JDK8/Java8源码在线阅读
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* accompanied this code).
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package java.security;
import java.util.Enumeration;
import java.util.Map;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Collections;
import java.io.ObjectStreamField;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
/**
* The BasicPermission class extends the Permission class, and
* can be used as the base class for permissions that want to
* follow the same naming convention as BasicPermission.
* <P>
* The name for a BasicPermission is the name of the given permission
* (for example, "exit",
* "setFactory", "print.queueJob", etc). The naming
* convention follows the hierarchical property naming convention.
* An asterisk may appear by itself, or if immediately preceded by a "."
* may appear at the end of the name, to signify a wildcard match.
* For example, "*" and "java.*" signify a wildcard match, while "*java", "a*b",
* and "java*" do not.
* <P>
* The action string (inherited from Permission) is unused.
* Thus, BasicPermission is commonly used as the base class for
* "named" permissions
* (ones that contain a name but no actions list; you either have the
* named permission or you don't.)
* Subclasses may implement actions on top of BasicPermission,
* if desired.
* <p>
* @see java.security.Permission
* @see java.security.Permissions
* @see java.security.PermissionCollection
* @see java.lang.SecurityManager
*
* @author Marianne Mueller
* @author Roland Schemers
*/
public abstract class BasicPermission extends Permission
implements java.io.Serializable
{
private static final long serialVersionUID = 6279438298436773498L;
// does this permission have a wildcard at the end?
private transient boolean wildcard;
// the name without the wildcard on the end
private transient String path;
// is this permission the old-style exitVM permission (pre JDK 1.6)?
private transient boolean exitVM;
/**
* initialize a BasicPermission object. Common to all constructors.
*/
private void init(String name) {
if (name == null)
throw new NullPointerException("name can't be null");
int len = name.length();
if (len == 0) {
throw new IllegalArgumentException("name can't be empty");
}
char last = name.charAt(len - 1);
// Is wildcard or ends with ".*"?
if (last == '*' && (len == 1 || name.charAt(len - 2) == '.')) {
wildcard = true;
if (len == 1) {
path = "";
} else {
path = name.substring(0, len - 1);
}
} else {
if (name.equals("exitVM")) {
wildcard = true;
path = "exitVM.";
exitVM = true;
} else {
path = name;
}
}
}
/**
* Creates a new BasicPermission with the specified name.
* Name is the symbolic name of the permission, such as
* "setFactory",
* "print.queueJob", or "topLevelWindow", etc.
*
* @param name the name of the BasicPermission.
*
* @throws NullPointerException if {@code name} is {@code null}.
* @throws IllegalArgumentException if {@code name} is empty.
*/
public BasicPermission(String name) {
super(name);
init(name);
}
/**
* Creates a new BasicPermission object with the specified name.
* The name is the symbolic name of the BasicPermission, and the
* actions String is currently unused.
*
* @param name the name of the BasicPermission.
* @param actions ignored.
*
* @throws NullPointerException if {@code name} is {@code null}.
* @throws IllegalArgumentException if {@code name} is empty.
*/
public BasicPermission(String name, String actions) {
super(name);
init(name);
}
/**
* Checks if the specified permission is "implied" by
* this object.
* <P>
* More specifically, this method returns true if:
* <ul>
* <li> <i>p</i>'s class is the same as this object's class, and
* <li> <i>p</i>'s name equals or (in the case of wildcards)
* is implied by this object's
* name. For example, "a.b.*" implies "a.b.c".
* </ul>
*
* @param p the permission to check against.
*
* @return true if the passed permission is equal to or
* implied by this permission, false otherwise.
*/
public boolean implies(Permission p) {
if ((p == null) || (p.getClass() != getClass()))
return false;
BasicPermission that = (BasicPermission) p;
if (this.wildcard) {
if (that.wildcard) {
// one wildcard can imply another
return that.path.startsWith(path);
} else {
// make sure ap.path is longer so a.b.* doesn't imply a.b
return (that.path.length() > this.path.length()) &&
that.path.startsWith(this.path);
}
} else {
if (that.wildcard) {
// a non-wildcard can't imply a wildcard
return false;
}
else {
return this.path.equals(that.path);
}
}
}
/**
* Checks two BasicPermission objects for equality.
