使用log4j2 API

时间:2015-10-19 12:47:43

标签: java logging log4j log4j2 apache-commons-logging

我正在将EAR应用程序从log4j迁移到log4j2。我有类在EAR的不同罐子中扩展appender,过滤器,布局,现在,我已将它们转换为插件。这意味着我在多个jar中有自定义插件(假设有3个罐子)。

我没有在packages中使用log4j2.xml属性,而是使用Dlog4j.configurationFile JVM参数初始化日志记录系统,该参数指向EAR log4j2.xml中的META-INF位置。

在所有三个jar项目中添加以下插件都不起作用。

<plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <executions>
                <execution>
                    <id>log4j-plugin-processor</id>
                    <goals>
                        <goal>compile</goal>
                    </goals>
                    <phase>process-classes</phase>
                    <configuration>
                        <proc>only</proc>
                        <annotationProcessors>
                            <annotationProcessor>org.apache.logging.log4j.core.config.plugins.processor.PluginProcessor</annotationProcessor>
                        </annotationProcessors>
                    </configuration>
                </execution>
            </executions>
        </plugin>

图案布局: 在下面的模式布局中,e是自定义模式,其中编写自定义模式转换器插件以转换此字符串。

<Pattern>%d %-5p [%c{1}] [EventId: %e] [%t] %m%n</Pattern>

上述模式布局的自定义转换器插件(在jar1中):

jar1在Log4J2Plugins.dat文件夹中的META-INF下有org.apache..个文件。

@Plugin(name = "EventPatternConverter", category = "Converter")
@ConverterKeys({"e"})

public class EventPatternConverter extends LogEventPatternConverter {

protected EventPatternConverter(String name, String style) {
    super(name, style);
}

public static EventPatternConverter newInstance(String[] options) {
  return new EventPatternConverter("e", "e");
}

@Override
public void format(LogEvent event, StringBuilder toAppendTo) {      
    String eventId= "";
    // Append empty string (OR) value        
    toAppendTo.append(eventId);
  }
}

但是,我收到以下错误

ERROR Unrecognized format specifier [e]

甚至,没有任何自定义插件被识别为我正在获得invalid element的其他自定义插件,这些插件在jar2,jar3中都可用,并且它们都有Log4J2Plugins.dat个文件。

ERROR File contains an invalid element or attribute "TestFilter"

我在EAR中使用log4j-api-2.4.jarlog4j-core-2.4.jarlog4j-jcl-2.4.jarlog4j-web-2.4.1.jarcommons-logging-1.1.1.jar个罐子。

我已定义了一个自定义模式转换器插件,并期望此转换器应用于所有模式布局,包括使用<patternlayout>定义的默认模式布局。这是对的吗?

如果是,请帮助,如果有人遇到此问题并指导我,如果我错误定义自定义插件,因为它们都没有从EAR中的jar中检测到。

1 个答案:

答案 0 :(得分:1)

编译自定义插件时,Log4J pom.xml定义了一个插件,可以自动生成文件中的缓存数据META-INF / org / apache / logging / log4j / core / config / plugins / Log4j2Plugins.dat 您可以在Maven项目中的目标/类下看到这一点。

log4j-core-2.x.x.jar还包含一个定义其缓存数据的Log4j2Plugins.dat。

问题是在使用ShrinkWrap测试EAR时会创建一个JAR,并且通常将log4j-core-2.xxjar Log4j2Plugins.dat添加到测试JAR中,因为它很可能是类路径中的第一个。 / p>

这意味着您的自定义插件缓存缺失。

使用ShrinkWrap的解决方案是创建一个新的Log4j2Plugins.dat,将所有必需的自定义插件缓存文件与核心合并,然后将其添加到JAR。

以下功能实现了......

private static void mergeLog4J2Log4j2PluginsFile(JavaArchive ja, Class... uniqueJARClasses) {
  // @Author: Johnathan Ingram <jingram@rogueware.org>
  // Log4J2 uses /META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat within a JAR to define custom plugins
  //        This is automatically generated by the plugin defined in the log4j-core-2.x.x pom.xml when compiling your custom plugin
  //        The problem with shrinkwrap is that the JAR is not preserved and only a single 
  //        /META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat
  //        file can exist as JAR files cannot be added to a JAR file as a library.
  //        This is normally the default contained in log4j-core-2.x.x.jar which does not expose any custom plugins
  //        To rectify, both the core and the custom plugin JAR file Log4j2Plugins.dat need to be merged into a single Log4j2Plugins.dat
  try {
     // List of a unique class in each JAR containing a Log4j2Plugins.dat requiring merging
     Vector<URL> datUrls = new Vector<URL>();
     for (Class klass : uniqueJARClasses) {
        // Find  the JAR the class belongs to
        URL classLoc = klass.getProtectionDomain().getCodeSource().getLocation();
        URL resourceURL = classLoc.toString().endsWith(".jar")
                ? new URL("jar:" + URLDecoder.decode(classLoc.toString(), "UTF-8") + "!/META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat")
                : new URL(URLDecoder.decode(classLoc.toString(), "UTF-8") + "/META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat");
        datUrls.add(resourceURL);
     }

     // Use the Log4J2 PluginCache to build a merged Log4j2Plugins.dat
     File mergedDatFile = new File("target/Log4j2Plugins.dat");
     try (FileOutputStream fo = new FileOutputStream(mergedDatFile)) {
        org.apache.logging.log4j.core.config.plugins.processor.PluginCache pc = new org.apache.logging.log4j.core.config.plugins.processor.PluginCache();
        pc.loadCacheFiles(datUrls.elements());
        pc.writeCache(fo);
     }

     // Replace the default Log4j2Plugins.dat if present
     ja.delete("/META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat");
     ja.addAsManifestResource(mergedDatFile, "org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat");

  } catch (Exception ex) {
     ex.printStackTrace(System.err);
  }
}

使用您的示例运行:

JavaArchive ja = ShrinkWrap.create(JavaArchive.class, "my-test.jar");
...
mergeLog4J2Log4j2PluginsFile(ja, org.apache.logging.log4j.core.config.plugins.processor.PluginCache.class, EventPatternConverter.class);