Appending to ObjectOutputStream (writing multiple objects w/o closing stream)

Question

Desclaimer My question is different from two following links

    public class AppendableObjectOutputStream extends ObjectOutputStream {
      public AppendableObjectOutputStream(OutputStream out) throws IOException {
        super(out);
      }

      @Override
      protected void writeStreamHeader() throws IOException {}
}

The problem with above solutions is that they do not support writing multiple objects to appendable stream w/o closing the stream.
If I open appendable stream, write multiple objects - then at time of reading I can read only first object properly and on trying to read second object, I get EOF exception.

If I proceed the way like write on object to appendable stream, close stream. Then again open stream, write another object close and so on. This way I am able to read multiple objects properly.

    fileOutputStream = new FileOutputStream("abc.dat",true);
     outputBuffer = new BufferedOutputStream(fileOutputStream);
     objectStream = new AppendableObjectOutputStream(outputBuffer);
     BucketUpdate b1 = new BucketUpdate("getAllProducts1",null,"1",null);
     BucketUpdate b2 = new BucketUpdate("getAllProducts2",null,"2",null);
     BucketUpdate b3 = new BucketUpdate("getAllProducts3",null,"3",null);
     objectStream.writeObject(b1);
     objectStream.writeObject(b2);
     objectStream.writeObject(b3);
     objectStream.close();

What implementation of `AppendableObjectOutputStream` do you use? — Sergey Aslanov, Jul 05 '11 at 07:14
@justYo have added code for my AppendableObjectOutputStream implementation — MoveFast, Jul 05 '11 at 08:01

score 5 · Accepted Answer · answered Jul 07 '11 at 05:31

5

Calling ObjectOutputStream.reset() after writing each object will fix this.

answered Jul 07 '11 at 05:31

Suraj Chandran

24,433
12
63
94

score 4 · Answer 2 · edited May 23 '17 at 10:30

4

If you check question you mentioned, you will see that you have to use AppendableObjectOutputStream only to append objects to file, if file already contains some objects. For empty file you have to use ordinary ObjectOutputStream because the header should be written to the beginning in this case.

edited May 23 '17 at 10:30

Community

1
1

answered Jul 05 '11 at 08:18

Sergey Aslanov

2,397
15
16

That sounds like a plausible solution, i would give it a try – gsfd Jul 05 '11 at 08:47

Appending to ObjectOutputStream (writing multiple objects w/o closing stream)

2 Answers2