org.springframework.expression.common
Class LiteralExpression

java.lang.Object
  extended by org.springframework.expression.common.LiteralExpression
All Implemented Interfaces:
Expression

public class LiteralExpression
extends Object
implements Expression

A very simple hardcoded implementation of the Expression interface that represents a string literal. It is used with CompositeStringExpression when representing a template expression which is made up of pieces - some being real expressions to be handled by an EL implementation like Spel, and some being just textual elements.

Since:
3.0
Author:
Andy Clement

Constructor Summary
LiteralExpression(String literalValue)
           
 
Method Summary
 String getExpressionString()
          Returns the original string used to create this expression, unmodified.
 String getValue()
          Evaluate this expression in the default standard context.
<T> T
getValue(Class<T> expectedResultType)
          Evaluate the expression in the default standard context.
 String getValue(EvaluationContext context)
          Evaluate this expression in the provided context and return the result of evaluation.
<T> T
getValue(EvaluationContext context, Class<T> expectedResultType)
          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.
 Class getValueType()
          Returns the most general type that can be passed to the Expression.setValue(EvaluationContext, Object) method using the default context.
 Class getValueType(EvaluationContext context)
          Returns the most general type that can be passed to the Expression.setValue(EvaluationContext, Object) method for the given context.
 TypeDescriptor getValueTypeDescriptor()
          Returns the most general type that can be passed to the Expression.setValue(EvaluationContext, Object) method using the default context.
 TypeDescriptor getValueTypeDescriptor(EvaluationContext context)
          Returns the most general type that can be passed to the Expression.setValue(EvaluationContext, Object) method for the given context.
 boolean isWritable(EvaluationContext context)
          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.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

LiteralExpression

public LiteralExpression(String literalValue)
Method Detail

getExpressionString

public final String getExpressionString()
Description copied from interface: Expression
Returns the original string used to create this expression, unmodified.

Specified by:
getExpressionString in interface Expression
Returns:
the original expression string

getValue

public String getValue()
Description copied from interface: Expression
Evaluate this expression in the default standard context.

Specified by:
getValue in interface Expression
Returns:
the evaluation result

getValue

public String getValue(EvaluationContext context)
Description copied from interface: Expression
Evaluate this expression in the provided context and return the result of evaluation.

Specified by:
getValue in interface Expression
Parameters:
context - the context in which to evaluate the expression
Returns:
the evaluation result

getValueType

public Class getValueType(EvaluationContext context)
Description copied from interface: Expression
Returns the most general type that can be passed to the Expression.setValue(EvaluationContext, Object) method for the given context.

Specified by:
getValueType in interface Expression
Parameters:
context - the context in which to evaluate the expression
Returns:
the most general type of value that can be set on this context

getValueTypeDescriptor

public TypeDescriptor getValueTypeDescriptor(EvaluationContext context)
Description copied from interface: Expression
Returns the most general type that can be passed to the Expression.setValue(EvaluationContext, Object) method for the given context.

Specified by:
getValueTypeDescriptor in interface Expression
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

getValueTypeDescriptor

public TypeDescriptor getValueTypeDescriptor()
Description copied from interface: Expression
Returns the most general type that can be passed to the Expression.setValue(EvaluationContext, Object) method using the default context.

Specified by:
getValueTypeDescriptor in interface Expression
Returns:
a type descriptor for the most general type of value that can be set on this context

setValue

public void setValue(EvaluationContext context,
                     Object value)
              throws EvaluationException
Description copied from interface: Expression
Set this expression in the provided context to the value provided.

Specified by:
setValue in interface Expression
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

getValue

public <T> T getValue(EvaluationContext context,
                      Class<T> expectedResultType)
           throws EvaluationException
Description copied from interface: Expression
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.

Specified by:
getValue in interface Expression
Parameters:
context - the context in which to evaluate the expression
expectedResultType - the class the caller would like the result to be
Returns:
the evaluation result
Throws:
EvaluationException - if there is a problem during evaluation

getValue

public <T> T getValue(Class<T> expectedResultType)
           throws EvaluationException
Description copied from interface: Expression
Evaluate the expression in the default standard 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.

Specified by:
getValue in interface Expression
Parameters:
expectedResultType - the class the caller would like the result to be
Returns:
the evaluation result
Throws:
EvaluationException - if there is a problem during evaluation

isWritable

public boolean isWritable(EvaluationContext context)
Description copied from interface: Expression
Determine if an expression can be written to, i.e. setValue() can be called.

Specified by:
isWritable in interface Expression
Parameters:
context - the context in which the expression should be checked
Returns:
true if the expression is writable

getValueType

public Class getValueType()
Description copied from interface: Expression
Returns the most general type that can be passed to the Expression.setValue(EvaluationContext, Object) method using the default context.

Specified by:
getValueType in interface Expression
Returns:
the most general type of value that can be set on this context