CODEWITHSUNDEEP
javaspringtomcatfile-upload
j0ntech
j0ntech

Reputation: 1168

File only partially uploaded to server

I'm trying to upload a file to my Spring server running on Tomcat7. It's a simple POST request, the code is below:

@RequestMapping(method = RequestMethod.POST)
    public void saveFile(HttpServletRequest request, @RequestParam("file_name") String fileName) {
        Logger.getLogger(FileRestAction.class).info("saving file with name " + fileName);
        try {
            byte[] buf = readFromRequest(request);
            String filePath = writeToFile(buf, fileName);
            File_ file = new File_(filePath, request.getContentType());
            Logger.getLogger(FileRestAction.class).info(request.getContentType() + " " + request.getContentLength());
            fService.save(file);
        } catch (IOException e) {
            Logger.getLogger(FileRestAction.class).error("Failed to upload file. " +
                    "Exception is: " + e.getMessage());
        }
    }

    private String writeToFile(byte[] buf, String fileName) throws IOException {
        String fileBasePath = ConfigurationProvider.getConfig().getString(Const.FILE_SAVE_PATH);
        File file = new File(fileBasePath + fileName);
        FileOutputStream fos = new FileOutputStream(file);
        fos.write(buf);
        fos.close();
        Logger.getLogger(FileRestAction.class).info("filepath: " + file.getAbsolutePath());
        return file.getAbsolutePath();
    }

    private byte[] readFromRequest(HttpServletRequest request) throws IOException {
        InputStream is = request.getInputStream();
        byte[] buf = new byte[request.getContentLength()];
        is.read(buf);
        is.close();
        return buf;
    }

Now the problem is that the file on the server is only "half-done", it's as if all the bytes aren't there. For example, if I send a 256x256 .png-file with a size of 54kB, the file written on the server is also 54kB and 256x256 in size, but the actual picture cuts off near the beginning (the rest is blank). No exceptions are thrown.

After a bit of testing I've found out that the cutoff is around 15-20Kb (images below that are fully uploaded).

Any ideas as to what might cause this?

EDIT: I changed the readFromRequest method according to what GreyBeardedGeek suggested. It's now as follows:

private byte[] readFromRequest(HttpServletRequest request) throws IOException {
        InputStream is = request.getInputStream();
        int fileLength = (int) request.getContentLength();
        byte[] buf = new byte[fileLength];
        int bytesRead = 0;
        while (true) {
            bytesRead += is.read(buf, bytesRead, fileLength - bytesRead);
            Logger.getLogger(FileRestAction.class).info("reading file: " + bytesRead + " bytes read");
            if (bytesRead == fileLength) break;
        }
        is.close();
        return buf;
    }

Upvotes: 1

Views: 499

Answers (1)

GreyBeardedGeek
GreyBeardedGeek

Reputation: 30088

InputStream.read is not guaranteed to read the amount of data that you ask for. The size that you ask for is the maximum number of bytes that it will read.

That's why the read() method returns the number of bytes actually read. See http://docs.oracle.com/javase/6/docs/api/java/io/InputStream.html#read(byte[])

So, the answer is to read multiple times, until read() returns -1

Upvotes: 2

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