Add a Log4j 2.x Java agent

[deliverable/lttng-ust.git] / doc / examples / java-log4j / HelloLog4j.java

diff --git a/doc/examples/java-log4j/HelloLog4j.java b/doc/examples/java-log4j/HelloLog4j.java
new file mode 100644 (file)
index 0000000..1870ef4
--- /dev/null
+++ b/doc/examples/java-log4j/HelloLog4j.java
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
+ * Copyright (C) 2014 - Christian Babeux <christian.babeux@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+import java.io.IOException;
+
+import org.apache.log4j.Appender;
+import org.apache.log4j.BasicConfigurator;
+import org.apache.log4j.Logger;
+import org.apache.log4j.Level;
+import org.lttng.ust.agent.log4j.LttngLogAppender;
+
+/**
+ * Example application using the LTTng-UST Java log4j agent.
+ *
+ * <p>
+ * To obtain LTTng trace events, you should run the following sequence of
+ * commands:
+ * </p>
+ *
+ * <ul>
+ * <li>$ lttng create</li>
+ * <li>$ lttng enable-event -l -a</li>
+ * <li>$ lttng start</li>
+ * <li>(run this program)</li>
+ * <li>$ lttng stop</li>
+ * <li>$ lttng view</li>
+ * <li>$ lttng destroy</li>
+ * </ul>
+ *
+ * @author Alexandre Montplaisir
+ * @author Christian Babeux
+ */
+public class HelloLog4j {
+
+       private static final Logger HELLO_LOG = Logger.getLogger(HelloLog4j.class);
+
+       /**
+        * Application start
+        *
+        * @param args
+        *            Command-line arguments
+        * @throws IOException
+        *             If the required native libraries cannot be found. You may
+        *             have to specify "-Djava.library.path=..." on the "java"
+        *             command line.
+        */
+       public static void main(String args[]) throws IOException {
+
+               /*
+                * Set lowest level to make sure all event levels are logged.
+                * Any jar can override the default log4j rootLogger level
+                * and a logger with no explicit level defaults to the non-null
+                * parent level. Events could be ignored if the inherited value
+                * is to low.
+                * e.g BSF  -> https://issues.apache.org/jira/browse/BSF-24
+                */
+               HELLO_LOG.setLevel(Level.ALL);
+
+               /* Start with the default Log4j configuration, which logs to console */
+               BasicConfigurator.configure();
+
+               /*
+                * Instantiate a LTTng log appender and attach it to the logger, which
+                * will now send the logged events to UST.
+                */
+               Appender lttngAppender = new LttngLogAppender();
+               HELLO_LOG.addAppender(lttngAppender);
+
+               /*
+                * Here we've set up the appender programmatically, but it could also be
+                * defined at runtime, by reading a configuration file for example:
+                */
+               // PropertyConfigurator.configure(fileName);
+
+               /* Trigger some tracing events using the Log4j Logger created before. */
+               HELLO_LOG.info("Hello World, the answer is " + 42);
+               HELLO_LOG.info("Another info event");
+               HELLO_LOG.error("An error event");
+
+               /* Cleanup */
+               HELLO_LOG.removeAppender(lttngAppender);
+               lttngAppender.close();
+       }
+}