Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class SecurityManager - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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java.lang
Class SecurityManager

java.lang.Object
  |
  +--java.lang.SecurityManager

Direct Known Subclasses:: RMISecurityManager

public class SecurityManager
extends Object

The security manager is a class that allows applications to implement a security policy. It allows an application to determine, before performing a possibly unsafe or sensitive operation, what the operation is and whether it is being attempted in a security context that allows the operation to be performed. The application can allow or disallow the operation.

The SecurityManager class contains many methods with names that begin with the word check. These methods are called by various methods in the Java libraries before those methods perform certain potentially sensitive operations. The invocation of such a check method typically looks like this:

     SecurityManager security = System.getSecurityManager();
     if (security != null) {
         security.checkXXX(argument,  . . . );
     }

The security manager is thereby given an opportunity to prevent completion of the operation by throwing an exception. A security manager routine simply returns if the operation is permitted, but throws a SecurityException if the operation is not permitted. The only exception to this convention is checkTopLevelWindow, which returns a boolean value.

The current security manager is set by the setSecurityManager method in class System. The current security manager is obtained by the getSecurityManager method.

The special method checkPermission(java.security.Permission) determines whether an access request indicated by a specified permission should be granted or denied. The default implementation calls

   AccessController.checkPermission(perm);

If a requested access is allowed, checkPermission returns quietly. If denied, a SecurityException is thrown.

As of JDK 1.2, the default implementation of each of the other check methods in SecurityManager is to call the SecurityManager checkPermission method to determine if the calling thread has permission to perform the requested operation.

Note that the checkPermission method with just a single permission argument always performs security checks within the context of the currently executing thread. Sometimes a security check that should be made within a given context will actually need to be done from within a different context (for example, from within a worker thread). The getSecurityContext method and the checkPermission method that includes a context argument are provided for this situation. The getSecurityContext method returns a "snapshot" of the current calling context. (The default implementation returns an AccessControlContext object.) A sample call is the following:

   Object context = null;
   SecurityManager sm = System.getSecurityManager();
   if (sm != null) context = sm.getSecurityContext();

The checkPermission method that takes a context object in addition to a permission makes access decisions based on that context, rather than on that of the current execution thread. Code within a different context can thus call that method, passing the permission and the previously-saved context object. A sample call, using the SecurityManager sm obtained as in the previous example, is the following:

   if (sm != null) sm.checkPermission(permission, context);

Permissions fall into these categories: File, Socket, Net, Security, Runtime, Property, AWT, Reflect, and Serializable. The classes managing these various permission categories are java.io.FilePermission, java.net.SocketPermission, java.net.NetPermission, java.security.SecurityPermission, java.lang.RuntimePermission, java.util.PropertyPermission, java.awt.AWTPermission, java.lang.reflect.ReflectPermission, and java.io.SerializablePermission.

All but the first two (FilePermission and SocketPermission) are subclasses of java.security.BasicPermission, which itself is an abstract subclass of the top-level class for permissions, which is java.security.Permission. BasicPermission defines the functionality needed for all permissions that contain a name that follows the hierarchical property naming convention (for example, "exitVM", "setFactory", "queuePrintJob", etc). An asterisk may appear at the end of the name, following a ".", or by itself, to signify a wildcard match. For example: "a.*" or "*" is valid, "*a" or "a*b" is not valid.

FilePermission and SocketPermission are subclasses of the top-level class for permissions (java.security.Permission). Classes like these that have a more complicated name syntax than that used by BasicPermission subclass directly from Permission rather than from BasicPermission. For example, for a java.io.FilePermission object, the permission name is the pathname of a file (or directory).

Some of the permission classes have an "actions" list that tells the actions that are permitted for the object. For example, for a java.io.FilePermission object, the actions list (such as "read, write") specifies which actions are granted for the specified file (or for files in the specified directory).

Other permission classes are for "named" permissions - ones that contain a name but no actions list; you either have the named permission or you don't.

Note: There is also a java.security.AllPermission permission that implies all permissions. It exists to simplify the work of system administrators who might need to perform multiple tasks that require all (or numerous) permissions.

See Permissions in JDK1.2 for permission-related information. This document includes, for example, a table listing the various SecurityManager check methods and the permission(s) the default implementation of each such method requires. It also contains a table of all the JDK 1.2 methods that require permissions, and for each such method tells which permission it requires.

For more information about SecurityManager changes made in JDK 1.2 and advice regarding porting of 1.1-style security managers, see the release documentation at http://java.sun.com/products/jdk/1.2/docs/guide/security/index.html.

Since:: JDK1.0
See Also:: ClassLoader, SecurityException, checkTopLevelWindow, getSecurityManager, setSecurityManager, AccessController, AccessControlContext, AccessControlException, Permission, BasicPermission, FilePermission, SocketPermission, PropertyPermission, RuntimePermission, AWTPermission, Policy, SecurityPermission, ProtectionDomain

Field Summary

protected boolean inCheck
          Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

Constructor Summary

SecurityManager()
          Constructs a new SecurityManager.

