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Google App Engine compliant variation of FreeMarker.
FreeMarker is a "template engine"; a generic tool to generate text output based on templates.
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package freemarker.log;
import java.security.AccessControlException;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.HashMap;
import java.util.Map;
/**
* Delegates logger creation to an actual logging library. By default it looks for logger libraries in this order (in
* FreeMarker 2.3.x): Log4J, Avalon LogKit, JUL (i.e., java.util.logging). Prior to FreeMarker 2.4, SLF4J and
* Apache Commons Logging aren't searched automatically due to backward compatibility constraints. But if you have
* {@code log4j-over-slf4j} properly installed (means, you have no real Log4j in your class path, and SLF4J has a
* backing implementation like {@code logback-classic}), then FreeMarker will use SLF4J directly instead of Log4j (since
* FreeMarker 2.3.22).
*
*
* If the auto detection sequence describet above doesn't give you the result that you want, see
* {@link #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY}.
*/
public abstract class Logger {
/**
* The {@value #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} system property is used to select a logger library explicitly,
* rather than relying on automatic selection. You meant to set this system property where the JVM is started, like
* {@code java ... -Dorg.freemarker.loggerLibrary=SLF4j}. Setting it from Java code isn't reliable, also it can
* cause confusion if you override the value set by others with {@code -D}.
*
*
* If the requested logging library is not available, an error will be printed to the stderr, then logging will be
* disabled.
*
*
* The supported values are:
*
* - {@value #LIBRARY_NAME_SLF4J}: Use SLF4J (recommended)
* - {@value #LIBRARY_NAME_COMMONS_LOGGING}: Use Apache Commons Logging.
* - {@value #LIBRARY_NAME_LOG4J}: Use Log4j.
* - {@value #LIBRARY_NAME_JUL}: Use {@code java.util.logging}.
* - {@value #LIBRARY_NAME_AVALON}: Use Avalon LogKit (deprecated)
* - {@value #LIBRARY_NAME_AUTO}: Use automatic selection (default behavior). See {@link Logger} class
* documentation for more.
* - {@value #LIBRARY_NAME_NONE}: Don't log.
*
*
* @since 2.3.22
*/
public static final String SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY = "org.freemarker.loggerLibrary";
/**
* Enum value used for {@link #selectLoggerLibrary(int)}; indicates auto-selection as described in the class
* documentation of {@link #Logger()}.
*/
public static final int LIBRARY_AUTO = -1;
private static final int MIN_LIBRARY_ENUM = LIBRARY_AUTO;
/**
* {@value #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} property value; indicates auto-selection as described in the class
* documentation of {@link #Logger()}. @since 2.3.22
*/
public static final String LIBRARY_NAME_AUTO = "auto";
/**
* Enum value used for {@link #selectLoggerLibrary(int)}; indicates that no logging should occur.
*/
public static final int LIBRARY_NONE = 0;
/**
* {@value #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} property value; indicates that no logging should occur. @since
* 2.3.22
*/
public static final String LIBRARY_NAME_NONE = "none";
/**
* Enum value used for {@link #selectLoggerLibrary(int)}; indicates that {@code java.util.logging} should be used.
*/
public static final int LIBRARY_JAVA = 1;
/**
* {@value #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} property value; indicates that {@code java.util.logging} should be
* used. @since 2.3.22
*/
public static final String LIBRARY_NAME_JUL = "JUL";
/**
* Enum value used for {@link #selectLoggerLibrary(int)}; indicates that Avalon LogKit should be used.
*
* @deprecated Avalon LogKit support will be removed sometimes in the future.
*/
@Deprecated
public static final int LIBRARY_AVALON = 2;
/**
* {@value #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} property value; indicates that Avalon LogKit should be used. @since
* 2.3.22
*
* @deprecated Avalon LogKit support will be removed sometimes in the future.
*/
// This value is also used as part of the factory class name.
