Hi,
On 11/28/06, Ted Roeloffzen <[EMAIL PROTECTED]> wrote:
> A common pattern I use when processing stream data is:
>
> InputStream data = ...;
> try {
> byte[] buffer = new byte[BUFFER_SIZE];
> for (int n = data.read(buffer); n != -1; n = data.read(buffer)) {
> // process n bytes of data in buffer
> }
> } finally {
> data.close();
> }
When I do this, i need to know how large the buffer needs to be, but i don't
know how big it is. Is there a way to go around that?
The for loop is designed to read the stream in blocks. For example, you can use:
private static final int BUFFER_SIZE = 1000;
... in which case the stream is read in blocks of up to a thousand
bytes. Each iteration of the for loop body will process a block of n
bytes stored in the allocated buffer.
For example if you want to store the image in a file or send it over
the network, you can do that by by writing the byte blocks to a
respective OutputStream, like this:
InputStream data = ...;
try {
OutputStream destination = ...;
try {
byte[] buffer = new byte[BUFFER_SIZE];
for (int n = data.read(buffer); n != -1; n = data.read(buffer)) {
destination.write(buffer, 0, n);
}
} finally {
destination.close();
}
} finally {
data.close();
}
If you need the whole binary stream available in memory as a byte
array, then you can use a ByteArrayOutputStream to accumulate the
data:
OutputStream destination = new ByteArrayOutputStream();
InputStream data = ...;
try {
byte[] buffer = new byte[BUFFER_SIZE];
for (int n = data.read(buffer); n != -1; n = data.read(buffer)) {
destination.write(buffer, 0, n);
}
} finally {
data.close();
}
byte[] bytes = destination.toByteArray();
I hope this helps! See
http://java.sun.com/docs/books/tutorial/essential/io/bytestreams.html
and the related documentation for more information.
BR,
Jukka Zitting
