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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 independent of any language like OGNL or the Unified EL.

Since:
3.0
Author:
Keith Donald, Andy Clement

Method Summary
 java.lang.String getExpressionString()
          Returns the original string used to create this expression, unmodified.
 java.lang.Object getValue()
          Evaluate this expression in the default standard context.
<T> T
getValue(java.lang.Class<T> desiredResultType)
          Evaluate the expression in the default context.
 java.lang.Object getValue(EvaluationContext context)
          Evaluate this expression in the provided context and return the result of evaluation.
<T> T
getValue(EvaluationContext context, java.lang.Class<T> desiredResultType)
          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.
 java.lang.Object getValue(EvaluationContext context, java.lang.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, java.lang.Object rootObject, java.lang.Class<T> desiredResultType)
          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.
 java.lang.Object getValue(java.lang.Object rootObject)
          Evaluate this expression against the specified root object
<T> T
getValue(java.lang.Object rootObject, java.lang.Class<T> desiredResultType)
          Evaluate the expression in the default context against the specified root object.
 java.lang.Class getValueType()
          Returns the most general type that can be passed to the setValue(EvaluationContext, Object) method using the default context.
 java.lang.Class getValueType(EvaluationContext context)
          Returns the most general type that can be passed to the setValue(EvaluationContext, Object) method for the given context.
 java.lang.Class getValueType(EvaluationContext context, java.lang.Object rootObject)
          Returns the most general type that can be passed to the setValue(EvaluationContext, Object) method for the given context.
 java.lang.Class getValueType(java.lang.Object rootObject)
          Returns the most general type that can be passed to the setValue(EvaluationContext, Object) method using the default context.
 TypeDescriptor getValueTypeDescriptor()
          Returns the most general type that can be passed to the setValue(EvaluationContext, Object) method using the default context.
 TypeDescriptor getValueTypeDescriptor(EvaluationContext context)
          Returns the most general type that can be passed to the setValue(EvaluationContext, Object) method for the given context.
 TypeDescriptor getValueTypeDescriptor(EvaluationContext context, java.lang.Object rootObject)
          Returns the most general type that can be passed to the setValue(EvaluationContext, Object) method for the given context.
 TypeDescriptor getValueTypeDescriptor(java.lang.Object rootObject)
          Returns the most general type that can be passed to the setValue(EvaluationContext, Object) method using the default context.
 boolean isWritable(EvaluationContext context)
          Determine if an expression can be written to, i.e.
 boolean isWritable(EvaluationContext context, java.lang.Object rootObject)
          Determine if an expression can be written to, i.e.
 boolean isWritable(java.lang.Object rootObject)
          Determine if an expression can be written to, i.e.
 void setValue(EvaluationContext context, java.lang.Object value)
          Set this expression in the provided context to the value provided.
 void setValue(EvaluationContext context, java.lang.Object rootObject, java.lang.Object value)
          Set this expression in the provided context to the value provided.
 void setValue(java.lang.Object rootObject, java.lang.Object value)
          Set this expression in the provided context to the value provided.
 

Method Detail

getValue

java.lang.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

java.lang.Object getValue(java.lang.Object rootObject)
                          throws EvaluationException
Evaluate this expression against the specified root object

Parameters:
rootObject - the root object against which properties/etc will be resolved
Returns:
the evaluation result
Throws:
EvaluationException - if there is a problem during evaluation

getValue

<T> T getValue(java.lang.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

<T> T getValue(java.lang.Object rootObject,
               java.lang.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 properties/etc will be resolved
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

java.lang.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

java.lang.Object getValue(EvaluationContext context,
                          java.lang.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 properties/etc will be resolved
Returns:
the evaluation result
Throws:
EvaluationException - if there is a problem during evaluation

getValue

<T> T getValue(EvaluationContext context,
               java.lang.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

<T> T getValue(EvaluationContext context,
               java.lang.Object rootObject,
               java.lang.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 properties/etc will be resolved
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

java.lang.Class getValueType()
                             throws EvaluationException
Returns the most general type that can be passed to the setValue(EvaluationContext, 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

java.lang.Class getValueType(java.lang.Object rootObject)
                             throws EvaluationException
Returns the most general type that can be passed to the setValue(EvaluationContext, 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

java.lang.Class getValueType(EvaluationContext context)
                             throws EvaluationException
Returns 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

java.lang.Class getValueType(EvaluationContext context,
                             java.lang.Object rootObject)
                             throws EvaluationException
Returns the most general type that can be passed to the setValue(EvaluationContext, 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

TypeDescriptor getValueTypeDescriptor()
                                      throws EvaluationException
Returns the most general type that can be passed to the setValue(EvaluationContext, Object) method using the default context.

Returns:
a type descriptor for the most general type of value that can be set on this context
Throws:
EvaluationException - if there is a problem determining the type

getValueTypeDescriptor

TypeDescriptor getValueTypeDescriptor(java.lang.Object rootObject)
                                      throws EvaluationException
Returns the most general type that can be passed to the setValue(EvaluationContext, Object) method using the default context.

Parameters:
rootObject - the root object against which to evaluate the expression
Returns:
a type descriptor for the most general type of value that can be set on this context
Throws:
EvaluationException - if there is a problem determining the type

getValueTypeDescriptor

TypeDescriptor getValueTypeDescriptor(EvaluationContext context)
                                      throws EvaluationException
Returns 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 the most general type of value that can be set on this context
Throws:
EvaluationException - if there is a problem determining the type

getValueTypeDescriptor

TypeDescriptor getValueTypeDescriptor(EvaluationContext context,
                                      java.lang.Object rootObject)
                                      throws EvaluationException
Returns the most general type that can be passed to the setValue(EvaluationContext, 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 the most general type of value that can be set on this context
Throws:
EvaluationException - if there is a problem determining the type

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

isWritable

boolean isWritable(EvaluationContext context,
                   java.lang.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
Throws:
EvaluationException - if there is a problem determining if it is writable

isWritable

boolean isWritable(java.lang.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
Throws:
EvaluationException - if there is a problem determining if it is writable

setValue

void setValue(EvaluationContext context,
              java.lang.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(java.lang.Object rootObject,
              java.lang.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,
              java.lang.Object rootObject,
              java.lang.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

getExpressionString

java.lang.String getExpressionString()
Returns the original string used to create this expression, unmodified.

Returns:
the original expression string
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