@Deprecated
public static final String LIBRARY_NAME_AVALON = "Avalon";
/**
* Enum value used for {@link #selectLoggerLibrary(int)}; indicates that Log4J should be used.
*/
public static final int LIBRARY_LOG4J = 3;
/**
* {@value #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} property value; indicates that Log4J should be used. @since 2.3.22
*/
// This value is also used as part of the factory class name.
public static final String LIBRARY_NAME_LOG4J = "Log4j";
/**
* Enum value used for {@link #selectLoggerLibrary(int)}; indicates that Apache commons-logging should be used.
*/
public static final int LIBRARY_COMMONS = 4;
/**
* {@value #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} property value; indicates that Apache commons-logging should be
* used. @since 2.3.22
*/
// This value is also used as part of the factory class name.
public static final String LIBRARY_NAME_COMMONS_LOGGING = "CommonsLogging";
/**
* Constant used with {@link #selectLoggerLibrary(int)}; indicates that SLF4J should be used.
*/
public static final int LIBRARY_SLF4J = 5;
/**
* {@value #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} property value; indicates that SLF4J should be used. @since 2.3.22
*/
// This value is also used as part of the factory class name.
public static final String LIBRARY_NAME_SLF4J = "SLF4J";
private static final int MAX_LIBRARY_ENUM = LIBRARY_SLF4J;
private static final String REAL_LOG4J_PRESENCE_CLASS = "org.apache.log4j.FileAppender";
private static final String LOG4J_OVER_SLF4J_TESTER_CLASS = "freemarker.log._Log4jOverSLF4JTester";
/**
* Order matters! Starts with the lowest priority.
*/
private static final String[] LIBRARIES_BY_PRIORITY = {
null, LIBRARY_NAME_JUL,
"org.apache.log.Logger", LIBRARY_NAME_AVALON,
"org.apache.log4j.Logger", LIBRARY_NAME_LOG4J,
/* In 2.3.x this two is skipped by LIBRARY_AUTO: */
"org.apache.commons.logging.Log", LIBRARY_NAME_COMMONS_LOGGING,
"org.slf4j.Logger", LIBRARY_NAME_SLF4J,
};
private static String getAvailabilityCheckClassName(int libraryEnum) {
if (libraryEnum == LIBRARY_AUTO || libraryEnum == LIBRARY_NONE) {
// Statically linked
return null;
}
return LIBRARIES_BY_PRIORITY[(libraryEnum - 1) * 2];
}
static {
if (LIBRARIES_BY_PRIORITY.length / 2 != MAX_LIBRARY_ENUM) {
throw new AssertionError();
}
}
private static String getLibraryName(int libraryEnum) {
if (libraryEnum == LIBRARY_AUTO) {
return LIBRARY_NAME_AUTO;
}
if (libraryEnum == LIBRARY_NONE) {
return LIBRARY_NAME_NONE;
}
return LIBRARIES_BY_PRIORITY[(libraryEnum - 1) * 2 + 1];
}
private static boolean isAutoDetected(int libraryEnum) {
// 2.4: Remove libraryEnum == LIBRARY_SLF4J || libraryEnum == LIBRARY_COMMONS
return !(libraryEnum == LIBRARY_AUTO || libraryEnum == LIBRARY_NONE
|| libraryEnum == LIBRARY_SLF4J || libraryEnum == LIBRARY_COMMONS);
}
private static int libraryEnum;
private static LoggerFactory loggerFactory;
private static boolean initializedFromSystemProperty;
private static String categoryPrefix = "";
private static final Map loggersByCategory = new HashMap();
/**
* Selects the logger library to use, unless it's already specified by the
* {@value #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} system property. Call this early in application initialization
* phase, before calling any other FreeMarker API-s, since once parts of the FreeMarker library bind to the logging
* subsystem, the change in this value will have no effect on them.
*
* @param libraryEnum
* One of LIBRARY_... constants. By default, {@link #LIBRARY_AUTO} is used.
