Package org.springframework.expression.spel.support

Class StandardEvaluationContext

java.lang.Object

org.springframework.expression.spel.support.StandardEvaluationContext

All Implemented Interfaces:

EvaluationContext

Direct Known Subclasses:

MethodBasedEvaluationContext

public class StandardEvaluationContext
extends Object
implements EvaluationContext

A powerful and highly configurable EvaluationContext implementation.

This context uses standard implementations of all applicable strategies, based on reflection to resolve properties, methods, and fields. Note, however, that you may need to manually configure a StandardTypeLocator with a specific ClassLoader to ensure that the SpEL expression parser is able to reliably locate user types. See setTypeLocator(TypeLocator) for details.

In addition to support for setting and looking up variables as defined in the EvaluationContext API, StandardEvaluationContext also provides support for registering and looking up functions. The registerFunction(...) methods provide a convenient way to register a function as a Method or a MethodHandle; however, a function can also be registered via setVariable(String, Object) or setVariables(Map). Since functions share a namespace with the variables in this evaluation context, care must be taken to ensure that function names and variable names do not overlap.

For a simpler, builder-style context variant for data-binding purposes, consider using SimpleEvaluationContext instead which allows for opting into several SpEL features as needed by specific use cases.

Since:

3.0

Author:

Andy Clement, Juergen Hoeller, Sam Brannen, Stephane Nicoll

See Also:

• SimpleEvaluationContext
• ReflectivePropertyAccessor
• ReflectiveConstructorResolver
• ReflectiveMethodResolver
• StandardTypeLocator
• StandardTypeConverter
• StandardTypeComparator
• StandardOperatorOverloader

Constructor Summary

Constructors

Constructor	Description
StandardEvaluationContext()	Create a StandardEvaluationContext with a null root object.
StandardEvaluationContext(Object rootObject)	Create a StandardEvaluationContext with the given root object.

Method Summary

Modifier and Type	Method	Description
void	addConstructorResolver(ConstructorResolver resolver)
void	addMethodResolver(MethodResolver resolver)
void	addPropertyAccessor(PropertyAccessor accessor)
void	applyDelegatesTo(StandardEvaluationContext evaluationContext)	Apply the internal delegates of this instance to the specified evaluationContext.
BeanResolver	getBeanResolver()	Return a bean resolver that can look up beans by name.
List<ConstructorResolver>	getConstructorResolvers()	Return a list of resolvers that will be asked in turn to locate a constructor.
List<MethodResolver>	getMethodResolvers()	Return a list of resolvers that will be asked in turn to locate a method.
OperatorOverloader	getOperatorOverloader()	Return an operator overloader that may support mathematical operations between more than the standard set of types.
List<PropertyAccessor>	getPropertyAccessors()	Return a list of accessors that will be asked in turn to read/write a property.
TypedValue	getRootObject()	Return the default root context object against which unqualified properties/methods/etc should be resolved.
TypeComparator	getTypeComparator()	Return a type comparator for comparing pairs of objects for equality.
TypeConverter	getTypeConverter()	Return a type converter that can convert (or coerce) a value from one type to another.
TypeLocator	getTypeLocator()	Get the configured TypeLocator that will be used to find types, either by short or fully-qualified name.
Object	lookupVariable(String name)	Look up a named variable or function within this evaluation context.
void	registerFunction(String name, MethodHandle methodHandle)	Register the specified MethodHandle as a SpEL function.
void	registerFunction(String name, Method method)	Register the specified Method as a SpEL function.
void	registerMethodFilter(Class<?> type, MethodFilter filter)	Register a MethodFilter which will be called during method resolution for the specified type.
boolean	removeConstructorResolver(ConstructorResolver resolver)
boolean	removeMethodResolver(MethodResolver methodResolver)
boolean	removePropertyAccessor(PropertyAccessor accessor)
void	setBeanResolver(BeanResolver beanResolver)
void	setConstructorResolvers(List<ConstructorResolver> constructorResolvers)
void	setMethodResolvers(List<MethodResolver> methodResolvers)
void	setOperatorOverloader(OperatorOverloader operatorOverloader)
void	setPropertyAccessors(List<PropertyAccessor> propertyAccessors)
void	setRootObject(Object rootObject)
void	setRootObject(Object rootObject, TypeDescriptor typeDescriptor)
void	setTypeComparator(TypeComparator typeComparator)
void	setTypeConverter(TypeConverter typeConverter)
void	setTypeLocator(TypeLocator typeLocator)	Set the TypeLocator to use to find types, either by short or fully-qualified name.
void	setVariable(String name, Object value)	Set a named variable in this evaluation context to a specified value.
void	setVariables(Map<String,Object> variables)	Set multiple named variables in this evaluation context to the specified values.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.expression.EvaluationContext

