org.springframework.expression

Interface Expression

All Known Implementing Classes:

CompositeStringExpression, LiteralExpression, SpelExpression

public interface Expression

An expression capable of evaluating itself against context objects. Encapsulates the details of a previously parsed expression string. Provides a common abstraction for expression evaluation.

Since:

3.0

Author:

Keith Donald, Andy Clement, Juergen Hoeller

Method Summary

Modifier and Type	Method and Description
String	getExpressionString() Return the original string used to create this expression (unmodified).
Object	getValue() Evaluate this expression in the default standard context.
<T> T	getValue(Class<T> desiredResultType) Evaluate the expression in the default context.
Object	getValue(EvaluationContext context) Evaluate this expression in the provided context and return the result of evaluation.
<T> T	getValue(EvaluationContext context, Class<T> desiredResultType) Evaluate the expression in a specified context which can resolve references to properties, methods, types, etc.
Object	getValue(EvaluationContext context, Object rootObject) Evaluate this expression in the provided context and return the result of evaluation, but use the supplied root context as an override for any default root object specified in the context.
<T> T	getValue(EvaluationContext context, Object rootObject, Class<T> desiredResultType) Evaluate the expression in a specified context which can resolve references to properties, methods, types, etc.
Object	getValue(Object rootObject) Evaluate this expression against the specified root object.
<T> T	getValue(Object rootObject, Class<T> desiredResultType) Evaluate the expression in the default context against the specified root object.
Class<?>	getValueType() Return the most general type that can be passed to a setValue(java.lang.Object, java.lang.Object) method using the default context.
Class<?>	getValueType(EvaluationContext context) Return the most general type that can be passed to the setValue(EvaluationContext, Object) method for the given context.
Class<?>	getValueType(EvaluationContext context, Object rootObject) Return the most general type that can be passed to the setValue(EvaluationContext, Object, Object) method for the given context.
Class<?>	getValueType(Object rootObject) Return the most general type that can be passed to the setValue(Object, Object) method using the default context.
TypeDescriptor	getValueTypeDescriptor() Return the most general type that can be passed to a setValue(java.lang.Object, java.lang.Object) method using the default context.
TypeDescriptor	getValueTypeDescriptor(EvaluationContext context) Return the most general type that can be passed to the setValue(EvaluationContext, Object) method for the given context.
TypeDescriptor	getValueTypeDescriptor(EvaluationContext context, Object rootObject) Return the most general type that can be passed to the setValue(EvaluationContext, Object, Object) method for the given context.
TypeDescriptor	getValueTypeDescriptor(Object rootObject) Return the most general type that can be passed to the setValue(Object, Object) method using the default context.
boolean	isWritable(EvaluationContext context) Determine if an expression can be written to, i.e.
boolean	isWritable(EvaluationContext context, Object rootObject) Determine if an expression can be written to, i.e.
boolean	isWritable(Object rootObject) Determine if an expression can be written to, i.e.
void	setValue(EvaluationContext context, Object value) Set this expression in the provided context to the value provided.
void	setValue(EvaluationContext context, Object rootObject, Object value) Set this expression in the provided context to the value provided.
void	setValue(Object rootObject, Object value) Set this expression in the provided context to the value provided.

Method Detail

getExpressionString

String getExpressionString()

Return the original string used to create this expression (unmodified).

Returns:

the original expression string

getValue

@Nullable
Object getValue()
                   throws EvaluationException

Evaluate this expression in the default standard context.

Returns:

the evaluation result

Throws:

EvaluationException - if there is a problem during evaluation

getValue

@Nullable
<T> T getValue(@Nullable
                         Class<T> desiredResultType)
                  throws EvaluationException

Evaluate the expression in the default context. If the result of the evaluation does not match (and cannot be converted to) the expected result type then an exception will be returned.

Parameters:

desiredResultType - the class the caller would like the result to be

Returns:

the evaluation result

Throws:

EvaluationException - if there is a problem during evaluation

getValue

@Nullable
Object getValue(@Nullable
                          Object rootObject)
                   throws EvaluationException

Evaluate this expression against the specified root object.

