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javax.security.auth

Class Subject

Implemented Interfaces:
Serializable
public final class Subject
extends Object
implements Serializable
See Also:
Serialized Form

Constructor Summary

Subject()
The basic constructor.
Subject(boolean readOnly, Principal> principals, Set pubCred, Set privCred)

Method Summary

Set getPrivateCredentials(Class clazz)
Set getPublicCredentials(Class clazz)
static Object
doAs(Subject subject, PrivilegedAction<T> action)
Run a method as another subject.
static Object
doAs(Subject subject, PrivilegedExceptionAction<T> action)
Run a method as another subject.
static Object
doAsPrivileged(Subject subject, PrivilegedAction<T> action, AccessControlContext acc)
Run a method as another subject.
static Object
doAsPrivileged(Subject subject, PrivilegedExceptionAction<T> action, AccessControlContext acc)
Run a method as another subject.
boolean
equals(Object o)
Determine whether this Object is semantically equal to another Object.
extends Principal> Set getPrincipals(Class clazz)
Set
getPrincipals()
Set
getPrivateCredentials()
Set
getPublicCredentials()
static Subject
getSubject(AccessControlContext context)
Returns the subject associated with the given AccessControlContext.

All this method does is retrieve the Subject object from the supplied context's DomainCombiner, if any, and if it is an instance of a SubjectDomainCombiner.

int
hashCode()
Get a value that represents this Object, as uniquely as possible within the confines of an int.
boolean
isReadOnly()
Returns whether or not this subject is read-only.
void
setReadOnly()
Marks this subject as read-only.
String
toString()
Convert this Object to a human-readable String.

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Subject

public Subject()
The basic constructor. Object is special, because it has no superclass, so there is no call to super().

Subject

public Subject(boolean readOnly,
               Principal> principals,
               Set pubCred,
               Set privCred)

Method Details

Set getPrivateCredentials

public  Set getPrivateCredentials(Class clazz)

Set getPublicCredentials

public  Set getPublicCredentials(Class clazz)

doAs

public static Object doAs(Subject subject,
                          PrivilegedAction<T> action)
Run a method as another subject. This method will obtain the current AccessControlContext for this thread, then creates another with a SubjectDomainCombiner with the given subject. The supplied action will then be run with the modified context.
Parameters:
subject - The subject to run as.
action - The action to run.
Returns:
The value returned by the privileged action.
Throws:
SecurityException - If the caller is not allowed to run under a different identity ("doAs" target of AuthPermission.

doAs

public static Object doAs(Subject subject,
                          PrivilegedExceptionAction<T> action)
            throws PrivilegedActionException
Run a method as another subject. This method will obtain the current AccessControlContext for this thread, then creates another with a SubjectDomainCombiner with the given subject. The supplied action will then be run with the modified context.
Parameters:
subject - The subject to run as.
action - The action to run.
Returns:
The value returned by the privileged action.
Throws:
SecurityException - If the caller is not allowed to run under a different identity ("doAs" target of AuthPermission.
PrivilegedActionException - If the action throws an exception.

doAsPrivileged

public static Object doAsPrivileged(Subject subject,
                                    PrivilegedAction<T> action,
                                    AccessControlContext acc)
Run a method as another subject. This method will create a new AccessControlContext derived from the given one, with a SubjectDomainCombiner with the given subject. The supplied action will then be run with the modified context.
Parameters:
subject - The subject to run as.
action - The action to run.
acc - The context to use.
Returns:
The value returned by the privileged action.
Throws:
SecurityException - If the caller is not allowed to run under a different identity ("doAsPrivileged" target of AuthPermission.

doAsPrivileged

public static Object doAsPrivileged(Subject subject,
                                    PrivilegedExceptionAction<T> action,
                                    AccessControlContext acc)
            throws PrivilegedActionException
Run a method as another subject. This method will create a new AccessControlContext derived from the given one, with a SubjectDomainCombiner with the given subject. The supplied action will then be run with the modified context.
Parameters:
subject - The subject to run as.
action - The action to run.
acc - The context to use.
Returns:
The value returned by the privileged action.
Throws:
SecurityException - If the caller is not allowed to run under a different identity ("doAsPrivileged" target of AuthPermission.
PrivilegedActionException - If the action throws an exception.

equals

public boolean equals(Object o)
Determine whether this Object is semantically equal to another Object.