Method Summary

void checkAccept(String host, int port)
          Throws a SecurityException if the calling thread is not permitted to accept a socket connection from the specified host and port number.

void checkAccess(Thread t)
          Throws a SecurityException if the calling thread is not allowed to modify the thread argument.

void checkAccess(ThreadGroup g)
          Throws a SecurityException if the calling thread is not allowed to modify the thread group argument.

void checkAwtEventQueueAccess()
          Throws a SecurityException if the calling thread is not allowed to access the AWT event queue.

void checkConnect(String host, int port)
          Throws a SecurityException if the calling thread is not allowed to open a socket connection to the specified host and port number.

void checkConnect(String host, int port, Object context)
          Throws a SecurityException if the specified security context is not allowed to open a socket connection to the specified host and port number.

void checkCreateClassLoader()
          Throws a SecurityException if the calling thread is not allowed to create a new class loader.

void checkDelete(String file)
          Throws a SecurityException if the calling thread is not allowed to delete the specified file.

void checkExec(String cmd)
          Throws a SecurityException if the calling thread is not allowed to create a subprocess.

void checkExit(int status)
          Throws a SecurityException if the calling thread is not allowed to cause the Java Virtual Machine to halt with the specified status code.

void checkLink(String lib)
          Throws a SecurityException if the calling thread is not allowed to dynamic link the library code specified by the string argument file.

void checkListen(int port)
          Throws a SecurityException if the calling thread is not allowed to wait for a connection request on the specified local port number.

void checkMemberAccess(Class clazz, int which)
          Throws a SecurityException if the calling thread is not allowed to access members.

void checkMulticast(InetAddress maddr)
          Throws a SecurityException if the calling thread is not allowed to use (join/leave/send/receive) IP multicast.

void checkMulticast(InetAddress maddr, byte ttl)
          Throws a SecurityException if the calling thread is not allowed to use (join/leave/send/receive) IP multicast.

void checkPackageAccess(String pkg)
          Throws a SecurityException if the calling thread is not allowed to access the package specified by the argument.

void checkPackageDefinition(String pkg)
          Throws a SecurityException if the calling thread is not allowed to define classes in the package specified by the argument.

void checkPermission(Permission perm)
          Throws a SecurityException if the requested access, specified by the given permission, is not permitted based on the security policy currently in effect.

void checkPermission(Permission perm, Object context)
          Throws a SecurityException if the specified security context is denied access to the resource specified by the given permission.

void checkPrintJobAccess()
          Throws a SecurityException if the calling thread is not allowed to initiate a print job request.

void checkPropertiesAccess()
          Throws a SecurityException if the calling thread is not allowed to access or modify the system properties.

void checkPropertyAccess(String key)
          Throws a SecurityException if the calling thread is not allowed to access the system property with the specified key name.

void checkRead(FileDescriptor fd)
          Throws a SecurityException if the calling thread is not allowed to read from the specified file descriptor.

void checkRead(String file)
          Throws a SecurityException if the calling thread is not allowed to read the file specified by the string argument.

void checkRead(String file, Object context)
          Throws a SecurityException if the specified security context is not allowed to read the file specified by the string argument.

void checkSecurityAccess(String target)
          Determines whether the permission with the specified permission target name should be granted or denied.

void checkSetFactory()
          Throws a SecurityException if the calling thread is not allowed to set the socket factory used by ServerSocket or Socket, or the stream handler factory used by URL.

void checkSystemClipboardAccess()
          Throws a SecurityException if the calling thread is not allowed to access the system clipboard.

boolean checkTopLevelWindow(Object window)
          Returns false if the calling thread is not trusted to bring up the top-level window indicated by the window argument.

void checkWrite(FileDescriptor fd)
          Throws a SecurityException if the calling thread is not allowed to write to the specified file descriptor.

void checkWrite(String file)
          Throws a SecurityException if the calling thread is not allowed to write to the file specified by the string argument.

protected int classDepth(String name)
          Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

protected int classLoaderDepth()
          Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

protected ClassLoader currentClassLoader()
          Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

protected Class currentLoadedClass()
          Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

protected Class[] getClassContext()
          Returns the current execution stack as an array of classes.

boolean getInCheck()
          Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

Object getSecurityContext()
          Creates an object that encapsulates the current execution environment.

ThreadGroup getThreadGroup()
          Returns the thread group into which to instantiate any new thread being created at the time this is being called.

protected boolean inClass(String name)
          Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

protected boolean inClassLoader()
          Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

Methods inherited from class java.lang.Object

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

Field Detail

inCheck

protected boolean inCheck

Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

This field is true if there is a security check in progress; false otherwise.

Constructor Detail

SecurityManager

public SecurityManager()

Constructs a new SecurityManager.

If there is a security manager already installed, this method first calls the security manager's checkPermission method with the RuntimePermission("createSecurityManager") permission to ensure the calling thread has permission to create a new security manager. This may result in throwing a SecurityException.

Throws:: SecurityException - if a security manager already exists and its checkPermission method doesn't allow creation of a new security manager.
See Also:: System.getSecurityManager(), checkPermission, RuntimePermission

Method Detail

getInCheck

public boolean getInCheck()

Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

Tests if there is a security check in progress.