Parameters:

rootObject - the root object against which to evaluate the expression

Returns:

the evaluation result

Throws:

EvaluationException - if there is a problem during evaluation

getValue

@Nullable
<T> T getValue(@Nullable
                         Object rootObject,
                         @Nullable
                         Class<T> desiredResultType)
                  throws EvaluationException

Evaluate the expression in the default context against the specified root object. If the result of the evaluation does not match (and cannot be converted to) the expected result type then an exception will be returned.

Parameters:

rootObject - the root object against which to evaluate the expression

desiredResultType - the class the caller would like the result to be

Returns:

the evaluation result

Throws:

EvaluationException - if there is a problem during evaluation

getValue

@Nullable
Object getValue(EvaluationContext context)
                   throws EvaluationException

Evaluate this expression in the provided context and return the result of evaluation.

Parameters:

context - the context in which to evaluate the expression

Returns:

the evaluation result

Throws:

EvaluationException - if there is a problem during evaluation

getValue

@Nullable
Object getValue(EvaluationContext context,
                          @Nullable
                          Object rootObject)
                   throws EvaluationException

Evaluate this expression in the provided context and return the result of evaluation, but use the supplied root context as an override for any default root object specified in the context.

Parameters:

context - the context in which to evaluate the expression

rootObject - the root object against which to evaluate the expression

Returns:

the evaluation result

Throws:

EvaluationException - if there is a problem during evaluation

getValue

@Nullable
<T> T getValue(EvaluationContext context,
                         @Nullable
                         Class<T> desiredResultType)
                  throws EvaluationException

Evaluate the expression in a specified context which can resolve references to properties, methods, types, etc. The type of the evaluation result is expected to be of a particular class and an exception will be thrown if it is not and cannot be converted to that type.

Parameters:

context - the context in which to evaluate the expression

desiredResultType - the class the caller would like the result to be

Returns:

the evaluation result

Throws:

EvaluationException - if there is a problem during evaluation

getValue

@Nullable
<T> T getValue(EvaluationContext context,
                         @Nullable
                         Object rootObject,
                         @Nullable
                         Class<T> desiredResultType)
                  throws EvaluationException

Evaluate the expression in a specified context which can resolve references to properties, methods, types, etc. The type of the evaluation result is expected to be of a particular class and an exception will be thrown if it is not and cannot be converted to that type. The supplied root object overrides any default specified on the supplied context.

Parameters:

context - the context in which to evaluate the expression

rootObject - the root object against which to evaluate the expression

desiredResultType - the class the caller would like the result to be

Returns:

the evaluation result

Throws:

EvaluationException - if there is a problem during evaluation

getValueType

@Nullable
Class<?> getValueType()
                         throws EvaluationException

Return the most general type that can be passed to a setValue(java.lang.Object, java.lang.Object) method using the default context.

Returns:

the most general type of value that can be set on this context

Throws:

EvaluationException - if there is a problem determining the type

getValueType

@Nullable
Class<?> getValueType(@Nullable
                                Object rootObject)
                         throws EvaluationException

Return the most general type that can be passed to the setValue(Object, Object) method using the default context.

Parameters:

rootObject - the root object against which to evaluate the expression

Returns:

the most general type of value that can be set on this context

Throws:

EvaluationException - if there is a problem determining the type

getValueType

@Nullable
Class<?> getValueType(EvaluationContext context)
                         throws EvaluationException

Return the most general type that can be passed to the setValue(EvaluationContext, Object) method for the given context.

Parameters:

context - the context in which to evaluate the expression

Returns:

the most general type of value that can be set on this context

Throws:

EvaluationException - if there is a problem determining the type

getValueType

@Nullable
Class<?> getValueType(EvaluationContext context,
                                @Nullable
                                Object rootObject)
                         throws EvaluationException

Return the most general type that can be passed to the setValue(EvaluationContext, Object, Object) method for the given context. The supplied root object overrides any specified in the context.

