Client applications can get named loggers by calling the {@code getLogger} * methods. They can also get anonymous loggers by calling the * {@code getAnonymousLogger} methods. Named loggers are organized in a * namespace hierarchy managed by a log manager. The naming convention is * usually the Java package naming convention. Anonymous loggers do not belong to any namespace. * *
Developers should use named loggers to enable logging to be controlled on a * per-{@code Logger} granularity. The recommended idiom is to create and assign the logger to * a {@code static final} field. This ensures that there's always a strong reference to the logger, * preventing it from being garbage collected. In particular, {@link LogManager#addLogger(Logger)} * will not keep your logger live. * *
Loggers "inherit" log level setting from their parent if their own level is * set to {@code null}. This is also true for the resource bundle. The logger's * resource bundle is used to localize the log messages if no resource bundle * name is given when a log method is called. If {@code getUseParentHandlers()} * returns {@code true}, loggers also inherit their parent's handlers. In this * context, "inherit" only means that "behavior" is inherited. The internal * field values will not change, for example, {@code getLevel()} still returns * {@code null}. *
* When loading a given resource bundle, the logger first tries to use the * context {@code ClassLoader}. If that fails, it tries the system {@code ClassLoader}. And if * that still fails, it searches up the class stack and uses each class's * {@code ClassLoader} to try to locate the resource bundle. *
* Some log methods accept log requests that do not specify the source class and * source method. In these cases, the logging framework will automatically infer * the calling class and method, but this is not guaranteed to be accurate. *
* Once a {@code LogRecord} object has been passed into the logging framework, * it is owned by the logging framework and the client applications should not * use it any longer. *
* All methods of this class are thread-safe. * * @see LogManager */ public class Logger { /** A handler for use when no handler optimization is possible. */ private static final DalvikLogHandler GENERAL_LOG_HANDLER = new DalvikLogHandler() { public void publish(Logger source, String tag, Level level, String message) { LogRecord record = new LogRecord(level, message); record.setLoggerName(source.name); source.setResourceBundle(record); source.log(record); } }; /** * The name of the global logger. Before using this, see the discussion of how to use * {@code Logger} in the class documentation. * @since 1.6 */ public static final String GLOBAL_LOGGER_NAME = "global"; /** * The global logger is provided as convenience for casual use. * @deprecated This is deadlock-prone. Use {@code Logger.getLogger(Logger.GLOBAL_LOGGER_NAME)} * as a direct replacement, but read the discussion of how to use {@link Logger} in the class * documentation. */ @Deprecated public static final Logger global = new Logger(GLOBAL_LOGGER_NAME, null); /** * When converting the concurrent collection of handlers to an array, we * always pass a zero-length array to avoid size miscalculations. Passing * properly-sized arrays is non-atomic, and risks a null element in the * result. */ private static final Handler[] EMPTY_HANDLERS_ARRAY = new Handler[0]; /** The name of this logger. */ private volatile String name; /** The parent logger of this logger. */ Logger parent; /** The logging level of this logger, or null if none is set. */ volatile Level levelObjVal; /** * The effective logging level of this logger. In order of preference this * is the first applicable of: *
This optimization has been measured to show a 2.75x improvement in * throughput in the common case: 154ns vs. 56ns per message on a Cortex-A8. * Direct use of {@code android.util.Log} takes 29ns per message. * *
Each time the handler configuration changes, either directly or
* indirectly, it's necessary to either turn on or off this optimization.
* When the optimization is off, {@link #dalvikLogHandler} is assigned to
* {@link #GENERAL_LOG_HANDLER} which can satisfy arbitrary configuration.
* When the optimization is possible, {@link #dalvikLogHandler} is assigned
* to the user's efficient implementation. In pratice this is usually the
* {@code com.android.internal.logging.AndroidHandler}.
*/
void updateDalvikLogHandler() {
DalvikLogHandler newLogHandler = GENERAL_LOG_HANDLER;
Logger parent = this.parent;
if (getClass() != Logger.class) {
/*
* Do nothing. Subclasses aren't eligible for the optimization
* because they may override methods like getHandlers() or
* log(LogRecord).
