- All Implemented Interfaces:
Serializable
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
.
- Since:
- 1.4
- See Also:
Principal
,DomainCombiner
, Serialized Form
-
Constructor Summary
ConstructorDescriptionSubject()
Create an instance of aSubject
with an emptySet
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 aSubject
with Principals and credentials. -
Method Summary
Modifier and TypeMethodDescriptionstatic <T> T
doAs(Subject subject, PrivilegedAction<T> action)
Perform work as a particularSubject
.static <T> T
doAs(Subject subject, PrivilegedExceptionAction<T> action)
Perform work as a particularSubject
.static <T> T
doAsPrivileged(Subject subject, PrivilegedAction<T> action, AccessControlContext acc)
Perform privileged work as a particularSubject
.static <T> T
doAsPrivileged(Subject subject, PrivilegedExceptionAction<T> action, AccessControlContext acc)
Perform privileged work as a particularSubject
.boolean
Compares the specified Object with thisSubject
for equality.Return theSet
of Principals associated with thisSubject
.getPrincipals(Class<T> c)
Return aSet
of Principals associated with thisSubject
that are instances or subclasses of the specifiedClass
.Return theSet
of private credentials held by thisSubject
.<T> Set<T>
getPrivateCredentials(Class<T> c)
Return aSet
of private credentials associated with thisSubject
that are instances or subclasses of the specifiedClass
.Return theSet
of public credentials held by thisSubject
.<T> Set<T>
getPublicCredentials(Class<T> c)
Return aSet
of public credentials associated with thisSubject
that are instances or subclasses of the specifiedClass
.static Subject
Get theSubject
associated with the providedAccessControlContext
.int
hashCode()
Returns a hashcode for thisSubject
.boolean
Query whether thisSubject
is read-only.void
Set thisSubject
to be read-only.toString()
Return the String representation of thisSubject
.
-
Constructor Details
-
Subject
public Subject()Create an instance of aSubject
with an emptySet
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. These Sets also prohibit null elements, and attempts to add or query a null element will result in aNullPointerException
.To modify the Principals Set, the caller must have
AuthPermission("modifyPrincipals")
. To modify the public credential Set, the caller must haveAuthPermission("modifyPublicCredentials")
. To modify the private credential Set, the caller must haveAuthPermission("modifyPrivateCredentials")
. -
Subject
public Subject(boolean readOnly, Set<? extends Principal> principals, Set<?> pubCredentials, Set<?> privCredentials)Create an instance of aSubject
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. These Sets also prohibit null elements, and attempts to add or query a null element will result in aNullPointerException
.To modify the Principals Set, the caller must have
AuthPermission("modifyPrincipals")
. To modify the public credential Set, the caller must haveAuthPermission("modifyPublicCredentials")
. To modify the private credential Set, the caller must haveAuthPermission("modifyPrivateCredentials")
.- Parameters:
readOnly
- true if theSubject
is to be read-only, and false otherwise.principals
- theSet
of Principals to be associated with thisSubject
.pubCredentials
- theSet
of public credentials to be associated with thisSubject
.privCredentials
- theSet
of private credentials to be associated with thisSubject
.- Throws:
NullPointerException
- if the specifiedprincipals
,pubCredentials
, orprivCredentials
arenull
, or a null value exists within any of these three Sets.
-
-
Method Details
-
setReadOnly
public void setReadOnly()Set thisSubject
to be read-only.Modifications (additions and removals) to this Subject's
Principal
Set
and credential Sets will be disallowed. Thedestroy
operation on this Subject's credentials will still be permitted.Subsequent attempts to modify the Subject's
Principal
and credential Sets will result in anIllegalStateException
being thrown. Also, once aSubject
is read-only, it can not be reset to being writable again.- Throws:
SecurityException
- if a security manager is installed and the caller does not have anAuthPermission("setReadOnly")
permission to set thisSubject
to be read-only.
-
isReadOnly
public boolean isReadOnly()Query whether thisSubject
is read-only.- Returns:
- true if this
Subject
is read-only, false otherwise.
-
getSubject
Get theSubject
associated with the providedAccessControlContext
.The
AccessControlContext
may contain many Subjects (from nesteddoAs
calls). In this situation, the most recentSubject
associated with theAccessControlContext
is returned.- Parameters:
acc
- theAccessControlContext
from which to retrieve theSubject
.- Returns:
- the
Subject
associated with the providedAccessControlContext
, ornull
if noSubject
is associated with the providedAccessControlContext
. - Throws:
SecurityException
- if a security manager is installed and the caller does not have anAuthPermission("getSubject")
permission to get theSubject
.NullPointerException
- if the providedAccessControlContext
isnull
.
