java/src/org/apache/commons/logging/Log.java

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+/*
+ * 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 org.apache.commons.logging;
+
+/**
+ * <p>A simple logging interface abstracting logging APIs.  In order to be
+ * instantiated successfully by {@link LogFactory}, classes that implement
+ * this interface must have a constructor that takes a single String
+ * parameter representing the "name" of this Log.</p>
+ *
+ * <p> The six logging levels used by <code>Log</code> are (in order):
+ * <ol>
+ * <li>trace (the least serious)</li>
+ * <li>debug</li>
+ * <li>info</li>
+ * <li>warn</li>
+ * <li>error</li>
+ * <li>fatal (the most serious)</li>
+ * </ol>
+ * The mapping of these log levels to the concepts used by the underlying
+ * logging system is implementation dependent.
+ * The implemention should ensure, though, that this ordering behaves
+ * as expected.</p>
+ *
+ * <p>Performance is often a logging concern.
+ * By examining the appropriate property,
+ * a component can avoid expensive operations (producing information
+ * to be logged).</p>
+ *
+ * <p> For example,
+ * <code><pre>
+ *    if (log.isDebugEnabled()) {
+ *        ... do something expensive ...
+ *        log.debug(theResult);
+ *    }
+ * </pre></code>
+ * </p>
+ *
+ * <p>Configuration of the underlying logging system will generally be done
+ * external to the Logging APIs, through whatever mechanism is supported by
+ * that system.</p>
+ *
+ * @author <a href="mailto:sanders@apache.org">Scott Sanders</a>
+ * @author Rod Waldhoff
+ * @version $Id: Log.java 424107 2006-07-20 23:15:42Z skitching $
+ */
+public interface Log {
+
+
+    // ----------------------------------------------------- Logging Properties
+
+
+    /**
+     * <p> Is debug logging currently enabled? </p>
+     *
+     * <p> Call this method to prevent having to perform expensive operations
+     * (for example, <code>String</code> concatenation)
+     * when the log level is more than debug. </p>
+     *
+     * @return true if debug is enabled in the underlying logger.
+     */
+    public boolean isDebugEnabled();
+
+
+    /**
+     * <p> Is error logging currently enabled? </p>
+     *
+     * <p> Call this method to prevent having to perform expensive operations
+     * (for example, <code>String</code> concatenation)
+     * when the log level is more than error. </p>
+     *
+     * @return true if error is enabled in the underlying logger.
+     */
+    public boolean isErrorEnabled();
+
+
+    /**
+     * <p> Is fatal logging currently enabled? </p>
+     *
+     * <p> Call this method to prevent having to perform expensive operations
+     * (for example, <code>String</code> concatenation)
+     * when the log level is more than fatal. </p>
+     *
+     * @return true if fatal is enabled in the underlying logger.
+     */
+    public boolean isFatalEnabled();
+
+
+    /**
+     * <p> Is info logging currently enabled? </p>
+     *
+     * <p> Call this method to prevent having to perform expensive operations
+     * (for example, <code>String</code> concatenation)
+     * when the log level is more than info. </p>
+     *
+     * @return true if info is enabled in the underlying logger.
+     */
+    public boolean isInfoEnabled();
+
+
+    /**
+     * <p> Is trace logging currently enabled? </p>
+     *
+     * <p> Call this method to prevent having to perform expensive operations
+     * (for example, <code>String</code> concatenation)
+     * when the log level is more than trace. </p>
+     *
+     * @return true if trace is enabled in the underlying logger.
+     */
+    public boolean isTraceEnabled();
+
+
+    /**
+     * <p> Is warn logging currently enabled? </p>
+     *
+     * <p> Call this method to prevent having to perform expensive operations
+     * (for example, <code>String</code> concatenation)
+     * when the log level is more than warn. </p>
+     *
+     * @return true if warn is enabled in the underlying logger.
+     */
+    public boolean isWarnEnabled();
+
+
+    // -------------------------------------------------------- Logging Methods
+
+
+    /**
+     * <p> Log a message with trace log level. </p>
+     *
+     * @param message log this message
+     */
+    public void trace(Object message);
+
+
+    /**
+     * <p> Log an error with trace log level. </p>
+     *
+     * @param message log this message
+     * @param t log this cause
+     */
+    public void trace(Object message, Throwable t);
+
+
+    /**
+     * <p> Log a message with debug log level. </p>
+     *
+     * @param message log this message
+     */
+    public void debug(Object message);
+
+
+    /**
+     * <p> Log an error with debug log level. </p>
+     *
+     * @param message log this message
+     * @param t log this cause
+     */
+    public void debug(Object message, Throwable t);
+
+
+    /**
+     * <p> Log a message with info log level. </p>
+     *
+     * @param message log this message
+     */
+    public void info(Object message);
+
+
+    /**
+     * <p> Log an error with info log level. </p>
+     *
+     * @param message log this message
+     * @param t log this cause
+     */
+    public void info(Object message, Throwable t);
+
+
+    /**
+     * <p> Log a message with warn log level. </p>
+     *
+     * @param message log this message
+     */
+    public void warn(Object message);
+
+
+    /**
+     * <p> Log an error with warn log level. </p>
+     *
+     * @param message log this message
+     * @param t log this cause
+     */
+    public void warn(Object message, Throwable t);
+
+
+    /**
+     * <p> Log a message with error log level. </p>
+     *
+     * @param message log this message
+     */
+    public void error(Object message);
+
+
+    /**
+     * <p> Log an error with error log level. </p>
+     *
+     * @param message log this message
+     * @param t log this cause
+     */
+    public void error(Object message, Throwable t);
+
+
+    /**
+     * <p> Log a message with fatal log level. </p>
+     *
+     * @param message log this message
+     */
+    public void fatal(Object message);
+
+
+    /**
+     * <p> Log an error with fatal log level. </p>
+     *
+     * @param message log this message
+     * @param t log this cause
+     */
+    public void fatal(Object message, Throwable t);
+
+
+}