*/
} else if (parent == null) {
// we use an iterator rather than size()+get() for safe concurrency
Iterator
* Notice : Loggers use a naming hierarchy. Thus "z.x.y" is a child of "z.x".
*
* @param name
* the name of this logger, may be {@code null} for anonymous
* loggers.
* @param resourceBundleName
* the name of the resource bundle used to localize logging
* messages, may be {@code null}.
* @throws MissingResourceException
* if the specified resource bundle can not be loaded.
*/
protected Logger(String name, String resourceBundleName) {
this.name = name;
initResourceBundle(resourceBundleName);
this.androidTag = DalvikLogging.loggerNameToTag(name);
updateDalvikLogHandler();
}
/**
* Load the specified resource bundle, use privileged code.
*
* @param resourceBundleName
* the name of the resource bundle to load, cannot be {@code null}.
* @return the loaded resource bundle.
* @throws MissingResourceException
* if the specified resource bundle can not be loaded.
*/
static ResourceBundle loadResourceBundle(String resourceBundleName) {
// try context class loader to load the resource
ClassLoader cl = Thread.currentThread().getContextClassLoader();
if (cl != null) {
try {
return ResourceBundle.getBundle(resourceBundleName, Locale.getDefault(), cl);
} catch (MissingResourceException ignored) {
// Failed to load using context class loader, ignore
}
}
// try system class loader to load the resource
cl = ClassLoader.getSystemClassLoader();
if (cl != null) {
try {
return ResourceBundle.getBundle(resourceBundleName, Locale.getDefault(), cl);
} catch (MissingResourceException ignored) {
// Failed to load using system class loader, ignore
}
}
throw new MissingResourceException("Failed to load the specified resource bundle \"" +
resourceBundleName + "\"", resourceBundleName, null);
}
/**
* Gets an anonymous logger to use internally in a thread. Anonymous loggers
* are not registered in the log manager's namespace. No security checks
* will be performed when updating an anonymous logger's control settings.
*
* The anonymous loggers' parent is set to be the root logger. This way it
* inherits the default logging level and handlers from the root logger.
*
* @return a new instance of anonymous logger.
*/
public static Logger getAnonymousLogger() {
return getAnonymousLogger(null);
}
/**
* Gets an anonymous logger to use internally in a thread. Anonymous loggers
* are not registered in the log manager's namespace. No security checks
* will be performed when updating an anonymous logger's control settings.
*
* The anonymous loggers' parent is set to be the root logger. This way it
* inherits default logging level and handlers from the root logger.
*
* @param resourceBundleName
* the name of the resource bundle used to localize log messages.
* @return a new instance of anonymous logger.
* @throws MissingResourceException
* if the specified resource bundle can not be loaded.
*/
public static Logger getAnonymousLogger(String resourceBundleName) {
Logger result = new Logger(null, resourceBundleName);
result.isNamed = false;
LogManager logManager = LogManager.getLogManager();
logManager.setParent(result, logManager.getLogger(""));
return result;
}
/**
* Initializes this logger's resource bundle.
*
* @throws IllegalArgumentException if this logger's resource bundle already
* exists and is different from the resource bundle specified.
*/
private synchronized void initResourceBundle(String resourceBundleName) {
String current = this.resourceBundleName;
if (current != null) {
if (current.equals(resourceBundleName)) {
return;
} else {
throw new IllegalArgumentException("Resource bundle name '" + resourceBundleName + "' is inconsistent with the existing '" + current + "'");
}
}
if (resourceBundleName != null) {
this.resourceBundle = loadResourceBundle(resourceBundleName);
this.resourceBundleName = resourceBundleName;
}
}
/**
* Gets a named logger. The returned logger may already exist or may be
* newly created. In the latter case, its level will be set to the
* configured level according to the {@code LogManager}'s properties.
*
* @param name
* the name of the logger to get, cannot be {@code null}.
* @return a named logger.
* @throws MissingResourceException
* If the specified resource bundle can not be loaded.
