背景

SpringBoot项目在启动时报 Exception in thread "main" java.lang.StackOverflowError。

问题排查

作为一个夜夜仰望星空的码农这个异常再熟悉不过了-"堆栈溢出"，

Exception in thread "main" java.lang.StackOverflowError
    at org.apache.logging.log4j.util.StackLocator.getCallerClass(StackLocator.java:108)
    at org.apache.logging.log4j.util.StackLocator.getCallerClass(StackLocator.java:121)
    at org.apache.logging.log4j.util.StackLocatorUtil.getCallerClass(StackLocatorUtil.java:55)
    at org.apache.logging.slf4j.Log4jLoggerFactory.getContext(Log4jLoggerFactory.java:42)
    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.apache.logging.slf4j.SLF4JLoggerContext.getLogger(SLF4JLoggerContext.java:39)
    at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:37)
    at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:29)
    at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:52)
    at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:29)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:358)
后面是重复日志，就不贴出来了

如果是个新手到这里可能就懵B啦，完全跟应用代码无关，全是log4j的日志，如何解决，而作为填坑老手的你肯定已经默默进入showTime时间，话不多说，这里造成堆栈溢出的原因就是log的Jar包冲突,使用命令

mvn dependency:tree

打印出jar包依赖树，或者使用idea的可视化工具show Dependencies 查看jar包依赖关系，我这里同时有log4j-slf4j-impl 和log4j-to-slf4j两种实现，去掉一种即可，其中log4j-to-slf4j是springboot2 自带，取消即可，代码如下：

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
            <exclusions>
                <exclusion>
                    <artifactId>logback-classic</artifactId>
                    <groupId>ch.qos.logback</groupId>
                </exclusion>
                <exclusion>
                    <artifactId>log4j-to-slf4j</artifactId>
                    <groupId>org.apache.logging.log4j</groupId>
                </exclusion>
            </exclusions>
        </dependency>

重新启动应用，至此我们的应用又可以清清爽爽的启动起来啦。