java - 使用 log4j2.xml 初始化 slf4j

Question

我想在 log4j 上使用 slf4j。我在 pom.xml 中添加了以下依赖项(我对 slf4j 使用 1.7.25，对 log4j2 使用 2.10.0):

<dependencies>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>${slf4j.version}</version>
    </dependency>


    <dependency>
       <groupId>org.apache.logging.log4j</groupId>
       <artifactId>log4j-slf4j-impl</artifactId>
       <version>${log4j.version}</version>
    </dependency>

    <dependency>
       <groupId>org.apache.logging.log4j</groupId>
       <artifactId>log4j-api</artifactId>
       <version>${log4j.version}</version>
    </dependency>

    <dependency>
       <groupId>org.apache.logging.log4j</groupId>
       <artifactId>log4j-core</artifactId>
       <version>${log4j.version}</version>
    </dependency>
</dependencies> 

一切都构建得很好，没有编译错误或缺少依赖项，但我未能在我的类中指定负责初始化 Logger 的配置 (log4j2.xml) 文件。在这种情况下，它总是打印相同的警告

log4j:WARN No appenders could be found for logger (com.mypackage.etc).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

我搜索了一种提供配置文件的正确方法，结果是这样的:

LoggerContext context = (org.apache.logging.log4j.core.LoggerContext) LogManager.getContext(false);
File file = new File("path/to/a/different/log4j2.xml");
context.setConfigLocation(file.toURI());

问题是，在我的情况下，LogManager.getContext(false) 将始终返回 Slf4JLoggerContext 的实例(考虑到我使用 slf4j 作为记录器的外观)并且初始化将失败并出现 ClassCastException。我试图存储 Slf4JLoggerContext 的那个实例，但它没有为上下文提供 setter 。我也没有找到从 log4j 中检索 LoggerContext 的方法。

有什么方法可以向 slf4j 提供配置文件 (log4j2.xml) 以便查看所有的 appender 和 loggers？

更新考虑这是我的配置文件(我替换了原始包和附加程序名称):

<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
    <Properties>
        <Property name="def.files.backup.count">10</Property>
        <Property name="log.file.path">${oo.home}/var/logs</Property>
        <Property name="def.file.max.size">10MB</Property>
        <Property name="log.level">WARN</Property>
    </Properties>

    <ThresholdFilter/>

    <Appenders>
        <RollingFile name="Appender1" fileName="${log.file.path}/file1.log" maxFileSize="${def.file.max.size}"
                     maxBackupIndex="${def.files.backup.count}">
            <PatternLayout>org.apache.log4j.PatternLayout</PatternLayout>
            <Policies>
                <SizeBasedTriggeringPolicy size="10MB"/>
            </Policies>
        </RollingFile>

        <RollingFile name="Appender2" fileName="${log.file.path}/file2.log"
                     maxFileSize="${def.file.max.size}"
                     maxBackupIndex="${def.files.backup.count}">
            <PatternLayout>org.apache.log4j.PatternLayout</PatternLayout>
            <Policies>
                <SizeBasedTriggeringPolicy size="10MB"/>
            </Policies>
        </RollingFile>

        <RollingFile name="Appender3" fileName="${log.file.path}/file3.log"
                     maxFileSize="${def.file.max.size}"
                     maxBackupIndex="${def.files.backup.count}">
            <PatternLayout>org.apache.log4j.PatternLayout</PatternLayout>
            <Policies>
                <SizeBasedTriggeringPolicy size="10MB"/>
            </Policies>
        </RollingFile>

    </Appenders>

    <Loggers>
        <AsyncLogger name="com.package1.oo" level="${log.level}" additivity="false">
            <AppenderRef ref="Appender1"/>
        </AsyncLogger>

        <AsyncLogger name="io.package2" level="${log.level}" additivity="false">
            <AppenderRef ref="Appender2"/>
        </AsyncLogger>

        <AsyncLogger name="com.package3.package3" level="${log.level}" additivity="false">
            <AppenderRef ref="Appender3"/>
        </AsyncLogger>

        <AsyncLogger name="org.package4" level="${log.level}">

        </AsyncLogger>

        <AsyncLogger name="com.package5.Class1" level="${log.level}">

        </AsyncLogger>

        <AsyncRoot level="${log.level}">
            <AppenderRef ref="Appender1"/>
            <AppenderRef ref="Appender2"/>
            <AppenderRef ref="Appender3"/>

        </AsyncRoot>
    </Loggers>

</Configuration>

Answer 1

我已经测试了这个配置。 log4j2 文件必须在您的类路径中。

行家

<dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-slf4j-impl</artifactId>
    </dependency>

log4j2.xml

此外，添加 xsd 有助于您创建配置。我已经为 spring 框架添加了 Logger。请注意，需要 jcl-over-slf4j 才能使用 spring 的内部日志记录

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="error"
               xmlns="http://logging.apache.org/log4j/2.0/config"
               xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
               xsi:schemaLocation="http://logging.apache.org/log4j/2.0/config
                https://raw.githubusercontent.com/apache/logging-log4j2/master/log4j-core/src/main/resources/Log4j-config.xsd">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%highlight{%d{HH:mm:ss.SSS} [%t] %-5level %logger{36}} - %msg%n"/>
        </Console>
    </Appenders>
    <Loggers>
        <Root level="debug">
            <AppenderRef ref="Console"/>
        </Root>
        <Logger name="org.springframework" level="error">
            <AppenderRef ref="Console"/>
        </Logger>
    </Loggers>
</Configuration>