Java in a Nutshell, 5th Edition [Electronic resources] نسخه متنی

The Subject class is the
key abstraction of the JAAS API. It represents a person or other
entity, and consists of:

• a java.util.Set of Principal
  objects that specify the identity (or identities) of the
  Subject.

• a Set of objects that specify the public
  credentials, such as the public key certificates of the
  Subject.

• a Set of objects that specify the private
  credentials, such as the private keys and Kerberos tickets of the
  Subject.

Subject defines methods that allow you to retreive
each of these three sets, or to retreive a subset of each set that
contains only objects of a specified Class. Unless
the Subject is read-only, you can use the methods
of java.util.Set to modify each of the three sets.
Once setReadOnly( ) has been called, however, the
sets become immutable and their contents may not be modified.

Application code does not typically create Subject
objects itself. Instead, it obtains a Subject that
represents the authenticated user of the application by calling the
login( )
and getSubject(
) methods of a
javax.security.auth.login.LoginContext object.

Once an authenticated Subject has been obtained
from a LoginContext, an application can call the
doAs( ) method to run code using the permissions
granted to that Subject combined with the
permissions granted to the code itself. doAs( )
runs the code defined in the run( ) method of a
PrivilegedAction or
PrivilegedExceptionAction object.
doAsPrivileged( ) is a similar method but executes
the specified run( ) method using the
Subject's permissions only, unconstrained by
unprivileged code in the call stack.

Note that many of the methods of this class throw a
SecurityException if the caller has not been
granted the requisite AuthPermission.

Figure 19-4. javax.security.auth.Subject

public final class

Subject implements Serializable {
// Public Constructors
public

Subject ( );
public

Subject (boolean

readOnly , java.util.Set<? extends java.security.Principal>

principals , java.util.Set<?>

pubCredentials ,
java.util.Set<?>

privCredentials );
// Public Class Methods
public static Object

doAs (Subject

subject , java.security.PrivilegedExceptionAction

action ) throws java.security.PrivilegedActionException;
public static Object

doAs (Subject

subject , java.security.PrivilegedAction

action );
public static Object

doAsPrivileged (Subject

subject , java.security.
PrivilegedExceptionAction

action , java.security.AccessControlContext

acc )
throws java.security.PrivilegedActionException;
public static Object

doAsPrivileged (Subject

subject , java.security.PrivilegedAction

action , java.security.AccessControlContext

acc );
public static Subject

getSubject (java.security.AccessControlContext

acc );
// Public Instance Methods
public java.util.Set<java.security.Principal>

getPrincipals ( );
public <T extends java.security.Principal> java.util.Set<T>

getPrincipals (Class<T>

c );
public java.util.Set<Object>

getPrivateCredentials ( );
public <T> java.util.Set<T>

getPrivateCredentials (Class<T>

c );
public java.util.Set<Object>

getPublicCredentials ( );
public <T> java.util.Set<T>

getPublicCredentials (Class<T>

c );
public boolean

isReadOnly ( ); default:false
public void

setReadOnly ( );
// Public Methods Overriding Object
public boolean

equals (Object

o );
public int

hashCode ( );
public String

toString ( );
}

Passed To

java.security.AuthProvider.login( ),
javax.security.auth.Policy.getPermissions( ),
SubjectDomainCombiner.SubjectDomainCombiner( ),
javax.security.auth.login.LoginContext.LoginContext(
), javax.security.auth.spi.LoginModule.initialize(
)

Returned By

SubjectDomainCombiner.getSubject( ),
javax.security.auth.login.LoginContext.getSubject(
)