Returns:: the value of the inCheck field. This field should contain true if a security check is in progress, false otherwise.
See Also:: inCheck

getClassContext

protected Class[] getClassContext()

Returns the current execution stack as an array of classes.

The length of the array is the number of methods on the execution stack. The element at index 0 is the class of the currently executing method, the element at index 1 is the class of that method's caller, and so on.

Returns:: the execution stack.

currentClassLoader

protected ClassLoader currentClassLoader()

Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

Returns the class loader of the most recently executing method from a class defined using a non-system class loader. A non-system class loader is defined as being a class loader that is not equal to the system class loader (as returned by ClassLoader.getSystemClassLoader()) or one of its ancestors.

This method will return null in the following three cases:

All methods on the execution stack are from classes defined using the system class loader or one of its ancestors.
All methods on the execution stack up to the first "privileged" caller (see AccessController.doPrivileged(java.security.PrivilegedAction)) are from classes defined using the system class loader or one of its ancestors.
A call to checkPermission with java.security.AllPermission does not result in a SecurityException.

Returns:: the class loader of the most recent occurrence on the stack of a method from a class defined using a non-system class loader.
See Also:: getSystemClassLoader, checkPermission

currentLoadedClass

protected Class currentLoadedClass()

Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

Returns the class of the most recently executing method from a class defined using a non-system class loader. A non-system class loader is defined as being a class loader that is not equal to the system class loader (as returned by ClassLoader.getSystemClassLoader()) or one of its ancestors.

This method will return null in the following three cases:

All methods on the execution stack are from classes defined using the system class loader or one of its ancestors.
All methods on the execution stack up to the first "privileged" caller (see AccessController.doPrivileged(java.security.PrivilegedAction)) are from classes defined using the system class loader or one of its ancestors.
A call to checkPermission with java.security.AllPermission does not result in a SecurityException.

Returns:: the class of the most recent occurrence on the stack of a method from a class defined using a non-system class loader.
See Also:: getSystemClassLoader, checkPermission

classDepth

protected int classDepth(String name)

Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

Returns the stack depth of the specified class.

Parameters:: name - the fully qualified name of the class to search for.
Returns:: the depth on the stack frame of the first occurrence of a method from a class with the specified name; -1 if such a frame cannot be found.

classLoaderDepth

protected int classLoaderDepth()

Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

Returns the stack depth of the most recently executing method from a class defined using a non-system class loader. A non-system class loader is defined as being a class loader that is not equal to the system class loader (as returned by ClassLoader.getSystemClassLoader()) or one of its ancestors.

This method will return -1 in the following three cases:

All methods on the execution stack are from classes defined using the system class loader or one of its ancestors.
All methods on the execution stack up to the first "privileged" caller (see AccessController.doPrivileged(java.security.PrivilegedAction)) are from classes defined using the system class loader or one of its ancestors.
A call to checkPermission with java.security.AllPermission does not result in a SecurityException.

Returns:: the depth on the stack frame of the most recent occurrence of a method from a class defined using a non-system class loader.
See Also:: getSystemClassLoader, checkPermission

inClass

protected boolean inClass(String name)

Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

Tests if a method from a class with the specified name is on the execution stack.

Parameters:: name - the fully qualified name of the class.
Returns:: true if a method from a class with the specified name is on the execution stack; false otherwise.

inClassLoader

protected boolean inClassLoader()

Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead.

Basically, tests if a method from a class defined using a class loader is on the execution stack.

Returns:: true if a call to currentClassLoader has a non-null return value.
See Also:: currentClassLoader

getSecurityContext

public Object getSecurityContext()

Creates an object that encapsulates the current execution environment. The result of this method is used, for example, by the three-argument checkConnect method and by the two-argument checkRead method. These methods are needed because a trusted method may be called on to read a file or open a socket on behalf of another method. The trusted method needs to determine if the other (possibly untrusted) method would be allowed to perform the operation on its own.

The default implementation of this method is to return an AccessControlContext object.

Returns:: an implementation-dependent object that encapsulates sufficient information about the current execution environment to perform some security checks later.
See Also:: checkConnect, checkRead, AccessControlContext

checkPermission

public void checkPermission(Permission perm)

Throws a SecurityException if the requested access, specified by the given permission, is not permitted based on the security policy currently in effect.

This method calls AccessController.checkPermission with the given permission.

Parameters:: perm - the requested permission.
Throws:: SecurityException - if access is not permitted based on the current security policy.
Since:: JDK1.2

checkPermission

public void checkPermission(Permission perm,
                            Object context)

Throws a SecurityException if the specified security context is denied access to the resource specified by the given permission. The context must be a security context returned by a previous call to getSecurityContext and the access control decision is based upon the configured security policy for that security context.

If context is an instance of AccessControlContext then the AccessControlContext.checkPermission method is invoked with the specified permission.

If context is not an instance of AccessControlContext then a SecurityException is thrown.

Parameters:: perm - the specified permission; context - a system-dependent security context.
Throws:: SecurityException - if the specified security context is denied access to the resource specified by the given permission.
Since:: JDK1.2
See Also:: getSecurityContext(), AccessControlContext.checkPermission(java.security.Permission)

checkCreateClassLoader

public void checkCreateClassLoader()

Throws a SecurityException if the calling thread is not allowed to create a new class loader.

