MethodExpressionImplpublic final class MethodExpressionImpl extends MethodExpression implements ExternalizableAn Expression that refers to a method on an object.
The {@link ExpressionFactory#createMethodExpression} method
can be used to parse an expression string and return a concrete instance
of MethodExpression that encapsulates the parsed expression.
The {@link FunctionMapper} is used at parse time, not evaluation time,
so one is not needed to evaluate an expression using this class.
However, the {@link ELContext} is needed at evaluation time.
The {@link #getMethodInfo} and {@link #invoke} methods will evaluate the
expression each time they are called. The {@link 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 {@link ELResolver#getValue}
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 {@link Expression} javadocs. |
Fields Summary |
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private Class | expectedType | private String | expr | private FunctionMapper | fnMapper | private VariableMapper | varMapper | private transient Node | node | private Class[] | paramTypes |
Constructors Summary |
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public MethodExpressionImpl()
super();
| public MethodExpressionImpl(String expr, Node node, FunctionMapper fnMapper, VariableMapper varMapper, Class expectedType, Class[] paramTypes)
super();
this.expr = expr;
this.node = node;
this.fnMapper = fnMapper;
this.varMapper = varMapper;
this.expectedType = expectedType;
this.paramTypes = paramTypes;
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Methods Summary |
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public boolean | equals(java.lang.Object obj)Determines whether the specified object is equal to this
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
FunctionMapper s mapped fn1:foo and
fn2:foo to the same method.
if (obj instanceof MethodExpressionImpl) {
MethodExpressionImpl me = (MethodExpressionImpl) obj;
return getNode().equals(me.getNode());
}
return false;
| public java.lang.String | getExpressionString()Returns the original String used to create this 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 .
return this.expr;
| public javax.el.MethodInfo | getMethodInfo(javax.el.ELContext context)Evaluates the expression relative to the provided context, and returns
information about the actual referenced method.
Node n = this.getNode();
EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
this.varMapper);
return n.getMethodInfo(ctx, this.paramTypes);
| private com.sun.el.parser.Node | getNode()
if (this.node == null) {
this.node = ExpressionBuilder.createNode(this.expr);
}
return this.node;
| public int | hashCode()Returns the hash code for this Expression .
See the note in the {@link #equals} 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.
return getNode().hashCode();
| public 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.
EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
this.varMapper);
return this.getNode().invoke(ctx, this.paramTypes, params);
| public boolean | isLiteralText()
return false;
| public void | readExternal(java.io.ObjectInput in)
this.expr = in.readUTF();
String type = in.readUTF();
if (!"".equals(type)) {
this.expectedType = ReflectionUtil.forName(type);
}
this.paramTypes = ReflectionUtil.toTypeArray(((String[]) in
.readObject()));
this.fnMapper = (FunctionMapper) in.readObject();
this.varMapper = (VariableMapper) in.readObject();
| public void | writeExternal(java.io.ObjectOutput out)
out.writeUTF(this.expr);
out.writeUTF((this.expectedType != null) ? this.expectedType.getName()
: "");
out.writeObject(ReflectionUtil.toTypeNameArray(this.paramTypes));
out.writeObject(this.fnMapper);
out.writeObject(this.varMapper);
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