Send Snapshot to server with socket

[federico.cappabianca]

In my application I do a snapshot in this way:

private void doSnapshot() {
        new Thread() {
            public void run() {
                try {
                    byte [] snap = vidCtrl.getSnapshot("encoding=jpeg");
                    if (snap != null) {
                        Image im = Image.createImage(snap, 0, snap.length);
                        ImageItem imi = new ImageItem("", im, Item.	PLAIN, "");
                        vidForm.append(imi);
                        inviaimg(snap);
                        System.out.println("La fotografia è stata inviata");
                        risposta_foto();
                       }
                } catch (MediaException me) {
                    System.err.println(me);
                }
            }
        }.start();
    }

And server receives:

             
byte[] image=new byte[900000];
leggi(image,60,true);

Function leggi:

public int leggi(byte[] buffer, int time, boolean pulisci){
        int num_bytes=0;
        try{
            // Aspetta la read per time secondi
            client.setSoTimeout(time*1000);
            // Legge il messaggio come flusso di byte
            if(pulisci) read_from_client=new BufferedInputStream(client.getInputStream());
            num_bytes=read_from_client.read(buffer,0,buffer.length);
            return num_bytes;
        }catch(SocketTimeoutException ex){
            System.err.println("Tempo scaduto per l'operazione di lettura");
            ex.printStackTrace();
            try{
                // Chiude la connessione
                System.out.println("CHIUSURA DEL THREAD DI SERVIZIO PER IL CLIENT "+client.getInetAddress()+":"+client.getPort());
                read_from_client.close();
                write_to_client.close();
                client.close();
            }catch(IOException dex){
                dex.printStackTrace();
                System.exit(0);
            }
        }catch(Exception ex){
            ex.printStackTrace();
            try{
                // Chiude la connessione
                System.out.println("CHIUSURA DEL THREAD DI SERVIZIO PER IL CLIENT "+client.getInetAddress()+":"+client.getPort());
                read_from_client.close();
                write_to_client.close();
                client.close();
            }catch(IOException dex){
                dex.printStackTrace();
                System.exit(0);
            }
        }
        return 0;
    }

When I try on emulator (Sun or Nokia) it run ok, but when I try on Nokia 5800 XE the server takes this error:

sun.awt.image.ImageFormatException: Invalid JPEG file structure: missing SOS marker
        at sun.awt.image.JPEGImageDecoder.readImage(Native Method)
        at sun.awt.image.JPEGImageDecoder.produceImage(JPEGImageDecoder.java:119)
        at sun.awt.image.InputStreamImageSource.doFetch(InputStreamImageSource.java:246)
        at sun.awt.image.ImageFetcher.fetchloop(ImageFetcher.java:172)
        at sun.awt.image.ImageFetcher.run(ImageFetcher.java:136)

Can you help me?

[grahamhughes]

if(pulisci) read_from_client=new BufferedInputStream(client.getInputStream());

Sorry to seem fussy, but can you stop putting an entire block on one line? It makes the code much harder to read. You might want to read the Sun Code Conventions for Java.

num_bytes=read_from_client.read(buffer,0,buffer.length);

How many bytes are actually being read? You're assuming this will read the entire image data, but it might not.

I'd suggest you use on the phone:

DataOutputStream dout = connection.openDataOutputStream();
dout.writeInt(snap.length);
dout.write(snap);

Then, on the server:

private static byte[] readImage() throws IOException {
    DataInputStream din = new DataInputStream(client.getInputStream());
    byte[] data;
    try {
        // how much data is there to read?
        int length = din.readInt();
        // create a buffer of the correct size
        data = new byte[length];
        // read blocks until we have all the data
        int readSoFar = 0;
        while (readSoFar < length) {
            readSoFar += din.read(data, readSoFar, length - readSoFar);
        }
    } finally {
        din.close();
    }
    return data;
}

Graham.

[grahamhughes]

Sorry, that could have been:

private static byte[] readImage() throws IOException {
    DataInputStream din = new DataInputStream(client.getInputStream());
    byte[] data;
    try {
        int length = din.readInt();
        data = new byte[length];
        din.readFully(data);
    } finally {
        din.close();
    }
    return data;
}

D'uh.