doc/examples/java-log4j2-ctx/HelloLog4j2Ctx.java

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright (C) 2022 EfficiOS Inc.
   5  */
   6
   7 import java.net.URI;
   8 import java.util.ArrayList;
   9
  10 import org.apache.logging.log4j.LogManager;
  11 import org.apache.logging.log4j.Logger;
  12 import org.apache.logging.log4j.core.LoggerContext;
  13
  14 /**
  15  * Example application using the LTTng-UST Java log4j agent.
  16  *
  17  * <p>
  18  * To obtain LTTng trace events, you should run the following sequence of
  19  * commands:
  20  * </p>
  21  *
  22  * <ul>
  23  * <li>$ lttng create</li>
  24  * <li>$ lttng enable-event -l -a</li>
  25  * <li>$ lttng start</li>
  26  * <li>(run this program)</li>
  27  * <li>$ lttng stop</li>
  28  * <li>$ lttng view</li>
  29  * <li>$ lttng destroy</li>
  30  * </ul>
  31  *
  32  */
  33 public class HelloLog4j2Ctx {
  34
  35         /**
  36          * Application start
  37          *
  38          * @param args Command-line arguments
  39          */
  40         public static void main(String args[]) {
  41
  42                 URI configFileUri1 = URI.create("./log4j2.ctx1.xml");
  43                 URI configFileUri2 = URI.create("./log4j2.ctx2.xml");
  44
  45                 LoggerContext loggerContext1 = (LoggerContext) LogManager.getContext(ClassLoader.getSystemClassLoader(), false,
  46                                 configFileUri1);
  47                 LoggerContext loggerContext2 = (LoggerContext) LogManager.getContext(ClassLoader.getSystemClassLoader(), false,
  48                                 configFileUri2);
  49
  50                 /* Loggers in different contexts with the same name. */
  51                 Logger logger1ctx1 = loggerContext1.getLogger(HelloLog4j2Ctx.class);
  52                 Logger logger1ctx2 = loggerContext2.getLogger(HelloLog4j2Ctx.class);
  53
  54                 Logger logger2ctx1 = loggerContext1.getLogger("Logger2");
  55                 Logger logger3ctx2 = loggerContext2.getLogger("Logger3");
  56
  57                 ArrayList<Logger> loggers = new ArrayList<Logger>();
  58
  59                 loggers.add(logger1ctx1);
  60                 loggers.add(logger1ctx2);
  61                 loggers.add(logger2ctx1);
  62                 loggers.add(logger3ctx2);
  63
  64                 for (Logger logger : loggers) {
  65                         /* Trigger some tracing events using the Log4j Logger created before. */
  66                         logger.info("Context config: Hello World, the answer is " + 42);
  67                         logger.info("Context config: Another info event");
  68                         logger.error("Context config: An error event");
  69                 }
  70         }
  71 }