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25 
26 package javax.management;
27 
28 
29 /**
30  * This class is used by the query building mechanism for isInstanceOf expressions.
31  * @serial include
32  *
33  * @since 1.6
34  */
35 class InstanceOfQueryExp extends QueryEval implements QueryExp {
36 
37     /* Serial version */
38     private static final long serialVersionUID = -1081892073854801359L;
39 
40     /**
41      * @serial The {@link StringValueExp} returning the name of the class
42      *         of which selected MBeans should be instances.
43      */
44     private StringValueExp classNameValue;
45 
46     /**
47      * Creates a new InstanceOfExp with a specific class name.
48      * @param classNameValue The {@link StringValueExp} returning the name of
49      *        the class of which selected MBeans should be instances.
50      */
51     // We are using StringValueExp here to be consistent with other queries,
52     // although we should actually either use a simple string (the classname)
53     // or a ValueExp - which would allow more complex queries - like for
54     // instance evaluating the class name from an AttributeValueExp.
55     // As it stands - using StringValueExp instead of a simple constant string
56     // doesn't serve any useful purpose besides offering a consistent
57     // look & feel.
InstanceOfQueryExp(StringValueExp classNameValue)58     public InstanceOfQueryExp(StringValueExp classNameValue) {
59         if (classNameValue == null) {
60             throw new IllegalArgumentException("Null class name.");
61         }
62 
63         this.classNameValue = classNameValue;
64     }
65 
66     /**
67      * Returns the class name.
68      * @returns The {@link StringValueExp} returning the name of
69      *        the class of which selected MBeans should be instances.
70      */
getClassNameValue()71     public StringValueExp getClassNameValue()  {
72         return classNameValue;
73     }
74 
75     /**
76      * Applies the InstanceOf on a MBean.
77      *
78      * @param name The name of the MBean on which the InstanceOf will be applied.
79      *
80      * @return  True if the MBean specified by the name is instance of the class.
81      * @exception BadAttributeValueExpException
82      * @exception InvalidApplicationException
83      * @exception BadStringOperationException
84      * @exception BadBinaryOpValueExpException
85      */
apply(ObjectName name)86     public boolean apply(ObjectName name)
87         throws BadStringOperationException,
88         BadBinaryOpValueExpException,
89         BadAttributeValueExpException,
90         InvalidApplicationException {
91 
92         // Get the class name value
93         final StringValueExp val;
94         try {
95             val = (StringValueExp) classNameValue.apply(name);
96         } catch (ClassCastException x) {
97             // Should not happen - unless someone wrongly implemented
98             // StringValueExp.apply().
99             final BadStringOperationException y =
100                     new BadStringOperationException(x.toString());
101             y.initCause(x);
102             throw y;
103         }
104 
105         // Test whether the MBean is an instance of that class.
106         try {
107             return getMBeanServer().isInstanceOf(name, val.getValue());
108         } catch (InstanceNotFoundException infe) {
109             return false;
110         }
111     }
112 
113     /**
114      * Returns a string representation of this InstanceOfQueryExp.
115      * @return a string representation of this InstanceOfQueryExp.
116      */
toString()117     public String toString() {
118        return "InstanceOf " + classNameValue.toString();
119    }
120 }
121