Java tutorial
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See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.util.logging; import java.io.*; import java.time.ZoneId; import java.time.ZonedDateTime; import jdk.internal.logger.SurrogateLogger; /** * Print a brief summary of the {@code LogRecord} in a human readable * format. The summary will typically be 1 or 2 lines. * * <p> * <a id="formatting"> * <b>Configuration:</b></a> * The {@code SimpleFormatter} is initialized with the format string * specified in the {@systemProperty java.util.logging.SimpleFormatter.format} * property to {@linkplain #format(LogRecord) format} the log messages. * This property can be defined * in the {@linkplain LogManager#getProperty logging properties} * configuration file * or as a system property. If this property is set in both * the logging properties and system properties, * the format string specified in the system property will be used. * If this property is not defined or the given format string * is {@linkplain java.util.IllegalFormatException illegal}, * the default format is implementation-specific. * * @since 1.4 * @see java.util.Formatter */ public class SimpleFormatter extends Formatter { // format string for printing the log record static String getLoggingProperty(String name) { return LogManager.getLogManager().getProperty(name); } private final String format = SurrogateLogger.getSimpleFormat(SimpleFormatter::getLoggingProperty); /** * Format the given LogRecord. * <p> * The formatting can be customized by specifying the format string * in the <a href="#formatting"> * {@code java.util.logging.SimpleFormatter.format}</a> property. * The given {@code LogRecord} will be formatted as if by calling: * <pre> * {@link String#format String.format}(format, date, source, logger, level, message, thrown); * </pre> * where the arguments are:<br> * <ol> * <li>{@code format} - the {@link java.util.Formatter * java.util.Formatter} format string specified in the * {@code java.util.logging.SimpleFormatter.format} property * or the default format.</li> * <li>{@code date} - a {@link ZonedDateTime} object representing * {@linkplain LogRecord#getInstant() event time} of the log record * in the {@link ZoneId#systemDefault()} system time zone.</li> * <li>{@code source} - a string representing the caller, if available; * otherwise, the logger's name.</li> * <li>{@code logger} - the logger's name.</li> * <li>{@code level} - the {@linkplain Level#getLocalizedName * log level}.</li> * <li>{@code message} - the formatted log message * returned from the {@link Formatter#formatMessage(LogRecord)} * method. It uses {@link java.text.MessageFormat java.text} * formatting and does not use the {@code java.util.Formatter * format} argument.</li> * <li>{@code thrown} - a string representing * the {@linkplain LogRecord#getThrown throwable} * associated with the log record and its backtrace * beginning with a newline character, if any; * otherwise, an empty string.</li> * </ol> * * <p>Some example formats:<br> * <ul> * <li> {@code java.util.logging.SimpleFormatter.format="%4$s: %5$s [%1$tc]%n"} * <p>This prints 1 line with the log level ({@code 4$}), * the log message ({@code 5$}) and the timestamp ({@code 1$}) in * a square bracket. * <pre> * WARNING: warning message [Tue Mar 22 13:11:31 PDT 2011] * </pre></li> * <li> {@code java.util.logging.SimpleFormatter.format="%1$tc %2$s%n%4$s: %5$s%6$s%n"} * <p>This prints 2 lines where the first line includes * the timestamp ({@code 1$}) and the source ({@code 2$}); * the second line includes the log level ({@code 4$}) and * the log message ({@code 5$}) followed with the throwable * and its backtrace ({@code 6$}), if any: * <pre> * Tue Mar 22 13:11:31 PDT 2011 MyClass fatal * SEVERE: several message with an exception * java.lang.IllegalArgumentException: invalid argument * at MyClass.mash(MyClass.java:9) * at MyClass.crunch(MyClass.java:6) * at MyClass.main(MyClass.java:3) * </pre></li> * <li> {@code java.util.logging.SimpleFormatter.format="%1$tb %1$td, %1$tY %1$tl:%1$tM:%1$tS %1$Tp %2$s%n%4$s: %5$s%n"} * <p>This prints 2 lines similar to the example above * with a different date/time formatting and does not print * the throwable and its backtrace: * <pre> * Mar 22, 2011 1:11:31 PM MyClass fatal * SEVERE: several message with an exception * </pre></li> * <li> {@code java.util.logging.SimpleFormatter.format="%1$tb %1$td, %1$tY %1$tl:%1$tM:%1$tS.%1$tN %1$Tp %2$s%n%4$s: %5$s%6$s%n"} * <p>Since JDK 9, {@code java.util.logging} uses {@link * java.time.Clock#systemUTC() java.time} to create more precise time * stamps. * The format above can be used to add a {@code .%1$tN} to the * date/time formatting so that nanoseconds will also be printed: * <pre> * Feb 06, 2015 5:33:10.279216000 PM example.Main main * INFO: This is a test * </pre></li> * </ul> * <p>This method can also be overridden in a subclass. * It is recommended to use the {@link Formatter#formatMessage} * convenience method to localize and format the message field. * * @param record the log record to be formatted. * @return a formatted log record */ @Override public String format(LogRecord record) { ZonedDateTime zdt = ZonedDateTime.ofInstant(record.getInstant(), ZoneId.systemDefault()); String source; if (record.getSourceClassName() != null) { source = record.getSourceClassName(); if (record.getSourceMethodName() != null) { source += " " + record.getSourceMethodName(); } } else { source = record.getLoggerName(); } String message = formatMessage(record); String throwable = ""; if (record.getThrown() != null) { StringWriter sw = new StringWriter(); PrintWriter pw = new PrintWriter(sw); pw.println(); record.getThrown().printStackTrace(pw); pw.close(); throwable = sw.toString(); } return String.format(format, zdt, source, record.getLoggerName(), record.getLevel().getLocalizedLevelName(), message, throwable); } }