www.pudn.com > cryptix-asn1-0.1.11.zip > PackageProperties.java

/* $Id: PackageProperties.java,v 1.1.1.1 2001/02/24 04:58:59 raif Exp $ 
 * 
 * Copyright (C) 1997-2001 The Cryptix Foundation Limited. All rights reserved. 
 * 
 * Use, modification, copying and distribution of this software is subject to 
 * the terms and conditions of the Cryptix General Licence. You should have 
 * received a copy of the Cryptix General Licence along with this library; if 
 * not, you can download a copy from http://www.cryptix.org/ 
 */ 
package cryptix.asn1.encoding; 
 
import java.io.File; 
import java.io.InputStream; 
import java.io.PrintWriter; 
import java.io.PrintStream; 
import java.util.Enumeration; 
import java.util.Properties; 
 
/** 
 * A class that acts as a central repository for a package specific properties. 
 * It reads a Java properties file supposed to contain package-specific 
 * properties. By convention, this properties file is assumed to be named: 
 * package.properties, where package is the package name of 
 * this class with the dots replaced by underscores; eg. if this class is 
 * defined as a.b.c.PackageProperties, then its corresponding properties 
 * file is assumed to be "a_b_c.properties" accessible from a root directory 
 * visible from the CLASSPATH of the current thread running this class in the 
 * file hierarchy: a/b/c/. Note that if there were more than one instance of 
 * this file, under more that one such root, the order in which the JVM/Java 
 * interpreter searches the nodes of the CLASSPATH will dictate which instance 
 * will be loaded/used.
 
 * 
 * A practical way to allow modification of a package properties file after 
 * it is jarred/zipped and deployed, is to define a special directory, say 
 * "properties" for example, and include it in the CLASSPATH, before the jar/ 
 * zip file containing the distribution. 
 * 
 * @version $Revision: 1.1.1.1 $ 
 * @author  David Hopwood 
 * @author  Jill Baker 
 * @author  Raif S. Naffah 
 */ 
class PackageProperties { 
 
	// Constants and variables with relevant static code 
	// ....................................................................... 
 
	static final boolean DEBUG_PACKAGE = true; 
 
	private static final String PACKAGE_NAME; // Blank Final 
	static { 
		String pname = PackageProperties.class.getName(); 
		pname = pname.substring(0, pname.lastIndexOf(".")); 
		PACKAGE_NAME = pname; 
   } 
 
	/** 
	 * Default properties in case .properties file was not found. 
	 */ 
	private static final String[][] DEFAULT_PROPERTIES = { 
		{ "Trace.*",       "false" }, 
		{ "Debug.Level.*", "0" } 
	}; 
 
	private static final Properties properties; // Blank Final 
	static { 
		if (DEBUG_PACKAGE) 
			System.err.println("*** Looking for "+PACKAGE_NAME+" properties"); 
 
		StringBuffer sb = new StringBuffer(); 
 
		sb.append(PACKAGE_NAME.replace('.', '_')); 
		sb.append(".properties"); 
 
		String it = "/properties/" + sb.toString(); 
		if (DEBUG_PACKAGE) 
			System.err.println("*** Loading "+it); 
 
		boolean ok = false; 
		Properties result = new Properties(); 
		try { 
			InputStream is = PackageProperties.class.getResourceAsStream(it); 
			result.load(is); 
         ok = true; 
			is.close(); 
			if (DEBUG_PACKAGE) 
				System.out.println("*** Properties file loaded OK..."); 
		} catch (Exception ignored) { 
		} 
 
		if (!ok) { 
			if (DEBUG_PACKAGE) { 
				System.err.println("*** WARNING: Unable to load \""+it+"\" from CLASSPATH."); 
				System.err.println("*** Will use default values instead..."); 
			} 
 
			for (int i = 0, limit = DEFAULT_PROPERTIES.length; i < limit; i++) 
				result.put(DEFAULT_PROPERTIES[i][0], DEFAULT_PROPERTIES[i][1]); 
 
			if (DEBUG_PACKAGE) 
				System.err.println("*** Default properties now set..."); 
		} 
 
      properties = result; 
	} 
 
	// Constructor(s) 
	// ....................................................................... 
 
