Class Subject
- java.lang.Object
-
- javax.security.auth.Subject
- 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
Constructor | Description |
---|---|
Subject() | Create an instance of a |
Subject(boolean readOnly,
Set<? extends Principal> principals,
Set<?> pubCredentials,
Set<?> privCredentials) | Create an instance of a |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
static <T> T | doAs(Subject subject,
PrivilegedAction<T> action) | Perform work as a particular |
static <T> T | doAs(Subject subject,
PrivilegedExceptionAction<T> action) | Perform work as a particular |
static <T> T | doAsPrivileged(Subject subject,
PrivilegedAction<T> action,
AccessControlContext acc) | Perform privileged work as a particular |
static <T> T | doAsPrivileged(Subject subject,
PrivilegedExceptionAction<T> action,
AccessControlContext acc) | Perform privileged work as a particular |
boolean | equals(Object o) | Compares the specified Object with this |
Set<Principal> | getPrincipals() | Return the |
<T extends Principal> | getPrincipals(Class<T> c) | Return a |
Set<Object> | getPrivateCredentials() | Return the |
<T> Set<T> | getPrivateCredentials(Class<T> c) | Return a |
Set<Object> | getPublicCredentials() | Return the |
<T> Set<T> | getPublicCredentials(Class<T> c) | Return a |
static Subject | getSubject(AccessControlContext acc) | Get the |
int | hashCode() | Returns a hashcode for this |
boolean | isReadOnly() | Query whether this |
void | setReadOnly() | Set this |
String | toString() | Return the String representation of this |
Methods declared in class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Constructor Detail
Subject
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. These Sets also prohibit null elements, and attempts to add or query a null element will result in a NullPointerException
.
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")
.
Subject
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. These Sets also prohibit null elements, and attempts to add or query a null element will result in a NullPointerException
.
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 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 Detail
setReadOnly
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 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 this Subject
is read-only.
- Returns:
- true if this
Subject
is read-only, false otherwise.
getSubject
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
- 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
public static <T> 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
.
- 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 PrivilegedActionException
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
.
- 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 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.
- 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 PrivilegedActionException
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.
- 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
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.
If a security manager is installed, the caller must have a AuthPermission("modifyPrincipals")
permission to modify the returned set, or a SecurityException
will be thrown.
- Returns:
- the
Set
of Principals associated with thisSubject
.
getPrincipals
public <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
.
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
.
- 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
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.
If a security manager is installed, the caller must have a AuthPermission("modifyPublicCredentials")
permission to modify the returned set, or a SecurityException
will be thrown.
- Returns:
- a
Set
of public credentials held by thisSubject
.
getPrivateCredentials
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.
If a security manager is installed, the caller must have a AuthPermission("modifyPrivateCredentials")
permission to modify the returned set, or a SecurityException
will be thrown.
While iterating through the Set
, a SecurityException
is thrown if a security manager is installed and the caller does not have a PrivateCredentialPermission
to access a particular Credential. The Iterator
is nevertheless advanced to the next element in the Set
.
- Returns:
- a
Set
of private credentials held by thisSubject
.
getPublicCredentials
public <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
.
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
.
- 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
public <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
.
If a security manager is installed, the caller must have a PrivateCredentialPermission
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
.
- 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
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.
- 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
public String toString()
Return the String representation of this Subject
.
hashCode
public int hashCode()
Returns a hashcode for this Subject
.
- 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)