4. Level 클래스

public void log(Level level, String msg) {  
    if (!isLoggable(level)) { // 로깅 허용 레벨이 아닐 경우 폐기
        return;  
    }  
    LogRecord lr = new LogRecord(level, msg);  
    doLog(lr);  
}

public class Level implements java.io.Serializable {
 
    /**
     * @serial  The non-localized name of the level.
     * 로그 레벨의 이름
     */
    private final String name;
 
    /**
     * @serial  The integer value of the level.
     * 각 레벨이 가진 정수형 숫자 값
     */
    private final int value;
 
    /**
     * @serial The resource bundle name to be used in localizing the level name.
     * 리소스 번들이름 - 주로 국제화(Localization)에서 사용되는 객체 
     */
    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>.
     * OFF - 로깅 처리를 비활성화 할 때 사용
     */
    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>.
     * SEVERE - 가장 심각한 수준의 내용을 로깅할 때 사용
     */
    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>.
     * WARNING - 잠재적인 문제가 발생할 수 있는 내용 로깅 시 사용
     */
    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 administrators.
     * This level is initialized to <CODE>800</CODE>.
     * INFO - 일반적인 정보를 남기는 로깅 수행 시 사용
     */
    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>.
     * CONFIG - 정적인 설정 정보를 로깅할 때 사용
     */
    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>.
     * FINE, FINER, FINEST - 상세한 추적 정보 로깅 시 사용
     */
    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>.
     * ALL - 모든 수준의 로그 기록 출력
     */
    public static final Level ALL = new Level("ALL", Integer.MIN_VALUE, defaultBundle);
}