Log4j2 RollingFile Appender - 在每个日志文件的开头添加自定义信息 [英] Log4j2 RollingFile Appender - add custom info at the start of each logfile

问题描述

将log4j2（beta9）与java 1.7一起使用。

Using log4j2 (beta9) with java 1.7.

我的完整log4j2.xml：

My complete log4j2.xml:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
  <Properties>
    <Property name="projectPrefix">Tts</Property>
    <Property name="rawPattern">%d %-5p [%t] %C{2} (%F:%L) - %m%n</Property>
    <Property name="coloredPattern">%d %highlight{%-5p}{FATAL=bright red, ERROR=red, WARN=yellow, INFO=cyan, DEBUG=green, TRACE=bright blue} %style{[%t] %C{2} (%F:%L) -}{bright,black} %m%n</Property>
    <Property name="fileName">Log/${projectPrefix}.log</Property>
    <Property name="filePattern">Log/${projectPrefix}-%i.log</Property>
  </Properties>
  <Appenders>
    <Console name="Stdout" target="SYSTEM_OUT">
      <PatternLayout pattern="${coloredPattern}"/>
    </Console>
    <RollingFile name="Logfile" fileName="${fileName}" filePattern="${filePattern}">
      <PatternLayout pattern="${rawPattern}"/>
      <Policies>
        <SizeBasedTriggeringPolicy size="16 MB"/>
      </Policies>
      <DefaultRolloverStrategy fileIndex="min" max="16"/>
    </RollingFile>
  </Appenders>
  <Loggers>
    <Root level="info">
      <AppenderRef ref="Stdout"/>
      <AppenderRef ref="Logfile"/>
    </Root>
  </Loggers>
</Configuration>

我想在每个日志文件的顶部添加一些自定义信息，比如我的应用程序的版本字符串，应用程序正常运行时间和系统正常运行时间。甚至在刚关闭的日志文件的底部写一些bye，bye / eof也没关系。

I want to add some custom info at the top of each logfile, like the version string of my application, the application uptime and the system uptime. And even writing some »bye, bye / eof« to the bottom of the just closed logfile would also be fine.

是否有像钩子或回调这样的东西得到通知当RollingFileAppander创建了一个新文件时，我可以将我的东西放在这些新的日志文件（或任何其他建议）中吗？

Is there something like a hook or callback to get notified when the RollingFileAppander has created a new file, so that I can put my things at first into these new logfile (or any other suggestion)?

推荐答案

好的，通过扩展DefaultRolloverStrategy就可以解决这个问题，如 here 。但

Ok, there is a working solution for this problem by extending DefaultRolloverStrategy like described here. But

• 它需要大约150行代码（包括包装RolloverDescription和appender.rolling.helper.Action）和


• 闻起来有点因为需要完全复制DefaultRolloverStrategy的工厂方法（使得此解决方案维护不友好，例如，如果DefaultRolloverStrategy在未来版本中获得更多配置参数）

要让log4j2调用我们的工厂方法，log4j2.xml的root标签必须与我们类的包一起归属，例如：

To let log4j2 call our factory method, the root tag of log4j2.xml must be attributed with the package of our class, e.g.:

<Configuration packages="de.jme.toolbox.logging">
...
</Configuration>

在我们自己的RolloverStrategy中，我们必须处理 @Plugin 和 @PluginFactory 如上所述这里。

and within our own RolloverStrategy we have to deal with @Plugin and @PluginFactory as described here.

