Log4j2不写入文件

Question

I'm using Log4j2 with yaml configuration. Logging to console works well, an external log file is created every time but it has no entries. Thanks for some hints.

Main method at src/main/java/my/example/log/ :

public class App {
    private static Logger LOG = LogManager.getLogger(App.class);

    public static void main(String[] args) {
      LOG.entry();
      LOG.info("Start of application");
      System.out.println("Hello World!");
      LOG.info("End of application");
      LOG.exit();
    }
}

log4j2.properties at src/main/java - if I delete / rename it, log4j shows a message that no config was found, so it uses this file:

name = PropertiesConfig
property.filename = logs/example.log     

appenders = console, rolling
appender.console.type = Console
appender.console.name = STDOUT
appender.console.layout.type = PatternLayout
appender.console.layout.pattern = %d{dd.MM.yyyy HH:mm:ss,SSS} %-5p %c{1}:%L - %m%n

appender.rolling.type = RollingFile
appender.rolling.name = roll
appender.rolling.fileName = ${filename}
appender.rolling.filePattern = logs/app/%d{MM-dd-yy-HH-mm-ss}-%i.log.gz
appender.rolling.layout.type = PatternLayout
appender.rolling.layout.pattern = %d{dd.MM.yyyy HH:mm:ss,SSS} %-5p %c{1}:%L - %m%n
appender.rolling.policies.type = Policies
appender.rolling.policies.time.type = TimeBasedTriggeringPolicy
appender.rolling.policies.time.interval = 2
appender.rolling.policies.time.modulate = true
appender.rolling.policies.size.type = SizeBasedTriggeringPolicy
appender.rolling.policies.size.size=100MB
appender.rolling.strategy.type = DefaultRolloverStrategy
appender.rolling.strategy.max = 5

loggers = rolling

logger.rolling.name = org.apache.logging.log4j.core.appender.rolling
logger.rolling.level = all
logger.rolling.additivity = true
logger.rolling.appenderRefs = rolling
logger.rolling.appenderRef.rolling.ref = roll

rootLogger.level = all
rootLogger.appenderRefs = stdout
rootLogger.appenderRef.stdout.ref = STDOUT

My Pom.xml :

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>App</groupId>
  <artifactId>ExampleApp</artifactId>
  <version>0.0.1</version>
  <packaging>jar</packaging>

  <name>ExampleApp</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.apache.logging.log4j</groupId>
      <artifactId>log4j-api</artifactId>
      <version>2.5</version>
    </dependency>
    <dependency>
      <groupId>org.apache.logging.log4j</groupId>
      <artifactId>log4j-core</artifactId>
      <version>2.5</version>
    </dependency>
  </dependencies>
</project>

If I run it I got this output in my console:

21.05.2016 14:17:52,397 TRACE App:13 - entry
21.05.2016 14:17:52,399 INFO  App:14 - Start of application
Hello World!
21.05.2016 14:17:52,399 INFO  App:16 - End of application
21.05.2016 14:17:52,399 TRACE App:17 - exit

The created but empty file is logs/example.log

Answer 1

you can try changing 2 lines at bottom of your log4j2.properties. Hope it helps.

name = PropertiesConfig
property.filename = logs/example.log     

appenders = console, rolling
appender.console.type = Console
appender.console.name = STDOUT
appender.console.layout.type = PatternLayout
appender.console.layout.pattern = %d{dd.MM.yyyy HH:mm:ss,SSS} %-5p %c{1}:%L - %m%n

appender.rolling.type = RollingFile
appender.rolling.name = roll
appender.rolling.fileName = ${filename}
appender.rolling.filePattern = logs/app/%d{MM-dd-yy-HH-mm-ss}-%i.log.gz
appender.rolling.layout.type = PatternLayout
appender.rolling.layout.pattern = %d{dd.MM.yyyy HH:mm:ss,SSS} %-5p %c{1}:%L - %m%n
appender.rolling.policies.type = Policies
appender.rolling.policies.time.type = TimeBasedTriggeringPolicy
appender.rolling.policies.time.interval = 2
appender.rolling.policies.time.modulate = true
appender.rolling.policies.size.type = SizeBasedTriggeringPolicy
appender.rolling.policies.size.size=100MB
appender.rolling.strategy.type = DefaultRolloverStrategy
appender.rolling.strategy.max = 5

loggers = rolling

logger.rolling.name = org.apache.logging.log4j.core.appender.rolling
logger.rolling.level = all
logger.rolling.additivity = true
logger.rolling.appenderRefs = rolling
logger.rolling.appenderRef.rolling.ref = roll

rootLogger.level = all
rootLogger.appenderRefs = rolling, stdout
rootLogger.appenderRef.rolling.ref = roll
rootLogger.appenderRef.stdout.ref = STDOUT

Answer 2

The file will be of course empty. You assigned your new logger a name org.apache.logging.log4j.core.appender.rolling . And the logger you requested is App (or anything alike). It won't log to your new org.apache.logging.log4j.core.appender.rolling , but the root logger, and root logger is configured to only log to STDOUT. That's all what just happened.

To solve this, change that new logger's name into something else (most likely your package name). Don't just cope-paste everything from the user guide.