File	Doc	Category	Size	Date	Package
Permissions.java	API Doc	Java SE 5 API	18022	Fri Aug 26 14:57:14 BST 2005	java.security

Permissions

• java.lang.Object
  • java.security.PermissionCollection

Fields Summary
private transient Map	permsMap Key is permissions Class, value is PermissionCollection for that class. Not serialized; see serialization section at end of class.
private transient boolean	hasUnresolved
private PermissionCollection	allPermission
private static final long	serialVersionUID
private static final ObjectStreamField[]	serialPersistentFields

Constructors Summary
public Permissions() Creates a new Permissions object containing no PermissionCollections. permsMap = new HashMap(11); allPermission = null;

Methods Summary
public void	add(java.security.Permission permission) Adds a permission object to the PermissionCollection for the class the permission belongs to. For example, if permission is a FilePermission, it is added to the FilePermissionCollection stored in this Permissions object. This method creates a new PermissionCollection object (and adds the permission to it) if an appropriate collection does not yet exist. param permission the Permission object to add. exception SecurityException if this Permissions object is marked as readonly. see PermissionCollection#isReadOnly() if (isReadOnly()) throw new SecurityException( "attempt to add a Permission to a readonly Permissions object"); PermissionCollection pc; synchronized (this) { pc = getPermissionCollection(permission, true); pc.add(permission); } // No sync; staleness -> optimizations delayed, which is OK if (permission instanceof AllPermission) { allPermission = pc; } if (permission instanceof UnresolvedPermission) { hasUnresolved = true; }
public java.util.Enumeration	elements() Returns an enumeration of all the Permission objects in all the PermissionCollections in this Permissions object. return an enumeration of all the Permissions. // go through each Permissions in the hash table // and call their elements() function. synchronized (this) { return new PermissionsEnumerator(permsMap.values().iterator()); }
private java.security.PermissionCollection	getPermissionCollection(java.security.Permission p, boolean createEmpty) Gets the PermissionCollection in this Permissions object for permissions whose type is the same as that of p. For example, if p is a FilePermission, the FilePermissionCollection stored in this Permissions object will be returned. If createEmpty is true, this method creates a new PermissionCollection object for the specified type of permission objects if one does not yet exist. To do so, it first calls the newPermissionCollection method on p. Subclasses of class Permission override that method if they need to store their permissions in a particular PermissionCollection object in order to provide the correct semantics when the PermissionCollection.implies method is called. If the call returns a PermissionCollection, that collection is stored in this Permissions object. If the call returns null and createEmpty is true, then this method instantiates and stores a default PermissionCollection that uses a hashtable to store its permission objects. createEmpty is ignored when creating empty PermissionCollection for unresolved permissions because of the overhead of determining the PermissionCollection to use. createEmpty should be set to false when this method is invoked from implies() because it incurs the additional overhead of creating and adding an empty PermissionCollection that will just return false. It should be set to true when invoked from add(). Class c = p.getClass(); PermissionCollection pc = (PermissionCollection) permsMap.get(c); if (!hasUnresolved && !createEmpty) { return pc; } else if (pc == null) { // Check for unresolved permissions pc = (hasUnresolved ? getUnresolvedPermissions(p) : null); // if still null, create a new collection if (pc == null && createEmpty) { pc = p.newPermissionCollection(); // still no PermissionCollection? // We'll give them a PermissionsHash. if (pc == null) pc = new PermissionsHash(); } if (pc != null) { permsMap.put(c, pc); } } return pc;
private java.security.PermissionCollection	getUnresolvedPermissions(java.security.Permission p) Resolves any unresolved permissions of type p. param p the type of unresolved permission to resolve return PermissionCollection containing the unresolved permissions, or null if there were no unresolved permissions of type p. // Called from within synchronized method so permsMap doesn't need lock UnresolvedPermissionCollection uc = (UnresolvedPermissionCollection) permsMap.get(UnresolvedPermission.class); // we have no unresolved permissions if uc is null if (uc == null) return null; List unresolvedPerms = uc.getUnresolvedPermissions(p); // we have no unresolved permissions of this type if unresolvedPerms is null if (unresolvedPerms == null) return null; java.security.cert.Certificate certs[] = null; Object signers[] = p.getClass().getSigners(); int n = 0; if (signers != null) { for (int j=0; j < signers.length; j++) { if (signers[j] instanceof java.security.cert.Certificate) { n++; } } certs = new java.security.cert.Certificate[n]; n = 0; for (int j=0; j < signers.length; j++) { if (signers[j] instanceof java.security.cert.Certificate) { certs[n++] = (java.security.cert.Certificate)signers[j]; } } } PermissionCollection pc = null; synchronized (unresolvedPerms) { int len = unresolvedPerms.size(); for (int i = 0; i < len; i++) { UnresolvedPermission up = (UnresolvedPermission)unresolvedPerms.get(i); Permission perm = up.resolve(p, certs); if (perm != null) { if (pc == null) { pc = p.newPermissionCollection(); if (pc == null) pc = new PermissionsHash(); } pc.add(perm); } } } return pc;
public boolean	implies(java.security.Permission permission) Checks to see if this object's PermissionCollection for permissions of the specified permission's type implies the permissions expressed in the permission object. Returns true if the combination of permissions in the appropriate PermissionCollection (e.g., a FilePermissionCollection for a FilePermission) together imply the specified permission. For example, suppose there is a FilePermissionCollection in this Permissions object, and it contains one FilePermission that specifies "read" access for all files in all subdirectories of the "/tmp" directory, and another FilePermission that specifies "write" access for all files in the "/tmp/scratch/foo" directory. Then if the implies method is called with a permission specifying both "read" and "write" access to files in the "/tmp/scratch/foo" directory, true is returned. Additionally, if this PermissionCollection contains the AllPermission, this method will always return true. param permission the Permission object to check. return true if "permission" is implied by the permissions in the PermissionCollection it belongs to, false if not. // No sync; staleness -> skip optimization, which is OK if (allPermission != null) { return true; // AllPermission has already been added } else { synchronized (this) { PermissionCollection pc = getPermissionCollection(permission, false); if (pc != null) { return pc.implies(permission); } else { // none found return false; } } }
private void	readObject(java.io.ObjectInputStream in) // Don't call defaultReadObject() // Read in serialized fields ObjectInputStream.GetField gfields = in.readFields(); // Get allPermission allPermission = (PermissionCollection) gfields.get("allPermission", null); // Get permissions Hashtable perms = (Hashtable)gfields.get("perms", null); permsMap = new HashMap(perms.size()*2); permsMap.putAll(perms); // Set hasUnresolved UnresolvedPermissionCollection uc = (UnresolvedPermissionCollection) permsMap.get(UnresolvedPermission.class); hasUnresolved = (uc != null && uc.elements().hasMoreElements());
private void	writeObject(java.io.ObjectOutputStream out) serialData Default fields. /* * Writes the contents of the permsMap field out as a Hashtable for * serialization compatibility with earlier releases. allPermission * unchanged. */ // Don't call out.defaultWriteObject() // Copy perms into a Hashtable Hashtable perms = new Hashtable(permsMap.size()*2); // no sync; estimate synchronized (this) { perms.putAll(permsMap); } // Write out serializable fields ObjectOutputStream.PutField pfields = out.putFields(); pfields.put("allPermission", allPermission); // no sync; staleness OK pfields.put("perms", perms); out.writeFields();