SimpleEvaluationContext (Spring Framework 5.3.39 API)

java.lang.Object
- org.springframework.expression.spel.support.SimpleEvaluationContext

All Implemented Interfaces:

EvaluationContext
```
public final class SimpleEvaluationContext
extends Object
implements EvaluationContext
```
A basic implementation of EvaluationContext that focuses on a subset of essential SpEL features and customization options, targeting simple condition evaluation and in particular data binding scenarios.
In many cases, the full extent of the SpEL language is not required and should be meaningfully restricted. Examples include but are not limited to data binding expressions, property-based filters, and others. To that effect, SimpleEvaluationContext is tailored to support only a subset of the SpEL language syntax, e.g. excluding references to Java types, constructors, and bean references.
When creating a SimpleEvaluationContext you need to choose the level of support that you need for data binding in SpEL expressions:
- Data binding for read-only access
- Data binding for read and write access
- A custom PropertyAccessor (typically not reflection-based), potentially combined with a DataBindingPropertyAccessor
Conveniently, forReadOnlyDataBinding() enables read-only access to properties via DataBindingPropertyAccessor. Similarly, forReadWriteDataBinding() enables read and write access to properties. Alternatively, configure custom accessors via forPropertyAccessors(org.springframework.expression.PropertyAccessor...), potentially disable assignment, and optionally activate method resolution and/or a type converter through the builder.
Note that SimpleEvaluationContext is typically not configured with a default root object. Instead it is meant to be created once and used repeatedly through getValue calls on a predefined Expression with both an EvaluationContext and a root object as arguments: Expression.getValue(EvaluationContext, Object).
For more power and flexibility, in particular for internal configuration scenarios, consider using StandardEvaluationContext instead.
Since:

4.3.15

Author:

Rossen Stoyanchev, Juergen Hoeller, Sam Brannen

See Also:

forReadOnlyDataBinding(), forReadWriteDataBinding(), forPropertyAccessors(org.springframework.expression.PropertyAccessor...), StandardEvaluationContext, StandardTypeConverter, DataBindingPropertyAccessor

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class SimpleEvaluationContext.Builder
Builder for SimpleEvaluationContext.

Nested Classes
Modifier and Type	Class and Description
`static class`	`SimpleEvaluationContext.Builder` Builder for `SimpleEvaluationContext`.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`TypedValue`	`assignVariable(String name, Supplier<TypedValue> valueSupplier)` `SimpleEvaluationContext` does not support variable assignment within expressions.
`static SimpleEvaluationContext.Builder`	`forPropertyAccessors(PropertyAccessor... accessors)` Create a `SimpleEvaluationContext` for the specified `PropertyAccessor` delegates: typically a custom `PropertyAccessor` specific to a use case — for example, for attribute resolution in a custom data structure — potentially combined with a `DataBindingPropertyAccessor` if property dereferences are needed as well.
`static SimpleEvaluationContext.Builder`	`forReadOnlyDataBinding()` Create a `SimpleEvaluationContext` for read-only access to public properties via `DataBindingPropertyAccessor`.
`static SimpleEvaluationContext.Builder`	`forReadWriteDataBinding()` Create a `SimpleEvaluationContext` for read-write access to public properties via `DataBindingPropertyAccessor`.
`BeanResolver`	`getBeanResolver()` `SimpleEvaluationContext` does not support the use of bean references.
`List<ConstructorResolver>`	`getConstructorResolvers()` Return an empty list, always, since this context does not support the use of type references.
`List<MethodResolver>`	`getMethodResolvers()` Return the specified `MethodResolver` delegates, if any.
`OperatorOverloader`	`getOperatorOverloader()` Return an instance of `StandardOperatorOverloader`.
`List<PropertyAccessor>`	`getPropertyAccessors()` Return the specified `PropertyAccessor` delegates, if any.
`TypedValue`	`getRootObject()` Return the specified root object, if any.
`TypeComparator`	`getTypeComparator()` Return an instance of `StandardTypeComparator`.
`TypeConverter`	`getTypeConverter()` The configured `TypeConverter`.
`TypeLocator`	`getTypeLocator()` `SimpleEvaluationContext` does not support use of type references.
`boolean`	`isAssignmentEnabled()` Determine if assignment is enabled within expressions evaluated by this evaluation context.
`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.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - getRootObject
```
public TypedValue getRootObject()
```
    Return the specified root object, if any.
    
    Specified by:
    
    getRootObject in interface EvaluationContext
  - getPropertyAccessors
```
public List<PropertyAccessor> getPropertyAccessors()
```
    Return the specified PropertyAccessor delegates, if any.
    
    Specified by:
    
    getPropertyAccessors in interface EvaluationContext
    
    See Also:
    
    forPropertyAccessors(org.springframework.expression.PropertyAccessor...)
  - getConstructorResolvers
```
public List<ConstructorResolver> getConstructorResolvers()
```
    Return an empty list, always, since this context does not support the use of type references.
    
    Specified by:
    
    getConstructorResolvers in interface EvaluationContext
  - getMethodResolvers
```
public List<MethodResolver> getMethodResolvers()
```
    Return the specified MethodResolver delegates, if any.
    
    Specified by:
    
    getMethodResolvers in interface EvaluationContext
    
    See Also:
    
    SimpleEvaluationContext.Builder.withMethodResolvers(org.springframework.expression.MethodResolver...)
  - getBeanResolver
```
@Nullable
public BeanResolver getBeanResolver()
```
    SimpleEvaluationContext does not support the use of bean references.
    
