Implementation of Java upload and download function

Upload download is a very simple function, but every time you use the time to check, here to tidy up

Front desk:

<form action= "xxoo.do" enctype= "Multipart/form-data" method= "POST" ><input type= "file" name= "file"/> < Button type= "Submit" class= "BTN btn-primary" > Submit </form>

Main Note:

Enctype= "Multipart/form-data" method= "POST"

Background:

Various frameworks have their own upload and download function, the implementation is very similar, after all, upload is to copy files, need an output stream. Through the firebug to see the upload, there will be two parameters to the background, one is the file stream, the variable name is consistent with the name in input, and one is the filename, the default is filename.

If you use Struts2. The filename is the variable name of the file stream +filename. As above is filefilename.

Backstage Direct: Fileutils.copyfile (Shopdatas, tempfile); there is no upload function using frames

If you download it, you're actually sending a inputstream to read the data out. Lazy to use the framework function, you can directly use the response response

Public void download (string newfilename) {Inputstream is = null;outputstream  os = null; Httpservletresponse response = servletactioncontext.getresponse (); try{String contentType= " Application/octet-stream ";   response.setcontenttype (ContentType);   response.setheader (" Content-disposition "," attachment;filename=\ "" +newfilename+ "\" "); Is=new bufferedinputstream (new  FileInputStream (NewFileName));    bytearrayoutputstream baos=new bytearrayoutputstream ();   os=new bufferedoutputstream (Response.getoutputstream ());     byte[]  buffer=new byte[4*1024];   int read=0;    while ((read= Is.read (buffer))!=-1) {      baos.write (buffer,0,read);  }   Os.write (Baos.tobytearray ());   }catch (exception e) {e.printstacktrace ();} Finally{closestream (os, is);}} 

Implementation of Java upload and download function