Java tutorial
/** * 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.hadoop.hbase.http.log; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.net.URL; import java.net.URLConnection; import java.util.regex.Pattern; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.commons.logging.impl.Jdk14Logger; import org.apache.commons.logging.impl.Log4JLogger; import org.apache.hadoop.hbase.classification.InterfaceAudience; import org.apache.hadoop.hbase.classification.InterfaceStability; import org.apache.hadoop.hbase.http.HttpServer; import org.apache.hadoop.util.ServletUtil; /** * Change log level in runtime. */ @InterfaceStability.Evolving public class LogLevel { public static final String USAGES = "\nUsage: General options are:\n" + "\t[-getlevel <host:httpPort> <name>]\n" + "\t[-setlevel <host:httpPort> <name> <level>]\n"; /** * A command line implementation */ public static void main(String[] args) { if (args.length == 3 && "-getlevel".equals(args[0])) { process("http://" + args[1] + "/logLevel?log=" + args[2]); return; } else if (args.length == 4 && "-setlevel".equals(args[0])) { process("http://" + args[1] + "/logLevel?log=" + args[2] + "&level=" + args[3]); return; } System.err.println(USAGES); System.exit(-1); } private static void process(String urlstring) { try { URL url = new URL(urlstring); System.out.println("Connecting to " + url); URLConnection connection = url.openConnection(); connection.connect(); BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream())); for (String line; (line = in.readLine()) != null;) if (line.startsWith(MARKER)) { System.out.println(TAG.matcher(line).replaceAll("")); } in.close(); } catch (IOException ioe) { System.err.println("" + ioe); } } static final String MARKER = "<!-- OUTPUT -->"; static final Pattern TAG = Pattern.compile("<[^>]*>"); /** * A servlet implementation */ @InterfaceAudience.LimitedPrivate({ "HDFS", "MapReduce" }) @InterfaceStability.Unstable public static class Servlet extends HttpServlet { private static final long serialVersionUID = 1L; @Override public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // Do the authorization if (!HttpServer.hasAdministratorAccess(getServletContext(), request, response)) { return; } PrintWriter out = ServletUtil.initHTML(response, "Log Level"); String logName = ServletUtil.getParameter(request, "log"); String level = ServletUtil.getParameter(request, "level"); if (logName != null) { out.println("<br /><hr /><h3>Results</h3>"); out.println(MARKER + "Submitted Log Name: <b>" + logName + "</b><br />"); Log log = LogFactory.getLog(logName); out.println(MARKER + "Log Class: <b>" + log.getClass().getName() + "</b><br />"); if (level != null) { out.println(MARKER + "Submitted Level: <b>" + level + "</b><br />"); } if (log instanceof Log4JLogger) { process(((Log4JLogger) log).getLogger(), level, out); } else if (log instanceof Jdk14Logger) { process(((Jdk14Logger) log).getLogger(), level, out); } else { out.println("Sorry, " + log.getClass() + " not supported.<br />"); } } out.println(FORMS); out.println(ServletUtil.HTML_TAIL); } static final String FORMS = "\n<br /><hr /><h3>Get / Set</h3>" + "\n<form>Log: <input type='text' size='50' name='log' /> " + "<input type='submit' value='Get Log Level' />" + "</form>" + "\n<form>Log: <input type='text' size='50' name='log' /> " + "Level: <input type='text' name='level' /> " + "<input type='submit' value='Set Log Level' />" + "</form>"; private static void process(org.apache.log4j.Logger log, String level, PrintWriter out) throws IOException { if (level != null) { if (!level.equals(org.apache.log4j.Level.toLevel(level).toString())) { out.println(MARKER + "Bad level : <b>" + level + "</b><br />"); } else { log.setLevel(org.apache.log4j.Level.toLevel(level)); out.println(MARKER + "Setting Level to " + level + " ...<br />"); } } out.println(MARKER + "Effective level: <b>" + log.getEffectiveLevel() + "</b><br />"); } private static void process(java.util.logging.Logger log, String level, PrintWriter out) throws IOException { if (level != null) { log.setLevel(java.util.logging.Level.parse(level)); out.println(MARKER + "Setting Level to " + level + " ...<br />"); } java.util.logging.Level lev; for (; (lev = log.getLevel()) == null; log = log.getParent()) ; out.println(MARKER + "Effective level: <b>" + lev + "</b><br />"); } } }