This method calls checkPermission with the RuntimePermission("createClassLoader") permission.

If you override this method, then you should make a call to super.checkCreateClassLoader at the point the overridden method would normally throw an exception.

Throws:: SecurityException - if the calling thread does not have permission to create a new class loader.
See Also:: ClassLoader.ClassLoader(), checkPermission

checkAccess

public void checkAccess(Thread t)

Throws a SecurityException if the calling thread is not allowed to modify the thread argument.

This method is invoked for the current security manager by the stop, suspend, resume, setPriority, setName, and setDaemon methods of class Thread.

If the thread argument is a system thread (belongs to the thread group with a null parent) then this method calls checkPermission with the RuntimePermission("modifyThread") permission. If the thread argument is not a system thread, this method just returns silently.

Applications that want a stricter policy should override this method. If this method is overridden, the method that overrides it should additionally check to see if the calling thread has the RuntimePermission("modifyThread") permission, and if so, return silently. This is to ensure that code granted that permission (such as the JDK itself) is allowed to manipulate any thread.

If this method is overridden, then super.checkAccess should be called by the first statement in the overridden method, or the equivalent security check should be placed in the overridden method.

Parameters:: t - the thread to be checked.
Throws:: SecurityException - if the calling thread does not have permission to modify the thread.
See Also:: resume, setDaemon, setName, setPriority, stop, suspend, checkPermission

checkAccess

public void checkAccess(ThreadGroup g)

Throws a SecurityException if the calling thread is not allowed to modify the thread group argument.

This method is invoked for the current security manager when a new child thread or child thread group is created, and by the setDaemon, setMaxPriority, stop, suspend, resume, and destroy methods of class ThreadGroup.

If the thread group argument is the system thread group ( has a null parent) then this method calls checkPermission with the RuntimePermission("modifyThreadGroup") permission. If the thread group argument is not the system thread group, this method just returns silently.

Applications that want a stricter policy should override this method. If this method is overridden, the method that overrides it should additionally check to see if the calling thread has the RuntimePermission("modifyThreadGroup") permission, and if so, return silently. This is to ensure that code granted that permission (such as the JDK itself) is allowed to manipulate any thread.

If this method is overridden, then super.checkAccess should be called by the first statement in the overridden method, or the equivalent security check should be placed in the overridden method.

Parameters:: g - the thread group to be checked.
Throws:: SecurityException - if the calling thread does not have permission to modify the thread group.
See Also:: destroy, resume, setDaemon, setMaxPriority, stop, suspend, checkPermission

checkExit

public void checkExit(int status)

Throws a SecurityException if the calling thread is not allowed to cause the Java Virtual Machine to halt with the specified status code.

This method is invoked for the current security manager by the exit method of class Runtime. A status of 0 indicates success; other values indicate various errors.

This method calls checkPermission with the RuntimePermission("exitVM") permission.

If you override this method, then you should make a call to super.checkExit at the point the overridden method would normally throw an exception.

Parameters:: status - the exit status.
Throws:: SecurityException - if the calling thread does not have permission to halt the Java Virtual Machine with the specified status.
See Also:: exit, checkPermission

checkExec

public void checkExec(String cmd)

Throws a SecurityException if the calling thread is not allowed to create a subprocess.

This method is invoked for the current security manager by the exec methods of class Runtime.

This method calls checkPermission with the FilePermission(cmd,"execute") permission.

If you override this method, then you should make a call to super.checkExec at the point the overridden method would normally throw an exception.

Parameters:: cmd - the specified system command.
Throws:: SecurityException - if the calling thread does not have permission to create a subprocess.
See Also:: Runtime.exec(java.lang.String), Runtime.exec(java.lang.String, java.lang.String[]), Runtime.exec(java.lang.String[]), Runtime.exec(java.lang.String[], java.lang.String[]), checkPermission

checkLink

public void checkLink(String lib)

Throws a SecurityException if the calling thread is not allowed to dynamic link the library code specified by the string argument file. The argument is either a simple library name or a complete filename.

This method is invoked for the current security manager by methods load and loadLibrary of class Runtime.

This method calls checkPermission with the RuntimePermission("loadLibrary."+lib) permission.

If you override this method, then you should make a call to super.checkLink at the point the overridden method would normally throw an exception.

Parameters:: lib - the name of the library.
Throws:: SecurityException - if the calling thread does not have permission to dynamically link the library.
See Also:: Runtime.load(java.lang.String), Runtime.loadLibrary(java.lang.String), checkPermission

checkRead

public void checkRead(FileDescriptor fd)

Throws a SecurityException if the calling thread is not allowed to read from the specified file descriptor.

This method calls checkPermission with the RuntimePermission("readFileDescriptor") permission.

If you override this method, then you should make a call to super.checkRead at the point the overridden method would normally throw an exception.

Parameters:: fd - the system-dependent file descriptor.
Throws:: SecurityException - if the calling thread does not have permission to access the specified file descriptor.
See Also:: FileDescriptor, checkPermission

checkRead

public void checkRead(String file)

Throws a SecurityException if the calling thread is not allowed to read the file specified by the string argument.

