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<TITLE>Creating a Custom Formatter for a Logger Handler (Java Developers Almanac Example)
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<A HREF="../java.util.logging/pkg.html">java.util.logging</A><font color="#666666" class="xsmall-font">
[20 examples]
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<B><A HREF="../java.util.logging/pkg.html#Formatters">Formatters</A></B><font color="#666666" class="xsmall-font">
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<h3>e400. Creating a Custom Formatter for a Logger Handler</h3>
A logger's handler uses a formatter to write a log record out to the
log file. The <code>java.util.logging</code> package provides two formatters; see
<a href="../java.util.logging/SetFormat.html" class="eglink"><b>e399</b> Setting the Formatter of a Logger Handler</a> for more information. However,
the logging package allows you to create custom formatters.
<P> This example creates a custom formatter that prints one line
for each log record and surrounds the log data with HTML tags.
<pre> // This custom formatter formats parts of a log record to a single line
class MyHtmlFormatter extends Formatter {
// This method is called for every log records
public String format(LogRecord rec) {
StringBuffer buf = new StringBuffer(1000);
// Bold any levels >= WARNING
if (rec.getLevel().intValue() >= Level.WARNING.intValue()) {
buf.append("<b>");
buf.append(rec.getLevel());
buf.append("</b>");
} else {
buf.append(rec.getLevel());
}
buf.append(' ');
buf.append(rec.getMillis());
buf.append(' ');
buf.append(formatMessage(rec));
buf.append('\n');
return buf.toString();
}
// This method is called just after the handler using this
// formatter is created
public String getHead(Handler h) {
return "<HTML><HEAD>"+(new Date())+"</HEAD><BODY><PRE>\n";
}
// This method is called just after the handler using this
// formatter is closed
public String getTail(Handler h) {
return "</PRE></BODY></HTML>\n";
}
}
</pre>
Here's some code to use the custom formatter:
<pre> // Get the logger
Logger logger = Logger.getLogger(<font color="#0066ff"><i>"com.mycompany"</i></font>);
try {
// Create a file handler that uses the custom formatter
FileHandler fh = new FileHandler(<font color="#0066ff"><i>"mylog.html"</i></font>);
fh.setFormatter(new MyHtmlFormatter());
logger.addHandler(fh);
} catch (IOException e) {
}
// Log some messages
logger.setLevel(<font color="#0066ff"><i>Level.ALL</i></font>);
logger.severe(<font color="#0066ff"><i>"my severe message"</i></font>);
logger.info(<font color="#0066ff"><i>"my info message"</i></font>);
logger.entering(this.getClass().getName(), <font color="#0066ff"><i>"myMethod"</i></font>, new Object[]{<font color="#0066ff"><i>"para1"</i></font>, <font color="#0066ff"><i>"para2"</i></font>});
</pre>
Here's the output from the example code above:
<pre> <HTML><HEAD>Fri Jan 11 13:32:57 PST 2002</HEAD><BODY><PRE>
<b>SEVERE</b> 1010784777240 my severe message
INFO 1010784777390 my info message
FINER 1010784777400 ENTRY para1 para2
</PRE></BODY></HTML>
</pre>
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<b>Related Examples</b></font></td>
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e399. <a class="eglink" href="SetFormat.html?l=rel">
Setting the Formatter of a Logger Handler
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See also:
<a class="eglink" href="/egs/java.util.logging/pkg.html?l=rel#Configuration">
Configuration
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<a class="eglink" href="/egs/java.util.logging/pkg.html?l=rel#File%20Size">
File Size
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<a class="eglink" href="/egs/java.util.logging/pkg.html?l=rel#Levels">
Levels
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