CODEWITHSUNDEEP
javaservletsuploadservlet-3.0
Víctor Hugo
Víctor Hugo

Reputation: 243

How to write incoming bytes directly to disk in a Servlet request?

I'd like to know if it is possible to write incoming bytes of a HttpServletRequest directly to disk without holding it in memory.

Note that I don't want to wait the entire request to complete, but handle partial data independently. Like chunks.

I'm curently using JBOSS and I get these bytes at ServletInputStream in doPost method only after the entire upload completes. But I want to "read and remove" these bytes from InputStream as I read it. There are huge files being uploaded and I'd like to work in a coordinated flow as shown below:

  1. 1024 bytes arrived in InputStream
  2. 1024 bytes read(and removed) from InputStream
  3. 1024 bytes wrote to Outputstream(in this case a FileOutputStream)

Is that possible? To work as a raw socket communication... And thus completely avoid OOM.

Upvotes: 2

Views: 449

Answers (1)

Luiggi Mendoza
Luiggi Mendoza

Reputation: 85781

You can read the data partially by using a chunk (buffer) of the desired size:

BufferedInputStream bis = new BufferedInputStream(yourInputStream);
BufferedOutputStream bos = new BufferedOutputStream(yourFileOutputStream);
final int FILE_CHUNK_SIZE = 1024 * 4; //easier to change to 8 KBs or any other size you want/need
byte[] chunk = new byte[FILE_CHUNK_SIZE];
int bytesRead = 0;
while ((bytesRead = input.read(chunk)) != -1) {
    bos.write(chunk, 0, bytesRead);
}
bos.close();
bis.close();

Upvotes: 2

Related Questions