最后这里我的完整log4j2.xml（你不需要所有的属性 - 这就是我喜欢的方式配置我的日志记录）：

Finally here my complete log4j2.xml (you don't need all that properties - that's just the way how I like to configure my logging):

<?xml version="1.0" encoding="UTF-8"?>
<Configuration packages="de.jme.toolbox.logging">
  <Properties>
    <Property name="projectPrefix">Tts</Property>
    <Property name="rawPattern">%d %-5p [%t] %C{2} (%F:%L) - %m%n</Property>
    <Property name="coloredPattern">%d %highlight{%-5p}{FATAL=bright red, ERROR=red, WARN=yellow, INFO=cyan, DEBUG=green, TRACE=bright blue} %style{[%t] %C{2} (%F:%L) -}{bright,black} %m%n</Property>
    <Property name="coloredShortPattern">%d %highlight{%-5p}{FATAL=bright red, ERROR=red, WARN=yellow, INFO=cyan, DEBUG=green, TRACE=bright blue} %style{[%t] -}{bright,black} %m%n</Property>
    <Property name="fileName">Log/${projectPrefix}.log</Property>
    <Property name="filePattern">Log/${projectPrefix}-%i.log</Property>
  </Properties>
  <Appenders>
    <Console name="Stdout" target="SYSTEM_OUT">
      <PatternLayout pattern="${coloredPattern}"/>
    </Console>
    <RollingFile name="Logfile" fileName="${fileName}" filePattern="${filePattern}">
      <PatternLayout pattern="${rawPattern}"/>
      <Policies>
        <SizeBasedTriggeringPolicy size="1 MB"/>
      </Policies>
      <MyRolloverStrategy fileIndex="min" max="16"/>
    </RollingFile>
  </Appenders>
  <Loggers>
    <Root level="info">
      <AppenderRef ref="Stdout"/>
      <AppenderRef ref="Logfile"/>
    </Root>
  </Loggers>
</Configuration>

此处MyRolloverStrategy.java：

And here MyRolloverStrategy.java:

package de.jme.toolbox.logging;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.zip.Deflater;

import org.apache.logging.log4j.core.appender.rolling.DefaultRolloverStrategy;
import org.apache.logging.log4j.core.appender.rolling.RollingFileManager;
import org.apache.logging.log4j.core.appender.rolling.RolloverDescription;
import org.apache.logging.log4j.core.appender.rolling.helper.Action;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.core.helpers.Integers;
import org.apache.logging.log4j.core.lookup.StrSubstitutor;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.status.StatusLogger;

/**
 * Own RolloverStrategy to hook the DefaultRolloverStrategy's rollover events
 *
 * Siehe auch:
 * - https://issues.apache.org/jira/browse/LOG4J2-486
 * - http://apache-logging.6191.n7.nabble.com/log4j2-getting-started-amp-rolling-files-tt8406.html#a42402
 * - http://stackoverflow.com/questions/20819376/log4j2-rollingfile-appender-add-custom-info-at-the-start-of-each-logfile
 *
 * @author Joe Merten
 */
@org.apache.logging.log4j.core.config.plugins.Plugin(name="MyRolloverStrategy", category="Core", printObject=true)
public class MyRolloverStrategy extends DefaultRolloverStrategy {

    protected static final Logger logger = StatusLogger.getLogger();

    // ==============================
    // ↓↓↓ Some stuff copied from ↓↓↓
    // https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk/log4j-core/src/main/java/org/apache/logging/log4j/core/appender/rolling/DefaultRolloverStrategy.java r1556050
    // Just changed »DefaultRolloverStrategy« to »MyRolloverStrategy«

    private static final int MIN_WINDOW_SIZE = 1;
    private static final int DEFAULT_WINDOW_SIZE = 7;

