A Subject
represents a grouping of related information
for a single entity, such as a person.
Such information includes the Subject's identities as well as
its security-related attributes
(passwords and cryptographic keys, for example).
Subjects may potentially have multiple identities.
Each identity is represented as a Principal
within the Subject
. Principals simply bind names to a
Subject
. For example, a Subject
that happens
to be a person, Alice, might have two Principals:
one which binds "Alice Bar", the name on her driver license,
to the Subject
, and another which binds,
"999-99-9999", the number on her student identification card,
to the Subject
. Both Principals refer to the same
Subject
even though each has a different name.
A Subject
may also own security-related attributes,
which are referred to as credentials.
Sensitive credentials that require special protection, such as
private cryptographic keys, are stored within a private credential
Set
. Credentials intended to be shared, such as
public key certificates or Kerberos server tickets are stored
within a public credential Set
. Different permissions
are required to access and modify the different credential Sets.
To retrieve all the Principals associated with a Subject
,
invoke the getPrincipals
method. To retrieve
all the public or private credentials belonging to a Subject
,
invoke the getPublicCredentials
method or
getPrivateCredentials
method, respectively.
To modify the returned Set
of Principals and credentials,
use the methods defined in the Set
class.
For example:
Subject subject; Principal principal; Object credential; // add a Principal and credential to the Subject subject.getPrincipals().add(principal); subject.getPublicCredentials().add(credential);
This Subject
class implements Serializable
.
While the Principals associated with the Subject
are serialized,
the credentials associated with the Subject
are not.
Note that the java.security.Principal
class
does not implement Serializable
. Therefore all concrete
Principal
implementations associated with Subjects
must implement Serializable
.
See Also
Public Constructor Summary
Subject()
Create an instance of a
Subject
with an empty Set of Principals and empty
Sets of public and private credentials. |
|
Public Method Summary
static <T> T | |
static <T> T | |
static <T> T |
doAsPrivileged(Subject subject, PrivilegedExceptionAction<T> action, AccessControlContext acc)
Perform privileged work as a particular
Subject . |
static <T> T |
doAsPrivileged(Subject subject, PrivilegedAction<T> action, AccessControlContext acc)
Perform privileged work as a particular
Subject . |
boolean | |
Set<Principal> |
getPrincipals()
Return the
Set of Principals associated with this
Subject . |
<T extends Principal> Set<T> |
getPrincipals(Class<T> c)
Return a
Set of Principals associated with this
Subject that are instances or subclasses of the specified
Class . |
<T> Set<T> |
getPrivateCredentials(Class<T> c)
Return a
Set of private credentials associated with this
Subject that are instances or subclasses of the specified
Class . |
Set<Object> |
getPrivateCredentials()
Return the
Set of private credentials held by this
Subject . |
Set<Object> |
getPublicCredentials()
Return the
Set of public credentials held by this
Subject . |
<T> Set<T> |
getPublicCredentials(Class<T> c)
Return a
Set of public credentials associated with this
Subject that are instances or subclasses of the specified
Class . |
static Subject |
getSubject(AccessControlContext acc)
Get the
Subject associated with the provided
AccessControlContext . |
int |
hashCode()
Returns a hashcode for this
Subject . |
boolean |
isReadOnly()
Query whether this
Subject is read-only. |
void |
setReadOnly()
Set this
Subject to be read-only. |
String |
toString()
Return the String representation of this
Subject . |
Inherited Method Summary
Public Constructors
public Subject ()
Create an instance of a Subject
with an empty Set
of Principals and empty
Sets of public and private credentials.
The newly constructed Sets check whether this Subject
has been set read-only before permitting subsequent modifications.
The newly created Sets also prevent illegal modifications
by ensuring that callers have sufficient permissions.
To modify the Principals Set, the caller must have
AuthPermission("modifyPrincipals")
.
To modify the public credential Set, the caller must have
AuthPermission("modifyPublicCredentials")
.
To modify the private credential Set, the caller must have
AuthPermission("modifyPrivateCredentials")
.
public Subject (boolean readOnly, Set<? extends Principal> principals, Set<?> pubCredentials, Set<?> privCredentials)
Create an instance of a Subject
with
Principals and credentials.
The Principals and credentials from the specified Sets
are copied into newly constructed Sets.
These newly created Sets check whether this Subject
has been set read-only before permitting subsequent modifications.
The newly created Sets also prevent illegal modifications
by ensuring that callers have sufficient permissions.
To modify the Principals Set, the caller must have
AuthPermission("modifyPrincipals")
.
To modify the public credential Set, the caller must have
AuthPermission("modifyPublicCredentials")
.