Parameters:

context - the context in which to evaluate the expression

rootObject - the root object against which to evaluate the expression

Returns:

the most general type of value that can be set on this context

Throws:

EvaluationException - if there is a problem determining the type

getValueTypeDescriptor

@Nullable
TypeDescriptor getValueTypeDescriptor()
                                         throws EvaluationException

Return the most general type that can be passed to a setValue(java.lang.Object, java.lang.Object) method using the default context.

Returns:

a type descriptor for values that can be set on this context

Throws:

EvaluationException - if there is a problem determining the type

getValueTypeDescriptor

@Nullable
TypeDescriptor getValueTypeDescriptor(@Nullable
                                                Object rootObject)
                                         throws EvaluationException

Return the most general type that can be passed to the setValue(Object, Object) method using the default context.

Parameters:

rootObject - the root object against which to evaluate the expression

Returns:

a type descriptor for values that can be set on this context

Throws:

EvaluationException - if there is a problem determining the type

getValueTypeDescriptor

@Nullable
TypeDescriptor getValueTypeDescriptor(EvaluationContext context)
                                         throws EvaluationException

Return the most general type that can be passed to the setValue(EvaluationContext, Object) method for the given context.

Parameters:

context - the context in which to evaluate the expression

Returns:

a type descriptor for values that can be set on this context

Throws:

EvaluationException - if there is a problem determining the type

getValueTypeDescriptor

@Nullable
TypeDescriptor getValueTypeDescriptor(EvaluationContext context,
                                                @Nullable
                                                Object rootObject)
                                         throws EvaluationException

Return the most general type that can be passed to the setValue(EvaluationContext, Object, Object) method for the given context. The supplied root object overrides any specified in the context.

Parameters:

context - the context in which to evaluate the expression

rootObject - the root object against which to evaluate the expression

Returns:

a type descriptor for values that can be set on this context

Throws:

EvaluationException - if there is a problem determining the type

isWritable

boolean isWritable(@Nullable
                   Object rootObject)
            throws EvaluationException

Determine if an expression can be written to, i.e. setValue() can be called.

Parameters:

rootObject - the root object against which to evaluate the expression

Returns:

true if the expression is writable; false otherwise

Throws:

EvaluationException - if there is a problem determining if it is writable

isWritable

boolean isWritable(EvaluationContext context)
            throws EvaluationException

Determine if an expression can be written to, i.e. setValue() can be called.

Parameters:

context - the context in which the expression should be checked

Returns:

true if the expression is writable; false otherwise

Throws:

EvaluationException - if there is a problem determining if it is writable

isWritable

boolean isWritable(EvaluationContext context,
                   @Nullable
                   Object rootObject)
            throws EvaluationException

Determine if an expression can be written to, i.e. setValue() can be called. The supplied root object overrides any specified in the context.

Parameters:

context - the context in which the expression should be checked

rootObject - the root object against which to evaluate the expression

Returns:

true if the expression is writable; false otherwise

Throws:

EvaluationException - if there is a problem determining if it is writable

setValue

void setValue(@Nullable
              Object rootObject,
              @Nullable
              Object value)
       throws EvaluationException

Set this expression in the provided context to the value provided.

Parameters:

rootObject - the root object against which to evaluate the expression

value - the new value

Throws:

EvaluationException - if there is a problem during evaluation

setValue

void setValue(EvaluationContext context,
              @Nullable
              Object value)
       throws EvaluationException

Set this expression in the provided context to the value provided.

Parameters:

context - the context in which to set the value of the expression

value - the new value

Throws:

EvaluationException - if there is a problem during evaluation

setValue

void setValue(EvaluationContext context,
              @Nullable
              Object rootObject,
              @Nullable
              Object value)
       throws EvaluationException

Set this expression in the provided context to the value provided. The supplied root object overrides any specified in the context.

Parameters:

context - the context in which to set the value of the expression

rootObject - the root object against which to evaluate the expression

value - the new value

Throws:

EvaluationException - if there is a problem during evaluation