[S2]struts2 validation error message problem

hi, this is my first web-based project using struts2.0. I met a problem when using the validation . It seems the error message haven't been cleared and each time I submit the form, then the error message was added after the previous error message, it means if i submit 10 times, then there will dis

[S2]Action attributes passing problem

I use singleton="false" in my spring config file, and then it generates one action instance for each request. There comes the problem, for example, I want to edit a user's profile, I get the user's profile in the UserAction's edit() method, and then forward to the eidt.jsp, then user eidt his prof

[S2]can I skip file upload validation when I did not upload a file?

image/png,image/gif,image/jpeg 102400 * saveCertificate the upload file is not nessary, so i want it to be validated when I upload a file, and skip validation when I did not upload a file, how should I do?