能给出一个Log4j2计算Location的示例代码吗？

简单呀！看看这个

public StackTraceElement calcLocation(final String fqcnOfLogger) {  
    if (fqcnOfLogger == null) {  
        return null;  
    }  
    // LOG4J2-1029 new Throwable().getStackTrace is faster than Thread.currentThread().getStackTrace().  
    final StackTraceElement[] stackTrace = new Throwable().getStackTrace();  
    boolean found = false;  
    for (int i = 0; i < stackTrace.length; i++) {  
        final String className = stackTrace[i].getClassName();  
        if (fqcnOfLogger.equals(className)) {  
            found = true;  
            continue;  
        }  
        if (found && !fqcnOfLogger.equals(className)) {  
            return stackTrace[i];  
        }  
    }  
    return null;  
}