*
* @throws ClassNotFoundException
* if an explicit logging library is asked for (that is, not {@value #LIBRARY_AUTO} or
* {@value #LIBRARY_NONE}) and it's not found in the classpath.
*
* @deprecated This method isn't reliable, unless you can somehow ensure that you access the FreeMarker classes
* first; use the {@value #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} Java system property instead, like
* {@code java ... -Dorg.freemarker.loggerLibrary=slf4j}. See
* {@link #SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY} for more.
*/
@Deprecated
public static void selectLoggerLibrary(int libraryEnum) throws ClassNotFoundException {
if (libraryEnum < MIN_LIBRARY_ENUM || libraryEnum > MAX_LIBRARY_ENUM) {
throw new IllegalArgumentException("Library enum value out of range");
}
synchronized (Logger.class) {
final boolean loggerFactoryWasAlreadySet = loggerFactory != null;
if (!loggerFactoryWasAlreadySet || libraryEnum != Logger.libraryEnum) {
// Creates the factory only if it can be done based on system property:
ensureLoggerFactorySet(true);
// The system property has precedence because this method was deprecated by it:
if (!initializedFromSystemProperty || loggerFactory == null) {
int replacedLibraryEnum = Logger.libraryEnum;
setLibrary(libraryEnum);
loggersByCategory.clear();
if (loggerFactoryWasAlreadySet) {
logWarnInLogger("Logger library was already set earlier to \""
+ getLibraryName(replacedLibraryEnum) + "\"; "
+ "change to \"" + getLibraryName(libraryEnum) + "\" won't effect loggers created "
+ "earlier.");
}
} else if (libraryEnum != Logger.libraryEnum) {
logWarnInLogger("Ignored " + Logger.class.getName() + ".selectLoggerLibrary(\""
+ getLibraryName(libraryEnum)
+ "\") call, because the \"" + SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY
+ "\" system property is set to \"" + getLibraryName(Logger.libraryEnum) + "\".");
}
}
}
}
/**
* Sets a category prefix. This prefix is prepended to any logger category name. This makes it possible to have
* different FreeMarker logger categories on a per-application basis (better said, per-classloader basis). By
* default the category prefix is the empty string. If you set a non-empty category prefix, be sure to include the
* trailing separator dot (i.e. "MyApp.") If you want to change the default setting, do it early in application
* initialization phase, before calling any other FreeMarker API since once various parts of the FreeMarker library
* bind to the logging subsystem, the change in this value will have no effect on them.
*
* @deprecated This wasn't reliable, unless you can somehow ensure that you access the FreeMarker classes first. As
* it's not known to be useful for users, consider it removed.
*/
@Deprecated
public static void setCategoryPrefix(String prefix) {
synchronized (Logger.class) {
if (prefix == null) {
throw new IllegalArgumentException();
}
categoryPrefix = prefix;
}
}
/**
* Logs a debugging message.
*/
public abstract void debug(String message);
/**
* Logs a debugging message with accompanying throwable.
*/
public abstract void debug(String message, Throwable t);
/**
* Logs an informational message.
*/
public abstract void info(String message);
/**
* Logs an informational message with accompanying throwable.
*/
public abstract void info(String message, Throwable t);
/**
* Logs a warning message.
*/
public abstract void warn(String message);
/**
* Logs a warning message with accompanying throwable.
*/
public abstract void warn(String message, Throwable t);
/**
* Logs an error message.
*/
public abstract void error(String message);
/**
* Logs an error message with accompanying throwable.
*/
public abstract void error(String message, Throwable t);
/**
* Returns true if this logger will log debug messages.
*/
public abstract boolean isDebugEnabled();
/**
* Returns true if this logger will log informational messages.
*/
public abstract boolean isInfoEnabled();
/**
* Returns true if this logger will log warning messages.
