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java.lang.Objectjavax.el.Expression
javax.el.ValueExpression
org.apache.el.ValueExpressionImpl
public final class ValueExpressionImpl
An Expression 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 return
true from isReadOnly().
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
of ValueExpression that encapsulates the parsed expression.
The FunctionMapper is used at parse time, not evaluation time,
so one is not needed to evaluate an expression using this class.
However, the ELContext is needed at evaluation time.
The getValue(javax.el.ELContext), setValue(javax.el.ELContext, java.lang.Object), isReadOnly(javax.el.ELContext) and
getType(javax.el.ELContext) methods will evaluate the expression each time they are
called. The ELResolver in the ELContext is used to
resolve the top-level variables and to determine the behavior of the
. and [] operators. For any of the four methods,
the ELResolver.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 the base
object. At the last resolution, the ValueExpression will
call the corresponding ELResolver.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) or
ELResolver.getType(javax.el.ELContext, java.lang.Object, java.lang.Object) method, depending on which was called on
the ValueExpression.
See the notes about comparison, serialization and immutability in
the Expression javadocs.
ELResolver,
Expression,
ExpressionFactory,
ValueExpression,
Serialized Form| Constructor Summary | |
|---|---|
ValueExpressionImpl()
|
|
ValueExpressionImpl(java.lang.String expr,
Node node,
javax.el.FunctionMapper fnMapper,
javax.el.VariableMapper varMapper,
java.lang.Class expectedType)
|
|
| Method Summary | |
|---|---|
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)
|
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)
|
| Methods inherited from class java.lang.Object |
|---|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
| Constructor Detail |
|---|
public ValueExpressionImpl()
public ValueExpressionImpl(java.lang.String expr,
Node node,
javax.el.FunctionMapper fnMapper,
javax.el.VariableMapper varMapper,
java.lang.Class expectedType)
| Method Detail |
|---|
public boolean equals(java.lang.Object obj)
equals in class javax.el.Expressionpublic java.lang.Class getExpectedType()
getExpectedType in class javax.el.ValueExpressionpublic java.lang.String getExpressionString()
getExpressionString in class javax.el.ExpressionexpectedType passed to the
ExpressionFactory.createValueExpression method
that created this ValueExpression.Expression.getExpressionString()
public java.lang.Class getType(javax.el.ELContext context)
throws javax.el.PropertyNotFoundException,
javax.el.ELException
getType in class javax.el.ValueExpressionjavax.el.PropertyNotFoundException
javax.el.ELException
public java.lang.Object getValue(javax.el.ELContext context)
throws javax.el.PropertyNotFoundException,
javax.el.ELException
getValue in class javax.el.ValueExpressionjavax.el.PropertyNotFoundException
javax.el.ELExceptionpublic int hashCode()
hashCode in class javax.el.Expressionpublic boolean isLiteralText()
isLiteralText in class javax.el.Expression
public boolean isReadOnly(javax.el.ELContext context)
throws javax.el.PropertyNotFoundException,
javax.el.ELException
isReadOnly in class javax.el.ValueExpressionjavax.el.PropertyNotFoundException
javax.el.ELException
public void readExternal(java.io.ObjectInput in)
throws java.io.IOException,
java.lang.ClassNotFoundException
readExternal in interface java.io.Externalizablejava.io.IOException
java.lang.ClassNotFoundException
public void setValue(javax.el.ELContext context,
java.lang.Object value)
throws javax.el.PropertyNotFoundException,
javax.el.PropertyNotWritableException,
javax.el.ELException
setValue in class javax.el.ValueExpressionjavax.el.PropertyNotFoundException
javax.el.PropertyNotWritableException
javax.el.ELException
public void writeExternal(java.io.ObjectOutput out)
throws java.io.IOException
writeExternal in interface java.io.Externalizablejava.io.IOExceptionpublic java.lang.String toString()
toString in class java.lang.Object
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