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java.lang.Objectjavax.el.Expression
javax.el.MethodExpression
org.apache.el.MethodExpressionImpl
public final class MethodExpressionImpl
An Expression that refers to a method on an object.
The ExpressionFactory.createMethodExpression(javax.el.ELContext, java.lang.String, java.lang.Class>, java.lang.Class>[]) method
can be used to parse an expression string and return a concrete instance
of MethodExpression 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 getMethodInfo(javax.el.ELContext) and invoke(javax.el.ELContext, java.lang.Object[]) 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 two 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 on which the method
appears. If the base object is null, a
NullPointerException must be thrown. At the last resolution,
the final property is then coerced to a String,
which provides the name of the method to be found. A method matching the
name and expected parameters provided at parse time is found and it is
either queried or invoked (depending on the method called on this
MethodExpression).
See the notes about comparison, serialization and immutability in
the Expression javadocs.
ELResolver,
Expression,
ExpressionFactory,
MethodExpression,
Serialized Form| Constructor Summary | |
|---|---|
MethodExpressionImpl()
|
|
MethodExpressionImpl(java.lang.String expr,
Node node,
javax.el.FunctionMapper fnMapper,
javax.el.VariableMapper varMapper,
java.lang.Class expectedType,
java.lang.Class[] paramTypes)
|
|
| Method Summary | |
|---|---|
boolean |
equals(java.lang.Object obj)
Determines whether the specified object is equal to this Expression. |
java.lang.String |
getExpressionString()
Returns the original String used to create this Expression,
unmodified. |
javax.el.MethodInfo |
getMethodInfo(javax.el.ELContext context)
Evaluates the expression relative to the provided context, and returns information about the actual referenced method. |
int |
hashCode()
Returns the hash code for this Expression. |
java.lang.Object |
invoke(javax.el.ELContext context,
java.lang.Object[] params)
Evaluates the expression relative to the provided context, invokes the method that was found using the supplied parameters, and returns the result of the method invocation. |
boolean |
isLiteralText()
|
void |
readExternal(java.io.ObjectInput in)
|
void |
writeExternal(java.io.ObjectOutput out)
|
| Methods inherited from class java.lang.Object |
|---|
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
|---|
public MethodExpressionImpl()
public MethodExpressionImpl(java.lang.String expr,
Node node,
javax.el.FunctionMapper fnMapper,
javax.el.VariableMapper varMapper,
java.lang.Class expectedType,
java.lang.Class[] paramTypes)
expr - node - fnMapper - expectedType - paramTypes - | Method Detail |
|---|
public boolean equals(java.lang.Object obj)
Expression.
The result is true if and only if the argument is not
null, is an Expression object that is the
of the same type (ValueExpression or
MethodExpression), and has an identical parsed
representation.
Note that two expressions can be equal if their expression Strings are
different. For example, ${fn1:foo()} and
${fn2:foo()} are equal if their corresponding
FunctionMappers mapped fn1:foo and
fn2:foo to the same method.
equals in class javax.el.Expressionobj - the Object to test for equality.
true if obj equals this
Expression; false otherwise.Hashtable,
Object.equals(java.lang.Object)public java.lang.String getExpressionString()
Expression,
unmodified.
This is used for debugging purposes but also for the purposes of comparison (e.g. to ensure the expression in a configuration file has not changed).
This method does not provide sufficient information to re-create an
expression. Two different expressions can have exactly the same
expression string but different function mappings. Serialization should
be used to save and restore the state of an Expression.
getExpressionString in class javax.el.ExpressionExpression.getExpressionString()
public javax.el.MethodInfo getMethodInfo(javax.el.ELContext context)
throws javax.el.PropertyNotFoundException,
javax.el.MethodNotFoundException,
javax.el.ELException
getMethodInfo in class javax.el.MethodExpressioncontext - The context of this evaluation
MethodInfo containing information
about the method the expression evaluated to.
java.lang.NullPointerException - if context is null or the base object is
null on the last resolution.
javax.el.PropertyNotFoundException - if one of the property resolutions failed because a specified
variable or property does not exist or is not readable.
javax.el.MethodNotFoundException - if no suitable method can be found.
javax.el.ELException - if an exception was thrown while performing property or
variable resolution. The thrown exception must be included as
the cause property of this exception, if available.MethodExpression.getMethodInfo(javax.el.ELContext)public int hashCode()
Expression.
See the note in the equals(java.lang.Object) method on how two expressions can be
equal if their expression Strings are different. Recall that if two
objects are equal according to the equals(Object) method,
then calling the hashCode method on each of the two
objects must produce the same integer result. Implementations must take
special note and implement hashCode correctly.
hashCode in class javax.el.ExpressionExpression.equals(java.lang.Object),
Hashtable,
Object.hashCode()
public java.lang.Object invoke(javax.el.ELContext context,
java.lang.Object[] params)
throws javax.el.PropertyNotFoundException,
javax.el.MethodNotFoundException,
javax.el.ELException
invoke in class javax.el.MethodExpressioncontext - The context of this evaluation.params - The parameters to pass to the method, or null
if no parameters.
null if the
method has a void return type).
java.lang.NullPointerException - if context is null or the base object is
null on the last resolution.
javax.el.PropertyNotFoundException - if one of the property resolutions failed because a specified
variable or property does not exist or is not readable.
javax.el.MethodNotFoundException - if no suitable method can be found.
javax.el.ELException - if an exception was thrown while performing property or
variable resolution. The thrown exception must be included as
the cause property of this exception, if available. If the
exception thrown is an InvocationTargetException,
extract its cause and pass it to the
ELException constructor.MethodExpression.invoke(javax.el.ELContext,
java.lang.Object[])
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 writeExternal(java.io.ObjectOutput out)
throws java.io.IOException
writeExternal in interface java.io.Externalizablejava.io.IOExceptionpublic boolean isLiteralText()
isLiteralText in class javax.el.Expression
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