public final class Subject extends Object implements Serializable
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
.
Principal
,
DomainCombiner
,
Serialized FormConstructor and Description |
---|
Subject()
Create an instance of a
Subject
with an empty Set of Principals and empty
Sets of public and private credentials. |
Subject(boolean readOnly,
Set<? extends Principal> principals,
Set<?> pubCredentials,
Set<?> privCredentials)
Create an instance of a
Subject with
Principals and credentials. |
Modifier and Type | Method and Description |
---|---|
static <T> T |
doAs(Subject subject,
PrivilegedAction<T> action)
Perform work as a particular
Subject . |
static <T> T |
doAs(Subject subject,
PrivilegedExceptionAction<T> action)
Perform work as a particular
Subject . |
static <T> T |
doAsPrivileged(Subject subject,
PrivilegedAction<T> action,
AccessControlContext acc)
Perform privileged work as a particular
Subject . |
static <T> T |
doAsPrivileged(Subject subject,
PrivilegedExceptionAction<T> action,
AccessControlContext acc)
Perform privileged work as a particular
Subject . |
boolean |
equals(Object o)
Compares the specified Object with this
Subject
for equality. |
Set<Principal> |
getPrincipals()
Return the
Set of Principals associated with this
Subject . |
<T extends Principal> |
getPrincipals(Class<T> c)
Return a
Set of Principals 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 . |
<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> |
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 . |
public Subject()
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)
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")
.
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
.NullPointerException
- if the specified
principals
, pubCredentials
,
or privCredentials
are null
.public void setReadOnly()
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.
SecurityException
- if the caller does not have permission
to set this Subject
to be read-only.public boolean isReadOnly()
Subject
is read-only.
Subject
is read-only, false otherwise.public static Subject getSubject(AccessControlContext acc)
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.
acc
- the AccessControlContext
from which to retrieve
the Subject
.Subject
associated with the provided
AccessControlContext
, or null
if no Subject
is associated
with the provided AccessControlContext
.SecurityException
- if the caller does not have permission
to get the Subject
. NullPointerException
- if the provided
AccessControlContext
is null
.public static <T> T doAs(Subject subject, PrivilegedAction<T> action)
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
.
T
- the type of the value returned by the PrivilegedAction's
run
method.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
. run
method.NullPointerException
- if the PrivilegedAction
is null
. SecurityException
- if the caller does not have permission
to invoke this method.public static <T> T doAs(Subject subject, PrivilegedExceptionAction<T> action) throws PrivilegedActionException
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
.
T
- the type of the value returned by the
PrivilegedExceptionAction's run
method.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
. run
method.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> T doAsPrivileged(Subject subject, PrivilegedAction<T> action, AccessControlContext acc)
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.
T
- the type of the value returned by the PrivilegedAction's
run
method.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. run
method.NullPointerException
- if the PrivilegedAction
is null
. SecurityException
- if the caller does not have permission
to invoke this method.public static <T> T doAsPrivileged(Subject subject, PrivilegedExceptionAction<T> action, AccessControlContext acc) throws PrivilegedActionException
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.
T
- the type of the value returned by the
PrivilegedExceptionAction's run
method.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. run
method.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 Set<Principal> getPrincipals()
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.
Set
of Principals associated with this
Subject
.public <T extends Principal> Set<T> getPrincipals(Class<T> c)
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
.
T
- the type of the class modeled by c
c
- the returned Set
of Principals will all be
instances of this class.Set
of Principals that are instances of the
specified Class
.NullPointerException
- if the specified Class
is null
.public Set<Object> getPublicCredentials()
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.
Set
of public credentials held by this
Subject
.public Set<Object> getPrivateCredentials()
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
.
Set
of private credentials held by this
Subject
.public <T> Set<T> getPublicCredentials(Class<T> c)
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
.
T
- the type of the class modeled by c
c
- the returned Set
of public credentials will all be
instances of this class.Set
of public credentials that are instances
of the specified Class
.NullPointerException
- if the specified Class
is null
.public <T> Set<T> getPrivateCredentials(Class<T> c)
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
.
T
- the type of the class modeled by c
c
- the returned Set
of private credentials will all be
instances of this class.Set
of private credentials that are instances
of the specified Class
.NullPointerException
- if the specified Class
is null
.public boolean equals(Object o)
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.
equals
in class Object
o
- Object to be compared for equality with this
Subject
.Subject
.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
.Object.hashCode()
,
HashMap
public String toString()
Subject
.
public int hashCode()
Subject
.
hashCode
in class Object
Subject
.SecurityException
- if the caller does not have permission
to access this Subject's private credentials.Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
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