This method calls checkPermission with the FilePermission(file,"read") permission.

If you override this method, then you should make a call to super.checkRead at the point the overridden method would normally throw an exception.

Parameters:: file - the system-dependent file name.
Throws:: SecurityException - if the calling thread does not have permission to access the specified file.
See Also:: checkPermission

checkRead

public void checkRead(String file,
                      Object context)

Throws a SecurityException if the specified security context is not allowed to read the file specified by the string argument. The context must be a security context returned by a previous call to getSecurityContext.

If context is an instance of AccessControlContext then the AccessControlContext.checkPermission method will be invoked with the FilePermission(file,"read") permission.

If context is not an instance of AccessControlContext then a SecurityException is thrown.

If you override this method, then you should make a call to super.checkRead at the point the overridden method would normally throw an exception.

Parameters:: file - the system-dependent filename.; context - a system-dependent security context.
Throws:: SecurityException - if the specified security context does not have permission to read the specified file.
See Also:: getSecurityContext(), AccessControlContext.checkPermission(java.security.Permission)

checkWrite

public void checkWrite(FileDescriptor fd)

Throws a SecurityException if the calling thread is not allowed to write to the specified file descriptor.

This method calls checkPermission with the RuntimePermission("writeFileDescriptor") permission.

If you override this method, then you should make a call to super.checkWrite at the point the overridden method would normally throw an exception.

Parameters:: fd - the system-dependent file descriptor.
Throws:: SecurityException - if the calling thread does not have permission to access the specified file descriptor.
See Also:: FileDescriptor, checkPermission

checkWrite

public void checkWrite(String file)

Throws a SecurityException if the calling thread is not allowed to write to the file specified by the string argument.

This method calls checkPermission with the FilePermission(file,"write") permission.

If you override this method, then you should make a call to super.checkWrite at the point the overridden method would normally throw an exception.

Parameters:: file - the system-dependent filename.
Throws:: SecurityException - if the calling thread does not have permission to access the specified file.
See Also:: checkPermission

checkDelete

public void checkDelete(String file)

Throws a SecurityException if the calling thread is not allowed to delete the specified file.

This method is invoked for the current security manager by the delete method of class File.

This method calls checkPermission with the FilePermission(file,"delete") permission.

If you override this method, then you should make a call to super.checkDelete at the point the overridden method would normally throw an exception.

Parameters:: file - the system-dependent filename.
Throws:: SecurityException - if the calling thread does not have permission to delete the file.
See Also:: File.delete(), checkPermission

checkConnect

public void checkConnect(String host,
                         int port)

Throws a SecurityException if the calling thread is not allowed to open a socket connection to the specified host and port number.

A port number of -1 indicates that the calling method is attempting to determine the IP address of the specified host name.

This method calls checkPermission with the SocketPermission(host+":"+port,"connect") permission if the port is not equal to -1. If the port is equal to -1, then it calls checkPermission with the SocketPermission(host,"resolve") permission.

If you override this method, then you should make a call to super.checkConnect at the point the overridden method would normally throw an exception.

Parameters:: host - the host name port to connect to.; port - the protocol port to connect to.
Throws:: SecurityException - if the calling thread does not have permission to open a socket connection to the specified host and port.
See Also:: checkPermission

checkConnect

public void checkConnect(String host,
                         int port,
                         Object context)

Throws a SecurityException if the specified security context is not allowed to open a socket connection to the specified host and port number.

A port number of -1 indicates that the calling method is attempting to determine the IP address of the specified host name.

If context is not an instance of AccessControlContext then a SecurityException is thrown.

Otherwise, the port number is checked. If it is not equal to -1, the context's checkPermission method is called with a SocketPermission(host+":"+port,"connect") permission. If the port is equal to -1, then the context's checkPermission method is called with a SocketPermission(host,"resolve") permission.

If you override this method, then you should make a call to super.checkConnect at the point the overridden method would normally throw an exception.

Parameters:: host - the host name port to connect to.; port - the protocol port to connect to.; context - a system-dependent security context.
Throws:: SecurityException - if the specified security context does not have permission to open a socket connection to the specified host and port.
See Also:: getSecurityContext(), AccessControlContext.checkPermission(java.security.Permission)

checkListen

public void checkListen(int port)

Throws a SecurityException if the calling thread is not allowed to wait for a connection request on the specified local port number.

If port is not 0, this method calls checkPermission with the SocketPermission("localhost:"+port,"listen"). If port is zero, this method calls checkPermission with SocketPermission("localhost:1024-","listen").

If you override this method, then you should make a call to super.checkListen at the point the overridden method would normally throw an exception.

Parameters:: port - the local port.
Throws:: SecurityException - if the calling thread does not have permission to listen on the specified port.
See Also:: checkPermission

checkAccept

public void checkAccept(String host,
                        int port)

Throws a SecurityException if the calling thread is not permitted to accept a socket connection from the specified host and port number.

This method is invoked for the current security manager by the accept method of class ServerSocket.

This method calls checkPermission with the SocketPermission(host+":"+port,"accept") permission.