*/
public static Logger getLogger(String name) {
return LogManager.getLogManager().getOrCreate(name, null);
}
/**
* Gets a named logger associated with the supplied resource bundle. The
* resource bundle will be used to localize logging messages.
*
* @param name
* the name of the logger to get, cannot be {@code null}.
* @param resourceBundleName
* the name of the resource bundle, may be {@code null}.
* @throws IllegalArgumentException
* if the logger identified by {@code name} is associated with a
* resource bundle and its name is not equal to
* {@code resourceBundleName}.
* @throws MissingResourceException
* if the name of the resource bundle cannot be found.
* @return a named logger.
*/
public static Logger getLogger(String name, String resourceBundleName) {
Logger result = LogManager.getLogManager()
.getOrCreate(name, resourceBundleName);
result.initResourceBundle(resourceBundleName);
return result;
}
/**
* Returns the global {@code Logger}.
* @since 1.7
*/
public static Logger getGlobal() {
return global;
}
/**
* Adds a handler to this logger. The {@code name} will be fed with log
* records received by this logger.
*
* @param handler
* the handler object to add, cannot be {@code null}.
*/
public void addHandler(Handler handler) {
if (handler == null) {
throw new NullPointerException("handler == null");
}
// Anonymous loggers can always add handlers
if (this.isNamed) {
LogManager.getLogManager().checkAccess();
}
this.handlers.add(handler);
updateDalvikLogHandler();
}
/**
* Set the logger's manager and initializes its configuration from the
* manager's properties.
*/
void setManager(LogManager manager) {
String levelProperty = manager.getProperty(name + ".level");
if (levelProperty != null) {
try {
manager.setLevelRecursively(Logger.this, Level.parse(levelProperty));
} catch (IllegalArgumentException invalidLevel) {
invalidLevel.printStackTrace();
}
}
String handlersPropertyName = name.isEmpty() ? "handlers" : name + ".handlers";
String handlersProperty = manager.getProperty(handlersPropertyName);
if (handlersProperty != null) {
for (String handlerName : handlersProperty.split(",|\\s")) {
if (handlerName.isEmpty()) {
continue;
}
final Handler handler;
try {
handler = (Handler) LogManager.getInstanceByClass(handlerName);
} catch (Exception invalidHandlerName) {
invalidHandlerName.printStackTrace();
continue;
}
try {
String level = manager.getProperty(handlerName + ".level");
if (level != null) {
handler.setLevel(Level.parse(level));
}
} catch (Exception invalidLevel) {
invalidLevel.printStackTrace();
}
handlers.add(handler);
}
}
updateDalvikLogHandler();
}
/**
* Gets all the handlers associated with this logger.
*
* @return an array of all the handlers associated with this logger.
*/
public Handler[] getHandlers() {
return handlers.toArray(EMPTY_HANDLERS_ARRAY);
}
/**
* Removes a handler from this logger. If the specified handler does not
* exist then this method has no effect.
*
* @param handler
* the handler to be removed.
*/
public void removeHandler(Handler handler) {
// Anonymous loggers can always remove handlers
if (this.isNamed) {
LogManager.getLogManager().checkAccess();
}
if (handler == null) {
return;
}
this.handlers.remove(handler);
updateDalvikLogHandler();
}
/**
* Gets the filter used by this logger.
*
* @return the filter used by this logger, may be {@code null}.
*/
public Filter getFilter() {
return this.filter;
}
/**
* Sets the filter used by this logger.
*
* @param newFilter
* the filter to set, may be {@code null}.
*/
public void setFilter(Filter newFilter) {
// Anonymous loggers can always set the filter
if (this.isNamed) {
LogManager.getLogManager().checkAccess();
}
filter = newFilter;
}
/**
* Gets the logging level of this logger. A {@code null} level indicates
* that this logger inherits its parent's level.
*
* @return the logging level of this logger.
*/
public Level getLevel() {
return levelObjVal;
}
/**
* Sets the logging level for this logger. A {@code null} level indicates
* that this logger will inherit its parent's level.
*
* @param newLevel
* the logging level to set.