-
doAs
Perform work as a particularSubject
.This method first retrieves the current Thread's
AccessControlContext
viaAccessController.getContext
, and then instantiates a newAccessControlContext
using the retrieved context along with a newSubjectDomainCombiner
(constructed using the providedSubject
). Finally, this method invokesAccessController.doPrivileged
, passing it the providedPrivilegedAction
, as well as the newly constructedAccessControlContext
.- Type Parameters:
T
- the type of the value returned by the PrivilegedAction'srun
method.- Parameters:
subject
- theSubject
that the specifiedaction
will run as. This parameter may benull
.action
- the code to be run as the specifiedSubject
.- Returns:
- the value returned by the PrivilegedAction's
run
method. - Throws:
NullPointerException
- if thePrivilegedAction
isnull
.SecurityException
- if a security manager is installed and the caller does not have anAuthPermission("doAs")
permission to invoke this method.
-
doAs
public static <T> T doAs(Subject subject, PrivilegedExceptionAction<T> action) throws PrivilegedActionExceptionPerform work as a particularSubject
.This method first retrieves the current Thread's
AccessControlContext
viaAccessController.getContext
, and then instantiates a newAccessControlContext
using the retrieved context along with a newSubjectDomainCombiner
(constructed using the providedSubject
). Finally, this method invokesAccessController.doPrivileged
, passing it the providedPrivilegedExceptionAction
, as well as the newly constructedAccessControlContext
.- Type Parameters:
T
- the type of the value returned by the PrivilegedExceptionAction'srun
method.- Parameters:
subject
- theSubject
that the specifiedaction
will run as. This parameter may benull
.action
- the code to be run as the specifiedSubject
.- Returns:
- the value returned by the
PrivilegedExceptionAction's
run
method. - Throws:
PrivilegedActionException
- if thePrivilegedExceptionAction.run
method throws a checked exception.NullPointerException
- if the specifiedPrivilegedExceptionAction
isnull
.SecurityException
- if a security manager is installed and the caller does not have anAuthPermission("doAs")
permission to invoke this method.
-
doAsPrivileged
public static <T> T doAsPrivileged(Subject subject, PrivilegedAction<T> action, AccessControlContext acc)Perform privileged work as a particularSubject
.This method behaves exactly as
Subject.doAs
, except that instead of retrieving the current Thread'sAccessControlContext
, it uses the providedAccessControlContext
. If the providedAccessControlContext
isnull
, this method instantiates a newAccessControlContext
with an empty collection of ProtectionDomains.- Type Parameters:
T
- the type of the value returned by the PrivilegedAction'srun
method.- Parameters:
subject
- theSubject
that the specifiedaction
will run as. This parameter may benull
.action
- the code to be run as the specifiedSubject
.acc
- theAccessControlContext
to be tied to the specified subject and action.- Returns:
- the value returned by the PrivilegedAction's
run
method. - Throws:
NullPointerException
- if thePrivilegedAction
isnull
.SecurityException
- if a security manager is installed and the caller does not have aAuthPermission("doAsPrivileged")
permission to invoke this method.
-
doAsPrivileged
public static <T> T doAsPrivileged(Subject subject, PrivilegedExceptionAction<T> action, AccessControlContext acc) throws PrivilegedActionExceptionPerform privileged work as a particularSubject
.This method behaves exactly as
Subject.doAs
, except that instead of retrieving the current Thread'sAccessControlContext
, it uses the providedAccessControlContext
. If the providedAccessControlContext
isnull
, this method instantiates a newAccessControlContext
with an empty collection of ProtectionDomains.- Type Parameters:
T
- the type of the value returned by the PrivilegedExceptionAction'srun
method.- Parameters:
subject
- theSubject
that the specifiedaction
will run as. This parameter may benull
.action
- the code to be run as the specifiedSubject
.acc
- theAccessControlContext
to be tied to the specified subject and action.- Returns:
- the value returned by the
PrivilegedExceptionAction's
run
method. - Throws:
PrivilegedActionException
- if thePrivilegedExceptionAction.run
method throws a checked exception.NullPointerException
- if the specifiedPrivilegedExceptionAction
isnull
.SecurityException
- if a security manager is installed and the caller does not have aAuthPermission("doAsPrivileged")
permission to invoke this method.
