OutOfMemoryError when downloading files

[Chris Wang]

Hi All,

I am creating a web application in which users can download multiple audio files from database as a zip file.

Here is the code segment:

try{
String fileName = "TestCase_Results_"+planId;
ByteArrayOutputStream bout=new ByteArrayOutputStream();
ZipOutputStream zout=new ZipOutputStream(bout);
ServletOutputStream out = httpServletResponse.getOutputStream();
zout.putNextEntry(new ZipEntry(fileName+".xml"));
zout.write(exportedTestCaseResults2XML.getBytes());
zout.closeEntry();
zout.putNextEntry(new ZipEntry(fileName+".html"));
zout.write(exportedTestCaseResults2HTML.getBytes());
zout.closeEntry();
List<String> recordings = documentAndRecordings.getRecordings();
for(String recording : recordings) {
if(recording != null && !recording.equals("")) {
final Blob blob = AIMT_DB.getRecoridngBlob(recording);
try {
Long.parseLong(recording);//make sure the name is a number.
zout.putNextEntry(new ZipEntry(recording+".wav"));
zout.write(blob.getBytes(1, (int)blob.length()));
zout.closeEntry();
} catch(Exception e) {
logger.error(e.getMessage());
}
}
}
zout.finish();

httpServletResponse.setContentType("application/zip");
httpServletResponse.setHeader("Content-Disposition","attachment; filename="+fileName+".zip;");
httpServletResponse.setContentLength(bout.size());

out.write(bout.toByteArray());
out.flush();

When I was testing this download feature, if the audio files are more or the size of a individual audio is bigger, I got an exception:
java.lang.OutOfMemoryError: Java heap space

How to fix this?

Any help is greatly appreciated!

Chris

[Adeel Ansari]

How about writing the zip file to the disk temporarily and then throw that to the user.

Or you can avoid this by increasing your heap space.

I would prefer the former one.

[Chris Wang]

Hi Adeel,

Thank you for your reply.

Actually I was improperly using a memory stream -- ByteArrayOutputStream as the actual stream for the ZipOutputStream, thus all the files will write to memory, for sure causing out-of-memory exception is just a matter of time.

To fix this I change the code as follows:
String fileName = "TestCase_Results_"+planId;
httpServletResponse.setContentType("application/zip");
httpServletResponse.setHeader("Content-Disposition","attachment; filename=TestCase_"+planId+"_Results.zip;");
ServletOutputStream out = httpServletResponse.getOutputStream();
ZipOutputStream zout=new ZipOutputStream(out);//use ServletOutputStream as actual OutputStream for zip file instead of ByteArrayOutputStream.
...

Cheers

Chris

[Adeel Ansari]

Right. I missed the point.
Thanks, Chris, for sharing the fix.
[ January 30, 2007: Message edited by: Adeel Ansari ]