如何在Eclipse创建的可运行jar中指定外部log4j2配置文件

Question

当通过命令行（cd进入包含可运行jar的目录）运行jar时，输出如下：

ERROR StatusLogger Unrecognized format specifier [d]
ERROR StatusLogger Unrecognized conversion specifier [d] starting at position 16 in conversion pattern.
ERROR StatusLogger Unrecognized format specifier [thread]
ERROR StatusLogger Unrecognized conversion specifier [thread] starting at position 25 in conversion pattern.
ERROR StatusLogger Unrecognized format specifier [level]
ERROR StatusLogger Unrecognized conversion specifier [level] starting at position 35 in conversion pattern.
ERROR StatusLogger Unrecognized format specifier [logger]
ERROR StatusLogger Unrecognized conversion specifier [logger] starting at position 47 in conversion pattern.
ERROR StatusLogger Unrecognized format specifier [msg]
ERROR StatusLogger Unrecognized conversion specifier [msg] starting at position 54 in conversion pattern.
ERROR StatusLogger Unrecognized format specifier [n]
ERROR StatusLogger Unrecognized conversion specifier [n] starting at position 56 in conversion pattern.
ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.

消息的最后一点告诉我，配置文件找不到，尽管它正在从某个地方读取配置模式布局（configuration PatternLayout）。当将选项-dlog4j.configurationFile选项添加到命令中时，会发生以下异常（除了前面的错误消息之外）：

Exception in thread "main" java.lang.ExceptionInInitializerError
Caused by: java.lang.NullPointerException: No Configuration was provided
        at java.util.Objects.requireNonNull(Unknown Source)
        at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java
:477)
        at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:561)
        at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:577)
        at org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:212)
        at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextF
actory.java:242)
        at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextF
actory.java:45)
        at org.apache.logging.log4j.LogManager.getContext(LogManager.java:174)
        at org.apache.logging.log4j.LogManager.getLogger(LogManager.java:618)
        at test.SmokeTest.<clinit>(SmokeTest.java:41)

我尝试将-dlog4j.configurationFile值指定为“c://path/to/config/log4j2.xml”和“file://c://path/to/config/log4j2.xml”，得到了相同的错误。异常消息中的最后一行是记录器的初始化。在代码中，我尝试使用以下选项初始化记录器：

 - private static final Logger logger =
   LogManager.getLogger("c:/path/to/config/log4j2.xml");
 - private static final Logger logger = LogManager.getLogger("logger name specified in config file");

在写入文件之前，我设置了log4j.ConfigurationFile系统属性。尝试了以下选项：

- System.setProperty("log4j.configurationFile", "C:\\path\\to\\config\\log4j2.xml")
- System.setProperty("log4j.configurationFile", "file://c:/path/to/config/log4j2.xml")

我还尝试使用basicconfigurator.configure（）和PropertyConfigurator.configure（）方法，从原始log4j(log4j-1.2.17.jar)导入import org.apache.log4j.basicconfigurator和PropertyConfigurator.configure（）。

考虑到log4j2可能无法从外部文件获得其配置，我将log4j2.xml文件的副本放在项目的src文件夹中。然后尝试用以下命令初始化记录器：

- private static final Logger logger = LogManager.getLogger(MyClass.class.getName());
- private static final Logger logger = LogManager.getLogger(SmokeTest.class);

此外，如果双击程序图标或从命令行运行而不使用-dlog4j.configurationfile选项，应用程序将启动，但不会生成日志。

请帮助我解决这个问题，如果你需要我提供任何进一步的信息，请让我知道。我知道以前也有人问过类似的问题，但我无法找到解决我问题的办法；可运行的jar、Eclipse、外部log4j2配置文件。不使用Ant或Maven。

Answer 1

我不知道你做错了什么，但这里有一个MCVE。

test.java

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class Test {
    private static transient Logger log = LogManager.getLogger(Test.class);
    public static void main(String[] args) {
        log.info("Hello World");
    }
}

log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
  <Appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
  </Appenders>
  <Loggers>
    <Root level="info">
      <AppenderRef ref="Console"/>
    </Root>
  </Loggers>
</Configuration>

java -Dlog4j.configurationFile=C:\path\to\log4j2.xml -jar Test.jar

14:06:23.728 [main] INFO  Test - Hello World