	/** 
	 * Trivial constructor to enforce Singleton pattern. 
	 */ 
	private PackageProperties() { 
		super(); 
	} 
 
 
	// Properties methods (excluding load and save, which are deliberately not 
	// supported). 
	// ....................................................................... 
 
	/** 
	 * Returns the value of a property for this algorithm. 
	 */ 
	public static String getProperty(String key) { 
		return properties.getProperty(key); 
	} 
 
	/** 
	 * Returns the value of a property for this algorithm, or return 
	 * value if the property was not set. 
	 */ 
	public static String getProperty(String key, String value) { 
		return properties.getProperty(key, value); 
	} 
 
	/** 
	 * Lists algorithm properties to the PrintStream out. 
	 */ 
	public static void list(PrintStream out) { 
		list(new PrintWriter(out, true)); 
	} 
 
	/** 
	 * Lists algorithm properties to the PrintWriter out. 
	 */ 
	public static void list(PrintWriter out) { 
		out.println("#"); 
		out.println("# ----- Begin "+PACKAGE_NAME+" properties -----"); 
		out.println("#"); 
		String key, value; 
		Enumeration enum = properties.propertyNames(); 
		while (enum.hasMoreElements()) { 
			key = (String) enum.nextElement(); 
			value = getProperty(key); 
			out.println(key + " = " + value); 
		} 
 
		out.println("#"); 
		out.println("# ----- End "+PACKAGE_NAME+" properties -----"); 
	} 
 
	public static Enumeration propertyNames() { 
		return properties.propertyNames(); 
	} 
 
 
	// Developer support: Tracing and debugging enquiry methods (package-private) 
	// ....................................................................... 
 
	/** 
	 * Returns true if tracing is requested for a given class.
 
	 * 
	 * User indicates this by setting the tracing boolean 
	 * property for label in the (algorithm).properties 
	 * file. The property's key is "Trace.label".
 
	 * 
	 * @param label  The name of a class. 
	 * @return True iff a boolean true value is set for a property with 
	 *      the key Trace.label. 
	 */ 
	static boolean isTraceable(String label) { 
		String s = getProperty("Trace."+label); 
		if (s == null) 
			return false; 
 
		return new Boolean(s.trim()).booleanValue(); 
	} 
 
	/** 
	 * Returns the debug level for a given class.
 
	 * 
	 * User indicates this by setting the numeric property with key 
	 * "Debug.Level.label".
 
	 * 
	 * If this property is not set, "Debug.Level.*" is looked up 
	 * next. If neither property is set, or if the first property found is 
	 * not a valid decimal integer, then this method returns 0. 
	 * 
	 * @param label  The name of a class. 
	 * @return  The required debugging level for the designated class. 
	 */ 
	static int getLevel(String label) { 
		String s = getProperty("Debug.Level."+label); 
		if (s == null) { 
			s = getProperty("Debug.Level.*"); 
			if (s == null) 
				return 0; 
		} 
 
		try { 
			return Integer.parseInt(s.trim()); 
		} catch (NumberFormatException x) { 
			return 0; 
		} 
	} 
 
	/** 
	* Returns the PrintWriter to which tracing and debugging output is to 
	* be sent.
 
	* 
	* User indicates this by setting the property with key Output 
	* to the literal out or err.
 
	* 
	* By default or if the set value is not allowed, System.err 
	* will be used. 
	*/ 
	static PrintWriter getOutput() { 
		String name = getProperty("Output"); 
		return (name != null && name.trim().equals("out")) ? 
			new PrintWriter(System.out, true) : 
			new PrintWriter(System.err, true); 
	} 
}