assignVariable, isAssignmentEnabled

Constructor Details

StandardEvaluationContext

public StandardEvaluationContext()

Create a StandardEvaluationContext with a null root object.

StandardEvaluationContext

public StandardEvaluationContext(@Nullable
 Object rootObject)

Create a StandardEvaluationContext with the given root object.

Parameters:

rootObject - the root object to use

See Also:

• setRootObject(java.lang.Object, org.springframework.core.convert.TypeDescriptor)

Method Details

setRootObject

public void setRootObject(@Nullable
 Object rootObject,
 TypeDescriptor typeDescriptor)

setRootObject

public void setRootObject(@Nullable
 Object rootObject)

getRootObject

public TypedValue getRootObject()

Description copied from interface: EvaluationContext

Return the default root context object against which unqualified properties/methods/etc should be resolved. This can be overridden when evaluating an expression.

Specified by:

getRootObject in interface EvaluationContext

setPropertyAccessors

public void setPropertyAccessors(List<PropertyAccessor> propertyAccessors)

getPropertyAccessors

public List<PropertyAccessor> getPropertyAccessors()

Description copied from interface: EvaluationContext

Return a list of accessors that will be asked in turn to read/write a property.

Specified by:

getPropertyAccessors in interface EvaluationContext

addPropertyAccessor

public void addPropertyAccessor(PropertyAccessor accessor)

removePropertyAccessor

public boolean removePropertyAccessor(PropertyAccessor accessor)

setConstructorResolvers

public void setConstructorResolvers(List<ConstructorResolver> constructorResolvers)

getConstructorResolvers

public List<ConstructorResolver> getConstructorResolvers()

Description copied from interface: EvaluationContext

Return a list of resolvers that will be asked in turn to locate a constructor.

Specified by:

getConstructorResolvers in interface EvaluationContext

addConstructorResolver

public void addConstructorResolver(ConstructorResolver resolver)

removeConstructorResolver

public boolean removeConstructorResolver(ConstructorResolver resolver)

setMethodResolvers

public void setMethodResolvers(List<MethodResolver> methodResolvers)

getMethodResolvers

public List<MethodResolver> getMethodResolvers()

Description copied from interface: EvaluationContext

Return a list of resolvers that will be asked in turn to locate a method.

Specified by:

getMethodResolvers in interface EvaluationContext

addMethodResolver

public void addMethodResolver(MethodResolver resolver)

removeMethodResolver

public boolean removeMethodResolver(MethodResolver methodResolver)

setBeanResolver

public void setBeanResolver(BeanResolver beanResolver)

getBeanResolver

@Nullable
public BeanResolver getBeanResolver()

Description copied from interface: EvaluationContext

Return a bean resolver that can look up beans by name.

Specified by:

getBeanResolver in interface EvaluationContext

setTypeLocator

public void setTypeLocator(TypeLocator typeLocator)

Set the TypeLocator to use to find types, either by short or fully-qualified name.

By default, a StandardTypeLocator will be used.

NOTE: Even if a StandardTypeLocator is sufficient, you may need to manually configure a StandardTypeLocator with a specific ClassLoader to ensure that the SpEL expression parser is able to reliably locate user types.

Parameters:

typeLocator - the TypeLocator to use

See Also:

• StandardTypeLocator(ClassLoader)
• getTypeLocator()

getTypeLocator

public TypeLocator getTypeLocator()

Get the configured TypeLocator that will be used to find types, either by short or fully-qualified name.

