com.cookingfox.logging.Logger Maven / Gradle / Ivy
package com.cookingfox.logging;
import com.cookingfox.logging.api.Entry;
import com.cookingfox.logging.api.LoggerAdapter;
/**
* Helper class for logging. Use {@link #init()} to initialize and configure the Logger. Use the
* other static methods for logging.
*
* @see Level
*/
public final class Logger {
//----------------------------------------------------------------------------------------------
// PRIVATE STATIC PROPERTIES
//----------------------------------------------------------------------------------------------
/**
* Static Logger instance (singleton).
*/
private static Logger INSTANCE;
/**
* Name of this class, used for filtering the stack trace entries when trying to determine the
* calling class name.
*
* @see #getCallerStackTrace()
*/
private static final String LOGGER_CLASS_NAME = Logger.class.getName();
/**
* The stack trace always includes a few entries that are related to the Logger internals, so
* these can be skipped when trying to determine the calling class name.
*
* @see #getCallerStackTrace()
*/
private static final int MIN_STACK_OFFSET = 3;
//----------------------------------------------------------------------------------------------
// INTERNAL STATIC METHODS
//----------------------------------------------------------------------------------------------
/**
* Creates and / or returns the singleton Logger instance.
*/
static Logger getInstance() {
return INSTANCE == null ? INSTANCE = new Logger() : INSTANCE;
}
/**
* Resets the logger. Only for internal use.
*/
static void reset() {
INSTANCE = null;
}
//----------------------------------------------------------------------------------------------
// PUBLIC STATIC METHODS
//----------------------------------------------------------------------------------------------
/**
* Initializes the Logger and returns its {@link Settings} object. Use the Settings object to
* add adapters and configure the behavior of the logger.
*/
public static Settings init() {
return getInstance().settings;
}
/**
* Log a message at debug level.
*
* @param message The message to log.
* @param args Values that need to be included in the log message
* (through {@link String#format(String, Object...)}).
* @see Level#DEBUG
*/
public static void debug(String message, Object... args) {
getInstance().log(Level.DEBUG, message, args);
}
/**
* Log a message at error level.
*
* @param message The message to log.
* @param args Values that need to be included in the log message
* (through {@link String#format(String, Object...)}).
* @see Level#ERROR
*/
public static void error(String message, Object... args) {
getInstance().log(Level.ERROR, message, args);
}
/**
* Log a message at info level.
*
* @param message The message to log.
* @param args Values that need to be included in the log message
* (through {@link String#format(String, Object...)}).
* @see Level#INFO
*/
public static void info(String message, Object... args) {
getInstance().log(Level.INFO, message, args);
}
/**
* Log a message at verbose level.
*
* @param message The message to log.
* @param args Values that need to be included in the log message
* (through {@link String#format(String, Object...)}).
* @see Level#VERBOSE
*/
public static void verbose(String message, Object... args) {
getInstance().log(Level.VERBOSE, message, args);
}
/**
* Log a message at warning level.
*
* @param message The message to log.
* @param args Values that need to be included in the log message
* (through {@link String#format(String, Object...)}).
* @see Level#WARN
*/
public static void warn(String message, Object... args) {
getInstance().log(Level.WARN, message, args);
}
//----------------------------------------------------------------------------------------------
// PRIVATE PROPERTIES
//----------------------------------------------------------------------------------------------
/**
* Logger configuration helper.
*/
private final Settings settings;
//----------------------------------------------------------------------------------------------
// CONSTRUCTOR
//----------------------------------------------------------------------------------------------
/**
* Private constructor: use the public static methods for access.
*/
private Logger() {
settings = new Settings();
}
//----------------------------------------------------------------------------------------------
// PRIVATE METHODS
//----------------------------------------------------------------------------------------------
/**
* Output the log message.
*
* @param level The logging level.
* @param message The message to log.
* @param args Values that need to be included in the log message
* (through {@link String#format(String, Object...)}).
*/
private void log(Level level, String message, Object... args) {
// disabled or no adapter: skip
if (!settings.enabled || settings.loggerAdapters.isEmpty()) {
return;
}
Entry entry = createLoggerEntry(message, args);
// call the log method corresponding to the level
for (LoggerAdapter loggerAdapter : settings.loggerAdapters) {
switch (level) {
case DEBUG:
loggerAdapter.debug(entry);
break;
case ERROR:
loggerAdapter.error(entry);
break;
case INFO:
loggerAdapter.info(entry);
break;
case VERBOSE:
loggerAdapter.verbose(entry);
break;
case WARN:
loggerAdapter.warn(entry);
break;
}
}
}
/**
* Create an Entry object using the logging parameters.
*
* @param message The message to log.
* @param args Values that need to be included in the log message
* (through {@link String#format(String, Object...)}).
*/
private Entry createLoggerEntry(String message, Object[] args) {
LoggerEntry entry = new LoggerEntry(message, args);
entry.defaultCallerClassName = LOGGER_CLASS_NAME;
entry.settings = settings;
entry.stackTrace = getCallerStackTrace();
return entry;
}
/**
* Finds the caller in the stack trace.
*
* @return The stack trace element of the caller.
*/
private StackTraceElement getCallerStackTrace() {
StackTraceElement[] stack = Thread.currentThread().getStackTrace();
// the first few entries of the stack trace are always related to the Logger process, so try
// to find the first entry that is not the Logger.
for (int i = MIN_STACK_OFFSET; i < stack.length - MIN_STACK_OFFSET; i++) {
StackTraceElement trace = stack[i];
if (!trace.getClassName().equals(LOGGER_CLASS_NAME)) {
return trace;
}
}
return null;
}
}
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