If you override this method, then you should make a call to super.checkAccept at the point the overridden method would normally throw an exception.

Parameters:: host - the host name of the socket connection.; port - the port number of the socket connection.
Throws:: SecurityException - if the calling thread does not have permission to accept the connection.
See Also:: ServerSocket.accept(), checkPermission

checkMulticast

public void checkMulticast(InetAddress maddr)

Throws a SecurityException if the calling thread is not allowed to use (join/leave/send/receive) IP multicast.

This method calls checkPermission with the java.net.SocketPermission(maddr.getHostAddress(), "accept,connect") permission.

If you override this method, then you should make a call to super.checkMulticast at the point the overridden method would normally throw an exception.

Parameters:: maddr - Internet group address to be used.
Throws:: SecurityException - if the calling thread is not allowed to use (join/leave/send/receive) IP multicast.
Since:: JDK1.1
See Also:: checkPermission

checkMulticast

public void checkMulticast(InetAddress maddr,
                           byte ttl)

Throws a SecurityException if the calling thread is not allowed to use (join/leave/send/receive) IP multicast.

This method calls checkPermission with the java.net.SocketPermission(maddr.getHostAddress(), "accept,connect") permission.

If you override this method, then you should make a call to super.checkMulticast at the point the overridden method would normally throw an exception.

Parameters:: maddr - Internet group address to be used.; ttl - value in use, if it is multicast send.
Throws:: SecurityException - if the calling thread is not allowed to use (join/leave/send/receive) IP multicast.
Since:: JDK1.1
See Also:: checkPermission

checkPropertiesAccess

public void checkPropertiesAccess()

Throws a SecurityException if the calling thread is not allowed to access or modify the system properties.

This method is used by the getProperties and setProperties methods of class System.

This method calls checkPermission with the PropertyPermission("*", "read,write") permission.

If you override this method, then you should make a call to super.checkPropertiesAccess at the point the overridden method would normally throw an exception.

Throws:: SecurityException - if the calling thread does not have permission to access or modify the system properties.
See Also:: System.getProperties(), System.setProperties(java.util.Properties), checkPermission

checkPropertyAccess

public void checkPropertyAccess(String key)

Throws a SecurityException if the calling thread is not allowed to access the system property with the specified key name.

This method is used by the getProperty method of class System.

This method calls checkPermission with the PropertyPermission(key, "read") permission.

If you override this method, then you should make a call to super.checkPropertyAccess at the point the overridden method would normally throw an exception.

Parameters:: key - a system property key.
Throws:: SecurityException - if the calling thread does not have permission to access the specified system property.
See Also:: System.getProperty(java.lang.String), checkPermission

checkTopLevelWindow

public boolean checkTopLevelWindow(Object window)

Returns false if the calling thread is not trusted to bring up the top-level window indicated by the window argument. In this case, the caller can still decide to show the window, but the window should include some sort of visual warning. If the method returns true, then the window can be shown without any special restrictions.

See class Window for more information on trusted and untrusted windows.

This method calls checkPermission with the AWTPermission("showWindowWithoutWarningBanner") permission, and returns true if a SecurityException is not thrown, otherwise it returns false.

If you override this method, then you should make a call to super.checkTopLevelWindow at the point the overridden method would normally return false, and the value of super.checkTopLevelWindow should be returned.

Parameters:: window - the new window that is being created.
Returns:: true if the calling thread is trusted to put up top-level windows; false otherwise.
Throws:: SecurityException - if creation is disallowed entirely.
See Also:: Window, checkPermission

checkPrintJobAccess

public void checkPrintJobAccess()

Throws a SecurityException if the calling thread is not allowed to initiate a print job request.

This method calls checkPermission with the RuntimePermission("queuePrintJob") permission.

If you override this method, then you should make a call to super.checkPrintJobAccess at the point the overridden method would normally throw an exception.

Throws:: SecurityException - if the calling thread does not have permission to initiate a print job request.
Since:: JDK1.1
See Also:: checkPermission

checkSystemClipboardAccess

public void checkSystemClipboardAccess()

Throws a SecurityException if the calling thread is not allowed to access the system clipboard.

This method calls checkPermission with the AWTPermission("accessClipboard") permission.

If you override this method, then you should make a call to super.checkSystemClipboardAccess at the point the overridden method would normally throw an exception.

Throws:: SecurityException - if the calling thread does not have permission to access the system clipboard.
Since:: JDK1.1
See Also:: checkPermission

checkAwtEventQueueAccess

public void checkAwtEventQueueAccess()

Throws a SecurityException if the calling thread is not allowed to access the AWT event queue.

This method calls checkPermission with the AWTPermission("accessEventQueue") permission.

If you override this method, then you should make a call to super.checkAwtEventQueueAccess at the point the overridden method would normally throw an exception.

Throws:: SecurityException - if the calling thread does not have permission to access the AWT event queue.
Since:: JDK1.1
See Also:: checkPermission

checkPackageAccess

public void checkPackageAccess(String pkg)

Throws a SecurityException if the calling thread is not allowed to access the package specified by the argument.

This method is used by the loadClass method of class loaders.