    Specified by:
    
    getBeanResolver in interface EvaluationContext
    
    Returns:
    
    always null
  - getTypeLocator
```
public TypeLocator getTypeLocator()
```
    SimpleEvaluationContext does not support use of type references.
    
    Specified by:
    
    getTypeLocator in interface EvaluationContext
    
    Returns:
    
    TypeLocator implementation that raises a SpelEvaluationException with SpelMessage.TYPE_NOT_FOUND.
  - getTypeConverter
```
public TypeConverter getTypeConverter()
```
    The configured TypeConverter.
    By default this is StandardTypeConverter.
    
    Specified by:
    
    getTypeConverter in interface EvaluationContext
    
    See Also:
    
    SimpleEvaluationContext.Builder.withTypeConverter(org.springframework.expression.TypeConverter), SimpleEvaluationContext.Builder.withConversionService(org.springframework.core.convert.ConversionService)
  - getTypeComparator
```
public TypeComparator getTypeComparator()
```
    Return an instance of StandardTypeComparator.
    
    Specified by:
    
    getTypeComparator in interface EvaluationContext
  - getOperatorOverloader
```
public OperatorOverloader getOperatorOverloader()
```
    Return an instance of StandardOperatorOverloader.
    
    Specified by:
    
    getOperatorOverloader in interface EvaluationContext
  - assignVariable
```
public TypedValue assignVariable(String name,
                                 Supplier<TypedValue> valueSupplier)
```
    SimpleEvaluationContext does not support variable assignment within expressions.
    
    Specified by:
    
    assignVariable in interface EvaluationContext
    
    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
    
    Throws:
    
    SpelEvaluationException - with SpelMessage.VARIABLE_ASSIGNMENT_NOT_SUPPORTED
    
    Since:
    
    5.2.24
  - setVariable
```
public void setVariable(String name,
                        @Nullable
                        Object value)
```
    Description copied from interface: EvaluationContext
    
    Set a named variable in this evaluation context to a specified value.
    In contrast to EvaluationContext.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.
    
    Specified by:
    
    setVariable in interface EvaluationContext
    
    Parameters:
    
    name - the name of the variable to set
    
    value - the value to be placed in the variable
  - lookupVariable
```
@Nullable
public Object lookupVariable(String name)
```
    Description copied from interface: EvaluationContext
    
    Look up a named variable within this evaluation context.
    
    Specified by:
    
    lookupVariable in interface EvaluationContext
    
    Parameters:
    
    name - the name of the variable to look up
    
    Returns:
    
    the value of the variable, or null if not found
  - isAssignmentEnabled
```
public boolean isAssignmentEnabled()
```
    Determine if assignment is enabled within expressions evaluated by this evaluation context.
    If this method returns false, the assignment (=), increment (++), and decrement (--) operators are disabled.
    
    Specified by:
    
    isAssignmentEnabled in interface EvaluationContext
    
    Returns:
    
    true if assignment is enabled; false otherwise
    
    Since:
    
    5.3.38
    
    See Also:
    
    forReadOnlyDataBinding(), SimpleEvaluationContext.Builder.withAssignmentDisabled()
  - forPropertyAccessors
```
public static SimpleEvaluationContext.Builder forPropertyAccessors(PropertyAccessor... accessors)
```
    Create a SimpleEvaluationContext for the specified PropertyAccessor delegates: typically a custom PropertyAccessor specific to a use case — for example, for attribute resolution in a custom data structure — potentially combined with a DataBindingPropertyAccessor if property dereferences are needed as well.
    By default, assignment is enabled within expressions evaluated by the context created via this factory method; however, assignment can be disabled via SimpleEvaluationContext.Builder.withAssignmentDisabled().
    
    Parameters:
    
    accessors - the accessor delegates to use
    
    See Also:
    
    DataBindingPropertyAccessor.forReadOnlyAccess(), DataBindingPropertyAccessor.forReadWriteAccess(), isAssignmentEnabled(), SimpleEvaluationContext.Builder.withAssignmentDisabled()
  - forReadOnlyDataBinding
```
public static SimpleEvaluationContext.Builder forReadOnlyDataBinding()
```
    Create a SimpleEvaluationContext for read-only access to public properties via DataBindingPropertyAccessor.
    Assignment is disabled within expressions evaluated by the context created via this factory method.
    
    See Also:
    
    DataBindingPropertyAccessor.forReadOnlyAccess(), forPropertyAccessors(org.springframework.expression.PropertyAccessor...), isAssignmentEnabled(), SimpleEvaluationContext.Builder.withAssignmentDisabled()
  - forReadWriteDataBinding
```
public static SimpleEvaluationContext.Builder forReadWriteDataBinding()
```
    Create a SimpleEvaluationContext for read-write access to public properties via DataBindingPropertyAccessor.
    By default, assignment is enabled within expressions evaluated by the context created via this factory method. Assignment can be disabled via SimpleEvaluationContext.Builder.withAssignmentDisabled(); however, it is preferable to use forReadOnlyDataBinding() if you desire read-only access.
    
    See Also:
    
    DataBindingPropertyAccessor.forReadWriteAccess(), forPropertyAccessors(org.springframework.expression.PropertyAccessor...), isAssignmentEnabled(), SimpleEvaluationContext.Builder.withAssignmentDisabled()

Class SimpleEvaluationContext

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Method Detail

getRootObject

getPropertyAccessors

getConstructorResolvers

getMethodResolvers

getBeanResolver

getTypeLocator

getTypeConverter

getTypeComparator

getOperatorOverloader

assignVariable

setVariable

lookupVariable

isAssignmentEnabled

forPropertyAccessors

forReadOnlyDataBinding

forReadWriteDataBinding