See setTypeLocator(TypeLocator) for further details.

Specified by:

getTypeLocator in interface EvaluationContext

See Also:

• setTypeLocator(TypeLocator)

setTypeConverter

public void setTypeConverter(TypeConverter typeConverter)

getTypeConverter

public TypeConverter getTypeConverter()

Description copied from interface: EvaluationContext

Return a type converter that can convert (or coerce) a value from one type to another.

Specified by:

getTypeConverter in interface EvaluationContext

setTypeComparator

public void setTypeComparator(TypeComparator typeComparator)

getTypeComparator

public TypeComparator getTypeComparator()

Description copied from interface: EvaluationContext

Return a type comparator for comparing pairs of objects for equality.

Specified by:

getTypeComparator in interface EvaluationContext

setOperatorOverloader

public void setOperatorOverloader(OperatorOverloader operatorOverloader)

getOperatorOverloader

public OperatorOverloader getOperatorOverloader()

Description copied from interface: EvaluationContext

Return an operator overloader that may support mathematical operations between more than the standard set of types.

Specified by:

getOperatorOverloader in interface EvaluationContext

setVariable

public void setVariable(@Nullable
 String name,
 @Nullable
 Object value)

Set a named variable in this evaluation context to a specified value.

If the specified name is null, it will be ignored. If the specified value is null, the named variable will be removed from this evaluation context.

In contrast to EvaluationContext.assignVariable(String,java.util.function.Supplier), this method should only be invoked programmatically when interacting directly with the EvaluationContext — for example, to provide initial configuration for the context.

Note that variables and functions share a common namespace in this evaluation context. See the class-level documentation for details.

Specified by:

setVariable in interface EvaluationContext

Parameters:

name - the name of the variable to set

value - the value to be placed in the variable

See Also:

• setVariables(Map)
• registerFunction(String, Method)
• registerFunction(String, MethodHandle)
• lookupVariable(String)

setVariables

public void setVariables(Map<String,Object> variables)

Set multiple named variables in this evaluation context to the specified values.

This is a convenience variant of setVariable(String, Object).

Note that variables and functions share a common namespace in this evaluation context. See the class-level documentation for details.

Parameters:

variables - the names and values of the variables to set

See Also:

• setVariable(String, Object)

registerFunction

public void registerFunction(String name,
 Method method)

Register the specified Method as a SpEL function.

Note that variables and functions share a common namespace in this evaluation context. See the class-level documentation for details.

Parameters:

name - the name of the function

method - the Method to register

See Also:

• registerFunction(String, MethodHandle)

registerFunction

public void registerFunction(String name,
 MethodHandle methodHandle)

Register the specified MethodHandle as a SpEL function.

Note that variables and functions share a common namespace in this evaluation context. See the class-level documentation for details.

Parameters:

name - the name of the function

methodHandle - the MethodHandle to register

Since:

6.1

See Also:

• registerFunction(String, Method)

lookupVariable

@Nullable
public Object lookupVariable(String name)

Look up a named variable or function within this evaluation context.

Note that variables and functions share a common namespace in this evaluation context. See the class-level documentation for details.

Specified by:

lookupVariable in interface EvaluationContext

Parameters:

name - the name of the variable or function to look up

Returns:

the value of the variable or function, or null if not found

registerMethodFilter

public void registerMethodFilter(Class<?> type,
 MethodFilter filter)
                          throws IllegalStateException

Register a MethodFilter which will be called during method resolution for the specified type.

The MethodFilter may remove methods and/or sort the methods which will then be used by SpEL as the candidates to look through for a match.

Parameters:

type - the type for which the filter should be called

filter - a MethodFilter, or null to unregister a filter for the type

Throws:

IllegalStateException - if the ReflectiveMethodResolver is not in use

applyDelegatesTo

public void applyDelegatesTo(StandardEvaluationContext evaluationContext)

Apply the internal delegates of this instance to the specified evaluationContext. Typically invoked right after the new context instance has been created to reuse the delegates. Does not modify the root object or any registered variables or functions.

Parameters:

evaluationContext - the evaluation context to update

Since:

6.1.1