| /* ==================================================================== |
| 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.poi.util; |
| |
| /** |
| * A logger interface that strives to make it as easy as possible for |
| * developers to write log calls, while simultaneously making those |
| * calls as cheap as possible by performing lazy evaluation of the log |
| * message.<p> |
| */ |
| @Internal |
| public abstract class POILogger { |
| |
| public static final int DEBUG = 1; |
| public static final int INFO = 3; |
| public static final int WARN = 5; |
| public static final int ERROR = 7; |
| public static final int FATAL = 9; |
| |
| /** Short strings for numeric log level. Use level as array index. */ |
| protected static final String LEVEL_STRINGS_SHORT[] = {"?", "D", "?", "I", "?", "W", "?", "E", "?", "F", "?"}; |
| /** Long strings for numeric log level. Use level as array index. */ |
| protected static final String LEVEL_STRINGS[] = {"?0?", "DEBUG", "?2?", "INFO", "?4?", "WARN", "?6?", "ERROR", "?8?", "FATAL", "?10+?"}; |
| |
| |
| /** |
| * package scope so it cannot be instantiated outside of the util |
| * package. You need a POILogger? Go to the POILogFactory for one |
| */ |
| POILogger() { |
| // no fields to initialize |
| } |
| |
| abstract public void initialize(String cat); |
| |
| /** |
| * Log a message |
| * |
| * @param level One of DEBUG, INFO, WARN, ERROR, FATAL |
| * @param obj1 The object to log. This is converted to a string. |
| */ |
| abstract protected void _log(int level, Object obj1); |
| |
| /** |
| * Log a message |
| * |
| * @param level One of DEBUG, INFO, WARN, ERROR, FATAL |
| * @param obj1 The object to log. This is converted to a string. |
| * @param exception An exception to be logged |
| */ |
| abstract protected void _log(int level, Object obj1, final Throwable exception); |
| |
| |
| /** |
| * Check if a logger is enabled to log at the specified level |
| * This allows code to avoid building strings or evaluating functions in |
| * the arguments to log. |
| * |
| * An example: |
| * <code><pre> |
| * if (logger.check(POILogger.INFO)) { |
| * logger.log(POILogger.INFO, "Avoid concatenating " + " strings and evaluating " + functions()); |
| * } |
| * </pre></code> |
| * |
| * @param level One of DEBUG, INFO, WARN, ERROR, FATAL |
| */ |
| abstract public boolean check(int level); |
| |
| /** |
| * Log a message. Lazily appends Object parameters together. |
| * If the last parameter is a {@link Throwable} it is logged specially. |
| * |
| * @param level One of DEBUG, INFO, WARN, ERROR, FATAL |
| * @param objs the objects to place in the message |
| */ |
| public void log(int level, Object... objs) { |
| if (!check(level)) return; |
| StringBuilder sb = new StringBuilder(32); |
| Throwable lastEx = null; |
| for (int i=0; i<objs.length; i++) { |
| if (i == objs.length-1 && objs[i] instanceof Throwable) { |
| lastEx = (Throwable)objs[i]; |
| } else { |
| sb.append(objs[i]); |
| } |
| } |
| |
| String msg = sb.toString(); |
| msg = msg.replaceAll("[\r\n]+", " "); // log forging escape |
| |
| // somehow this ambiguity works and doesn't lead to a loop, |
| // but it's confusing ... |
| if (lastEx == null) { |
| _log(level, msg); |
| } else { |
| _log(level, msg, lastEx); |
| } |
| } |
| } |