To modify the private credential Set, the caller must have
AuthPermission("modifyPrivateCredentials")
.
Parameters
readOnly | true if the Subject is to be read-only,
and false otherwise. |
---|---|
principals | the Set of Principals
to be associated with this Subject . |
pubCredentials | the Set of public credentials
to be associated with this Subject . |
privCredentials | the Set of private credentials
to be associated with this Subject . |
Throws
NullPointerException | if the specified
principals , pubCredentials ,
or privCredentials are null .
|
---|
Public Methods
public static T doAs (Subject subject, PrivilegedExceptionAction<T> action)
Perform work as a particular Subject
.
This method first retrieves the current Thread's
AccessControlContext
via
AccessController.getContext
,
and then instantiates a new AccessControlContext
using the retrieved context along with a new
SubjectDomainCombiner
(constructed using
the provided Subject
).
Finally, this method invokes AccessController.doPrivileged
,
passing it the provided PrivilegedExceptionAction
,
as well as the newly constructed AccessControlContext
.
Parameters
subject | the Subject that the specified
action will run as. This parameter
may be null . |
---|---|
action | the code to be run as the specified
Subject . |
Returns
- the value returned by the
PrivilegedExceptionAction's
run
method.
Throws
PrivilegedActionException | if the
PrivilegedExceptionAction.run
method throws a checked exception. |
---|---|
NullPointerException | if the specified
PrivilegedExceptionAction is
null . |
SecurityException | if the caller does not have permission to invoke this method. |
public static T doAs (Subject subject, PrivilegedAction<T> action)
Perform work as a particular Subject
.
This method first retrieves the current Thread's
AccessControlContext
via
AccessController.getContext
,
and then instantiates a new AccessControlContext
using the retrieved context along with a new
SubjectDomainCombiner
(constructed using
the provided Subject
).
Finally, this method invokes AccessController.doPrivileged
,
passing it the provided PrivilegedAction
,
as well as the newly constructed AccessControlContext
.
Parameters
subject | the Subject that the specified
action will run as. This parameter
may be null . |
---|---|
action | the code to be run as the specified
Subject . |
Returns
- the value returned by the PrivilegedAction's
run
method.
Throws
NullPointerException | if the PrivilegedAction
is null . |
---|---|
SecurityException | if the caller does not have permission to invoke this method. |
public static T doAsPrivileged (Subject subject, PrivilegedExceptionAction<T> action, AccessControlContext acc)
Perform privileged work as a particular Subject
.
This method behaves exactly as Subject.doAs
,
except that instead of retrieving the current Thread's
AccessControlContext
, it uses the provided
AccessControlContext
. If the provided
AccessControlContext
is null
,
this method instantiates a new AccessControlContext
with an empty collection of ProtectionDomains.
Parameters
subject | the Subject that the specified
action will run as. This parameter
may be null . |
---|---|
action | the code to be run as the specified
Subject . |
acc | the AccessControlContext to be tied to the
specified subject and action. |
Returns
- the value returned by the
PrivilegedExceptionAction's
run
method.
Throws
PrivilegedActionException | if the
PrivilegedExceptionAction.run
method throws a checked exception. |
---|---|
NullPointerException | if the specified
PrivilegedExceptionAction is
null . |
SecurityException | if the caller does not have permission to invoke this method. |
public static T doAsPrivileged (Subject subject, PrivilegedAction<T> action, AccessControlContext acc)
Perform privileged work as a particular Subject
.
This method behaves exactly as Subject.doAs
,
except that instead of retrieving the current Thread's
AccessControlContext
, it uses the provided
AccessControlContext
. If the provided
AccessControlContext
is null
,
this method instantiates a new AccessControlContext
with an empty collection of ProtectionDomains.
Parameters
subject | the Subject that the specified
action will run as. This parameter
may be null . |
---|---|
action | the code to be run as the specified
Subject . |
acc | the AccessControlContext to be tied to the
specified subject and action. |
Returns
- the value returned by the PrivilegedAction's
run
method.
Throws
NullPointerException | if the PrivilegedAction
is null . |
---|---|
SecurityException | if the caller does not have permission to invoke this method. |
public boolean equals (Object o)
Compares the specified Object with this Subject
for equality. Returns true if the given object is also a Subject
and the two Subject
instances are equivalent.
More formally, two Subject
instances are
equal if their Principal
and Credential
Sets are equal.
Parameters
o | Object to be compared for equality with this
Subject . |
---|
Returns
- true if the specified Object is equal to this
Subject
.
