Upload Image with Socket Java [closed]

Using raw and raw socket, this question deals with 4 points:

  

NOTE : For simplicity and brevity I am not using buffered streams ; do not do this in production code without knowing very well that you do not want to use buffered streams , as they usually help a lot in the performance of read and write operations.

File reading

To start, we need a way. I'll call path , assuming it's a variable that will be filled correctly. To open the file for reading, we use FileInputStream . To read the first 255 bytes of a file, we can do this:

InputStream in = new FileInputStream(path);

byte[] buffer = new byte[255];
int readBytes = in.read(buffer);
in.close();

To not forget to close the feature, we can use AutoCloseable and try-with-recources :

try (InputStream in = new FileInputStream(path)) {

    byte[] buffer = new byte[255];
    int readBytes = in.read(buffer);
}

Writing in socket

To write to the socket, we need to open a socket and get its OutpuStream . To open the socket, get the stream and write "any string", we can do so (Documentation :

try (
    Socket bareSocket = new Socket(hostName, portNumber);
    OutputStream out = bareSocket.getOutputStream();
) {
    out.write("uma string qualquer".getBytes());
}

Note that it is always necessary to close everything, so I put everything in a block try-with-resources .

Then, with OutputStream open, we need to write everything that is read from InputStream of file to OutputStream of socket. The Apache folks have already solved this problem for folks with IOUtils.copy . So, writing on the socket with the contents of the file would look like this:

try (
    Socket bareSocket = new Socket(hostName, portNumber);
    OutputStream out = bareSocket.getOutputStream();
    InputStream in = new FileInputStream(path)
) {
    IOUtils.copy(in, out);
}

Server socket opening

Oracle itself provides a code sample using ServerSocket : link

There are no secrets here, just create a ServerSocket object using a port and, when it receives a connection call, get the socket generated with accept() . Something like this, for a% informed%:

try (
        ServerSocket serverSocket = new ServerSocket(portNumber);
        Socket clientSocket = serverSocket.accept();
        InputStream in = clientSocket.getInputStream();
    ) {
    // abri a conexão, agora faça coisas...
}

Reading a server socket

Since we already have portNumber , we can usually use it as another InputStream any. For example, if you want to write the image to the file in InputStream path, do so:

try (
        ServerSocket serverSocket = new ServerSocket(portNumber);
        Socket clientSocket = serverSocket.accept();
        InputStream in = clientSocket.getInputStream();
        OutputStream out = new FileOutputStream(pathDestino, false);
    ) {
    IOUtils.copy(in, out);
}