level.java

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/*
 * @(#)Level.java	1.12 03/01/27
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.util.logging;
import java.util.ResourceBundle;

/**
 * The Level class defines a set of standard logging levels that
 * can be used to control logging output.  The logging Level objects
 * are ordered and are specified by ordered integers.  Enabling logging
 * at a given level also enables logging at all higher levels.
 * <p>
 * Clients should normally use the predefined Level constants such
 * as Level.SEVERE.
 * <p>
 * The levels in descending order are:
 * <ul>
 * <li>SEVERE (highest value)
 * <li>WARNING
 * <li>INFO
 * <li>CONFIG
 * <li>FINE
 * <li>FINER
 * <li>FINEST  (lowest value)
 * </ul>
 * In addition there is a level OFF that can be used to turn
 * off logging, and a level ALL that can be used to enable
 * logging of all messages.
 * <p>
 * It is possible for third parties to define additional logging
 * levels by subclassing Level.  In such cases subclasses should
 * take care to chose unique integer level values and to ensure that 
 * they maintain the Object uniqueness property across serialization
 * by defining a suitable readResolve method.
 *
 * @version 1.12, 01/27/03
 * @since 1.4
 */

public class Level implements java.io.Serializable {
    private static java.util.ArrayList known = new java.util.ArrayList();
    private static String defaultBundle = "sun.util.logging.resources.logging";

    /**
     * @serial  The non-localized name of the level.
     */
    private final String name;

    /**
     * @serial  The integer value of the level.
     */
    private final int value;

    /**
     * @serial The resource bundle name to be used in localizing the level name.
     */
    private final String resourceBundleName;

    /**
     * OFF is a special level that can be used to turn off logging.
     * This level is initialized to <CODE>Integer.MAX_VALUE</CODE>.
     */
    public static final Level OFF = new Level("OFF",Integer.MAX_VALUE, defaultBundle);

    /**
     * SEVERE is a message level indicating a serious failure.
     * <p>
     * In general SEVERE messages should describe events that are
     * of considerable importance and which will prevent normal
     * program execution.   They should be reasonably intelligible
     * to end users and to system administrators.
     * This level is initialized to <CODE>1000</CODE>.
     */
    public static final Level SEVERE = new Level("SEVERE",1000, defaultBundle);

    /**
     * WARNING is a message level indicating a potential problem.
     * <p>
     * In general WARNING messages should describe events that will
     * be of interest to end users or system managers, or which
     * indicate potential problems.
     * This level is initialized to <CODE>900</CODE>.
     */
    public static final Level WARNING = new Level("WARNING", 900, defaultBundle);

    /**
     * INFO is a message level for informational messages.
     * <p>
     * Typically INFO messages will be written to the console
     * or its equivalent.  So the INFO level should only be 
     * used for reasonably significant messages that will
     * make sense to end users and system admins.
     * This level is initialized to <CODE>800</CODE>.
     */
    public static final Level INFO = new Level("INFO", 800, defaultBundle);

    /**
     * CONFIG is a message level for static configuration messages.
     * <p>
     * CONFIG messages are intended to provide a variety of static
     * configuration information, to assist in debugging problems
     * that may be associated with particular configurations.
     * For example, CONFIG message might include the CPU type,
     * the graphics depth, the GUI look-and-feel, etc.
     * This level is initialized to <CODE>700</CODE>. 
     */
    public static final Level CONFIG = new Level("CONFIG", 700, defaultBundle);

    /**
     * FINE is a message level providing tracing information.
     * <p>
     * All of FINE, FINER, and FINEST are intended for relatively
     * detailed tracing.  The exact meaning of the three levels will
     * vary between subsystems, but in general, FINEST should be used
     * for the most voluminous detailed output, FINER for somewhat
     * less detailed output, and FINE for the  lowest volume (and
     * most important) messages.
     * <p>
     * In general the FINE level should be used for information
     * that will be broadly interesting to developers who do not have
     * a specialized interest in the specific subsystem.
     * <p>
     * FINE messages might include things like minor (recoverable)
     * failures.  Issues indicating potential performance problems
     * are also worth logging as FINE.
     * This level is initialized to <CODE>500</CODE>.
     */
    public static final Level FINE = new Level("FINE", 500, defaultBundle);

    /**
     * FINER indicates a fairly detailed tracing message.
     * By default logging calls for entering, returning, or throwing
     * an exception are traced at this level.
     * This level is initialized to <CODE>400</CODE>.
     */
    public static final Level FINER = new Level("FINER", 400, defaultBundle);

    /**
     * FINEST indicates a highly detailed tracing message.
     * This level is initialized to <CODE>300</CODE>. 
     */
    public static final Level FINEST = new Level("FINEST", 300, defaultBundle);

    /**
     * ALL indicates that all messages should be logged.
     * This level is initialized to <CODE>Integer.MIN_VALUE</CODE>.
     */
    public static final Level ALL = new Level("ALL", Integer.MIN_VALUE, defaultBundle);