* Checks that <i>obj</i>'s class is the same as this object's class
* and has the same name as this object.
* <P>
* @param obj the object we are testing for equality with this object.
* @return true if <i>obj</i>'s class is the same as this object's class
* and has the same name as this BasicPermission object, false otherwise.
*/
public boolean equals(Object obj) {
if (obj == this)
return true;
if ((obj == null) || (obj.getClass() != getClass()))
return false;
BasicPermission bp = (BasicPermission) obj;
return getName().equals(bp.getName());
}
/**
* Returns the hash code value for this object.
* The hash code used is the hash code of the name, that is,
* {@code getName().hashCode()}, where {@code getName} is
* from the Permission superclass.
*
* @return a hash code value for this object.
*/
public int hashCode() {
return this.getName().hashCode();
}
/**
* Returns the canonical string representation of the actions,
* which currently is the empty string "", since there are no actions for
* a BasicPermission.
*
* @return the empty string "".
*/
public String getActions() {
return "";
}
/**
* Returns a new PermissionCollection object for storing BasicPermission
* objects.
*
* <p>BasicPermission objects must be stored in a manner that allows them
* to be inserted in any order, but that also enables the
* PermissionCollection {@code implies} method
* to be implemented in an efficient (and consistent) manner.
*
* @return a new PermissionCollection object suitable for
* storing BasicPermissions.
*/
public PermissionCollection newPermissionCollection() {
return new BasicPermissionCollection(this.getClass());
}
/**
* readObject is called to restore the state of the BasicPermission from
* a stream.
*/
private void readObject(ObjectInputStream s)
throws IOException, ClassNotFoundException
{
s.defaultReadObject();
// init is called to initialize the rest of the values.
init(getName());
}
/**
* Returns the canonical name of this BasicPermission.
* All internal invocations of getName should invoke this method, so
* that the pre-JDK 1.6 "exitVM" and current "exitVM.*" permission are
* equivalent in equals/hashCode methods.
*
* @return the canonical name of this BasicPermission.
*/
final String getCanonicalName() {
return exitVM ? "exitVM.*" : getName();
}
}
/**
* A BasicPermissionCollection stores a collection
* of BasicPermission permissions. BasicPermission objects
* must be stored in a manner that allows them to be inserted in any
* order, but enable the implies function to evaluate the implies
* method in an efficient (and consistent) manner.
*
* A BasicPermissionCollection handles comparing a permission like "a.b.c.d.e"
* with a Permission such as "a.b.*", or "*".
*
* @see java.security.Permission
* @see java.security.Permissions
*
*
* @author Roland Schemers
*
* @serial include
*/
final class BasicPermissionCollection
extends PermissionCollection
implements java.io.Serializable
{
private static final long serialVersionUID = 739301742472979399L;
/**
* Key is name, value is permission. All permission objects in
* collection must be of the same type.
* Not serialized; see serialization section at end of class.
*/
private transient Map<String, Permission> perms;
/**
* This is set to {@code true} if this BasicPermissionCollection
* contains a BasicPermission with '*' as its permission name.
*
* @see #serialPersistentFields
*/
private boolean all_allowed;
/**
* The class to which all BasicPermissions in this
* BasicPermissionCollection belongs.
*
* @see #serialPersistentFields
*/
private Class<?> permClass;
/**
* Create an empty BasicPermissionCollection object.
*
*/
public BasicPermissionCollection(Class<?> clazz) {
perms = new HashMap<String, Permission>(11);
all_allowed = false;
permClass = clazz;
}
/**
* Adds a permission to the BasicPermissions. The key for the hash is
* permission.path.
