java.lang.SecurityManager
public abstract classA running Java program may have a security manager, which is an instance of classSecurityManager
{ protected booleaninCheck
; protectedSecurityManager
()
throws SecurityException; protected Class[]getClassContext
(); protected intclassDepth
(String name); protected booleaninClass
(String name); protected ClassLoadercurrentClassLoader
(); protected intclassLoaderDepth
(); protected booleaninClassLoader
(); public booleangetInCheck
(); public voidcheckCreateClassLoader
()
throws SecurityException; public voidcheckAccess
(Thread t)
throws SecurityException; public voidcheckAccess
(ThreadGroup g)
throws SecurityException; public voidcheckExit
(int status)
throws SecurityException; public voidcheckExec
(String cmd)
throws SecurityException; public voidcheckPropertiesAccess
()
throws SecurityException; public voidcheckPropertyAccess
(String key)
throws SecurityException; public voidcheckLink
(String libname)
throws SecurityException; public voidcheckRead
(int fd)
throws SecurityException; public voidcheckRead
(String file)
throws SecurityException; public voidcheckWrite
(int fd)
throws SecurityException; public voidcheckWrite
(String file)
throws SecurityException; public voidcheckDelete
(String file)
throws SecurityException; public voidcheckConnect
(String host, int port)
throws SecurityException; public voidcheckListen
(int port)
throws SecurityException; public voidcheckAccept
(String host, int port)
throws SecurityException; public voidcheckSetFactory
()
throws SecurityException; public booleancheckTopLevelWindow
()
throws SecurityException; public voidcheckPackageAccess
(String packageName)
throws SecurityException; public voidcheckPackageDefinition
(String packageName)
throws SecurityException; }
SecurityManager
. The current security manager is the one returned by the method invocation System.getSecurityManager()
(§20.18.4).
The SecurityManager
class contains a large number of methods whose names begin with "check
". They are called by various methods throughout the Java libraries before those methods perform certain sensitive operations. The invocation of such a check method typically looks like this:
SecurityManager security = System.getSecurityManager(); if (security != null) { security.checkXXX(arguments); }The security manager is thereby given an opportunity to prevent completion of the operation by throwing an exception. The usual convention is that a security manager checking routine simply returns if the operation is permitted, or throws a
SecurityException
if the operation is not permitted. In one case, namely checkTopLevelWindow
(§20.17.27), the checking routine must return a boolean
value to indicate one of two levels of permission.20.17.1 protected boolean
inCheck
= false;
By convention, this field should be assigned the value true
whenever a security
check is in progress. This matters when one of the checking routines needs to call
outside code to do its work. Outside code can then use the method getInCheck
(§20.17.9) to test the status of this flag.
20.17.2 protected
SecurityManager
()
throws SecurityException
This constructor checks to see whether a security manager has already been
installed (§20.18.5); if so, creation of another security manager is not permitted,
and so a SecurityException
is thrown.
20.17.3 protected Class[]
getClassContext
()
This utility method for security managers scans the execution stack for the current
thread and returns an array with one component for each stack frame. The component
at position 0
corresponds to the top of the stack. If a component is a Class
object, then the corresponding stack frame is for an invocation of a method of the
class represented by that Class
object.
20.17.4 protected int
classDepth
(String name)
This utility method for security managers searches the execution stack for the current
thread to find the most recently invoked method whose execution has not yet
completed and whose class has name
as its fully qualified name. If such a method
is found, its distance from the top of the stack is returned as a nonnegative integer;
otherwise, -1
is returned.
20.17.5 protected boolean
inClass
(String name)
This utility method for security managers searches the execution stack for the current
thread to find the most recently invoked method whose execution has not yet
completed and whose class has name
as its fully qualified name. If such a method
is found, true
is returned; otherwise, false
is returned.
20.17.6 protected ClassLoader
currentClassLoader
()
This utility method for security managers searches the execution stack for the current
thread to find the most recently invoked method whose execution has not yet
completed and whose class was created by a class loader (§20.14). If such a
method is found, a reference to the ClassLoader
object for its class is returned;
otherwise, null
is returned.
20.17.7 protected int
classLoaderDepth
()
This utility method for security managers searches the execution stack for the current
thread to find the most recently invoked method whose execution has not yet
completed and whose class was created by a class loader (§20.14). If such a
method is found, its distance from the top of the stack is returned as a nonnegative
integer; otherwise, -1
is returned.
