org.springframework.expression

Interface EvaluationContext

All Known Implementing Classes:

MethodBasedEvaluationContext, SimpleEvaluationContext, StandardEvaluationContext

public interface EvaluationContext

Expressions are executed in an evaluation context. It is in this context that references are resolved when encountered during expression evaluation.

There are two default implementations of this interface.

• SimpleEvaluationContext: a simpler builder-style EvaluationContext variant for data-binding purposes, which allows for opting into several SpEL features as needed.
• StandardEvaluationContext: a powerful and highly configurable EvaluationContext implementation, which can be extended, rather than having to implement everything manually.

Since:

3.0

Author:

Andy Clement, Juergen Hoeller, Sam Brannen

Method Summary

Modifier and Type	Method and Description
default TypedValue	assignVariable(String name, Supplier<TypedValue> valueSupplier) Assign the value created by the specified Supplier to a named variable within this evaluation context.
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() Return a type locator that can be used to find types, either by short or fully qualified name.
Object	lookupVariable(String name) Look up a named variable within this evaluation context.
void	setVariable(String name, Object value) Set a named variable in this evaluation context to a specified value.

Method Detail

getRootObject

TypedValue getRootObject()

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

getPropertyAccessors

List<PropertyAccessor> getPropertyAccessors()

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

getConstructorResolvers

List<ConstructorResolver> getConstructorResolvers()

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

getMethodResolvers

List<MethodResolver> getMethodResolvers()

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

getBeanResolver

@Nullable
BeanResolver getBeanResolver()

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

getTypeLocator

TypeLocator getTypeLocator()

Return a type locator that can be used to find types, either by short or fully qualified name.

getTypeConverter

TypeConverter getTypeConverter()

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

getTypeComparator

TypeComparator getTypeComparator()

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

getOperatorOverloader

OperatorOverloader getOperatorOverloader()

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

assignVariable

default TypedValue assignVariable(String name,
                                  Supplier<TypedValue> valueSupplier)

Assign the value created by the specified Supplier to a named variable within this evaluation context.

In contrast to setVariable(String, Object), this method should only be invoked to support the assignment operator (=) within an expression.

By default, this method delegates to setVariable(String, Object), providing the value created by the valueSupplier. Concrete implementations may override this default method to provide different semantics.

Parameters:

name - the name of the variable to assign

valueSupplier - the supplier of the value to be assigned to the variable

Returns:

a TypedValue wrapping the assigned value

Since:

5.2.24

setVariable

void setVariable(String name,
                 @Nullable
                 Object value)

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

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

Parameters:

name - the name of the variable to set

value - the value to be placed in the variable

lookupVariable

@Nullable
Object lookupVariable(String name)

Look up a named variable within this evaluation context.

Parameters:

name - the name of the variable to look up

Returns:

the value of the variable, or null if not found