*/
public void setLevel(Level newLevel) {
// Anonymous loggers can always set the level
LogManager logManager = LogManager.getLogManager();
if (this.isNamed) {
logManager.checkAccess();
}
logManager.setLevelRecursively(this, newLevel);
}
/**
* Gets the flag which indicates whether to use the handlers of this
* logger's parent to publish incoming log records, potentially recursively
* up the namespace.
*
* @return {@code true} if set to use parent's handlers, {@code false}
* otherwise.
*/
public boolean getUseParentHandlers() {
return this.notifyParentHandlers;
}
/**
* Sets the flag which indicates whether to use the handlers of this
* logger's parent, potentially recursively up the namespace.
*
* @param notifyParentHandlers
* the new flag indicating whether to use the parent's handlers.
*/
public void setUseParentHandlers(boolean notifyParentHandlers) {
// Anonymous loggers can always set the useParentHandlers flag
if (this.isNamed) {
LogManager.getLogManager().checkAccess();
}
this.notifyParentHandlers = notifyParentHandlers;
updateDalvikLogHandler();
}
/**
* Gets the nearest parent of this logger in the namespace, a {@code null}
* value will be returned if called on the root logger.
*
* @return the parent of this logger in the namespace.
*/
public Logger getParent() {
return parent;
}
/**
* Sets the parent of this logger in the namespace. This method should be
* used by the {@code LogManager} object only.
*
* @param parent
* the parent logger to set.
*/
public void setParent(Logger parent) {
if (parent == null) {
throw new NullPointerException("parent == null");
}
// even anonymous loggers are checked
LogManager logManager = LogManager.getLogManager();
logManager.checkAccess();
logManager.setParent(this, parent);
}
/**
* Gets the name of this logger, {@code null} for anonymous loggers.
*
* @return the name of this logger.
*/
public String getName() {
return this.name;
}
/**
* Gets the loaded resource bundle used by this logger to localize logging
* messages. If the value is {@code null}, the parent's resource bundle will be
* inherited.
*
* @return the loaded resource bundle used by this logger.
*/
public ResourceBundle getResourceBundle() {
return this.resourceBundle;
}
/**
* Gets the name of the loaded resource bundle used by this logger to
* localize logging messages. If the value is {@code null}, the parent's resource
* bundle name will be inherited.
*
* @return the name of the loaded resource bundle used by this logger.
*/
public String getResourceBundleName() {
return this.resourceBundleName;
}
/**
* This method is for compatibility. Tests written to the reference
* implementation API imply that the isLoggable() method is not called
* directly. This behavior is important because subclass may override
* isLoggable() method, so that affect the result of log methods.
*/
private boolean internalIsLoggable(Level l) {
int effectiveLevel = levelIntVal;
if (effectiveLevel == Level.OFF.intValue()) {
// always return false if the effective level is off
return false;
}
return l.intValue() >= effectiveLevel;
}
/**
* Determines whether this logger will actually log messages of the
* specified level. The effective level used to do the determination may be
* inherited from its parent. The default level is {@code Level.INFO}.
*
* @param l
* the level to check.
* @return {@code true} if this logger will actually log this level,
* otherwise {@code false}.
*/
public boolean isLoggable(Level l) {
return internalIsLoggable(l);
}
/**
* Sets the resource bundle and its name for a supplied LogRecord object.
* This method first tries to use this logger's resource bundle if any,
* otherwise try to inherit from this logger's parent, recursively up the
* namespace.
*/
private void setResourceBundle(LogRecord record) {
for (Logger p = this; p != null; p = p.parent) {
String resourceBundleName = p.resourceBundleName;
if (resourceBundleName != null) {
record.setResourceBundle(p.resourceBundle);
record.setResourceBundleName(resourceBundleName);
return;
}
}
}
/**
* Logs a message indicating that a method has been entered. A log record
* with log level {@code Level.FINER}, log message "ENTRY", the specified
* source class name and source method name is submitted for logging.
*
* @param sourceClass
* the calling class name.
* @param sourceMethod
* the method name.
