/*
* @(#)PackageManager.java 1.6 02/08/21
*
* Copyright (c) 1996-2002 Sun Microsystems, Inc. All rights reserved.
*/
package javax.media;
import java.util.Vector;
import java.lang.reflect.*;
/**
* A <CODE>PackageManager</CODE> maintains a persistent store of
* package-prefix lists. A package prefix specifies the
* prefix for a complete class name. A factory uses
* a package-prefix list to find a class that
* might belong to any of the packages that are referenced
* in the prefix list.<p>
*
* The <code>Manager</code> uses package-prefix lists
* to find protocol handlers and content handlers for time-based
* media.<p>
*
* The current version of a package-prefix list is obtained with
* the <code>get<package-prefix>List</code> method. This method returns the prefix
* list in use; any changes to the list take effect immediately.
*
* Unless it is made persistent with
* <code>commit<package-prefix>List</code>, a package-prefix list is only valid
* while the <code>Manager</code> is referenced.
*
* The <code>commit<package-prefix>List</code> method ensures that any changes made
* to a package-prefix list are still visible the next time that
* the <code>Manager</code> is referenced.
*
* @see Manager
* @version 1.6, 02/08/21.
*/
public class PackageManager {
static private PackageManager pm = null;
static private Method mGetProtocolPrefixList = null;
static private Method mSetProtocolPrefixList = null;
static private Method mCommitProtocolPrefixList = null;
static private Method mGetContentPrefixList = null;
static private Method mSetContentPrefixList = null;
static private Method mCommitContentPrefixList = null;
static final private Class [] sigNone = new Class[0];
static final private Class [] sigVector = { Vector.class };
/**
* The package prefix used when searching for protocol
* handlers.
*
* @see Manager
*/
static private Vector protoPrefixList;
static {
// Default value
protoPrefixList = new Vector();
protoPrefixList.addElement("javax");
protoPrefixList.addElement("com.sun");
try {
Class pmClass = Class.forName("javax.media.pm.PackageManager");
if (pmClass != null) {
Object tryPM = pmClass.newInstance();
if (tryPM instanceof PackageManager) {
pm = (PackageManager) tryPM;
mGetProtocolPrefixList =
getDeclaredMethod(pmClass, "getProtocolPrefixList",
sigNone);
mSetProtocolPrefixList =
getDeclaredMethod(pmClass, "setProtocolPrefixList",
sigVector);
mCommitProtocolPrefixList =
getDeclaredMethod(pmClass, "commitProtocolPrefixList",
sigNone);
mGetContentPrefixList =
getDeclaredMethod(pmClass, "getContentPrefixList",
sigNone);
mSetContentPrefixList =
getDeclaredMethod(pmClass, "setContentPrefixList",
sigVector);
mCommitContentPrefixList =
getDeclaredMethod(pmClass, "commitContentPrefixList",
sigNone);
}
}
} catch (ClassNotFoundException cnfe) {
System.err.println(cnfe);
} catch (InstantiationException ie) {
System.err.println(ie);
} catch (IllegalAccessException iae) {
System.err.println(iae);
} catch (SecurityException se) {
System.out.println("PackageManager: SecurityException: " + se);
System.err.println(se);
} catch (NoSuchMethodException nsme) {
}
}
/* Private method to invoke a method using reflection API */
private static Object runMethod(Method m, Object [] params) {
try {
return m.invoke(null, params);
} catch (IllegalAccessException iae) {
} catch (IllegalArgumentException iare) {
} catch (InvocationTargetException ite) {
}
return null;
}
/**
* Get the current value of the protocol package-prefix list.
* <p>
* @return The protocol package-prefix list.
*/
static public Vector getProtocolPrefixList() {
if (pm != null && mGetProtocolPrefixList != null) {
return (Vector) runMethod(mGetProtocolPrefixList, null);
} else
return protoPrefixList;
}
/**
* Set the protocol package-prefix list.
* This is required for changes to take effect.
*
* @param list The new package-prefix list to use.
*/
static public void setProtocolPrefixList(Vector list) {
if (pm != null && mSetProtocolPrefixList != null) {
Object [] params = new Object[1];
params[0] = list.clone();
runMethod(mSetProtocolPrefixList, params);
protoPrefixList = getProtocolPrefixList();
} else
protoPrefixList = (Vector)list.clone();
}
/**
* Make changes to the protocol package-prefix list persistent.
* <p>
* This method throws a <code>SecurityException</code> if the calling thread
* does not have access to system properties.
*
*/
static public void commitProtocolPrefixList() {
if (pm != null && mCommitProtocolPrefixList != null) {
runMethod(mCommitProtocolPrefixList, null);
}
}
/*************************************************************************
* Content Prefix List
*************************************************************************/
/**
* The package prefix used when searching for content
* handlers.
*
* @see Manager
*/
static private Vector contentPrefixList;
static {
// Default value
contentPrefixList = new Vector();
contentPrefixList.addElement("javax");
contentPrefixList.addElement("com.sun");
}
/**
* Get the current value of the content package-prefix list.
* Any changes made to this list take effect immediately.
* <p>
*
* @return The content package-prefix list.
*/
static public Vector getContentPrefixList() {
if (pm != null && mGetContentPrefixList != null) {
return (Vector) runMethod(mGetContentPrefixList, null);
} else
return contentPrefixList;
}
/**
* Set the current value of the content package-prefix list.
* This is required for changes to take effect.
*
* @param list The content package-prefix list to set.
*/
static public void setContentPrefixList(Vector list) {
if (pm != null && mSetContentPrefixList != null) {
Object [] params = new Object[1];
params[0] = list.clone();
runMethod(mSetContentPrefixList, params);
contentPrefixList = getContentPrefixList();
} else
contentPrefixList = (Vector)list.clone();
}
/**
* Make changes to the content prefix-list persistent.
* <p>
* This method throws a <code>SecurityException</code> if the calling thread
* does not have access to system properties.
*
*/
static public void commitContentPrefixList() {
if (pm != null && mCommitContentPrefixList != null) {
runMethod(mCommitContentPrefixList, null);
}
}
/**
* netscape browser throws SecurityException when you call
* Class.getDeclaredMethod or Class.getDeclaredMethods
* There is a privilege called UniversalMemberAccess which should
* allow this call. But Netscape has disabled this privilege; they
* mention this in in their security faq. So, we call getMethod and
* using getDeclaringClass method, check to see if it the subclass
* overrided it or not.
* Note: this code is used in all cases, not just netscape
*/
static Method getDeclaredMethod(Class c, String name, Class[] params)
throws NoSuchMethodException {
Method m = c.getMethod(name, params);
if (m.getDeclaringClass() == c) {
return m;
} else {
return null;
}
}
}