[logback-dev] svn commit: r1053 - in logback/trunk: logback-examples logback-examples/src/main/java/chapter4 logback-site/src/site/xdocTemplates/manual
noreply.seb at qos.ch
noreply.seb at qos.ch
Fri Dec 1 18:13:51 CET 2006
Author: seb
Date: Fri Dec 1 18:13:51 2006
New Revision: 1053
Added:
logback/trunk/logback-examples/src/main/java/chapter4/CountingConsoleAppender.java
logback/trunk/logback-examples/src/main/java/chapter4/countingConsole.xml
Modified:
logback/trunk/logback-examples/ (props changed)
logback/trunk/logback-site/src/site/xdocTemplates/manual/appenders.xml
Log:
added "create your own appender" section in chapter 4
Added: logback/trunk/logback-examples/src/main/java/chapter4/CountingConsoleAppender.java
==============================================================================
--- (empty file)
+++ logback/trunk/logback-examples/src/main/java/chapter4/CountingConsoleAppender.java Fri Dec 1 18:13:51 2006
@@ -0,0 +1,65 @@
+/**
+ * Logback: the reliable, generic, fast and flexible logging framework.
+ *
+ * Copyright (C) 1999-2006, QOS.ch
+ *
+ * This library is free software, you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation.
+ */
+
+package chapter4;
+
+import ch.qos.logback.core.AppenderBase;
+import ch.qos.logback.core.Layout;
+
+
+public class CountingConsoleAppender extends AppenderBase {
+ static int DEFAULT_LIMIT = 10;
+ int counter = 0;
+ int limit = DEFAULT_LIMIT;
+
+ private Layout layout;
+
+ public CountingConsoleAppender() {
+ }
+
+ public void setLimit(int limit) {
+ this.limit = limit;
+ }
+
+ public int getLimit() {
+ return limit;
+ }
+
+ @Override
+ public void start() {
+ if (this.layout == null) {
+ addError("No layout set for the appender named ["+ name +"].");
+ return;
+ }
+
+ super.start();
+ }
+
+ public void append(Object eventObject) {
+
+ if (counter >= limit) {
+ return;
+ }
+
+ // output the events as formatted by our layout
+ System.out.print(this.layout.doLayout(eventObject));
+
+ // prepare for next event
+ counter++;
+ }
+
+ public Layout getLayout() {
+ return layout;
+ }
+
+ public void setLayout(Layout layout) {
+ this.layout = layout;
+ }
+}
Added: logback/trunk/logback-examples/src/main/java/chapter4/countingConsole.xml
==============================================================================
--- (empty file)
+++ logback/trunk/logback-examples/src/main/java/chapter4/countingConsole.xml Fri Dec 1 18:13:51 2006
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+
+<configuration>
+
+
+ <appender name="CUSTOM" class="chapter4.CountingConsoleAppender">
+ <layout class="ch.qos.logback.classic.PatternLayout">
+ <Pattern>%date [%thread] %-5level %logger - %msg%n</Pattern>
+ </layout>
+ <limit>5</limit>
+ </appender>
+
+ <root>
+ <level value="debug"/>
+ <appender-ref ref="CUSTOM" />
+ </root>
+</configuration>
+
+
+
Modified: logback/trunk/logback-site/src/site/xdocTemplates/manual/appenders.xml
==============================================================================
--- logback/trunk/logback-site/src/site/xdocTemplates/manual/appenders.xml (original)
+++ logback/trunk/logback-site/src/site/xdocTemplates/manual/appenders.xml Fri Dec 1 18:13:51 2006
@@ -2633,5 +2633,107 @@
<appender-ref ref="DB" />
</configuration></pre></div>
- </body>
+
+ <a name="WriteOwnAppender" />
+ <h2>Writing your own Appender</h2>
+
+
+ <p>You can easily write your appender by sub-classing <code>AppenderBase</code>.
+ It handles support for filters, status among other functionality shared by most appenders.
+ The derived class only needs to implement one method, namely
+ <code>append(Object eventObject)</code>.
+ </p>
+
+ <p>The <code>CountingConsoleAppender</code>, which we list next, appends a limited
+ number of incoming events on the console. It shuts down after the limit is reached.
+ It uses a <code>Layout</code> to format the events and accepts a parameter,
+ thus a few more methods are needed.
+ </p>
+
+<em>Example 4.16: <code>CountingConsoleAppender</code> (logback-examples/src/main/java/chapter4/CountingConsoleAppender.java)</em>
+<div class="source"><pre>package chapter4;
+
+import ch.qos.logback.core.AppenderBase;
+import ch.qos.logback.core.Layout;
+
+
+public class CountingConsoleAppender extends AppenderBase {
+ static int DEFAULT_LIMIT = 16;
+ int counter = 0;
+ int limit = DEFAULT_LIMIT;
+
+ private Layout layout;
+
+ public CountingConsoleAppender() {
+ }
+
+ public void setLimit(int limit) {
+ this.limit = limit;
+ }
+
+ public int getLimit() {
+ return limit;
+ }
+
+ @Override
+ public void start() {
+ if (this.layout == null) {
+ addError("No layout set for the appender named ["+ name +"].");
+ return;
+ }
+
+ super.start();
+ }
+
+ public void append(Object eventObject) {
+
+ if (counter >= limit) {
+ return;
+ }
+
+ // output the events as formatted by our layout
+ System.out.print(this.layout.doLayout(eventObject));
+
+ // prepare for next event
+ counter++;
+ }
+
+ public Layout getLayout() {
+ return layout;
+ }
+
+ public void setLayout(Layout layout) {
+ this.layout = layout;
+ }
+}</pre></div>
+
+ <p>
+ The <code>start()</code> method checks for the presence of a <code>Layout</code>.
+ In case none is found, the appender is not started.
+ </p>
+
+ <p>
+ This custom appender illustrates a two points:
+ </p>
+
+ <ul>
+ <li>
+ All options that follow the setter/getter JavaBeans conventions
+ are handled transparently. The <code>start()</code> method, that is
+ called automatically, has the responsability to check that the given
+ options are coherent.
+ </li>
+ <li>
+ The <code>AppenderBase.doAppend()</code> method invokes the append()
+ method of its derived classes where actual output operations occur.
+ It is in this method that appenders format events by invoking their layouts.
+ </li>
+ </ul>
+
+ <p>
+ The <code>CountingConsoleAppender</code> can be configured like any appender.
+ See sample file <em>logback-examples/src/main/java/chapter4/countingConsole.xml</em>
+ for an example.
+ </p>
+ </body>
</document>
\ No newline at end of file
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