doc/examples/java-log4j/Hello.java

   1 /*
   2  * Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
   3  * Copyright (C) 2014 - Christian Babeux <christian.babeux@efficios.com>
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a copy
   6  * of this software and associated documentation files (the "Software"), to
   7  * deal in the Software without restriction, including without limitation the
   8  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
   9  * sell copies of the Software, and to permit persons to whom the Software is
  10  * furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be included in
  13  * all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 import java.io.IOException;
  25
  26 import org.apache.log4j.Appender;
  27 import org.apache.log4j.BasicConfigurator;
  28 import org.apache.log4j.Logger;
  29 import org.apache.log4j.Level;
  30 import org.lttng.ust.agent.log4j.LttngLogAppender;
  31
  32 /**
  33  * Example application using the LTTng-UST Java log4j agent.
  34  *
  35  * <p>
  36  * To obtain LTTng trace events, you should run the following sequence of
  37  * commands:
  38  * </p>
  39  *
  40  * <ul>
  41  * <li>$ lttng create</li>
  42  * <li>$ lttng enable-event -l -a</li>
  43  * <li>$ lttng start</li>
  44  * <li>(run this program)</li>
  45  * <li>$ lttng stop</li>
  46  * <li>$ lttng view</li>
  47  * <li>$ lttng destroy</li>
  48  * </ul>
  49  *
  50  * @author Alexandre Montplaisir
  51  * @author Christian Babeux
  52  */
  53 public class Hello {
  54
  55         private static final Logger HELLO_LOG = Logger.getLogger(Hello.class);
  56
  57         /**
  58          * Application start
  59          *
  60          * @param args
  61          *            Command-line arguments
  62          * @throws IOException
  63          *             If the required native libraries cannot be found. You may
  64          *             have to specify "-Djava.library.path=..." on the "java"
  65          *             command line.
  66          */
  67         public static void main(String args[]) throws IOException {
  68
  69                 /*
  70                  * Set lowest level to make sure all event levels are logged.
  71                  * Any jar can override the default log4j rootLogger level
  72                  * and a logger with no explicit level defaults to the non-null
  73                  * parent level. Events could be ignored if the inherited value
  74                  * is to low.
  75                  * e.g BSF  -> https://issues.apache.org/jira/browse/BSF-24
  76                  */
  77                 HELLO_LOG.setLevel(Level.ALL);
  78
  79                 /* Start with the default Log4j configuration, which logs to console */
  80                 BasicConfigurator.configure();
  81
  82                 /*
  83                  * Instantiate a LTTng log appender and attach it to the logger, which
  84                  * will now send the logged events to UST.
  85                  */
  86                 Appender lttngAppender = new LttngLogAppender();
  87                 HELLO_LOG.addAppender(lttngAppender);
  88
  89                 /*
  90                  * Here we've set up the appender programmatically, but it could also be
  91                  * defined at runtime, by reading a configuration file for example:
  92                  */
  93                 // PropertyConfigurator.configure(fileName);
  94
  95                 /* Trigger some tracing events using the Log4j Logger created before. */
  96                 HELLO_LOG.info("Hello World, the answer is " + 42);
  97                 HELLO_LOG.info("Another info event");
  98                 HELLO_LOG.error("An error event");
  99
 100                 /* Cleanup */
 101                 HELLO_LOG.removeAppender(lttngAppender);
 102                 lttngAppender.close();
 103         }
 104 }