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25 
26 package sun.security.action;
27 
28 /**
29  * A convenience class for retrieving the string value of a system
30  * property as a privileged action.
31  *
32  * <p>An instance of this class can be used as the argument of
33  * <code>AccessController.doPrivileged</code>.
34  *
35  * <p>The following code retrieves the value of the system
36  * property named <code>"prop"</code> as a privileged action: <p>
37  *
38  * <pre>
39  * String s = java.security.AccessController.doPrivileged
40  *                      (new GetPropertyAction("prop"));
41  * </pre>
42  *
43  * @author Roland Schemers
44  * @see java.security.PrivilegedAction
45  * @see java.security.AccessController
46  * @since 1.2
47  */
48 
49 public class GetPropertyAction
50         implements java.security.PrivilegedAction<String> {
51     private String theProp;
52     private String defaultVal;
53 
54     /**
55      * Constructor that takes the name of the system property whose
56      * string value needs to be determined.
57      *
58      * @param theProp the name of the system property.
59      */
GetPropertyAction(String theProp)60     public GetPropertyAction(String theProp) {
61         this.theProp = theProp;
62     }
63 
64     /**
65      * Constructor that takes the name of the system property and the default
66      * value of that property.
67      *
68      * @param theProp the name of the system property.
69      * @param defaulVal the default value.
70      */
GetPropertyAction(String theProp, String defaultVal)71     public GetPropertyAction(String theProp, String defaultVal) {
72         this.theProp = theProp;
73         this.defaultVal = defaultVal;
74     }
75 
76     /**
77      * Determines the string value of the system property whose
78      * name was specified in the constructor.
79      *
80      * @return the string value of the system property,
81      *         or the default value if there is no property with that key.
82      */
run()83     public String run() {
84         String value = System.getProperty(theProp);
85         return (value == null) ? defaultVal : value;
86     }
87 }
88