public static Object getValue(Object tree, Map context, Object root)
            throws OgnlException
    {
        return getValue(tree, context, root, null);
    }
public static Object getValue(Object tree, Map context, Object root)
            throws OgnlException
    {
        return getValue(tree, context, root, null);
    }
public static Object getValue ( Object tree , Map context , Object root ) throws OgnlException { return getValue ( tree , context , root , null ) ; }
Evaluates the given OGNL expression tree to extract a value from the given root object. The
default context is set for the given context and root via <CODE>addDefaultContext()</CODE>.

@param tree
the OGNL expression tree to evaluate, as returned by parseExpression()
@param context
the naming context for the evaluation
@param root
the root object for the OGNL expression
@return the result of evaluating the expression
@throws MethodFailedException
if the expression called a method which failed
@throws NoSuchPropertyException
if the expression referred to a nonexistent property
@throws InappropriateExpressionException
if the expression can't be used in this context
@throws OgnlException
if there is a pathological environmental problem
Evaluates the given OGNL expression tree to extract a value from the given root object . The default context is set for the given context and root via <CODE > addDefaultContext () < / CODE > .