如何在log4j.xml中加载SpringBoot属性

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="location" value="classpath:application.properties"/>
</bean>

<appender name="console" class="org.apache.log4j.ConsoleAppender">
    <param name="Target" value="System.out"/>
    <layout class="org.apache.log4j.PatternLayout">
        <param name="ConversionPattern" value="${log.pattern}"/>
    </layout>
</appender>

@SpringBootApplication
@ImportResource("classpath:log4j.xml")
public class YourApplication {
    public static void main(String[] args) {
        SpringApplication.run(YourApplication.class, args);
    }
}