Throws
SecurityException | if the caller does not have permission
to access the private credentials for this Subject ,
or if the caller does not have permission to access the
private credentials for the provided Subject .
|
---|
public Set<Principal> getPrincipals ()
Return the Set
of Principals associated with this
Subject
. Each Principal
represents
an identity for this Subject
.
The returned Set
is backed by this Subject's
internal Principal
Set
. Any modification
to the returned Set
affects the internal
Principal
Set
as well.
Returns
- The
Set
of Principals associated with thisSubject
.
public Set<T> getPrincipals (Class<T> c)
Return a Set
of Principals associated with this
Subject
that are instances or subclasses of the specified
Class
.
The returned Set
is not backed by this Subject's
internal Principal
Set
. A new
Set
is created and returned for each method invocation.
Modifications to the returned Set
will not affect the internal Principal
Set
.
Parameters
c | the returned Set of Principals will all be
instances of this class. |
---|
Returns
- a
Set
of Principals that are instances of the specifiedClass
.
Throws
NullPointerException | if the specified Class
is null .
|
---|
public Set<T> getPrivateCredentials (Class<T> c)
Return a Set
of private credentials associated with this
Subject
that are instances or subclasses of the specified
Class
.
The caller must have permission to access all of the
requested Credentials, or a SecurityException
will be thrown.
The returned Set
is not backed by this Subject's
internal private Credential Set
. A new
Set
is created and returned for each method invocation.
Modifications to the returned Set
will not affect the internal private Credential Set
.
Parameters
c | the returned Set of private credentials will all be
instances of this class. |
---|
Returns
- a
Set
of private credentials that are instances of the specifiedClass
.
Throws
NullPointerException | if the specified Class
is null .
|
---|
public Set<Object> getPrivateCredentials ()
Return the Set
of private credentials held by this
Subject
.
The returned Set
is backed by this Subject's
internal private Credential Set
. Any modification
to the returned Set
affects the internal private
Credential Set
as well.
A caller requires permissions to access the Credentials
in the returned Set
, or to modify the
Set
itself. A SecurityException
is thrown if the caller does not have the proper permissions.
While iterating through the Set
,
a SecurityException
is thrown
if the caller does not have permission to access a
particular Credential. The Iterator
is nevertheless advanced to next element in the Set
.
Returns
- A
Set
of private credentials held by thisSubject
.
public Set<Object> getPublicCredentials ()
Return the Set
of public credentials held by this
Subject
.
The returned Set
is backed by this Subject's
internal public Credential Set
. Any modification
to the returned Set
affects the internal public
Credential Set
as well.
Returns
- A
Set
of public credentials held by thisSubject
.
public Set<T> getPublicCredentials (Class<T> c)
Return a Set
of public credentials associated with this
Subject
that are instances or subclasses of the specified
Class
.
The returned Set
is not backed by this Subject's
internal public Credential Set
. A new
Set
is created and returned for each method invocation.
Modifications to the returned Set
will not affect the internal public Credential Set
.
Parameters
c | the returned Set of public credentials will all be
instances of this class. |
---|
Returns
- a
Set
of public credentials that are instances of the specifiedClass
.
Throws
NullPointerException | if the specified Class
is null .
|
---|
public static Subject getSubject (AccessControlContext acc)
Get the Subject
associated with the provided
AccessControlContext
.
The AccessControlContext
may contain many
Subjects (from nested doAs
calls).
In this situation, the most recent Subject
associated
with the AccessControlContext
is returned.
Parameters
acc | the AccessControlContext from which to retrieve
the Subject . |
---|
Returns
- the
Subject
associated with the providedAccessControlContext
, ornull
if noSubject
is associated with the providedAccessControlContext
.
Throws
SecurityException | if the caller does not have permission
to get the Subject . |
---|---|
NullPointerException | if the provided
AccessControlContext is null .
|
public int hashCode ()
Returns a hashcode for this Subject
.
Returns
- a hashcode for this
Subject
.
Throws
SecurityException | if the caller does not have permission to access this Subject's private credentials. |
---|
public boolean isReadOnly ()
Query whether this Subject
is read-only.
Returns
- true if this
Subject
is read-only, false otherwise.
public void setReadOnly ()
Set this Subject
to be read-only.
Modifications (additions and removals) to this Subject's
Principal
Set
and
credential Sets will be disallowed.
The destroy
operation on this Subject's credentials will
still be permitted.
Subsequent attempts to modify the Subject's Principal
and credential Sets will result in an
IllegalStateException
being thrown.
Also, once a Subject
is read-only,
it can not be reset to being writable again.
Throws
SecurityException | if the caller does not have permission
to set this Subject to be read-only.
|
---|
public String toString ()
Return the String representation of this Subject
.
Returns
- the String representation of this
Subject
.