20.17.8 protected boolean
inClassLoader
()
This utility method for security managers searches the execution stack for the current
thread to find the most recently invoked method whose execution has not yet
completed and whose class was created by a class loader (§20.14). If such a
method is found, true
is returned; otherwise false
is returned.
20.17.9 public boolean
getInCheck
()
The value of the inCheck
field (§20.17.1) is returned.
20.17.10 public void
checkCreateClassLoader
()
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if creation of a class loader is not permitted.
This method is invoked for the current security manager (§20.18.4) by the constructor for class ClassLoader
(§20.14.1).
The checkCreateClassLoader
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if a class loader creation operation is to be permitted with a security manager installed.
20.17.11 public void
checkAccess
(Thread t)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if an operation that would modify the thread t
is not permitted.
This method is invoked for the current security manager (§20.18.4) by method checkAccess
(§20.20.12) of class Thread
.
The checkAccess
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if a thread modification operation is to be permitted with a security manager installed.
20.17.12 public void
checkAccess
(ThreadGroup g)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if an operation that would modify the thread group g
is not permitted.
This method is invoked for the current security manager (§20.18.4) by method checkAccess
(§20.21.4) of class ThreadGroup
.
The checkAccess
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if a thread group modification operation is to be permitted with a security manager installed.
20.17.13 public void
checkExit
(int status)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if an exit operation that would terminate the running Java Virtual Machine is not
permitted.
This method is invoked for the current security manager (§20.18.4) by method exit
(§20.16.2) of class Runtime
.
The checkExit
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if the exit operation is to be permitted with a security manager installed.
20.17.14 public void
checkExec
(String cmd)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if a command exec
operation is not permitted. The argument cmd
is the name of
the command to be executed.
This method is invoked for the current security manager (§20.18.4) by method exec
(§20.16.6) of class Runtime
.
The checkExec
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if a command exec
operation is to be permitted with a security manager installed.
20.17.15 public void
checkPropertiesAccess
()
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if getting or setting the system properties data structure is not permitted.
This method is invoked for the current security manager (§20.18.4) by the methods getProperties
(§20.18.7) and setProperties
(§20.18.8) of class System
.
The checkPropertiesAccess
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if a properties access operation is to be permitted with a security manager installed.
20.17.16 public void
checkPropertyAccess
(String key)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if getting the value of the system property named by the key
is not permitted.
This method is invoked for the current security manager (§20.18.4) by the methods getProperty
of one argument (§20.18.9) and getProperty
of two arguments (§20.18.10) of class System
.
The checkPropertyAccess
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if accessing the value of a system property is to be permitted with a security manager installed.
20.17.17 public void
checkLink
(String libname)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if dynamic linking of the specified library code file is not permitted. The argument
may be a simple library name or a complete file name.
This method is invoked for the current security manager (§20.18.4) by methods load
(§20.16.13) and loadLibrary
(§20.16.14) of class Runtime
.
The checkLink
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if a dynamic code linking operation is to be permitted with a security manager installed.
20.17.18 public void
checkRead
(int fd)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if creating an input stream using the specified file descriptor is not permitted.
This method is invoked for the current security manager (§20.18.4) by one constructor for java.io.FileInputStream
(§22.4.3).
The checkRead
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if creating an input stream from an existing file descriptor is to be permitted with a security manager installed.
20.17.19 public void
checkRead
(String file)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if reading the specified file or directory, or examining associated file-system information,
or testing for its existence, is not permitted.
This method is invoked for the current security manager (§20.18.4) by two constructors for java.io.FileInputStream
(§22.4.1, §22.4.2); by two constructors for java.io.RandomAccessFile
(§22.23.1, §22.23.2); and by methods exists
(§22.24.16), canRead
(§22.24.17), isFile
(§22.24.19), isDirectory
(§22.24.20), lastModified
(§22.24.21), length
(§22.24.22), list
with no arguments (§22.24.25), and list
with one argument (§22.24.26) of the class java.io.File
.
The checkRead
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if read access to a file is to be permitted with a security manager installed.
20.17.20 public void
checkWrite
(int fd)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if creating an output stream using the specified file descriptor is not permitted.
