* The most usefull method is the isCompatibleWith() method that
* compares a desired version of a specification with the version of the
* specification as implemented by a package. A package is considered
* compatible with another version if the version of the specification is
* equal or higher then the requested version. Version numbers are represented
* as strings of positive numbers seperated by dots (e.g. "1.2.0").
* The first number is called the major number, the second the minor,
* the third the micro, etc. A version is considered higher then another
* version if it has a bigger major number then the another version or when
* the major numbers of the versions are equal if it has a bigger minor number
* then the other version, etc. (If a version has no minor, micro, etc numbers
* then they are considered the be 0.)
*
* @since 1.2
* @author Mark Wielaard (mark@klomp.org)
*/
public class Package
{
/** The name of the Package */
final private String name;
/** The name if the implementation */
final private String implTitle;
/** The vendor that wrote this implementation */
final private String implVendor;
/** The version of this implementation */
final private String implVersion;
/** The name of the specification */
final private String specTitle;
/** The name of the specification designer */
final private String specVendor;
/** The version of this specification */
final private String specVersion;
/** If sealed the origin of the package classes, otherwise null */
final private URL sealed;
/**
* A package local constructor for the Package class.
* All parameters except the name of the package may be
* null.
* There are no public constructors defined for Package this is a package
* local constructor that is used by java.lang.Classloader.definePackage().
*
* @param name The name of the Package
* @param specTitle The name of the specification
* @param specVendor The name of the specification designer
* @param specVersion The version of this specification
* @param implTitle The name of the implementation
* @param implVendor The vendor that wrote this implementation
* @param implVersion The version of this implementation
* @param sealed If sealed the origin of the package classes
*/
Package(String name,
String specTitle, String specVendor, String specVersion,
String implTitle, String implVendor, String implVersion, URL sealed)
{
if (name == null)
throw new IllegalArgumentException("null Package name");
this.name = name;
this.implTitle = implTitle;
this.implVendor = implVendor;
this.implVersion = implVersion;
this.specTitle = specTitle;
this.specVendor = specVendor;
this.specVersion = specVersion;
this.sealed = sealed;
}
/**
* Returns the Package name.
*/
public String getName()
{
return name;
}
/**
* Returns the name of the implementation or null if unknown.
*/
public String getImplementationTitle()
{
return implTitle;
}
/**
* Returns the vendor that wrote this implementation or null if unknown.
*/
public String getImplementationVendor()
{
return implVendor;
}
/**
* Returns the version of this implementation or null if unknown.
*/
public String getImplementationVersion()
{
return implVersion;
}
/**
* Returns the name of the specification or null if unknown.
*/
public String getSpecificationTitle()
{
return specTitle;
}
/**
* Returns the name of the specification designer or null if unknown.
*/
public String getSpecificationVendor()
{
return specVendor;
}
/**
* Returns the version of the specification or null if unknown.
*/
public String getSpecificationVersion()
{
return specVersion;
}
/**
* Returns true if this Package is sealed.
*/
public boolean isSealed()
{
return (sealed != null);
}
/**
* Returns true if this Package is sealed and the origin of the classes is
* the given URL.
*
* @param url
*/
public boolean isSealed(URL url)
{
return url.equals(sealed);
}
/**
* Checks if the version of the specification is higher or at least as high
* as the desired version.
* @param version the (minimal) desired version of the specification
* @exception NumberFormatException when either version or the
* specification version is not a correctly formatted version number
* @exception NullPointerException if the supplied version or the
* Package specification version is null.
*/
public boolean isCompatibleWith(String version) throws NumberFormatException
{
StringTokenizer versionTokens = new StringTokenizer(version, ".");
StringTokenizer specTokens = new StringTokenizer(specVersion, ".");
try
{
while (versionTokens.hasMoreElements())
{
int vers = Integer.parseInt(versionTokens.nextToken());
int spec = Integer.parseInt(specTokens.nextToken());
if (spec < vers)
return false;
else if (spec > vers)
return true;
// They must be equal, next Token please!
}
}
catch (NoSuchElementException e)
{
// this must have been thrown by spec.netToken() so return false
return false;
}
// They must have been exactly the same version.
// Or the specVersion has more subversions. That is also good.
return true;
}
/**
* Returns the named package if it is known by the callers class loader.
* It may return null if the package is unknown, when there is no
* information on that particular package available or when the callers
* classloader is null.
* @param name the name of the desired package
*/
public static Package getPackage(String name)
{
// Get the caller's classloader
SecurityManager sm = System.getSecurityManager();
Class c = sm.getClassContext()[1];
ClassLoader cl = c.getClassLoader();
if (cl != null)
return cl.getPackage(name);
else
return null;
}
/**
* Returns all the packages that are known to the callers class loader.
* It may return an empty array if the classloader of the caller is null.
*/
public static Package[] getPackages()
{
// Get the caller's classloader
SecurityManager sm = System.getSecurityManager();
Class c = sm.getClassContext()[1];
ClassLoader cl = c.getClassLoader();
if (cl != null)
return cl.getPackages();
else
return new Package[0];
}
/**
* Returns the hashCode of the name of this package.
*/
public int hashCode()
{
return name.hashCode();
}
/**
* Returns a string representation of this package name, specification,
* implementation and class origin if sealed.
*/
public String toString()
{
return "package: " + name +
" spec: " + specTitle +
" version: " + specVersion +
" vendor: " + specVendor +
" implementation: " + implTitle +
" version: " + implVersion +
" vendor: " + implVendor + " sealed: " + sealed;
}
}