-
getPrincipals
Return theSet
of Principals associated with thisSubject
. EachPrincipal
represents an identity for thisSubject
.The returned
Set
is backed by this Subject's internalPrincipal
Set
. Any modification to the returnedSet
affects the internalPrincipal
Set
as well.If a security manager is installed, the caller must have a
AuthPermission("modifyPrincipals")
permission to modify the returned set, or aSecurityException
will be thrown.- Returns:
- the
Set
of Principals associated with thisSubject
.
-
getPrincipals
Return aSet
of Principals associated with thisSubject
that are instances or subclasses of the specifiedClass
.The returned
Set
is not backed by this Subject's internalPrincipal
Set
. A newSet
is created and returned for each method invocation. Modifications to the returnedSet
will not affect the internalPrincipal
Set
.- Type Parameters:
T
- the type of the class modeled byc
- Parameters:
c
- the returnedSet
of Principals will all be instances of this class.- Returns:
- a
Set
of Principals that are instances of the specifiedClass
. - Throws:
NullPointerException
- if the specifiedClass
isnull
.
-
getPublicCredentials
Return theSet
of public credentials held by thisSubject
.The returned
Set
is backed by this Subject's internal public CredentialSet
. Any modification to the returnedSet
affects the internal public CredentialSet
as well.If a security manager is installed, the caller must have a
AuthPermission("modifyPublicCredentials")
permission to modify the returned set, or aSecurityException
will be thrown.- Returns:
- a
Set
of public credentials held by thisSubject
.
-
getPrivateCredentials
Return theSet
of private credentials held by thisSubject
.The returned
Set
is backed by this Subject's internal private CredentialSet
. Any modification to the returnedSet
affects the internal private CredentialSet
as well.If a security manager is installed, the caller must have a
AuthPermission("modifyPrivateCredentials")
permission to modify the returned set, or aSecurityException
will be thrown.While iterating through the
Set
, aSecurityException
is thrown if a security manager is installed and the caller does not have aPrivateCredentialPermission
to access a particular Credential. TheIterator
is nevertheless advanced to the next element in theSet
.- Returns:
- a
Set
of private credentials held by thisSubject
.
-
getPublicCredentials
Return aSet
of public credentials associated with thisSubject
that are instances or subclasses of the specifiedClass
.The returned
Set
is not backed by this Subject's internal public CredentialSet
. A newSet
is created and returned for each method invocation. Modifications to the returnedSet
will not affect the internal public CredentialSet
.- Type Parameters:
T
- the type of the class modeled byc
- Parameters:
c
- the returnedSet
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 specifiedClass
isnull
.
-
getPrivateCredentials
Return aSet
of private credentials associated with thisSubject
that are instances or subclasses of the specifiedClass
.If a security manager is installed, the caller must have a
PrivateCredentialPermission
to access all of the requested Credentials, or aSecurityException
will be thrown.The returned
Set
is not backed by this Subject's internal private CredentialSet
. A newSet
is created and returned for each method invocation. Modifications to the returnedSet
will not affect the internal private CredentialSet
.- Type Parameters:
T
- the type of the class modeled byc
- Parameters:
c
- the returnedSet
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 specifiedClass
isnull
.
-
equals
Compares the specified Object with thisSubject
for equality. Returns true if the given object is also a Subject and the twoSubject
instances are equivalent. More formally, twoSubject
instances are equal if theirPrincipal
andCredential
Sets are equal.- Overrides:
equals
in classObject
- Parameters:
o
- Object to be compared for equality with thisSubject
.- Returns:
- true if the specified Object is equal to this
Subject
. - Throws:
SecurityException
- if a security manager is installed and the caller does not have aPrivateCredentialPermission
permission to access the private credentials for thisSubject
or the providedSubject
.- See Also:
Object.hashCode()
,HashMap
-
toString
Return the String representation of thisSubject
. -
hashCode
public int hashCode()Returns a hashcode for thisSubject
.- Overrides:
hashCode
in classObject
- Returns:
- a hashcode for this
Subject
. - Throws:
SecurityException
- if a security manager is installed and the caller does not have aPrivateCredentialPermission
permission to access this Subject's private credentials.- See Also:
Object.equals(java.lang.Object)
,System.identityHashCode(java.lang.Object)
-