This method is invoked for the current security manager (§20.18.4) by one constructor for java.io.FileOutputStream
(§22.16.3).
The checkWrite
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if creating an output stream from an existing file descriptor is to be permitted with a security manager installed.
20.17.21 public void
checkWrite
(String file)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if writing, modifying, creating (for output), or renaming the specified file or directory
is not permitted.
This method is invoked for the current security manager (§20.18.4) by two constructors for java.io.FileOutputStream
(§22.16.1, §22.16.2); by two constructors for java.io.RandomAccessFile
(§22.23.1, §22.23.2); and by methods canWrite
(§22.24.18), mkdir
(§22.24.23), and renameTo
(§22.24.27) of class java.io.File
.
The checkWrite
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if write access to a file is to be permitted with a security manager installed.
20.17.22 public void
checkDelete
(String file)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if deleting the specified file is not permitted.
This method is invoked for the current security manager (§20.18.4) by method delete
(§22.24.28) of class java.io.File
.
The checkDelete
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if a file deletion operation is to be permitted with a security manager installed.
20.17.23 public void
checkConnect
(String host, int port)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if connecting to the indicated port
of the indicated network host
is not permitted.
This method is invoked for the current security manager (§20.18.4) by two constructors for class java.net.Socket
, methods send
and receive
of class java.net.DatagramSocket
, and methods getByName
and getAllByName
of class java.net.InetAddress
. (These classes are not documented in this specification. See The Java Application Programming Interface.)
The checkConnect
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if a network connection is to be permitted with a security manager installed.
20.17.24 public void
checkListen
(int port)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if listening to the specified local network port
is not permitted.
This method is invoked for the current security manager (§20.18.4) by the constructor of one argument for class java.net.DatagramSocket
and by the constructors for class java.net.ServerSocket
. (These classes are not documented in this specification. See The Java Application Programming Interface.)
The checkListen
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if listening to a local network port is to be permitted with a security manager installed.
20.17.25 public void
checkAccept
(String host, int port)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if accepting a connection from the indicated port
of the indicated network host
is not permitted.
This method is invoked for the current security manager (§20.18.4) by method accept
of class java.net.ServerSocket
. (This class is not documented in this specification. See The Java Application Programming Interface.)
The checkAccept
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if accepting a network connection is to be permitted with a security manager installed.
20.17.26 public void
checkSetFactory
()
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if installing a "factory" for a socket, server socket, URL, or URL connection is not
permitted.
This method is invoked for the current security manager (§20.18.4) by:
method setSocketFactory of class java.net.ServerSocket method setSocketImplFactory of class java.net.Socket method setURLStreamHandlerFactory of class java.net.URL method setContentHandlerFactory of class java.net.URLConnection(These classes are not documented in this specification. See The Java Application Programming Interface.)
The checkSetFactory
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if a factory installation operation is to be permitted with a security manager installed.
20.17.27 public boolean
checkTopLevelWindow
()
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if creation of a top-level window is not permitted. If creation of a top-level window
is permitted, then this method should return false
if the window ought to
bear a clear warning that it is a window for an executable applet. A returned value
of true
means that the security manager places no restriction on window creation.
This method is invoked for the current security manager (§20.18.4) by the constructors for class java.awt.Window
. (This class is not documented in this specification. See The Java Application Programming Interface.)
The checkTopLevelWindow
method defined by class SecurityManager
always returns false
. A subclass must override this method if a window creation operation is to be unrestricted or forbidden with a security manager installed.
20.17.28 public void
checkPackageAccess
(String packageName)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if the current applet is not permitted to access the package named by the argument.
This method is intended for use by Java-capable web browsers.
The checkPackageAccess
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if package access by an applet is to be permitted with a security manager installed.
20.17.29 public void
checkPackageDefinition
(String packageName)
throws SecurityException
The general contract of this method is that it should throw a SecurityException
if the current applet is not permitted to define a class (or interface) in the package
named by the argument. This method is intended for use by Java-capable web
browsers.
The checkPackageAccess
method defined by class SecurityManager
always throws a SecurityException
. A subclass must override this method if class definition by an applet is to be permitted with a security manager installed.
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Java Language Specification (HTML generated by Suzette Pelouch on February 24, 1998)
Copyright © 1996 Sun Microsystems, Inc.
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