Class ValueExpressionImpl
- java.lang.Object
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- javax.el.Expression
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- javax.el.ValueExpression
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- com.sun.el.ValueExpressionImpl
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- All Implemented Interfaces:
java.io.Externalizable
,java.io.Serializable
public final class ValueExpressionImpl extends javax.el.ValueExpression implements java.io.Externalizable
AnExpression
that can get or set a value.In previous incarnations of this API, expressions could only be read.
ValueExpression
objects can now be used both to retrieve a value and to set a value. Expressions that can have a value set on them are referred to as l-value expressions. Those that cannot are referred to as r-value expressions. Not all r-value expressions can be used as l-value expressions (e.g."${1+1}"
or"${firstName} ${lastName}"
). See the EL Specification for details. Expressions that cannot be used as l-values must always returntrue
fromisReadOnly()
.The
ExpressionFactory.createValueExpression(javax.el.ELContext, java.lang.String, java.lang.Class<?>)
method can be used to parse an expression string and return a concrete instance ofValueExpression
that encapsulates the parsed expression. TheFunctionMapper
is used at parse time, not evaluation time, so one is not needed to evaluate an expression using this class. However, theELContext
is needed at evaluation time.The
getValue(javax.el.ELContext)
,setValue(javax.el.ELContext, java.lang.Object)
,isReadOnly(javax.el.ELContext)
andgetType(javax.el.ELContext)
methods will evaluate the expression each time they are called. TheELResolver
in theELContext
is used to resolve the top-level variables and to determine the behavior of the.
and[]
operators. For any of the four methods, theELResolver.getValue(javax.el.ELContext, java.lang.Object, java.lang.Object)
method is used to resolve all properties up to but excluding the last one. This provides thebase
object. At the last resolution, theValueExpression
will call the correspondingELResolver.getValue(javax.el.ELContext, java.lang.Object, java.lang.Object)
,ELResolver.setValue(javax.el.ELContext, java.lang.Object, java.lang.Object, java.lang.Object)
,ELResolver.isReadOnly(javax.el.ELContext, java.lang.Object, java.lang.Object)
orELResolver.getType(javax.el.ELContext, java.lang.Object, java.lang.Object)
method, depending on which was called on theValueExpression
.See the notes about comparison, serialization and immutability in the
Expression
javadocs.- Version:
- $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: dochez $
- Author:
- Jacob Hookom [jacob@hookom.net]
- See Also:
ELResolver
,Expression
,ExpressionFactory
,ValueExpression
, Serialized Form
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Constructor Summary
Constructors Constructor Description ValueExpressionImpl()
ValueExpressionImpl(java.lang.String expr, Node node, javax.el.FunctionMapper fnMapper, javax.el.VariableMapper varMapper, java.lang.Class expectedType)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
equals(java.lang.Object obj)
java.lang.Class
getExpectedType()
java.lang.String
getExpressionString()
Returns the type the result of the expression will be coerced to after evaluation.java.lang.Class
getType(javax.el.ELContext context)
java.lang.Object
getValue(javax.el.ELContext context)
javax.el.ValueReference
getValueReference(javax.el.ELContext context)
int
hashCode()
boolean
isLiteralText()
boolean
isReadOnly(javax.el.ELContext context)
void
readExternal(java.io.ObjectInput in)
void
setValue(javax.el.ELContext context, java.lang.Object value)
java.lang.String
toString()
void
writeExternal(java.io.ObjectOutput out)
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Constructor Detail
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ValueExpressionImpl
public ValueExpressionImpl()
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ValueExpressionImpl
public ValueExpressionImpl(java.lang.String expr, Node node, javax.el.FunctionMapper fnMapper, javax.el.VariableMapper varMapper, java.lang.Class expectedType)
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Method Detail
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equals
public boolean equals(java.lang.Object obj)
- Specified by:
equals
in classjavax.el.Expression
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getExpectedType
public java.lang.Class getExpectedType()
- Specified by:
getExpectedType
in classjavax.el.ValueExpression
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getExpressionString
public java.lang.String getExpressionString()
Returns the type the result of the expression will be coerced to after evaluation.- Specified by:
getExpressionString
in classjavax.el.Expression
- Returns:
- the
expectedType
passed to theExpressionFactory.createValueExpression
method that created thisValueExpression
. - See Also:
Expression.getExpressionString()
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getType
public java.lang.Class getType(javax.el.ELContext context) throws javax.el.PropertyNotFoundException, javax.el.ELException
- Specified by:
getType
in classjavax.el.ValueExpression
- Throws:
javax.el.PropertyNotFoundException
javax.el.ELException
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getValueReference
public javax.el.ValueReference getValueReference(javax.el.ELContext context) throws javax.el.PropertyNotFoundException, javax.el.ELException
- Overrides:
getValueReference
in classjavax.el.ValueExpression
- Throws:
javax.el.PropertyNotFoundException
javax.el.ELException
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getValue
public java.lang.Object getValue(javax.el.ELContext context) throws javax.el.PropertyNotFoundException, javax.el.ELException
- Specified by:
getValue
in classjavax.el.ValueExpression
- Throws:
javax.el.PropertyNotFoundException
javax.el.ELException
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hashCode
public int hashCode()
- Specified by:
hashCode
in classjavax.el.Expression
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isLiteralText
public boolean isLiteralText()
- Specified by:
isLiteralText
in classjavax.el.Expression
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isReadOnly
public boolean isReadOnly(javax.el.ELContext context) throws javax.el.PropertyNotFoundException, javax.el.ELException
- Specified by:
isReadOnly
in classjavax.el.ValueExpression
- Throws:
javax.el.PropertyNotFoundException
javax.el.ELException
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readExternal
public void readExternal(java.io.ObjectInput in) throws java.io.IOException, java.lang.ClassNotFoundException
- Specified by:
readExternal
in interfacejava.io.Externalizable
- Throws:
java.io.IOException
java.lang.ClassNotFoundException
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setValue
public void setValue(javax.el.ELContext context, java.lang.Object value) throws javax.el.PropertyNotFoundException, javax.el.PropertyNotWritableException, javax.el.ELException
- Specified by:
setValue
in classjavax.el.ValueExpression
- Throws:
javax.el.PropertyNotFoundException
javax.el.PropertyNotWritableException
javax.el.ELException
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writeExternal
public void writeExternal(java.io.ObjectOutput out) throws java.io.IOException
- Specified by:
writeExternal
in interfacejava.io.Externalizable
- Throws:
java.io.IOException
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toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
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