Struts2 File upload--Limit file size and type

When files are uploaded, it is possible to limit the size and type of files.

Struts 2 supports the restriction of setting parameters directly on the FileUpload interceptor.

When referencing the FileUpload interceptor, you can specify 3 parameters (specify <param> child elements):

Allowedtypes	Specifies the type of file that is allowed to be uploaded, separated by commas if there are multiple types. Note: This is not an extension of the file, but a corresponding contenttype.
MaximumSize	Specifies the maximum number of bytes allowed to upload files.
Allowedextensions	Specifies the extension of the file that is allowed to be uploaded.

If the uploaded file does not meet the above parameters specified conditions, it will jump to a call input <result>, general input will refer back to the page before submission, that is, File upload page.

<packagename= "Default" namespace= "/" extends= "Struts-default" > <actionname= "Upload" class= "cn.itcast.user.action.FileUploadAction" method= "Upload" > <!--The parameter value of the directory in which the uploaded files are passed to the Fileuploadaction--> <paramname= "Uploadpath" >D:\</param> <!--reference FileUpload Interceptor--> <interceptor-refname= "FileUpload" > <!--set the size of a single upload file, unit bytes--> <paramname= "MaximumSize" >20000000</param> <!--set a single upload file with the extension "JPG" and multiple extensions separated by ","--> <paramname= "Allowedextensions" >.jpg</param> <!--set the MIME type of a single upload file, separated by "," between multiple types--> <paramname= "Allowedtypes" >image/jpeg</param> </interceptor-ref> <!--when the display declaration uses a specific interceptor, the 18 interceptors in the default interceptor stack do not work. If you want the interceptor in the default interceptor stack to work, you need to display a declaration using the default interceptor stack--> <interceptor-refname= "Defaultstack"/> <resultname= "Input" >/jsp/upload.jsp</result> <result>/jsp/success/upload_success.jsp</result> </action> </package>