(default-clean) on project”?

出現情況：maven在clean或者install一個專案時，會出現此異常

解決方法：

1.有可能這個專案正在跑著在，關閉掉就好

2.有可能某個配置檔案開啟著在，修改完沒有儲存關閉

用英語來講就是：

This usually happens in Windows environments when the target folder is "locked". E.g. 

when you are running your web application (looks like you do) and want to perform a mvn clean.
 

The application server/servlet engine locks the files so that mvn clean cannot delete 

the files because they are locked. 

Try to run this command when the web application is not running.

Edit: This also may happen if you have the target folder open in explorer 

or editing a text file from target folder, etc.