Add LogUtils and HttpLogging

SPR-17012

spring-core/src/main/java/org/springframework/util/log/CompositeLog.java

@@ -0,0 +1,158 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed 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 org.springframework.util.log;
+
+import java.util.List;
+import java.util.function.Predicate;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.impl.NoOpLog;
+
+/**
+ * Implementation of {@link Log} that wraps a list of loggers and delegates to
+ * the first one for which logging is enabled at the given level.
+ *
+ * @author Rossen Stoyanchev
+ * @since 5.1
+ * @see LogUtils#getCompositeLog
+ */
+class CompositeLog implements Log {
+
+	private static final Log noOpLog = new NoOpLog();
+
+
+	private final Log fatalLogger;
+
+	private final Log errorLogger;
+
+	private final Log warnLogger;
+
+	private final Log infoLogger;
+
+	private final Log debugLogger;
+
+	private final Log traceLogger;
+
+
+	/**
+	 * Constructor with list of loggers. For optimal performance, the constructor
+	 * checks and remembers which logger is on for each log category.
+	 * @param loggers the loggers to use
+	 */
+	public CompositeLog(List<Log> loggers) {
+		this.fatalLogger = initLogger(loggers, Log::isFatalEnabled);
+		this.errorLogger = initLogger(loggers, Log::isErrorEnabled);
+		this.warnLogger  = initLogger(loggers, Log::isWarnEnabled);
+		this.infoLogger  = initLogger(loggers, Log::isInfoEnabled);
+		this.debugLogger = initLogger(loggers, Log::isDebugEnabled);
+		this.traceLogger = initLogger(loggers, Log::isTraceEnabled);
+	}
+
+	private static Log initLogger(List<Log> loggers, Predicate<Log> predicate) {
+		return loggers.stream().filter(predicate).findFirst().orElse(noOpLog);
+	}
+
+
+	@Override
+	public boolean isFatalEnabled() {
+		return this.fatalLogger != noOpLog;
+	}
+
+	@Override
+	public boolean isErrorEnabled() {
+		return this.errorLogger != noOpLog;
+	}
+
+	@Override
+	public boolean isWarnEnabled() {
+		return this.warnLogger != noOpLog;
+	}
+
+	@Override
+	public boolean isInfoEnabled() {
+		return this.infoLogger != noOpLog;
+	}
+
+	@Override
+	public boolean isDebugEnabled() {
+		return this.debugLogger != noOpLog;
+	}
+
+	@Override
+	public boolean isTraceEnabled() {
+		return this.traceLogger != noOpLog;
+	}
+
+	@Override
+	public void fatal(Object message) {
+		this.fatalLogger.fatal(message);
+	}
+
+	@Override
+	public void fatal(Object message, Throwable ex) {
+		this.fatalLogger.fatal(message, ex);
+	}
+
+	@Override
+	public void error(Object message) {
+		this.errorLogger.error(message);
+	}
+
+	@Override
+	public void error(Object message, Throwable ex) {
+		this.errorLogger.error(message);
+	}
+
+	@Override
+	public void warn(Object message) {
+		this.warnLogger.warn(message);
+	}
+
+	@Override
+	public void warn(Object message, Throwable ex) {
+		this.warnLogger.warn(message, ex);
+	}
+
+	@Override
+	public void info(Object message) {
+		this.infoLogger.info(message);
+	}
+
+	@Override
+	public void info(Object message, Throwable ex) {
+		this.infoLogger.info(message, ex);
+	}
+
+	@Override
+	public void debug(Object message) {
+		this.debugLogger.debug(message);
+	}
+
+	@Override
+	public void debug(Object message, Throwable ex) {
+		this.debugLogger.debug(message, ex);
+	}
+
+	@Override
+	public void trace(Object message) {
+		this.traceLogger.trace(message);
+	}
+
+	@Override
+	public void trace(Object message, Throwable ex) {
+		this.traceLogger.trace(message, ex);
+	}
+}

spring-core/src/main/java/org/springframework/util/log/LogUtils.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed 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 org.springframework.util.log;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+/**
+ * Utilities to assist with logging. Mainly for internal use within the framework
+ * with Appache Commons Logging.
+ *
+ * @author Rossen Stoyanchev
+ * @since 5.1
+ */
+public abstract class LogUtils {
+
+	/**
+	 * Create a composite logger that delegates to a primary or falls back on a
+	 * secondary logger if logging for the primary logger is not enabled.
+	 * <p>This may be used for fallback logging from lower level packages that
+	 * logically should log together with some higher level package but the two
+	 * don't happen to share a suitable parent package (e.g. logging for the web
+	 * and lower level http and codec packages). For such cases the primary,
+	 * class-based logger can be wrapped with a shared fallback logger.
+	 * @param primaryLogger primary logger to try first
+	 * @param secondaryLogger secondary logger
+	 * @param tertiaryLoggers optionally, more fallback loggers
+	 * @return the resulting logger to use
+	 */
+	public static Log getCompositeLog(Log primaryLogger, Log secondaryLogger, Log... tertiaryLoggers) {
+		List<Log> loggers = new ArrayList<>(2 + tertiaryLoggers.length);
+		loggers.add(primaryLogger);
+		loggers.add(secondaryLogger);
+		Collections.addAll(loggers, tertiaryLoggers);
+		return new CompositeLog(loggers);
+	}
+
+	/**
+	 * Create a "hidden" logger whose name is intentionally prefixed with "_"
+	 * because its output is either too verbose or otherwise deemed as optional
+	 * or unnecessary to see at any log level by default under the normal package
+	 * based log hierarchy.
+	 * @param clazz the class for which to create a logger
+	 * @return the created logger
+	 */
+	public static Log getHiddenLog(Class<?> clazz) {
+		return LogFactory.getLog("_" + clazz.getName());
+	}
+
+}

spring-core/src/main/java/org/springframework/util/log/package-info.java

@@ -0,0 +1,9 @@
+/**
+ * Useful helper classes for logging.
+ */
+@NonNullApi
+@NonNullFields
+package org.springframework.util.log;
+
+import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;