com.google.gwt.gen2.logging.shared.SmartLogHandler.java Source code

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Here is the source code for com.google.gwt.gen2.logging.shared.SmartLogHandler.java

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/*
 * Copyright 2008 Google Inc.
 * 
 * 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 com.google.gwt.gen2.logging.shared;

/**
 * A {@link LogHandler} decorator which is sensitive to log levels and lazily
 * creates the underlying log handler.
 * 
 */
public abstract class SmartLogHandler implements LogHandler {
    private Level logLevel;
    private LogHandler wrapped;

    /**
     * Constructor.
     */
    public SmartLogHandler() {
    }

    /**
     * Get the log level specifying which messages will be logged by this
     * <tt>Handler</tt>. Message levels lower than this level will be discarded.
     * 
     * @return the level of messages being logged.
     */
    public Level getLevel() {
        if (logLevel == null) {
            return Level.ALL;
        }
        return logLevel;
    }

    public void onLog(LogEvent event) {
        if (getLevel().wouldLog(event)) {
            if (wrapped == null) {
                ensureLogHandler();
                assert wrapped != null : "You must can setLogHandler before or after ensureLogHandler() is called";
            }
            wrapped.onLog(event);
        }
    }

    /**
     * Set the log level specifying which message levels will be logged by this
     * <tt>Handler</tt>. Message levels lower than this value will be discarded.
     * <p>
     * The intention is to allow developers to turn on voluminous logging, but to
     * limit the messages that are sent to certain <tt>Handlers</tt>.
     * 
     * @param newLevel the new value for the log level
     * 
     */
    public void setLevel(Level newLevel) {
        logLevel = newLevel;
    }

    /**
     * Sets the wrapped log handler.
     * 
     * @param wrapped the wrapped handler
     */
    public void setLogHandler(LogHandler wrapped) {
        this.wrapped = wrapped;
    }

    /**
     * Called when the underlying log handler needs to be accessed. User code
     * should ensure that {@link SmartLogHandler#setLogHandler(LogHandler)} has
     * been called at least once during this method.
     * 
     */
    protected abstract void ensureLogHandler();

}