This method first gets a list of restricted packages by obtaining a comma-separated list from a call to java.security.Security.getProperty("package.access"), and checks to see if pkg starts with or equals any of the restricted packages. If it does, then checkPermission gets called with the RuntimePermission("accessClassInPackage."+pkg) permission.

If this method is overridden, then super.checkPackageAccess should be called as the first line in the overridden method.

Parameters:: pkg - the package name.
Throws:: SecurityException - if the calling thread does not have permission to access the specified package.
See Also:: loadClass, getProperty, checkPermission

checkPackageDefinition

public void checkPackageDefinition(String pkg)

Throws a SecurityException if the calling thread is not allowed to define classes in the package specified by the argument.

This method is used by the loadClass method of some class loaders.

This method first gets a list of restricted packages by obtaining a comma-separated list from a call to java.security.Security.getProperty("package.definition"), and checks to see if pkg starts with or equals any of the restricted packages. If it does, then checkPermission gets called with the RuntimePermission("defineClassInPackage."+pkg) permission.

If this method is overridden, then super.checkPackageDefinition should be called as the first line in the overridden method.

Parameters:: pkg - the package name.
Throws:: SecurityException - if the calling thread does not have permission to define classes in the specified package.
See Also:: ClassLoader.loadClass(java.lang.String, boolean), getProperty, checkPermission

checkSetFactory

public void checkSetFactory()

Throws a SecurityException if the calling thread is not allowed to set the socket factory used by ServerSocket or Socket, or the stream handler factory used by URL.

This method calls checkPermission with the RuntimePermission("setFactory") permission.

If you override this method, then you should make a call to super.checkSetFactory at the point the overridden method would normally throw an exception.

Throws:: SecurityException - if the calling thread does not have permission to specify a socket factory or a stream handler factory.
See Also:: setSocketFactory, setSocketImplFactory, setURLStreamHandlerFactory, checkPermission

checkMemberAccess

public void checkMemberAccess(Class clazz,
                              int which)

Throws a SecurityException if the calling thread is not allowed to access members.

The default policy is to allow access to PUBLIC members, as well as access to classes that have the same class loader as the caller. In all other cases, this method calls checkPermission with the RuntimePermission("accessDeclaredMembers") permission.

If this method is overridden, then a call to super.checkMemberAccess cannot be made, as the default implementation of checkMemberAccess relies on the code being checked being at a stack depth of 4.

Parameters:: clazz - the class that reflection is to be performed on.; which - type of access, PUBLIC or DECLARED.
Throws:: SecurityException - if the caller does not have permission to access members.
Since:: JDK1.1
See Also:: Member, checkPermission

checkSecurityAccess

public void checkSecurityAccess(String target)

Determines whether the permission with the specified permission target name should be granted or denied.

If the requested permission is allowed, this method returns quietly. If denied, a SecurityException is raised.

This method creates a SecurityPermission object for the given permission target name and calls checkPermission with it.

See the documentation for SecurityPermission for a list of possible permission target names.

If you override this method, then you should make a call to super.checkSecurityAccess at the point the overridden method would normally throw an exception.

Parameters:: target - the target name of the SecurityPermission.
Throws:: SecurityException - if the calling thread does not have permission for the requested access.
Since:: JDK1.1
See Also:: checkPermission

getThreadGroup

public ThreadGroup getThreadGroup()

Returns the thread group into which to instantiate any new thread being created at the time this is being called. By default, it returns the thread group of the current thread. This should be overridden by a specific security manager to return the appropriate thread group.

Since:: JDK1.1
See Also:: ThreadGroup

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Field Summary
`protected boolean`	`inCheck` Deprecated. This type of security checking is not recommended. It is recommended that the `checkPermission` call be used instead.

Constructor Summary
`SecurityManager()` Constructs a new `SecurityManager`.

