Why does it appear
- Person information management, upload avatar
- Product information management, upload product pictures
- and many more
Import the jar package
- Apache provides a component for uploading form files (commons-upload)
- Also import a dependency package commons-io.jar
- BeanUtils.jar, copy the data in the map to JavaBean
Form
- The request method must be post
- There must be a component for uploading files in the form
- The form must set enctype="multipart/form-data"
Objects needed to upload files
- DiskFileItemFactory: an engineering class for file upload
- ServletFileUpload: the most core class for uploading files
- IOUtils: Tools for copying files
- BeanUtils: A tool class for object copy
- FileItem: the operation class of the form attribute
Case study
- Single file upload: files with duplicate file names
- Multiple file upload
- Multi-element upload in the form: there is a problem with multiple selection boxes in the form
file download
- Download as a stream
- Need to set the response header
response.setContentType("application/x-msdownload");
response.setHeader("Content-Disposition", "attachment;filename="+fileName);
- The problem of garbled Chinese characters in download