*/
public abstract boolean isWarnEnabled();
/**
* Returns true if this logger will log error messages.
*/
public abstract boolean isErrorEnabled();
/**
* Returns true if this logger will log fatal error messages.
*/
public abstract boolean isFatalEnabled();
/**
* Returns a logger for the specified category.
*
* @param category
* a dot separated hierarchical category name. If a category prefix is in effect, it's prepended to the
* category name.
*/
public static Logger getLogger(String category) {
if (categoryPrefix.length() != 0) {
category = categoryPrefix + category;
}
synchronized (loggersByCategory) {
Logger logger = (Logger) loggersByCategory.get(category);
if (logger == null) {
ensureLoggerFactorySet(false);
logger = loggerFactory.getLogger(category);
loggersByCategory.put(category, logger);
}
return logger;
}
}
private static void ensureLoggerFactorySet(boolean onlyIfCanBeSetFromSysProp) {
if (loggerFactory != null) return;
synchronized (Logger.class) {
if (loggerFactory != null) return;
String sysPropVal = getSystemProperty(SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY);
final int libraryEnum;
if (sysPropVal != null) {
sysPropVal = sysPropVal.trim();
boolean foundMatch = false;
int matchedEnum = MIN_LIBRARY_ENUM;
do {
if (sysPropVal.equalsIgnoreCase(getLibraryName(matchedEnum))) {
foundMatch = true;
} else {
matchedEnum++;
}
} while (matchedEnum <= MAX_LIBRARY_ENUM && !foundMatch);
if (!foundMatch) {
logWarnInLogger("Ignored invalid \"" + SYSTEM_PROPERTY_NAME_LOGGER_LIBRARY
+ "\" system property value: \"" + sysPropVal + "\"");
if (onlyIfCanBeSetFromSysProp) return;
}
libraryEnum = foundMatch ? matchedEnum : LIBRARY_AUTO;
} else {
if (onlyIfCanBeSetFromSysProp) return;
libraryEnum = LIBRARY_AUTO;
}
try {
setLibrary(libraryEnum);
if (sysPropVal != null) {
initializedFromSystemProperty = true;
}
} catch (Throwable e) {
final boolean disableLogging = !(onlyIfCanBeSetFromSysProp && sysPropVal != null);
logErrorInLogger(
"Couldn't set up logger for \"" + getLibraryName(libraryEnum) + "\""
+ (disableLogging ? "; logging disabled" : "."), e);
if (disableLogging) {
try {
setLibrary(LIBRARY_NONE);
} catch (ClassNotFoundException e2) {
throw new RuntimeException("Bug", e2);
}
}
}
}
}
/**
* @throws ClassNotFoundException
* If the requested logger library is not available. Never thrown for {@link #LIBRARY_AUTO}.
*/
private static LoggerFactory createLoggerFactory(int libraryEnum) throws ClassNotFoundException {
if (libraryEnum == LIBRARY_AUTO) {
for (int libraryEnumToTry = MAX_LIBRARY_ENUM; libraryEnumToTry >= MIN_LIBRARY_ENUM; libraryEnumToTry--) {
if (!isAutoDetected(libraryEnumToTry)) continue;
if (libraryEnumToTry == LIBRARY_LOG4J && hasLog4LibraryThatDelegatesToWorkingSLF4J()) {
libraryEnumToTry = LIBRARY_SLF4J;
}
try {
return createLoggerFactoryForNonAuto(libraryEnumToTry);
} catch (ClassNotFoundException e) {
// Expected, intentionally suppressed.
} catch (Throwable e) {
logErrorInLogger(
"Unexpected error when initializing logging for \""
+ getLibraryName(libraryEnumToTry) + "\".",
e);
}
}
logWarnInLogger("Auto detecton couldn't set up any logger libraries; FreeMarker logging suppressed.");
return new _NullLoggerFactory();
} else {
return createLoggerFactoryForNonAuto(libraryEnum);
}
}
/**
* @throws ClassNotFoundException
* If the required logger library is not available.