*
* @param permission the Permission object to add.
*
* @exception IllegalArgumentException - if the permission is not a
* BasicPermission, or if
* the permission is not of the
* same Class as the other
* permissions in this collection.
*
* @exception SecurityException - if this BasicPermissionCollection object
* has been marked readonly
*/
public void add(Permission permission) {
if (! (permission instanceof BasicPermission))
throw new IllegalArgumentException("invalid permission: "+
permission);
if (isReadOnly())
throw new SecurityException("attempt to add a Permission to a readonly PermissionCollection");
BasicPermission bp = (BasicPermission) permission;
// make sure we only add new BasicPermissions of the same class
// Also check null for compatibility with deserialized form from
// previous versions.
if (permClass == null) {
// adding first permission
permClass = bp.getClass();
} else {
if (bp.getClass() != permClass)
throw new IllegalArgumentException("invalid permission: " +
permission);
}
synchronized (this) {
perms.put(bp.getCanonicalName(), permission);
}
// No sync on all_allowed; staleness OK
if (!all_allowed) {
if (bp.getCanonicalName().equals("*"))
all_allowed = true;
}
}
/**
* Check and see if this set of permissions implies the permissions
* expressed in "permission".
*
* @param permission the Permission object to compare
*
* @return true if "permission" is a proper subset of a permission in
* the set, false if not.
*/
public boolean implies(Permission permission) {
if (! (permission instanceof BasicPermission))
return false;
BasicPermission bp = (BasicPermission) permission;
// random subclasses of BasicPermission do not imply each other
if (bp.getClass() != permClass)
return false;
// short circuit if the "*" Permission was added
if (all_allowed)
return true;
// strategy:
// Check for full match first. Then work our way up the
// path looking for matches on a.b..*
String path = bp.getCanonicalName();
//System.out.println("check "+path);
Permission x;
synchronized (this) {
x = perms.get(path);
}
if (x != null) {
// we have a direct hit!
return x.implies(permission);
}
// work our way up the tree...
int last, offset;
offset = path.length()-1;
while ((last = path.lastIndexOf(".", offset)) != -1) {
path = path.substring(0, last+1) + "*";
//System.out.println("check "+path);
synchronized (this) {
x = perms.get(path);
}
if (x != null) {
return x.implies(permission);
}
offset = last -1;
}
// we don't have to check for "*" as it was already checked
// at the top (all_allowed), so we just return false
return false;
}
/**
* Returns an enumeration of all the BasicPermission objects in the
* container.
*
* @return an enumeration of all the BasicPermission objects.
*/
public Enumeration<Permission> elements() {
// Convert Iterator of Map values into an Enumeration
synchronized (this) {
return Collections.enumeration(perms.values());
}
}
// Need to maintain serialization interoperability with earlier releases,
// which had the serializable field:
//
// @serial the Hashtable is indexed by the BasicPermission name
//
// private Hashtable permissions;
/**
* @serialField permissions java.util.Hashtable
* The BasicPermissions in this BasicPermissionCollection.
* All BasicPermissions in the collection must belong to the same class.
* The Hashtable is indexed by the BasicPermission name; the value
* of the Hashtable entry is the permission.
* @serialField all_allowed boolean
* This is set to {@code true} if this BasicPermissionCollection
* contains a BasicPermission with '*' as its permission name.
* @serialField permClass java.lang.Class
* The class to which all BasicPermissions in this
* BasicPermissionCollection belongs.
*/
private static final ObjectStreamField[] serialPersistentFields = {
new ObjectStreamField("permissions", Hashtable.class),
new ObjectStreamField("all_allowed", Boolean.TYPE),
new ObjectStreamField("permClass", Class.class),
};
/**
* @serialData Default fields.
*/
/*
* Writes the contents of the perms field out as a Hashtable for
* serialization compatibility with earlier releases. all_allowed
* and permClass unchanged.
*/
private void writeObject(ObjectOutputStream out) throws IOException {
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