    @PluginFactory
    public static MyRolloverStrategy createStrategy(
            @PluginAttribute("max") final String max,
            @PluginAttribute("min") final String min,
            @PluginAttribute("fileIndex") final String fileIndex,
            @PluginAttribute("compressionLevel") final String compressionLevelStr,
            @PluginConfiguration final Configuration config) {
        final boolean useMax = fileIndex == null ? true : fileIndex.equalsIgnoreCase("max");
        int minIndex;
        if (min != null) {
            minIndex = Integer.parseInt(min);
            if (minIndex < 1) {
                LOGGER.error("Minimum window size too small. Limited to " + MIN_WINDOW_SIZE);
                minIndex = MIN_WINDOW_SIZE;
            }
        } else {
            minIndex = MIN_WINDOW_SIZE;
        }
        int maxIndex;
        if (max != null) {
            maxIndex = Integer.parseInt(max);
            if (maxIndex < minIndex) {
                maxIndex = minIndex < DEFAULT_WINDOW_SIZE ? DEFAULT_WINDOW_SIZE : minIndex;
                LOGGER.error("Maximum window size must be greater than the minimum windows size. Set to " + maxIndex);
            }
        } else {
            maxIndex = DEFAULT_WINDOW_SIZE;
        }
        final int compressionLevel = Integers.parseInt(compressionLevelStr, Deflater.DEFAULT_COMPRESSION);
        return new MyRolloverStrategy(minIndex, maxIndex, useMax, compressionLevel, config.getStrSubstitutor());
    }
    // ↑↑↑ Some stuff copied from ↑↑↑
    // ==============================

    protected MyRolloverStrategy(int minIndex, int maxIndex, boolean useMax, int compressionLevel, StrSubstitutor subst) {
        super(minIndex, maxIndex, useMax, compressionLevel, subst);
    }

    // Wrapper class only for setting a hook to execute()
    static class MyAction implements Action {
        final Action delegate;
        final String fileName;

        public MyAction(final Action delegate, final String fileName) {
            this.delegate = delegate;
            this.fileName = fileName;
        }

        @Override public void run() {
            delegate.run();
        }

        @Override public boolean execute() throws IOException {
            try {
                BufferedWriter writer = null;
                try {
                    writer = new BufferedWriter(new FileWriter(new File(fileName), true));
                    writer.write("****************************\n");
                    writer.write("*** Bye, bye old logfile ***\n");
                    writer.write("****************************\n");
                } finally {
                    if (writer != null)
                        writer.close();
                }
            } catch (Throwable e) {
                logger.error("Writing to bottom of old logfile \"" + fileName + "\" with", e);
            }

            boolean ret = delegate.execute();

            try {
                BufferedWriter writer = null;
                try {
                    writer = new BufferedWriter(new FileWriter(new File(fileName), true));
                    writer.write("*************************\n");
                    writer.write("*** Hello new logfile ***\n");
                    writer.write("*************************\n");
                } finally {
                    if (writer != null)
                        writer.close();
                }
            } catch (Throwable e) {
                logger.error("Writing to top of new logfile \"" + fileName + "\" with", e);
            }

            return ret;
        }

        @Override public void close() {
            delegate.close();
        }

        @Override public boolean isComplete() {
            return delegate.isComplete();
        }
    }

    // Wrapper class only for setting a hook to getSynchronous().execute()
    static class MyRolloverDescription implements RolloverDescription {
        final RolloverDescription delegate;

        public MyRolloverDescription(final RolloverDescription delegate) {
            this.delegate = delegate;
        }

        @Override public String getActiveFileName() {
            return delegate.getActiveFileName();
        }

        @Override public boolean getAppend() {
            //return delegate.getAppend();
            // As long as we already put some data to the top of the new logfile, subsequent writes should be performed with "append".
            return true;
        }

        // The synchronous action is for renaming, here we want to hook
        @Override public Action getSynchronous() {
            Action delegateAction = delegate.getSynchronous();
            if (delegateAction == null) return null;
            return new MyAction(delegateAction, delegate.getActiveFileName());
        }

        // The asynchronous action is for compressing, we don't need to hook here
        @Override public Action getAsynchronous() {
            return delegate.getAsynchronous();
        }
    }

    public RolloverDescription rollover(final RollingFileManager manager) {
        RolloverDescription ret = super.rollover(manager);
        return new MyRolloverDescription(ret);
    }
}

在将来版本的log4j2中解决此要求可能会更容易，如果我发布的功能请求将会实施。

Solving this requirement might be easier in future versions of log4j2, if my posted feature request would implemented.

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