Creating a custom layout in Logback

问题:

I am trying to create a custom layout in logback as shown in an example in chapter 6 in the manual:

package com.dces.util;

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.LayoutBase;

public class LoggingConsoleLayout extends LayoutBase<ILoggingEvent>{

@Override
public String doLayout(ILoggingEvent event) {
    StringBuffer sbuf = new StringBuffer(128);
    sbuf.append("-- ");
    sbuf.append("[");
    sbuf.append(event.getLevel());
    sbuf.append("]");
    sbuf.append(event.getLoggerName());
    sbuf.append(" - ");
    sbuf.append(event.getFormattedMessage().replaceAll("\n", "\n\t"));
    sbuf.append(CoreConstants.LINE_SEPARATOR);
    return sbuf.toString();
}

Then I configured the XML file as follows:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
        <!-- <pattern> %-5level [%logger{0}] - %msg%n </pattern> -->
         <layout class="com.dces.util.LoggingConsoleLayout" />
    </encoder>
</appender>

<root level="trace">
    <appender-ref ref="STDOUT" />
</root>
</configuration>

However, I get the following error when I try to create a logger as following:

public class Main {
     private static Logger logger = (Logger)LoggerFactory.getLogger(Main.class);
     public static void main(String [] args)
     {
         logger.info("Testing");
     }
}

Here is the error message that I get:

05:40:11,519 |-ERROR in ch.qos.logback.core.joran.util.PropertySetter@3462fc6c - Could not invoke method setLayout in class ch.qos.logback.classic.encoder.PatternLayoutEncoder with parameter of type com.dces.util.LoggingConsoleLayout java.lang.reflect.InvocationTargetException
at java.lang.reflect.InvocationTargetException
at  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at  at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at  at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at  at java.lang.reflect.Method.invoke(Unknown Source)
at  at ch.qos.logback.core.joran.util.PropertySetter.invokeMethodWithSingleParameterOnThisObject(PropertySetter.java:293)
at  at ch.qos.logback.core.joran.util.PropertySetter.setComplexProperty(PropertySetter.java:356)
at  at ch.qos.logback.core.joran.action.NestedComplexPropertyIA.end(NestedComplexPropertyIA.java:179)
at  at ch.qos.logback.core.joran.spi.Interpreter.callEndAction(Interpreter.java:318)
at  at ch.qos.logback.core.joran.spi.Interpreter.endElement(Interpreter.java:197)
at  at ch.qos.logback.core.joran.spi.Interpreter.endElement(Interpreter.java:183)
at  at ch.qos.logback.core.joran.spi.EventPlayer.play(EventPlayer.java:62)
at  at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:157)
at  at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:143)
at  at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:106)
at  at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:56)
at  at ch.qos.logback.classic.util.ContextInitializer.configureByResource(ContextInitializer.java:75)
at  at ch.qos.logback.classic.util.ContextInitializer.autoConfig(ContextInitializer.java:148)
at  at org.slf4j.impl.StaticLoggerBinder.init(StaticLoggerBinder.java:85)
at  at org.slf4j.impl.StaticLoggerBinder.<clinit>(StaticLoggerBinder.java:55)
at  at org.slf4j.LoggerFactory.bind(LoggerFactory.java:128)
at  at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:107)
at  at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:295)
at  at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:269)
at  at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:281)
at  at com.dces.Main.<clinit>(Main.java:8)
Caused by: java.lang.UnsupportedOperationException: one cannot set the layout of ch.qos.logback.classic.encoder.PatternLayoutEncoder
at  at ch.qos.logback.core.pattern.PatternLayoutEncoderBase.setLayout(PatternLayoutEncoderBase.java:64)
at  ... 25 common frames omitted
05:40:11,538 |-ERROR in ch.qos.logback.classic.PatternLayout("null") - Empty or null pattern.

回答1:

The default encoder is PatternLayoutEncoder which is a subclass of PatternLayoutEncoderBase. PatternLayoutEncoderBase only supports setting a log pattern such as:

<encoder>
     <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
</encoder>

You can use LayoutWrappingEncoder instead

  <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
        <layout class="com.dces.util.LoggingConsoleLayout" />
  </encoder>