    /**
     * Create a named Level with a given integer value.
     * <p>
     * Note that this constructor is "protected" to allow subclassing.
     * In general clients of logging should use one of the constant Level
     * objects such as SEVERE or FINEST.  However, if clients need to
     * add new logging levels, they may subclass Level and define new
     * constants.
     * @param name  the name of the Level, for example "SEVERE".
     * @param value an integer value for the level.
     */
    protected Level(String name, int value) {
	this(name, value, null);
    }

    /**
     * Create a named Level with a given integer value and a
     * given localization resource name.
     * <p>
     * @param name  the name of the Level, for example "SEVERE".
     * @param value an integer value for the level.
     * @param resourceBundleName name of a resource bundle to use in
     *    localizing the given name (may be null).
     */
    protected Level(String name, int value, String resourceBundleName) {
        this.name = name;
        this.value = value;
	this.resourceBundleName = resourceBundleName;
	synchronized (Level.class) {
	    known.add(this);
	}
    }

    /**
     * Return the level's localization resource bundle name, or
     * null if no localization bundle is defined.
     *
     * @return localization resource bundle name
     */
    public String getResourceBundleName() {
	return resourceBundleName;
    }

    /**
     * Return the non-localized string name of the Level.
     *
     * @return non-localized name
     */
    public String getName() {
	return name;
    }

    /**
     * Return the localized string name of the Level, for
     * the current default locale. 
     * <p>
     * If no localization information is available, the
     * non-localized name is returned.
     *
     * @return localized name
     */
    public String getLocalizedName() {
	try {
	    ResourceBundle rb = ResourceBundle.getBundle(resourceBundleName);
	    return rb.getString(name);
	} catch (Exception ex) {
	    return name;
	}
    }

    /**
     * @return the non-localized name of the Level, for example "INFO".
     */
    public final String toString() {
	return name;
    }

    /**
     * Get the integer value for this level.  This integer value
     * can be used for efficient ordering comparisons between
     * Level objects.
     * @return the integer value for this level.
     */
    public final int intValue() {
	return value;
    }

    // Serialization magic to prevent "doppelgangers".
    // This is a peformance optimization.
    private Object readResolve() {
	synchronized (Level.class) {
	    for (int i = 0; i < known.size(); i++) {
		Level other = (Level) known.get(i);
		if (this.name.equals(other.name) && this.value == other.value
			&& (this.resourceBundleName == other.resourceBundleName ||
			    (this.resourceBundleName != null &&
			    this.resourceBundleName.equals(other.resourceBundleName)))) {
		    return other;
		}
	    }
	    // Woops.  Whoever sent us this object knows 
	    // about a new log level.  Add it to our list.
	    known.add(this);
	    return this;
	}
    }

    /**
     * Parse a level name string into a Level.
     * <p>
     * The argument string may consist of either a level name
     * or an integer value.
     * <p>
     * For example:
     * <ul>
     * <li>	"SEVERE"
     * <li>	"1000"
     * </ul>
     * @param  name   string to be parsed
     * @return parsed value
     * @throws NullPointerException if the name is null
     * @throws IllegalArgumentException if the value is neither one of the
     *		known names nor an integer.
     */
    public static synchronized Level parse(String name) throws IllegalArgumentException {
	// Check that name is not null.
	name.length();

	// Look for a known Level with the given non-localized name.
	for (int i = 0; i < known.size(); i++) {
	    Level l = (Level) known.get(i);
	    if (name.equals(l.name)) {
		return l;
	    }
	}

	// Now, check if the given name is an integer.  If so,
	// first look for a Level with the given value and then
	// if necessary create one.
	try {
	    int x = Integer.parseInt(name);
	    for (int i = 0; i < known.size(); i++) {
	        Level l = (Level) known.get(i);
		if (l.value == x) {
		    return l;
		}
	    }	
	    // Create a new Level.
	    return new Level(name, x);
	} catch (NumberFormatException ex) {
	    // Not an integer.
	    // Drop through.
	}

	// Finally, look for a known level with the given localized name,
	// in the current default locale.
	// This is relatively expensive, but not excessively so.
	for (int i = 0; i < known.size(); i++) {
	    Level l = (Level) known.get(i);
	    if (name.equals(l.getLocalizedName())) {
		return l;
	    }
	}

        // OK, we'ved tried everything and failed
        throw new IllegalArgumentException("Bad level \"" + name + "\"");
    }

    /**
     * Compare two objects for value equality.
     * @return true if and only if the two objects have the same level value.
     */
    public boolean equals(Object ox) {
	try {
	    Level lx = (Level)ox;
	    return (lx.value == this.value);
	} catch (Exception ex) {
	    return false;
	}
    }

    /**
     * Generate a hashcode.
     * @return a hashcode based on the level value
     */
    public int hashCode() {
	return this.value;
    }
}