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SciJava Common is a shared library for SciJava software. It provides a plugin framework, with an extensible mechanism for service discovery, backed by its own annotation processor, so that plugins can be loaded dynamically. It is used by downstream projects in the SciJava ecosystem, such as ImageJ and SCIFIO.
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package org.scijava.log;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import org.scijava.service.AbstractService;
/**
* Base class for {@link LogService} implementationst.
*
* @author Johannes Schindelin
*/
public abstract class AbstractLogService extends AbstractService implements
LogService
{
private int currentLevel = System.getenv("DEBUG") == null ? INFO : DEBUG;
private final Map classAndPackageLevels =
new HashMap<>();
// -- abstract methods --
/**
* Displays a message.
*
* @param msg the message to display.
*/
protected abstract void log(final String msg);
/**
* Displays an exception.
*
* @param t the exception to display.
*/
protected abstract void log(final Throwable t);
// -- constructor --
public AbstractLogService() {
// check SciJava log level system properties for initial logging levels
// global log level property
final String logProp = System.getProperty(LOG_LEVEL_PROPERTY);
final int level = level(logProp);
if (level >= 0) setLevel(level);
if (getLevel() == 0) {
// use the default, which is WARN unless the DEBUG env. variable is set
setLevel(System.getenv("DEBUG") == null ? INFO : DEBUG);
}
// populate custom class- and package-specific log level properties
final String logLevelPrefix = LOG_LEVEL_PROPERTY + ":";
final Properties props = System.getProperties();
for (final Object propKey : props.keySet()) {
if (!(propKey instanceof String)) continue;
final String propName = (String) propKey;
if (!propName.startsWith(logLevelPrefix)) continue;
final String classOrPackageName =
propName.substring(logLevelPrefix.length());
setLevel(classOrPackageName, level(props.getProperty(propName)));
}
}
// -- helper methods --
protected void log(final int level, final Object msg, final Throwable t) {
if (level > getLevel()) return;
if (msg != null || t == null) {
log(level, msg);
}
if (t != null) log(t);
}
protected void log(final int level, final Object msg) {
final String prefix = getPrefix(level);
log((prefix == null ? "" : prefix + " ") + msg);
}
protected String getPrefix(final int level) {
switch (level) {
case ERROR:
return "[ERROR]";
case WARN:
return "[WARNING]";
case INFO:
return "[INFO]";
case DEBUG:
return "[DEBUG]";
case TRACE:
return "[TRACE]";
default:
return null;
}
}
// -- LogService methods --
@Override
public void debug(final Object msg) {
log(DEBUG, msg, null);
}
@Override
public void debug(final Throwable t) {
log(DEBUG, null, t);
}
@Override
public void debug(final Object msg, final Throwable t) {
log(DEBUG, msg, t);
}
@Override
public void error(final Object msg) {
log(ERROR, msg, null);
}
@Override
public void error(final Throwable t) {
log(ERROR, null, t);
}
@Override
public void error(final Object msg, final Throwable t) {
log(ERROR, msg, t);
}
@Override
public void info(final Object msg) {
log(INFO, msg, null);
}
@Override
public void info(final Throwable t) {
log(INFO, null, t);
}
@Override
public void info(final Object msg, final Throwable t) {
log(INFO, msg, t);
}
@Override
public void trace(final Object msg) {
log(TRACE, msg, null);
}
@Override
public void trace(final Throwable t) {
log(TRACE, null, t);
}
@Override
public void trace(final Object msg, final Throwable t) {
log(TRACE, msg, t);
}
@Override
public void warn(final Object msg) {
log(WARN, msg, null);
}
@Override
public void warn(final Throwable t) {
log(WARN, null, t);
}
@Override
public void warn(final Object msg, final Throwable t) {
log(WARN, msg, t);
}
@Override
public boolean isDebug() {
return getLevel() >= DEBUG;
}
@Override
public boolean isError() {
return getLevel() >= ERROR;
}
@Override
public boolean isInfo() {
return getLevel() >= INFO;
}
@Override
public boolean isTrace() {
return getLevel() >= TRACE;
}
@Override
public boolean isWarn() {
return getLevel() >= WARN;
}
@Override
public int getLevel() {
if (!classAndPackageLevels.isEmpty()) {
// check for a custom log level for calling class or its parent packages
String classOrPackageName = callingClass();
while (classOrPackageName != null) {
final Integer level = classAndPackageLevels.get(classOrPackageName);
if (level != null) return level;
classOrPackageName = parentPackage(classOrPackageName);
}
}
// no custom log level; return the global log level
return currentLevel;
}
@Override
public void setLevel(final int level) {
currentLevel = level;
}
@Override
public void setLevel(final String classOrPackageName, final int level) {
classAndPackageLevels.put(classOrPackageName, level);
}
// -- Helper methods --
/** Extracts the log level value from a string. */
private int level(final String logProp) {
if (logProp == null) return -1;
// check whether it's a string label (e.g., "debug")
final String log = logProp.trim().toLowerCase();
if (log.startsWith("n")) return NONE;
if (log.startsWith("e")) return ERROR;
if (log.startsWith("w")) return WARN;
if (log.startsWith("i")) return INFO;
if (log.startsWith("d")) return DEBUG;
if (log.startsWith("t")) return TRACE;
// check whether it's a numerical value (e.g., 5)
try {
return Integer.parseInt(log);
}
catch (final NumberFormatException exc) {
// nope!
}
return -1;
}
private String callingClass() {
final String thisClass = AbstractLogService.class.getName();
for (final StackTraceElement element : new Exception().getStackTrace()) {
final String className = element.getClassName();
// NB: Skip stack trace elements from other methods of this class.
if (!thisClass.equals(className)) return className;
}
return null;
}
private String parentPackage(final String classOrPackageName) {
final int dot = classOrPackageName.lastIndexOf(".");
if (dot < 0) return null;
return classOrPackageName.substring(0, dot);
}
}