Improve logging

pom.xml

@@ -10,7 +10,7 @@
 	</parent>
 
 	<artifactId>scijava-common</artifactId>
-	<version>2.41.1-SNAPSHOT</version>
+	<version>3.0.0-SNAPSHOT</version>
 
 	<name>SciJava Common</name>
 	<description>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 both ImageJ and SCIFIO.</description>

src/main/java/org/scijava/log/AbstractLogService.java

@@ -8,13 +8,13 @@
  * %%
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
- * 
+ *
  * 1. Redistributions of source code must retain the above copyright notice,
  *    this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright notice,
  *    this list of conditions and the following disclaimer in the documentation
  *    and/or other materials provided with the distribution.
- * 
+ *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
@@ -31,40 +31,27 @@
 
 package org.scijava.log;
 
+import java.io.PrintStream;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;
 
 import org.scijava.service.AbstractService;
 
 /**
- * Base implementation of an abstract {@link LogService}.
- * 
+ * Base class for {@link LogService} implementationst.
+ *
  * @author Johannes Schindelin
  */
-public abstract class AbstractLogService extends AbstractService implements LogService {
+public abstract class AbstractLogService extends AbstractService implements
+	LogService
+{
 
 	private int currentLevel = System.getenv("DEBUG") == null ? INFO : DEBUG;
 
-	private Map<String, Integer> classAndPackageLevels =
+	private final Map<String, Integer> classAndPackageLevels =
 		new HashMap<String, Integer>();
 
-	// -- 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() {
@@ -87,120 +74,116 @@ public AbstractLogService() {
 			if (!(propKey instanceof String)) continue;
 			final String propName = (String) propKey;
 			if (!propName.startsWith(logLevelPrefix)) continue;
-			final String classOrPackageName = propName.substring(logLevelPrefix.length());
+			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);
-	}
+	// -- Internal methods --
 
-	protected void log(final int level, final Object msg) {
-		final String prefix = getPrefix(level);
-		log((prefix == null ? "" : prefix + " ") + msg);
-	}
+	/**
+	 * Displays a message and/or exception at the given logging level.
+	 *
+	 * @param level The logging level of the information.
+	 * @param msg The message to display.
+	 * @param t The exception to display.
+	 */
+	protected abstract void log(final int level, final Object msg,
+		final Throwable t);
 
-	protected String getPrefix(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;
-		}
+	/**
+	 * Displays a message and/or exception at the given logging level, using the
+	 * specific output stream.
+	 *
+	 * @param stream The output stream to which the information should be sent.
+	 * @param level The logging level of the information.
+	 * @param msg The message to display.
+	 * @param t The exception to display.
+	 */
+	protected void log(final PrintStream stream, final int level,
+		final Object msg, final Throwable t)
+	{
+		if (msg != null || t == null) stream.println(getPrefix(level) + msg);
+		if (t != null) t.printStackTrace(stream);
 	}
 
 	// -- LogService methods --
 
 	@Override
-	public void debug(Object msg) {
-		log(DEBUG, msg, null);
+	public void debug(final Object msg) {
+		if (isDebug()) log(DEBUG, msg, null);
 	}
 
 	@Override
-	public void debug(Throwable t) {
-		log(DEBUG, null, t);
+	public void debug(final Throwable t) {
+		if (isDebug()) log(DEBUG, null, t);
 	}
 
 	@Override
-	public void debug(Object msg, Throwable t) {
-		log(DEBUG, msg, t);
+	public void debug(final Object msg, final Throwable t) {
+		if (isDebug()) log(DEBUG, msg, t);
 	}
 
 	@Override
-	public void error(Object msg) {
-		log(ERROR, msg, null);
+	public void error(final Object msg) {
+		if (isError()) log(ERROR, msg, null);
 	}
 
 	@Override
-	public void error(Throwable t) {
-		log(ERROR, null, t);
+	public void error(final Throwable t) {
+		if (isError()) log(ERROR, null, t);
 	}
 
 	@Override
-	public void error(Object msg, Throwable t) {
-		log(ERROR, msg, t);
+	public void error(final Object msg, final Throwable t) {
+		if (isError()) log(ERROR, msg, t);
 	}
 
 	@Override
-	public void info(Object msg) {
-		log(INFO, msg, null);
+	public void info(final Object msg) {
+		if (isInfo()) log(INFO, msg, null);
 	}
 
 	@Override
-	public void info(Throwable t) {
-		log(INFO, null, t);
+	public void info(final Throwable t) {
+		if (isInfo()) log(INFO, null, t);
 	}
 
 	@Override
-	public void info(Object msg, Throwable t) {
-		log(INFO, msg, t);
+	public void info(final Object msg, final Throwable t) {
+		if (isInfo()) log(INFO, msg, t);
 	}
 