*/
public void entering(String sourceClass, String sourceMethod) {
if (!internalIsLoggable(Level.FINER)) {
return;
}
LogRecord record = new LogRecord(Level.FINER, "ENTRY");
record.setLoggerName(this.name);
record.setSourceClassName(sourceClass);
record.setSourceMethodName(sourceMethod);
setResourceBundle(record);
log(record);
}
/**
* Logs a message indicating that a method has been entered. A log record
* with log level {@code Level.FINER}, log message "ENTRY", the specified
* source class name, source method name and one parameter is submitted for
* logging.
*
* @param sourceClass
* the source class name.
* @param sourceMethod
* the source method name.
* @param param
* the parameter for the method call.
*/
public void entering(String sourceClass, String sourceMethod, Object param) {
if (!internalIsLoggable(Level.FINER)) {
return;
}
LogRecord record = new LogRecord(Level.FINER, "ENTRY" + " {0}");
record.setLoggerName(this.name);
record.setSourceClassName(sourceClass);
record.setSourceMethodName(sourceMethod);
record.setParameters(new Object[] { param });
setResourceBundle(record);
log(record);
}
/**
* Logs a message indicating that a method has been entered. A log record
* with log level {@code Level.FINER}, log message "ENTRY", the specified
* source class name, source method name and array of parameters is
* submitted for logging.
*
* @param sourceClass
* the source class name.
* @param sourceMethod
* the source method name.
* @param params
* an array of parameters for the method call.
*/
public void entering(String sourceClass, String sourceMethod,
Object[] params) {
if (!internalIsLoggable(Level.FINER)) {
return;
}
String msg = "ENTRY";
if (params != null) {
StringBuilder msgBuffer = new StringBuilder("ENTRY");
for (int i = 0; i < params.length; i++) {
msgBuffer.append(" {").append(i).append("}");
}
msg = msgBuffer.toString();
}
LogRecord record = new LogRecord(Level.FINER, msg);
record.setLoggerName(this.name);
record.setSourceClassName(sourceClass);
record.setSourceMethodName(sourceMethod);
record.setParameters(params);
setResourceBundle(record);
log(record);
}
/**
* Logs a message indicating that a method is exited. A log record with log
* level {@code Level.FINER}, log message "RETURN", the specified source
* class name and source method name is submitted for logging.
*
* @param sourceClass
* the calling class name.
* @param sourceMethod
* the method name.
*/
public void exiting(String sourceClass, String sourceMethod) {
if (!internalIsLoggable(Level.FINER)) {
return;
}
LogRecord record = new LogRecord(Level.FINER, "RETURN");
record.setLoggerName(this.name);
record.setSourceClassName(sourceClass);
record.setSourceMethodName(sourceMethod);
setResourceBundle(record);
log(record);
}
/**
* Logs a message indicating that a method is exited. A log record with log
* level {@code Level.FINER}, log message "RETURN", the specified source
* class name, source method name and return value is submitted for logging.
*
* @param sourceClass
* the source class name.
* @param sourceMethod
* the source method name.
* @param result
* the return value of the method call.
*/
public void exiting(String sourceClass, String sourceMethod, Object result) {
if (!internalIsLoggable(Level.FINER)) {
return;
}
LogRecord record = new LogRecord(Level.FINER, "RETURN" + " {0}");
record.setLoggerName(this.name);
record.setSourceClassName(sourceClass);
record.setSourceMethodName(sourceMethod);
record.setParameters(new Object[] { result });
setResourceBundle(record);
log(record);
}
/**
* Logs a message indicating that an exception is thrown. A log record with
* log level {@code Level.FINER}, log message "THROW", the specified source
* class name, source method name and the {@code Throwable} object is
* submitted for logging.
*
* @param sourceClass
* the source class name.
* @param sourceMethod
* the source method name.
* @param thrown
* the {@code Throwable} object.
*/
public void throwing(String sourceClass, String sourceMethod,
Throwable thrown) {
if (!internalIsLoggable(Level.FINER)) {
return;
}
LogRecord record = new LogRecord(Level.FINER, "THROW");
record.setLoggerName(this.name);
record.setSourceClassName(sourceClass);
record.setSourceMethodName(sourceMethod);
record.setThrown(thrown);
setResourceBundle(record);
log(record);
}
/**
* Logs a message of level {@code Level.SEVERE}; the message is transmitted
* to all subscribed handlers.
