.\sdklog\sdkclient_error.log (系统找不到指定的路径。)

Question

log4j:ERROR setFile(null,true) call failed.
java.io.FileNotFoundException: .\sdklog\sdkclient_error.log (系统找不到指定的路径。)
at java.io.FileOutputStream.openAppend(Native Method)
at java.io.FileOutputStream.(FileOutputStream.java:177)
at java.io.FileOutputStream.(FileOutputStream.java:102)
at org.apache.log4j.FileAppender.setFile(FileAppender.java:272)
出现上面的异常该怎么处理？