Added in API level 1

Summary: Ctors | Methods | Inherited Methods

Subject

public final class Subject
extends Object implements Serializable

java.lang.Object
↳	javax.security.auth.Subject

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:

Principal
DomainCombiner

Summary

Public constructors
`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.

Public methods
`static <T> T`	`doAs(Subject subject, PrivilegedExceptionAction<T> action)` Perform work as a particular `Subject`.
`static <T> T`	`doAs(Subject subject, PrivilegedAction<T> action)` Perform work as a particular `Subject`.
`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`	`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> 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 methods

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public constructors

Subject

Added in API level 1

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").

Subject

Added in API level 1

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.

Parameters
`readOnly`	`boolean`: true if the `Subject` is to be read-only, and false otherwise.
`principals`	`Set`: the `Set` of Principals to be associated with this `Subject`.
`pubCredentials`	`Set`: the `Set` of public credentials to be associated with this `Subject`.
`privCredentials`	`Set`: the `Set` of private credentials to be associated with this `Subject`.

Throws
`NullPointerException`	if the specified `principals`, `pubCredentials`, or `privCredentials` are `null`.

Public methods

doAs

Added in API level 1

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`	`Subject`: the `Subject` that the specified `action` will run as. This parameter may be `null`.
`action`	`PrivilegedExceptionAction`: the code to be run as the specified `Subject`.

Returns
`T`	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.

doAs

Added in API level 1

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`	`Subject`: the `Subject` that the specified `action` will run as. This parameter may be `null`.
`action`	`PrivilegedAction`: the code to be run as the specified `Subject`.

Returns
`T`	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.

doAsPrivileged

Added in API level 1

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`	`Subject`: the `Subject` that the specified `action` will run as. This parameter may be `null`.
`action`	`PrivilegedExceptionAction`: the code to be run as the specified `Subject`.
`acc`	`AccessControlContext`: the `AccessControlContext` to be tied to the specified subject and action.

Returns
`T`	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.

doAsPrivileged

Added in API level 1

public static T doAsPrivileged (Subject subject, 
                PrivilegedAction<T> action, 
                AccessControlContext acc)

Perform privileged work as a particular Subject.

Parameters
`subject`	`Subject`: the `Subject` that the specified `action` will run as. This parameter may be `null`.
`action`	`PrivilegedAction`: the code to be run as the specified `Subject`.
`acc`	`AccessControlContext`: the `AccessControlContext` to be tied to the specified subject and action.

Returns
`T`	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.

equals

Added in API level 1

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`: Object to be compared for equality with this `Subject`.

Returns
`boolean`	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`.

getPrincipals

Added in API level 1

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
`Set<Principal>`	The `Set` of Principals associated with this `Subject`.

getPrincipals

Added in API level 1

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`	`Class`: the returned `Set` of Principals will all be instances of this class.

Returns
`Set<T>`	a `Set` of Principals that are instances of the specified `Class`.

Throws
`NullPointerException`	if the specified `Class` is `null`.

getPrivateCredentials

Added in API level 1

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`	`Class`: the returned `Set` of private credentials will all be instances of this class.

Returns
`Set<T>`	a `Set` of private credentials that are instances of the specified `Class`.

Throws
`NullPointerException`	if the specified `Class` is `null`.

getPrivateCredentials

Added in API level 1

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
`Set<Object>`	A `Set` of private credentials held by this `Subject`.

getPublicCredentials

Added in API level 1

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
`Set<Object>`	A `Set` of public credentials held by this `Subject`.

getPublicCredentials

Added in API level 1

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`	`Class`: the returned `Set` of public credentials will all be instances of this class.

Returns
`Set<T>`	a `Set` of public credentials that are instances of the specified `Class`.

Throws
`NullPointerException`	if the specified `Class` is `null`.

getSubject

Added in API level 1

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`	`AccessControlContext`: the `AccessControlContext` from which to retrieve the `Subject`.

Returns
`Subject`	the `Subject` associated with the provided `AccessControlContext`, or `null` if no `Subject` is associated with the provided `AccessControlContext`.

Throws
`SecurityException`	if the caller does not have permission to get the `Subject`.
`NullPointerException`	if the provided `AccessControlContext` is `null`.

hashCode

Added in API level 1

public int hashCode ()

Returns a hashcode for this Subject.

Returns
`int`	a hashcode for this `Subject`.

Throws
`SecurityException`	if the caller does not have permission to access this Subject's private credentials.

isReadOnly

Added in API level 1

public boolean isReadOnly ()

Query whether this Subject is read-only.

Returns
`boolean`	true if this `Subject` is read-only, false otherwise.

setReadOnly

Added in API level 1

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.

toString

Added in API level 1

public String toString ()

Return the String representation of this Subject.

Returns
`String`	the String representation of this `Subject`.