java - spring boot2.0中log4j2日志无法输出到文件中，谁能帮帮我？

Question

我的项目有一个使用log4j实现的日志模块。之前项目的spring boot版本是1.5.8，最近升级到spring boot2.0打包项目后报错，按照网上的解决方案，我把log4j替换成了log4j2，然后去掉了spring boot默认日志模块的包成功，程序可以正常运行。但是日志模块功能有问题。可以在控制台正确输出日志，但是无法将日志导出到文件中，但并不是所有的日志信息都不能输出到文件中。将日志输出到启动类中的文件就可以了。这是我的日志模块的主要代码

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.Logger;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.appender.ConsoleAppender;
import org.apache.logging.log4j.core.config.Configurator;
import org.apache.logging.log4j.core.config.builder.api.*;
import org.apache.logging.log4j.core.config.builder.impl.BuiltConfiguration;

公共(public)类 LoggerUtil { 静态记录器记录器= null;

public static void fatal(String message) {
    if (logger != null) {
        logger.fatal(message);
    }
}

public static void debug(String msg) {
    if (logger != null) {
        logger.debug(msg);
    }
}

public static void info(String message) {
    if (logger != null) {
        logger.info(message);
    }
}

public static void warn(String message) {
    if (logger != null) {
        logger.warn(message);
    }
}

public static void error(String message) {
    if (logger != null) {
        logger.error(message);
    }
}

public static void initLogger(String filePrefix, String level) {
    ConfigurationBuilder<BuiltConfiguration> builder = ConfigurationBuilderFactory.newConfigurationBuilder();
    builder.setStatusLevel(Level.ERROR);
    builder.setConfigurationName("RollingBuilder");
    // create a console appender
    AppenderComponentBuilder appenderBuilder =
            builder.newAppender("Stdout", "CONSOLE")
                    .addAttribute("target", ConsoleAppender.Target.SYSTEM_OUT)
                    .add(builder.newFilter("ThresholdFilter", Filter.Result.ACCEPT, Filter.Result.DENY)
                            .addAttribute("level", Level.ERROR));
    appenderBuilder.add(builder.newLayout("PatternLayout")
            .addAttribute("pattern", "%d [%t] %-5level: %msg%n%throwable"));
    builder.add(appenderBuilder);
    // create a rolling file appender
    LayoutComponentBuilder layoutBuilder = builder.newLayout("PatternLayout")
            .addAttribute("pattern", "%d [%t] %-5level: %msg%n");
    ComponentBuilder triggeringPolicy = builder.newComponent("Policies")
            .addComponent(builder.newComponent("CronTriggeringPolicy").addAttribute("schedule", "0 0 0 * * ?"));
    appenderBuilder = builder.newAppender("rolling", "RollingFile")
            .addAttribute("filePattern", filePrefix + "-%d{yyyyMMdd}.log")
            .add(layoutBuilder)
            .addComponent(triggeringPolicy);
    builder.add(appenderBuilder);
    // create the new logger
    builder.add(builder.newLogger("Logger", Level.DEBUG)
            .add(builder.newAppenderRef("rolling"))
            .addAttribute("additivity", false));

    builder.add(builder.newRootLogger(getLogLevel(level))
            .add(builder.newAppenderRef("Stdout"))
            .add(builder.newAppenderRef("rolling")));
    LoggerContext ctx = Configurator.initialize(builder.build());
    logger = ctx.getLogger(KnowledgelibapiApplication.class.getName());
}

private static Level getLogLevel(String level) {
    switch (level.toUpperCase()) {
        case "FATAL":
            return Level.FATAL;
        case "DEBUG":
            return Level.DEBUG;
        case "INFO":
            return Level.INFO;
        case "WARN":
            return Level.WARN;
        case "ERROR":
            return Level.ERROR;
        default:
            return Level.WARN;
    }
}

}

Answer 1

将日志输出到文件的解决方案是在 src/main/resources 下创建 log4j2.xml 文件，并在类中使用 LogManager 创建记录器，如下所示:

private static Logger logger = LogManager.getLogger(MyClass.class);

然后使用logger.info或logger.debug或logger.error将日志输出到文件。

示例 log4j2.xml 文件内容:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
    <Appenders>
        <!-- Console Appender -->
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{yyyy-MMM-dd HH:mm:ss a} [%t] %-5level %logger{36} - %msg%n" />
        </Console>
        <!-- File Appender -->
        <File name="File" fileName="d:/app.log">
            <PatternLayout pattern="%d{yyyy-MMM-dd HH:mm:ss a} [%t] %-5level %logger{36} - %msg%n" />
        </File>

    </Appenders>

    <Loggers>
        <!-- Log everything in custom package -->
        <Logger name="your base package" level="debug" additivity="false">
            <AppenderRef ref="Console" />
            <AppenderRef ref="File" />
        </Logger>
    </Loggers>
</Configuration>

希望这对您有帮助...