There are some fairly strict requirements on this method which subclasses must follow:

  • It must be transitive. If a.equals(b) and b.equals(c), then a.equals(c) must be true as well.
  • It must be symmetric. a.equals(b) and b.equals(a) must have the same value.
  • It must be reflexive. a.equals(a) must always be true.
  • It must be consistent. Whichever value a.equals(b) returns on the first invocation must be the value returned on all later invocations.
  • a.equals(null) must be false.
  • It must be consistent with hashCode(). That is, a.equals(b) must imply a.hashCode() == b.hashCode(). The reverse is not true; two objects that are not equal may have the same hashcode, but that has the potential to harm hashing performance.

This is typically overridden to throw a ClassCastException if the argument is not comparable to the class performing the comparison, but that is not a requirement. It is legal for a.equals(b) to be true even though a.getClass() != b.getClass(). Also, it is typical to never cause a NullPointerException.

In general, the Collections API (java.util) use the equals method rather than the == operator to compare objects. However, IdentityHashMap is an exception to this rule, for its own good reasons.

The default implementation returns this == o.

Overrides:
equals in interface Object
Parameters:
Returns:
whether this Object is semantically equal to another
See Also:
Object.hashCode()

extends Principal> Set getPrincipals

public extends Principal> Set getPrincipals(Class clazz)

getPrincipals

public Set getPrincipals()

getPrivateCredentials

public Set getPrivateCredentials()
getPublicCredentials
public Set getPublicCredentials()
getSubject
public static Subject getSubject(AccessControlContext context)
 Returns the subject associated with the given AccessControlContext.

 
All this method does is retrieve the Subject object from the supplied
 context's DomainCombiner, if any, and if it is an instance of
 a SubjectDomainCombiner.

Parameters:
context - The context to retrieve the subject from.
Returns:
The subject assoctiated with the context, or null
if there is none.
Throws:
NullPointerException - If subject is null.
SecurityException - If the caller does not have permission to get
the subject ("getSubject" target of AuthPermission.
hashCode
public int hashCode()
 Get a value that represents this Object, as uniquely as
 possible within the confines of an int.

 
There are some requirements on this method which
 subclasses must follow:


 
  • Semantic equality implies identical hashcodes.  In other
     words, if a.equals(b) is true, then
     a.hashCode() == b.hashCode() must be as well.
     However, the reverse is not necessarily true, and two
     objects may have the same hashcode without being equal.
  • It must be consistent.  Whichever value o.hashCode()
     returns on the first invocation must be the value
     returned on all later invocations as long as the object
     exists.  Notice, however, that the result of hashCode may
     change between separate executions of a Virtual Machine,
     because it is not invoked on the same object.


 
Notice that since hashCode is used in
Hashtable and other hashing classes,
  a poor implementation will degrade the performance of hashing
 (so don't blindly implement it as returning a constant!). Also,
 if calculating the hash is time-consuming, a class may consider
 caching the results.

 
The default implementation returns
 System.identityHashCode(this)

Overrides:
hashCode in interface Object
Returns:
the hash code for this Object
See Also:
Object.equals(Object), System.identityHashCode(Object)
isReadOnly
public boolean isReadOnly()
 Returns whether or not this subject is read-only.

Returns:
True is this subject is read-only.
setReadOnly
public void setReadOnly()
 Marks this subject as read-only.

Throws:
SecurityException - If the caller does not have permission to
set this subject as read-only ("setReadOnly" target of
AuthPermission.
toString
public String toString()
 Convert this Object to a human-readable String.
 There are no limits placed on how long this String
 should be or what it should contain.  We suggest you
 make it as intuitive as possible to be able to place
 it into System.out.println()
 and such.

 
It is typical, but not required, to ensure that this method
 never completes abruptly with a RuntimeException.

 
This method will be called when performing string
 concatenation with this object.  If the result is
 null, string concatenation will instead
 use "null".

 
The default implementation returns
 getClass().getName() + "@" +
      Integer.toHexString(hashCode()).

Overrides:
toString in interface Object
Returns:
the String representing this Object, which may be null
See Also:
getClass(), Object.hashCode(), Class.getName(), Integer.toHexString(int)
 Subject.java -- a single entity in the system.
   Copyright (C) 2004, 2005 Free Software Foundation, Inc.

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