 	@Override
-	public void trace(Object msg) {
-		log(TRACE, msg, null);
+	public void trace(final Object msg) {
+		if (isTrace()) log(TRACE, msg, null);
 	}
 
 	@Override
-	public void trace(Throwable t) {
-		log(TRACE, null, t);
+	public void trace(final Throwable t) {
+		if (isTrace()) log(TRACE, null, t);
 	}
 
 	@Override
-	public void trace(Object msg, Throwable t) {
-		log(TRACE, msg, t);
+	public void trace(final Object msg, final Throwable t) {
+		if (isTrace()) log(TRACE, msg, t);
 	}
 
 	@Override
-	public void warn(Object msg) {
-		log(WARN, msg, null);
+	public void warn(final Object msg) {
+		if (isWarn()) log(WARN, msg, null);
 	}
 
 	@Override
-	public void warn(Throwable t) {
-		log(WARN, null, t);
+	public void warn(final Throwable t) {
+		if (isWarn()) log(WARN, null, t);
 	}
 
 	@Override
-	public void warn(Object msg, Throwable t) {
-		log(WARN, msg, t);
+	public void warn(final Object msg, final Throwable t) {
+		if (isWarn()) log(WARN, msg, t);
 	}
 
 	@Override
@@ -248,13 +231,30 @@ public void setLevel(final int level) {
 		currentLevel = level;
 	}
 
-	//@Override
+	@Override
 	public void setLevel(final String classOrPackageName, final int level) {
 		classAndPackageLevels.put(classOrPackageName, level);
 	}
 
 	// -- Helper methods --
 
+	private 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 "";
+		}
+	}
+
 	/** Extracts the log level value from a string. */
 	private int level(final String logProp) {
 		if (logProp == null) return -1;
@@ -289,7 +289,7 @@ private String callingClass() {
 	}
 
 	private String parentPackage(final String classOrPackageName) {
-		int dot = classOrPackageName.lastIndexOf(".");
+		final int dot = classOrPackageName.lastIndexOf(".");
 		if (dot < 0) return null;
 		return classOrPackageName.substring(0, dot);
 	}

src/main/java/org/scijava/log/DefaultLogService.java

@@ -0,0 +1,58 @@
+/*
+ * #%L
+ * SciJava Common shared library for SciJava software.
+ * %%
+ * Copyright (C) 2009 - 2015 Board of Regents of the University of
+ * Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
+ * Institute of Molecular Cell Biology and Genetics.
+ * %%
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ * #L%
+ */
+
+package org.scijava.log;
+
+import org.scijava.Priority;
+import org.scijava.plugin.Plugin;
+import org.scijava.service.Service;
+
+/**
+ * Default implementation of {@link LogService}.
+ * <p>
+ * It uses the standard output and error streams, logging critical messages (
+ * {@link LogService#WARN} and {@link LogService#ERROR} levels) to
+ * {@code stderr}, and non-critical messages ({@link LogService#INFO},
+ * {@link LogService#DEBUG} and {@link LogService#TRACE} levels) to
+ * {@code stdout}.
+ * </p>
+ * 
+ * @author Curtis Rueden
+ */
+@Plugin(type = Service.class, priority = Priority.LOW_PRIORITY)
+public class DefaultLogService extends AbstractLogService {
+
+	@Override
+	protected void log(final int level, final Object msg, final Throwable t) {
+		log(level > WARN ? System.out : System.err, level, msg, t);
+	}
+
+}

src/main/java/org/scijava/log/LogService.java

@@ -100,4 +100,6 @@ public interface LogService extends SciJavaService {
 
 	void setLevel(int level);
 
+	void setLevel(String classOrPackageName, int level);
+
 }

src/main/java/org/scijava/script/AbstractScriptEngine.java

@@ -39,8 +39,8 @@
 import javax.script.ScriptEngineFactory;
 import javax.script.ScriptException;
 
+import org.scijava.log.DefaultLogService;
 import org.scijava.log.LogService;
-import org.scijava.log.StderrLogService;
 
 /**
  * This class implements dummy versions for ScriptEngine's methods that are not
@@ -70,7 +70,7 @@ public abstract class AbstractScriptEngine implements ScriptEngine {
 
 	public synchronized LogService log() {
 		if (log == null) {
-			log = new StderrLogService();
+			log = new DefaultLogService();
 		}
 		return log;
 	}

src/main/java/org/scijava/script/History.java

@@ -33,6 +33,7 @@
 
 import org.scijava.prefs.PrefService;
 import org.scijava.util.LastRecentlyUsed;
+import org.scijava.util.Prefs;
 
 /**
  * Container for a script language's interpreter history.