com.antelmann
Class LicenseManager

java.lang.Object
  com.antelmann.LicenseManager

All Implemented Interfaces:

Iterable<License>

public final class LicenseManager
extends Object
implements Iterable<License>

LicenseManager provides the ability to use limited licenses based on classes and package names. Note that the LicenseManager only accepts Licenses that are properly signed, i.e. they will have to be created by an authorized issuer.

Once the LicenseManager is initialized, a set of licenses is installed from the licenses.dat file in the resource directory from the distribution; if any licenses therein are invalid or the file is non-existent, the resulting errors are ignored and the LicenseManager contains no licenses to begin with.

Generally, an application can go without using the LicenseManager explicitly. The class com.antelmann.util.Settings provides a few convenience methods that may suffice for a standard application.

Since:

12/31/2003

Author:

Holger Antelmann

See Also:

Settings, License, Licensed, LicenseHandler, LicensingException, Settings.checkLicense(Object), Settings.installLicense(com.antelmann.License)

Method Summary

void	check(Object licensee) checks for a valid license for the given object and only returns gracefully if a valid license was found.
JTable	createTable() creates a table containing all licenses of this manager.
License	getLicense(Object licensee) returns the license used for the given licensee.
static LicenseManager	getLicenseManager() returns the global LicenseManager object (there is only one)
Collection<License>	getLicenses() returns an unmodifiable view of the embedded licenses
License	install(License l) installs the given license into this LicenseManager, so that it can be found if a check on the licensee is made.
Iterator<License>	iterator()
void	loadFrom(File file) a convenience method that installs serialized licenses from a file
void	loadFrom(InputStream stream) a convenience method that installs serialized licenses from a stream.
void	loadFrom(URL url) a convenience method that installs serialized licenses from a URL
void	removeAllLicenses()
License	removeLicense(License l)
License	signLicense(License l) requires a certain developer class as well as a developer private key to be present - not shipped with the distribution.
void	store(OutputStream stream) every license contained within is written as a serialized byte array
void	verifyLicense(License l) checks the signature against the certificate.

Methods inherited from class java.lang.Object

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

Method Detail

createTable

public JTable createTable()

creates a table containing all licenses of this manager.

See Also:

LicenseTableModel

getLicenseManager

public static LicenseManager getLicenseManager()
                                        throws SecurityException

returns the global LicenseManager object (there is only one)

Throws:

SecurityException - if the correct certificate cannot be found

signLicense

public License signLicense(License l)
                    throws Exception

requires a certain developer class as well as a developer private key to be present - not shipped with the distribution. A license must not be altered anymore after calling this method successfully. This method uses reflection to access the required private class.

Returns:

the signed license (same object as the one passed in)

Throws:

Exception - whenever the special developer class is not present (which is usually the case).

loadFrom

public void loadFrom(File file)
              throws IOException

a convenience method that installs serialized licenses from a file

Throws:

IOException

loadFrom

public void loadFrom(URL url)
              throws IOException

a convenience method that installs serialized licenses from a URL

Throws:

IOException

loadFrom

public void loadFrom(InputStream stream)
              throws IOException

a convenience method that installs serialized licenses from a stream. Possible LicensingExceptions are ignored.

Throws:

IOException - if a license to be imported is not valid

store

public void store(OutputStream stream)
           throws IOException

every license contained within is written as a serialized byte array

Throws:

IOException

getLicenses

public Collection<License> getLicenses()

returns an unmodifiable view of the embedded licenses

iterator

public Iterator<License> iterator()

Specified by:

iterator in interface Iterable<License>

check

public void check(Object licensee)
           throws LicensingException

checks for a valid license for the given object and only returns gracefully if a valid license was found. The use() method of the license object will be called if a valid license was found.

Throws:

LicensingException - if either no license was found or the found license was invalid

See Also:

License.use(), getLicense(Object)

install

public License install(License l)
                throws LicensingException

installs the given license into this LicenseManager, so that it can be found if a check on the licensee is made. Only properly signed licenses can be installed.

Returns:

the previously installed license for the licensee embedded within the given license - if any

Throws:

LicensingException - if the license cannot be verified (i.e. if it is not properly signed)

See Also:

check(Object), verifyLicense(License)

removeLicense

public License removeLicense(License l)

removeAllLicenses

public void removeAllLicenses()

getLicense

public License getLicense(Object licensee)

returns the license used for the given licensee. If no license is found, null is returned. Note that there may be multiple licenses that may apply to a licensee; this method always returns the license that is most specific to the given licensee, even if that license turns out to be invalid. If an alternative installed license should be used instead (one that belongs to a super package and includes sub-packages), the invalid specific license must be removed from the LicenseManager.

verifyLicense

public void verifyLicense(License l)
                   throws LicensingException

checks the signature against the certificate. Note: a license passing this verification may still be invalid due to expiration or other constrains.

Throws:

LicensingException