API java : Policy

java.security
Class Policy

java.lang.Object
  java.security.Policy

public abstract class Policy
extends Object

This is an abstract class for representing the system security policy for a Java application environment (specifying which permissions are available for code from various sources). That is, the security policy is represented by a Policy subclass providing an implementation of the abstract methods in this Policy class.

There is only one Policy object in effect at any given time.

The source location for the policy information utilized by the Policy object is up to the Policy implementation. The policy configuration may be stored, for example, as a flat ASCII file, as a serialized binary file of the Policy class, or as a database.

The currently-installed Policy object can be obtained by calling the getPolicy method, and it can be changed by a call to the setPolicy method (by code with permission to reset the Policy).

The refresh method causes the policy object to refresh/reload its current configuration.

This is implementation-dependent. For example, if the policy object stores its policy in configuration files, calling refresh will cause it to re-read the configuration policy files. The refreshed policy may not have an effect on classes in a particular ProtectionDomain. This is dependent on the Policy provider's implementation of the implies method and the PermissionCollection caching strategy.

The default Policy implementation can be changed by setting the value of the "policy.provider" security property (in the Java security properties file) to the fully qualified name of the desired Policy implementation class. The Java security properties file is located in the file named <JAVA_HOME>/lib/security/java.security, where <JAVA_HOME> refers to the directory where the JDK was installed.

See Also:

CodeSource, PermissionCollection, SecureClassLoader

Constructor Summary
Policy()

 

Method Summary
abstract  PermissionCollection	getPermissions(CodeSource codesource)           Evaluates the global policy and returns a PermissionCollection object specifying the set of permissions allowed for code from the specified code source.
PermissionCollection	getPermissions(ProtectionDomain domain)           Evaluates the global policy and returns a PermissionCollection object specifying the set of permissions allowed given the characteristics of the protection domain.
static Policy	getPolicy()           Returns the installed Policy object.
boolean	implies(ProtectionDomain domain, Permission permission)           Evaluates the global policy for the permissions granted to the ProtectionDomain and tests whether the permission is granted.
abstract  void	refresh()           Refreshes/reloads the policy configuration.
static void	setPolicy(Policy p)           Sets the system-wide Policy object.

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Constructor Detail

Policy

public Policy()

getPolicy

public static Policy getPolicy()

Returns the installed Policy object. This value should not be cached, as it may be changed by a call to setPolicy. This method first calls SecurityManager.checkPermission with a SecurityPermission("getPolicy") permission to ensure it's ok to get the Policy object..

Returns:

the installed Policy.

Throws:

SecurityException - if a security manager exists and its checkPermission method doesn't allow getting the Policy object.

See Also:

SecurityManager.checkPermission(Permission), setPolicy(java.security.Policy)

setPolicy

public static void setPolicy(Policy p)

Sets the system-wide Policy object. This method first calls SecurityManager.checkPermission with a SecurityPermission("setPolicy") permission to ensure it's ok to set the Policy.

Parameters:

p - the new system Policy object.

Throws:

SecurityException - if a security manager exists and its checkPermission method doesn't allow setting the Policy.

See Also:

SecurityManager.checkPermission(Permission), getPolicy()

getPermissions

public abstract PermissionCollection getPermissions(CodeSource codesource)

Evaluates the global policy and returns a PermissionCollection object specifying the set of permissions allowed for code from the specified code source.

Parameters:

codesource - the CodeSource associated with the caller. This encapsulates the original location of the code (where the code came from) and the public key(s) of its signer.

Returns:

the set of permissions allowed for code from codesource according to the policy.The returned set of permissions must be a new mutable instance and it must support heterogeneous Permission types.

getPermissions

public PermissionCollection getPermissions(ProtectionDomain domain)

Evaluates the global policy and returns a PermissionCollection object specifying the set of permissions allowed given the characteristics of the protection domain.

Parameters:

domain - the ProtectionDomain associated with the caller.

Returns:

the set of permissions allowed for the domain according to the policy.The returned set of permissions must be a new mutable instance and it must support heterogeneous Permission types.

Since:

1.4

See Also:

ProtectionDomain, SecureClassLoader

implies

public boolean implies(ProtectionDomain domain,
                       Permission permission)

Evaluates the global policy for the permissions granted to the ProtectionDomain and tests whether the permission is granted.

Parameters:

domain - the ProtectionDomain to test

permission - the Permission object to be tested for implication.

Returns:

true if "permission" is a proper subset of a permission granted to this ProtectionDomain.

Since:

1.4

See Also:

ProtectionDomain

refresh

public abstract void refresh()

Refreshes/reloads the policy configuration. The behavior of this method depends on the implementation. For example, calling refresh on a file-based policy will cause the file to be re-read.