/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @author Alexey V. Varlamov
* @version $Revision$
*/
package java.security;
import java.io.Serializable;
/**
* {@code Permission} is the common base class of all permissions that
* participate in the access control security framework around
* {@link AccessController} and {@link AccessControlContext}. A permission
* constitutes of a name and associated actions.
*
* @since Android 1.0
*/
public abstract class Permission implements Guard, Serializable {
private static final long serialVersionUID = -5636570222231596674L;
private final String name;
/**
* Compares the specified object with this {@code Permission} for equality
* and returns {@code true} if the specified object is equal, {@code false}
* otherwise.
* <p>
* The {@link #implies(Permission)} method should be used for making access
* control checks.
* </p>
*
* @param obj
* object to be compared for equality with this {@code
* Permission}.
* @return {@code true} if the specified object is equal to this {@code
* Permission}, otherwise {@code false}.
* @since Android 1.0
*/
public abstract boolean equals(Object obj);
/**
* Returns the hash code value for this {@code Permission}. Returns the same
* hash code for {@code Permission}s that are equal to each other as
* required by the general contract of {@link Object#hashCode}.
*
* @return the hash code value for this {@code Permission}.
* @see Object#equals(Object)
* @see Permission#equals(Object)
* @since Android 1.0
*/
public abstract int hashCode();
/**
* Returns a comma separated string identifying the actions associated with
* this permission. The returned actions are in canonical form. For example:
*
* <pre>
* sp0 = new SocketPermission("www.google.com", "connect,resolve")
* sp1 = new SocketPermission("www.google.com", "resolve,connect")
* sp0.getActions().equals(sp1.getActions()) //yields true
* </pre>
*
* Both permissions return "connect,resolve" (in that order) if {@code
* #getActions()} is invoked. Returns an empty String, if no actions are
* associated with this permission.
*
* @return the actions associated with this permission or an empty string if
* no actions are associated with this permission.
* @since Android 1.0
*/
public abstract String getActions();
/**
* Indicates whether the specified permission is implied by this permission.
* The {@link AccessController} uses this method to check whether permission
* protected access is allowed with the present policy.
*
* @param permission
* the permission to check against this permission.
* @return {@code true} if the specified permission is implied by this
* permission, {@code false} otherwise.
* @since Android 1.0
*/
public abstract boolean implies(Permission permission);
/**
* Constructs a new instance of {@code Permission} with its name.
*
* @param name
* the name of the permission.
* @since Android 1.0
*/
public Permission(String name) {
this.name = name;
}
/**
* Returns the name of this permission.
*
* @return the name of this permission.
* @since Android 1.0
*/
public final String getName() {
return name;
}
/**
* Invokes {@link SecurityManager#checkPermission(Permission)} with this
* permission as its argument. This method implements the {@link Guard}
* interface.
*
* @param obj
* as specified in {@link Guard#checkGuard(Object)} but ignored
* in this implementation.
* @throws SecurityException
* if this permission is not granted.
* @see Guard
* @see SecurityManager#checkPermission(Permission)
* @since Android 1.0
*/
public void checkGuard(Object obj) throws SecurityException {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(this);
}
}
/**
* Returns a specific {@link PermissionCollection} container for permissions
* of this type. Returns {@code null} if any permission collection can be
* used.
* <p>
* Subclasses may override this method to return an appropriate collection
* for the specific permissions they implement.
* </p>
*
* @return an empty {@link PermissionCollection} or {@code null} if any
* permission collection can be used.
* @since Android 1.0
*/
public PermissionCollection newPermissionCollection() {
return null;
}
/**
* Returns a string containing a concise, human-readable description of the
* this {@code Permission} including its name and its actions.
*
* @return a printable representation for this {@code Permission}.
* @since Android 1.0
*/
public String toString() {
String actions = getActions();
actions = (actions == null || actions.length() == 0) ? "" : " " //$NON-NLS-1$ //$NON-NLS-2$
+ getActions();
return "(" + getClass().getName() + " " + getName() + actions + ")"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
}
}
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