ICU-6710 Add ICULogger class to ICU4J.

X-SVN-Rev: 26488

icu4j/main/classes/core/src/com/ibm/icu/impl/ICULogger.java

@@ -0,0 +1,152 @@
+/*
+ *******************************************************************************
+ * Copyright (C) 2009, International Business Machines Corporation and         *
+ * others. All Rights Reserved.                                                *
+ *******************************************************************************
+ */
+package com.ibm.icu.impl;
+
+import java.util.logging.ConsoleHandler;
+import java.util.logging.Logger;
+import java.util.logging.Level;
+
+/**
+ *
+ * Extends the Java Logger class adding a method to turn off/on logging.
+ * Classes where logging is wanted contains a static ICULogger object
+ * with logging turned off by default unless the system property 
+ * "icu4j.debug.logging" is set to "all"
+ * 
+ * If "icu4j.debug.logging" is not set to "all", then the individual loggers needs
+ * to be turned on manually. (e.g. TimeZone.TimeZoneLogger.turnLoggingOn())
+ * <p>
+ * To use logging, the system property "icu4j.debug.logging" must be set to "on" or "all",
+ * otherwise the static ICULogger object will be null. This will help lower any unneccessary
+ * resource usage when logging is not desired.
+ * 
+ * @author       Michael Ow
+ * @draft ICU 4.4
+ */
+
+public class ICULogger extends Logger {
+    private static enum LOGGER_STATUS { ON, OFF, NULL };
+    private static final String GLOBAL_FLAG_TURN_ON_LOGGING = "all";
+    private static final String SYSTEM_PROP_LOGGER = "icu4j.debug.logging";
+    
+    private LOGGER_STATUS currentStatus;
+    
+    /**
+     * ICULogger constructor that calls the parent constructor with the desired parameters.
+     */
+    private ICULogger(String name, String resourceBundleName) {
+        super(name, resourceBundleName);
+    }
+    
+    /**
+     * Set the status to either on or off. Set the level of the logger to INFO.
+     */
+    private void setStatus(LOGGER_STATUS newStatus) {
+        if (currentStatus != newStatus) {
+            /* Default to level INFO */
+            if (currentStatus == LOGGER_STATUS.OFF && newStatus == LOGGER_STATUS.ON) {
+                this.setLevel(Level.INFO);
+            }
+            
+            currentStatus = newStatus;
+            
+            if (currentStatus == LOGGER_STATUS.OFF){
+                this.setLevel(Level.OFF);
+            }
+        }
+    }
+    
+    /**
+     * Check the system property SYSTEM_PROP_LOGGER to see if it is set.
+     * return true if it is otherwise return false.
+     */
+    private static LOGGER_STATUS checkGlobalLoggingFlag() {
+        String prop = System.getProperty(SYSTEM_PROP_LOGGER);
+        
+        if (prop != null) {
+            if (prop.equals(GLOBAL_FLAG_TURN_ON_LOGGING)) {
+                return LOGGER_STATUS.ON;
+            }
+            return LOGGER_STATUS.OFF;
+        }
+        
+        return LOGGER_STATUS.NULL;
+    }
+    
+    /**
+     * Instantiates a new ICULogger object with logging turned off by default.
+     *
+     * @param name to be use by the logger (usually is the class name)
+     * @return a new ICULogger object
+     * @draft ICU 4.4
+     */
+    public static ICULogger getICULogger(String name) {
+        return getICULogger(name, null);
+    }
+    
+    /**
+     * Instantiates a new ICULogger object with logging turned off by default
+     * unless the system property "icu4j.debug.logging" is set to "all"
+     *
+     * @param name to be use by the logger (usually is the class name)
+     * @param ResourceBundle name to localize messages (can be null)
+     * @return a new ICULogger object
+     * @draft ICU 4.4
+     */
+    public static ICULogger getICULogger(String name, String resourceBundleName) {
+        LOGGER_STATUS flag = checkGlobalLoggingFlag();
+        if (flag != LOGGER_STATUS.NULL) {
+            ICULogger logger = new ICULogger(name, resourceBundleName);
+            
+            /* Add a default handler to logger*/
+            logger.addHandler(new ConsoleHandler());
+            
+            /* Turn off logging by default unless SYSTEM_PROP_LOGGER property is set to "all" */
+            if (flag == LOGGER_STATUS.ON) {
+                logger.turnOnLogging();
+            } else {
+                logger.turnOffLogging();
+            }
+            
+            return logger;
+        }
+        return null;
+    }
+    
+    /**
+     * Determined if logging is turned on or off. The return value is true if logging is on.
+     *
+     * @return whether logging is turned on or off.
+     * @draft ICU 4.4
+     */
+    public boolean isLoggingOn() {
+        if (currentStatus == LOGGER_STATUS.ON) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+    
+    /**
+     * Turn logging on.
+     *
+     * @draft ICU 4.4
+     */
+    public void turnOnLogging() {
+        setStatus(LOGGER_STATUS.ON);
+    }
+    
+    /**
+     * Turn logging off.
+     *
+     * @draft ICU 4.4
+     */
+    public void turnOffLogging() {
+        setStatus(LOGGER_STATUS.OFF);
+    }
+    
+}