*
* @param msg
* the message to log.
*/
public void severe(String msg) {
log(Level.SEVERE, msg);
}
/**
* Logs a message of level {@code Level.WARNING}; the message is
* transmitted to all subscribed handlers.
*
* @param msg
* the message to log.
*/
public void warning(String msg) {
log(Level.WARNING, msg);
}
/**
* Logs a message of level {@code Level.INFO}; the message is transmitted
* to all subscribed handlers.
*
* @param msg
* the message to log.
*/
public void info(String msg) {
log(Level.INFO, msg);
}
/**
* Logs a message of level {@code Level.CONFIG}; the message is transmitted
* to all subscribed handlers.
*
* @param msg
* the message to log.
*/
public void config(String msg) {
log(Level.CONFIG, msg);
}
/**
* Logs a message of level {@code Level.FINE}; the message is transmitted
* to all subscribed handlers.
*
* @param msg
* the message to log.
*/
public void fine(String msg) {
log(Level.FINE, msg);
}
/**
* Logs a message of level {@code Level.FINER}; the message is transmitted
* to all subscribed handlers.
*
* @param msg
* the message to log.
*/
public void finer(String msg) {
log(Level.FINER, msg);
}
/**
* Logs a message of level {@code Level.FINEST}; the message is transmitted
* to all subscribed handlers.
*
* @param msg
* the message to log.
*/
public void finest(String msg) {
log(Level.FINEST, msg);
}
/**
* Logs a message of the specified level. The message is transmitted to all
* subscribed handlers.
*
* @param logLevel
* the level of the specified message.
* @param msg
* the message to log.
*/
public void log(Level logLevel, String msg) {
if (!internalIsLoggable(logLevel)) {
return;
}
dalvikLogHandler.publish(this, androidTag, logLevel, msg);
}
/**
* Logs a message of the specified level with the supplied parameter. The
* message is then transmitted to all subscribed handlers.
*
* @param logLevel
* the level of the given message.
* @param msg
* the message to log.
* @param param
* the parameter associated with the event that is logged.
*/
public void log(Level logLevel, String msg, Object param) {
if (!internalIsLoggable(logLevel)) {
return;
}
LogRecord record = new LogRecord(logLevel, msg);
record.setLoggerName(this.name);
record.setParameters(new Object[] { param });
setResourceBundle(record);
log(record);
}
/**
* Logs a message of the specified level with the supplied parameter array.
* The message is then transmitted to all subscribed handlers.
*
* @param logLevel
* the level of the given message
* @param msg
* the message to log.
* @param params
* the parameter array associated with the event that is logged.
*/
public void log(Level logLevel, String msg, Object[] params) {
if (!internalIsLoggable(logLevel)) {
return;
}
LogRecord record = new LogRecord(logLevel, msg);
record.setLoggerName(this.name);
record.setParameters(params);
setResourceBundle(record);
log(record);
}
/**
* Logs a message of the specified level with the supplied {@code Throwable}
* object. The message is then transmitted to all subscribed handlers.
*
* @param logLevel
* the level of the given message.
* @param msg
* the message to log.
* @param thrown
* the {@code Throwable} object associated with the event that is
* logged.
*/
public void log(Level logLevel, String msg, Throwable thrown) {
if (!internalIsLoggable(logLevel)) {
return;
}
LogRecord record = new LogRecord(logLevel, msg);
record.setLoggerName(this.name);
record.setThrown(thrown);
setResourceBundle(record);
log(record);
}
/**
* Logs a given log record. Only records with a logging level that is equal
* or greater than this logger's level will be submitted to this logger's
* handlers for logging. If {@code getUseParentHandlers()} returns {@code
* true}, the log record will also be submitted to the handlers of this
* logger's parent, potentially recursively up the namespace.
*
* Since all other log methods call this method to actually perform the
* logging action, subclasses of this class can override this method to
* catch all logging activities.
*