com.foreach.common.web.util.Log4jWebUtils Maven / Gradle / Ivy

" ).append( "

" ).append( logger.getName() ).append( "

" ); output.append( "" ).append( level ); output.append( "

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A number of general purpose libraries for Java. Dependencies are kept minimal but Spring framework is considered a base requirement for most libraries.

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/*
 * Copyright 2014 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 com.foreach.common.web.util;

import com.foreach.common.spring.logging.Log4JUtils;
import org.apache.log4j.Level;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;

import javax.servlet.http.HttpServletRequest;
import java.util.Arrays;
import java.util.List;
import java.util.Map;

/**
 * This class contains methods to display and change the log levels of registered Log4j loggers dynamically with an http client.
 * 
 * To configure log levels dynamically, do the following:
 * 

 * In your controller, define a get method that will serve the update form to the client.
 * Use the method {@link #getLoggersHtmlContent} to obtain the html content to be served.
 * Define a post method to process the client response. From this routine you need only call
 * {@link #setLoggerLevels} to update the log levels to the user provided values.
 * 
 *
 * @version 1.0
 */
public class Log4jWebUtils
{
	protected Log4jWebUtils() {
		// protected constructor, so that this class can be extended.
	}

	/**
	 * This method generates the html content for a web page containing a form to change the log level of registered log4j loggers.
	 * The html body can be directly sent to the browser by defining spring annotation @ResponseBody on a controller method.
	 * 
	 * Eg. HttpServletResponse.getWriter().write( "html content" );
	 * 

	 * Use this method to display the registered loggers and their current log level.
	 *
	 * @param applicationName a label to be used in the html body, so the user knows which application's loggers are shown.
	 * @param formAction      the url that maps to the controller method that calls
	 *                        {@link #setLoggerLevels}
	 * @param includePageTags true to include html start/end tags (eg. ''), false to generate only html form content
	 * @return a string with html content.
	 */
	public static String getLoggersHtmlContent( String applicationName, String formAction, boolean includePageTags ) {
		List loggers = Log4JUtils.getClassLoggers();
		List levels =
				Arrays.asList( Level.OFF, Level.FATAL, Level.ERROR, Level.WARN, Level.INFO, Level.DEBUG );

		StringBuffer output = new StringBuffer();

		if ( includePageTags ) {
			output.append( "Manage Loggers - " ).append( applicationName ).append(
					"" );
		}

		output.append( "
Manage Loggers - " ).append( applicationName ).append( "" );
		output.append( "" );
		output.append( "" );
		output.append( "" ).append( "" );

		for ( Logger logger : loggers ) {
			output.append( "" ).append( "" );
			for ( Level level : levels ) {
				output.append( "" );
			}
			output.append( "" );
		}
		output.append( "" ).append(
				"" );
		output.append( " 
" ).append(
				"
" ).append( logger.getName() ).append( " " );
				output.append( "" ).append( level );
				output.append( "
 
" );
		output.append( "" );

		if ( includePageTags ) {
			output.append( "" );
		}

		return output.toString();
	}

	/**
	 * This method will update the levels of registered Loggers to the new levels
	 * retrieved from the given HttpServletRequest object.
	 * 
	 * You should call this method from within the controller method that maps to
	 * the formAction parameter you provided to {@link #getLoggersHtmlContent}.
	 *
	 * @param request the http request object containing the updated log levels.
	 */
	public static void setLoggerLevels( HttpServletRequest request ) {
		Map params = request.getParameterMap();
		for ( Map.Entry entry : params.entrySet() ) {
			String name = entry.getKey();
			if ( LogManager.exists( name ) != null ) {
				String[] levels = entry.getValue();
				Level level = Level.toLevel( levels[0] );
				Logger.getLogger( name ).setLevel( level );
			}
		}
	}

}