*/
private static LoggerFactory createLoggerFactoryForNonAuto(int libraryEnum) throws ClassNotFoundException {
final String availabilityCheckClassName = getAvailabilityCheckClassName(libraryEnum);
if (availabilityCheckClassName != null) { // Dynamically created factory
Class.forName(availabilityCheckClassName);
String libraryName = getLibraryName(libraryEnum);
try {
return (LoggerFactory) Class.forName(
"freemarker.log._" + libraryName + "LoggerFactory").newInstance();
} catch (Exception e) {
throw new RuntimeException(
"Unexpected error when creating logger factory for \"" + libraryName + "\".", e);
}
} else { // Non-dynamically created factory
if (libraryEnum == LIBRARY_JAVA) {
return new _JULLoggerFactory();
} else if (libraryEnum == LIBRARY_NONE) {
return new _NullLoggerFactory();
} else {
throw new RuntimeException("Bug");
}
}
}
private static boolean hasLog4LibraryThatDelegatesToWorkingSLF4J() {
try {
Class.forName(getAvailabilityCheckClassName(LIBRARY_LOG4J));
Class.forName(getAvailabilityCheckClassName(LIBRARY_SLF4J));
} catch (Throwable e) {
return false;
}
try {
Class.forName(REAL_LOG4J_PRESENCE_CLASS);
return false;
} catch (ClassNotFoundException e) {
try {
Object r = Class.forName(LOG4J_OVER_SLF4J_TESTER_CLASS)
.getMethod("test", new Class[] {}).invoke(null);
return ((Boolean) r).booleanValue();
} catch (Throwable e2) {
return false;
}
}
}
private synchronized static void setLibrary(int libraryEnum) throws ClassNotFoundException {
loggerFactory = createLoggerFactory(libraryEnum);
Logger.libraryEnum = libraryEnum;
}
private static void logWarnInLogger(String message) {
logInLogger(false, message, null);
}
private static void logErrorInLogger(String message, Throwable exception) {
logInLogger(true, message, exception);
}
private static void logInLogger(boolean error, String message, Throwable exception) {
boolean canUseRealLogger;
synchronized (Logger.class) {
canUseRealLogger = loggerFactory != null && !(loggerFactory instanceof _NullLoggerFactory);
}
if (canUseRealLogger) {
try {
final Logger logger = Logger.getLogger("freemarker.logger");
if (error) {
logger.error(message);
} else {
logger.warn(message);
}
} catch (Throwable e) {
canUseRealLogger = false;
}
}
if (!canUseRealLogger) {
System.err.println((error ? "ERROR" : "WARN") + " "
+ LoggerFactory.class.getName() + ": " + message);
if (exception != null) {
System.err.println("\tException: " + tryToString(exception));
while (exception.getCause() != null) {
exception = exception.getCause();
System.err.println("\tCaused by: " + tryToString(exception));
}
}
}
}
/**
* Don't use {@link freemarker.template.utility.SecurityUtilities#getSystemProperty(String, String)} here, as it
* (might) depends on the logger, hence interfering with the initialization.
*/
private static String getSystemProperty(final String key) {
try {
return (String) AccessController.doPrivileged(
new PrivilegedAction() {
@Override
public Object run() {
return System.getProperty(key, null);
}
});
} catch (AccessControlException e) {
logWarnInLogger("Insufficient permissions to read system property \"" + key + "\".");
return null;
} catch (Throwable e) {
logErrorInLogger("Failed to read system property \"" + key + "\".", e);
return null;
}
}
/**
* Don't use {@link freemarker.template.utility.StringUtil#tryToString(Object)} here, as it might depends on the
* logger, hence interfering with the initialization.
*/
private static String tryToString(Object object) {
if (object == null) return null;
try {
return object.toString();
} catch (Throwable e) {
return object.getClass().getName();
}
}
}