PropertyPermission (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

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Java™ Platform
Standard Ed. 6

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java.util
Class PropertyPermission

java.lang.Object
  java.security.Permission
      java.security.BasicPermission
          java.util.PropertyPermission

All Implemented Interfaces:: Serializable, Guard

public final class PropertyPermission
extends BasicPermission
extends BasicPermission

This class is for property permissions.

The name is the name of the property ("java.home", "os.name", etc). The naming convention follows the hierarchical property naming convention. Also, an asterisk may appear at the end of the name, following a ".", or by itself, to signify a wildcard match. For example: "java.*" or "*" is valid, "*java" or "a*b" is not valid.

The actions to be granted are passed to the constructor in a string containing a list of zero or more comma-separated keywords. The possible keywords are "read" and "write". Their meaning is defined as follows:

read: read permission. Allows System.getProperty to be called.
write: write permission. Allows System.setProperty to be called.

The actions string is converted to lowercase before processing.

Care should be taken before granting code permission to access certain system properties. For example, granting permission to access the "java.home" system property gives potentially malevolent code sensitive information about the system environment (the Java installation directory). Also, granting permission to access the "user.name" and "user.home" system properties gives potentially malevolent code sensitive information about the user environment (the user's account name and home directory).

Since:: 1.2
See Also:: BasicPermission, Permission, Permissions, PermissionCollection, SecurityManager

Constructor Summary

PropertyPermission(String name, String actions)
          Creates a new PropertyPermission object with the specified name.

Method Summary

boolean equals(Object obj)
          Checks two PropertyPermission objects for equality.

String getActions()
          Returns the "canonical string representation" of the actions.

int hashCode()
          Returns the hash code value for this object.

boolean implies(Permission p)
          Checks if this PropertyPermission object "implies" the specified permission.

PermissionCollection newPermissionCollection()
          Returns a new PermissionCollection object for storing PropertyPermission objects.

Methods inherited from class java.security.Permission

checkGuard, getName, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Summary
`PropertyPermission(String name, String actions)` Creates a new PropertyPermission object with the specified name.

Method Summary
`boolean`	`equals(Object obj)` Checks two PropertyPermission objects for equality.
`String`	`getActions()` Returns the "canonical string representation" of the actions.
`int`	`hashCode()` Returns the hash code value for this object.
`boolean`	`implies(Permission p)` Checks if this PropertyPermission object "implies" the specified permission.
`PermissionCollection`	`newPermissionCollection()` Returns a new PermissionCollection object for storing PropertyPermission objects.

Methods inherited from class java.security.Permission
`checkGuard, getName, toString`

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

Constructor Detail

PropertyPermission

public PropertyPermission(String name,
                          String actions)

Creates a new PropertyPermission object with the specified name. The name is the name of the system property, and actions contains a comma-separated list of the desired actions granted on the property. Possible actions are "read" and "write".

Parameters:: name - the name of the PropertyPermission.; actions - the actions string.
Throws:: NullPointerException - if name is null.; IllegalArgumentException - if name is empty or if actions is invalid.

Method Detail

implies

public boolean implies(Permission p)

Checks if this PropertyPermission object "implies" the specified permission.

More specifically, this method returns true if:

p is an instanceof PropertyPermission,
p's actions are a subset of this object's actions, and
p's name is implied by this object's name. For example, "java.*" implies "java.home".

Overrides:: implies in class BasicPermission

Parameters:: p - the permission to check against.
Returns:: true if the specified permission is implied by this object, false if not.

equals

public boolean equals(Object obj)

Checks two PropertyPermission objects for equality. Checks that obj is a PropertyPermission, and has the same name and actions as this object.

Overrides:: equals in class BasicPermission

Parameters:: obj - the object we are testing for equality with this object.
Returns:: true if obj is a PropertyPermission, and has the same name and actions as this PropertyPermission object.
See Also:: Object.hashCode(), Hashtable

hashCode

public int hashCode()

Returns the hash code value for this object. The hash code used is the hash code of this permissions name, that is, getName().hashCode(), where getName is from the Permission superclass.

Overrides:: hashCode in class BasicPermission

Returns:: a hash code value for this object.
See Also:: Object.equals(java.lang.Object), Hashtable

getActions

public String getActions()

Returns the "canonical string representation" of the actions. That is, this method always returns present actions in the following order: read, write. For example, if this PropertyPermission object allows both write and read actions, a call to getActions will return the string "read,write".

Overrides:: getActions in class BasicPermission

Returns:: the canonical string representation of the actions.

newPermissionCollection

public PermissionCollection newPermissionCollection()

Returns a new PermissionCollection object for storing PropertyPermission objects.

Overrides:: newPermissionCollection in class BasicPermission

Returns:: a new PermissionCollection object suitable for storing PropertyPermissions.