in interface PropertyAccessor

Parameters:

context - the evaluation context in which the access is being attempted

target - the target object upon which the property is being accessed

name - 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

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 interface PropertyAccessor

Parameters:

context - the evaluation context in which the access is being attempted

target - the target object upon which the property is being accessed

name - 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

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 if PropertyAccessor.canWrite(org.springframework.expression.EvaluationContext, java.lang.Object, java.lang.String) also returns true.

Specified by:

write in interface PropertyAccessor

Parameters:

context - the evaluation context in which the access is being attempted

target - the target object upon which the property is being accessed

name - the name of the property being accessed

newValue - the new value for the property

Throws:

AccessException - if there is any problem writing to the property value

getLastReadInvokerPair

@Deprecated
 @Nullable
public Member getLastReadInvokerPair()

Deprecated. as of 4.3.15 since it is not used within the framework anymore

Get the last read invoker pair.

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

protected boolean isCandidateForProperty(Method method,
                                         Class<?> targetClass)

Determine whether the given Method 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 evaluate

targetClass - the concrete target class that is being introspected

Since:

4.3.15

getPropertyMethodSuffixes

protected String[] getPropertyMethodSuffixes(String propertyName)

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

protected String getPropertyMethodSuffix(String propertyName)

Return the method suffix for a given property name. The default implementation uses JavaBean conventions.

findField

@Nullable
protected Field findField(String name,
                                    Class<?> clazz,
                                    boolean mustBeStatic)

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.

See Also:

ReflectivePropertyAccessor.OptimalPropertyAccessor