程序包 java.io

类 FilePermission

java.lang.Object

java.security.Permission

java.io.FilePermission

所有已实现的接口:

Serializable, Guard

public final class FilePermission
extends Permission
implements Serializable

This class represents access to a file or directory. A FilePermission consists of a pathname and a set of actions valid for that pathname.

Pathname is the pathname of the file or directory granted the specified actions. A pathname that ends in "/*" (where "/" is the file separator character, File.separatorChar) indicates all the files and directories contained in that directory. A pathname that ends with "/-" indicates (recursively) all files and subdirectories contained in that directory. Such a pathname is called a wildcard pathname. Otherwise, it's a simple pathname.

A pathname consisting of the special token "<<ALL FILES>>" matches any file.

Note: A pathname consisting of a single "*" indicates all the files in the current directory, while a pathname consisting of a single "-" indicates all the files in the current directory and (recursively) all files and subdirectories contained in the current directory.

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

read

read permission

write

write permission

execute

execute permission. Allows Runtime.exec to be called. Corresponds to SecurityManager.checkExec.

delete

delete permission. Allows File.delete to be called. Corresponds to SecurityManager.checkDelete.

readlink

read link permission. Allows the target of a symbolic link to be read by invoking the readSymbolicLink method.

The actions string is converted to lowercase before processing.

Be careful when granting FilePermissions. Think about the implications of granting read and especially write access to various files and directories. The "<<ALL FILES>>" permission with write action is especially dangerous. This grants permission to write to the entire file system. One thing this effectively allows is replacement of the system binary, including the JVM runtime environment.

Please note: Code can always read a file from the same directory it's in (or a subdirectory of that directory); it does not need explicit permission to do so.

从以下版本开始:

1.2

另请参阅:

Permission, Permissions, PermissionCollection

构造器概要

构造器

构造器	说明
FilePermission(String path, String actions)	Creates a new FilePermission object with the specified actions.

方法概要

限定符和类型	方法	说明
String	getActions()	Returns the "canonical string representation" of the actions.
boolean	implies(Permission p)	Checks if this FilePermission object "implies" the specified permission.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

从类继承的方法 java.security.Permission

checkGuard, getName, newPermissionCollection

构造器详细资料

FilePermission

public FilePermission(String path,
                      String actions)

Creates a new FilePermission object with the specified actions. path is the pathname of a file or directory, and actions contains a comma-separated list of the desired actions granted on the file or directory. Possible actions are "read", "write", "execute", "delete", and "readlink".

A pathname that ends in "/*" (where "/" is the file separator character, File.separatorChar) indicates all the files and directories contained in that directory. A pathname that ends with "/-" indicates (recursively) all files and subdirectories contained in that directory. The special pathname "<<ALL FILES>>" matches any file.

A pathname consisting of a single "*" indicates all the files in the current directory, while a pathname consisting of a single "-" indicates all the files in the current directory and (recursively) all files and subdirectories contained in the current directory.

A pathname containing an empty string represents an empty path.

参数:

path - the pathname of the file/directory.

actions - the action string.

抛出:

IllegalArgumentException - If actions is null, empty or contains an action other than the specified possible actions.

方法详细资料

implies

public boolean implies(Permission p)

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

More specifically, this method returns true if:

• p is an instanceof FilePermission,
• p's actions are a proper subset of this object's actions, and
• p's pathname is implied by this object's pathname. For example, "/tmp/*" implies "/tmp/foo", since "/tmp/*" encompasses all files in the "/tmp" directory, including the one named "foo".

Precisely, a simple pathname implies another simple pathname if and only if they are equal. A simple pathname never implies a wildcard pathname. A wildcard pathname implies another wildcard pathname if and only if all simple pathnames implied by the latter are implied by the former. A wildcard pathname implies a simple pathname if and only if

• if the wildcard flag is "*", the simple pathname's path must be right inside the wildcard pathname's path.
• if the wildcard flag is "-", the simple pathname's path must be recursively inside the wildcard pathname's path.

"<<ALL FILES>>" implies every other pathname. No pathname, except for "<<ALL FILES>>" itself, implies "<<ALL FILES>>".

指定者:

implies 在类中 Permission

参数:

p - the permission to check against.

返回:

true if the specified permission is not null and is implied by this object, false otherwise.

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, execute, delete, readlink. For example, if this FilePermission object allows both write and read actions, a call to getActions will return the string "read,write".

指定者:

getActions 在类中 Permission

返回:

the canonical string representation of the actions.