OpenJDK 8：无法解析主机名

Question

我正在尝试在 Ubuntu 8u131-b11-0ubuntu1.17.04.1 上使用 log4j 2.8 运行 slf4j。当通过 Maven 运行简单的 Java 类时，openjdk 无法解析本地主机名：

  Exception in thread "AWT-EventQueue-0" java.lang.NoSuchFieldError: preferIPv6Address
    at java.base/java.net.InetAddress.init(Native Method)
    at java.base/java.net.InetAddress.init(Native Method)
    at java.base/java.net.InetAddress.<clinit>(InetAddress.java:333)
    at org.apache.logging.log4j.core.util.NetUtils.getLocalHostname(NetUtils.java:53)
    at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:539)
    at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:617)
    at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:634)
    at org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:229)
    at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:152)
    at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:45)
    at org.apache.logging.log4j.LogManager.getContext(LogManager.java:194)
    at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getContext(AbstractLoggerAdapter.java:122)
    at org.apache.logging.slf4j.Log4jLoggerFactory.getContext(Log4jLoggerFactory.java:43)
    at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:46)
    at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:29)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:358)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:383)

似乎这个方法

public static InetAddress getLocalHost() throws UnknownHostException 

在Oracle Java中，实现方式与其他Java版本不同。

/etc/hosts 包含IPv6记录：

::1     ip6-localhost ip6-loopback 

- Tombart

Answer 1

这个问题是由于系统上安装了JDK9引起的。Log4j 2.8目前还不兼容Java 9。

要解决此问题，可以卸载JDK9或将首选项设置为JDK8。在Debian上：

sudo update-alternatives --config java

- Tombart