Method Summary
`void`	`checkAccept(String host, int port)` Throws a `SecurityException` if the calling thread is not permitted to accept a socket connection from the specified host and port number.
`void`	`checkAccess(Thread t)` Throws a `SecurityException` if the calling thread is not allowed to modify the thread argument.
`void`	`checkAccess(ThreadGroup g)` Throws a `SecurityException` if the calling thread is not allowed to modify the thread group argument.
`void`	`checkAwtEventQueueAccess()` Throws a `SecurityException` if the calling thread is not allowed to access the AWT event queue.
`void`	`checkConnect(String host, int port)` Throws a `SecurityException` if the calling thread is not allowed to open a socket connection to the specified host and port number.
`void`	`checkConnect(String host, int port, Object context)` Throws a `SecurityException` if the specified security context is not allowed to open a socket connection to the specified host and port number.
`void`	`checkCreateClassLoader()` Throws a `SecurityException` if the calling thread is not allowed to create a new class loader.
`void`	`checkDelete(String file)` Throws a `SecurityException` if the calling thread is not allowed to delete the specified file.
`void`	`checkExec(String cmd)` Throws a `SecurityException` if the calling thread is not allowed to create a subprocess.
`void`	`checkExit(int status)` Throws a `SecurityException` if the calling thread is not allowed to cause the Java Virtual Machine to halt with the specified status code.
`void`	`checkLink(String lib)` Throws a `SecurityException` if the calling thread is not allowed to dynamic link the library code specified by the string argument file.
`void`	`checkListen(int port)` Throws a `SecurityException` if the calling thread is not allowed to wait for a connection request on the specified local port number.
`void`	`checkMemberAccess(Class clazz, int which)` Throws a `SecurityException` if the calling thread is not allowed to access members.
`void`	`checkMulticast(InetAddress maddr)` Throws a `SecurityException` if the calling thread is not allowed to use (join/leave/send/receive) IP multicast.
`void`	`checkMulticast(InetAddress maddr, byte ttl)` Throws a `SecurityException` if the calling thread is not allowed to use (join/leave/send/receive) IP multicast.
`void`	`checkPackageAccess(String pkg)` Throws a `SecurityException` if the calling thread is not allowed to access the package specified by the argument.
`void`	`checkPackageDefinition(String pkg)` Throws a `SecurityException` if the calling thread is not allowed to define classes in the package specified by the argument.
`void`	`checkPermission(Permission perm)` Throws a `SecurityException` if the requested access, specified by the given permission, is not permitted based on the security policy currently in effect.
`void`	`checkPermission(Permission perm, Object context)` Throws a `SecurityException` if the specified security context is denied access to the resource specified by the given permission.
`void`	`checkPrintJobAccess()` Throws a `SecurityException` if the calling thread is not allowed to initiate a print job request.
`void`	`checkPropertiesAccess()` Throws a `SecurityException` if the calling thread is not allowed to access or modify the system properties.
`void`	`checkPropertyAccess(String key)` Throws a `SecurityException` if the calling thread is not allowed to access the system property with the specified `key` name.
`void`	`checkRead(FileDescriptor fd)` Throws a `SecurityException` if the calling thread is not allowed to read from the specified file descriptor.
`void`	`checkRead(String file)` Throws a `SecurityException` if the calling thread is not allowed to read the file specified by the string argument.
`void`	`checkRead(String file, Object context)` Throws a `SecurityException` if the specified security context is not allowed to read the file specified by the string argument.
`void`	`checkSecurityAccess(String target)` Determines whether the permission with the specified permission target name should be granted or denied.
`void`	`checkSetFactory()` Throws a `SecurityException` if the calling thread is not allowed to set the socket factory used by `ServerSocket` or `Socket`, or the stream handler factory used by `URL`.
`void`	`checkSystemClipboardAccess()` Throws a `SecurityException` if the calling thread is not allowed to access the system clipboard.
`boolean`	`checkTopLevelWindow(Object window)` Returns `false` if the calling thread is not trusted to bring up the top-level window indicated by the `window` argument.
`void`	`checkWrite(FileDescriptor fd)` Throws a `SecurityException` if the calling thread is not allowed to write to the specified file descriptor.
`void`	`checkWrite(String file)` Throws a `SecurityException` if the calling thread is not allowed to write to the file specified by the string argument.
`protected int`	`classDepth(String name)` Deprecated. This type of security checking is not recommended. It is recommended that the `checkPermission` call be used instead.
`protected int`	`classLoaderDepth()` Deprecated. This type of security checking is not recommended. It is recommended that the `checkPermission` call be used instead.
`protected ClassLoader`	`currentClassLoader()` Deprecated. This type of security checking is not recommended. It is recommended that the `checkPermission` call be used instead.
`protected Class`	`currentLoadedClass()` Deprecated. This type of security checking is not recommended. It is recommended that the `checkPermission` call be used instead.
`protected Class[]`	`getClassContext()` Returns the current execution stack as an array of classes.
`boolean`	`getInCheck()` Deprecated. This type of security checking is not recommended. It is recommended that the `checkPermission` call be used instead.
`Object`	`getSecurityContext()` Creates an object that encapsulates the current execution environment.
`ThreadGroup`	`getThreadGroup()` Returns the thread group into which to instantiate any new thread being created at the time this is being called.
`protected boolean`	`inClass(String name)` Deprecated. This type of security checking is not recommended. It is recommended that the `checkPermission` call be used instead.
`protected boolean`	`inClassLoader()` Deprecated. This type of security checking is not recommended. It is recommended that the `checkPermission` call be used instead.

Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class SecurityManager - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

java.lang Class SecurityManager

inCheck

SecurityManager

getInCheck

getClassContext

currentClassLoader

currentLoadedClass

classDepth

classLoaderDepth

inClass

inClassLoader

getSecurityContext

checkPermission

checkPermission

checkCreateClassLoader

checkAccess

checkAccess

checkExit

checkExec

checkLink

checkRead

checkRead

checkRead

checkWrite

checkWrite

checkDelete

checkConnect

checkConnect

checkListen

checkAccept

checkMulticast

checkMulticast

checkPropertiesAccess

checkPropertyAccess

checkTopLevelWindow

checkPrintJobAccess

checkSystemClipboardAccess

checkAwtEventQueueAccess

checkPackageAccess

checkPackageDefinition

checkSetFactory

checkMemberAccess

checkSecurityAccess

getThreadGroup

java.lang
Class SecurityManager