Develop Reference

java: Transfer a file to the server and get the file from the server in upper case

i want to send a .txt file from the client to server and get it back in upper case.
But this code do nothing.can anyone tell what is wrong here..?
SERVER : getting file from client and sending it back in upper case to the client.
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Arrays;
public class Assignment4_Server {
public static void main(String[] args) throws IOException {
byte[] bytearray = new byte[4096];
try (ServerSocket ss = new ServerSocket(4444)) {
Socket s = ss.accept();
InputStream is = s.getInputStream();
OutputStream os = s.getOutputStream();
int count;
String data = null ;
while((count = is.read(bytearray))>0){
data = Arrays.toString(bytearray).toUpperCase();
byte[] bytearrayout = data.getBytes();
os.write(bytearrayout);
}
s.close();
}
}
}
CLIENT : sending text.txt file to the server and getting file back after converted in upper case.
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
public class Assignment4_client {
public static void main(String[] args) throws IOException {
File file = new File("test.txt");
byte[] bytearray = new byte[4096];
Socket sc = new Socket("localhost",4444);
//send file
int countS , countR;
FileInputStream fis = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(fis);
OutputStream os = sc.getOutputStream();
while((countS = bis.read(bytearray))>0){
os.write(bytearray);
}
//recieve file in uppercase from server
InputStream is = sc.getInputStream();
byte[] bytearray2 = new byte[4096];
FileOutputStream fos = new FileOutputStream(file);
BufferedOutputStream bos = new BufferedOutputStream(fos);
while((countR = is.read(bytearray2))>0){
bos.write(bytearray2);
}
}
}

Here is a code that should help you. But before reading it you should be aware of what is happening:
Your client is not sending a 'stop reading' information to the server (read the client code below). That's why the server is stuck in the while loop when it is trying to read the data sent by the client. That is probably why you have tried to send the data back directly to the client. Shut down the socket output from the client side to respect the Socket contract and correctly free the socket (see TCP/IP).
The solution given doesn't take in account that the server should stay up after it has done its duty. Then, the server will not be able to serve more than one client at a time. This server is offering a one time service, which is pointless. To overcome this issue you should put everything in a while loop and bind every new server process into a new thread (I let you do that, its quite a joy).
The server doesn't take in account the whole size of the data an it could possibly run into an out of memory error if the data is too heavy. You should find a way to avoid this problem in a real implementation.
Both program should catch the exception and log it somewhere so you could be aware of any errors.
Writing a server is not so simple. You should normally write some kind of protocol with headers and other stuff like that. To avoid that, use objects like ObjectOutputStream and ObjectInputStream but it has some limitation like constraining your server in the Java world.
CLIENT
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.net.Socket;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;
public class Client {
public void send(File file)
{
Socket sc = null;
try
{
byte[] bytearray = new byte[4096];
sc = new Socket("localhost", 4444);
// 1. Read the file, send its content, close it.
int count;
FileInputStream fis = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(fis);
OutputStream os = sc.getOutputStream();
while((count = bis.read(bytearray))>0)
{
os.write(bytearray);
}
fis.close();
sc.shutdownOutput();
// 2. Delete old file, receive data, write it to new File.
InputStream is = sc.getInputStream();
bytearray = new byte[4096];
// Eventually do what you want with the file: new one, append, etc.
file.delete();
file.createNewFile();
FileOutputStream fos = new FileOutputStream(file);
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
count = 0;
while((count = is.read(bytearray)) > 0)
{
bos.write(bytearray, 0, count);
}
fos.close();
bos.close();
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
if (sc != null)
{
try
{
sc.close();
} catch (IOException e) {}
}
}
}
}
SERVER
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
public class Server
{
Server()
{
Socket s = null;
byte[] bytearray = new byte[4096];
try (ServerSocket ss = new ServerSocket(4444))
{
s = ss.accept();
InputStream is = s.getInputStream();
// 1. Recieve data and put it to UpperCase.
String data = "";
int count;
while((count = is.read(bytearray)) > 0)
{
data += new String(bytearray, 0, count);
}
data = data.toUpperCase();
System.out.println(data);
// 2. Send back data.
OutputStream os = s.getOutputStream();
os.write(data.getBytes());
os.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
TEST PROGRAM
This one should help you to test your both programs in the same project in an IDE.
import java.io.File;
public class Test
{
public static void main(String[] args)
{
Client c = new Client();
(new Thread()
{
public void run()
{
Server s = new Server();
}
}).start();
c.send(new File("test.txt"));
}
}

What is wrong here is two simple things.
The server is reading until end of stream, on a socket that must be used for the reply. The client therefore cannot close it after sending the request to provide the EOS, so it must shutdown the socket for output after sending the request.
Your copy loops are wrong. The general form is:
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
You are ignoring the read count when writing, so you will write junk at end of stream, or any other time that read() doesn't fill buffer, which can be any time at all.

FileNotFound Exception in FileOutputStream

I'm getting error of FileNotFound. Basically, I'm trying to upload file from client to server.
Please, help me with it.
This is client.java class
package ftppackage;
import java.net.*;
import java.io.*;
public class Client {
public static void main (String [] args ) throws IOException {
Socket socket = new Socket("127.0.0.1",15123);
File transferFile = new File ("D:\\AsiaAd.wmv");
byte [] bytearray = new byte [(int)transferFile.length()];
FileInputStream fin = new FileInputStream(transferFile);
BufferedInputStream bin = new BufferedInputStream(fin);
bin.read(bytearray,0,bytearray.length);
OutputStream os = socket.getOutputStream();
System.out.println("Sending Files...");
os.write(bytearray,0,bytearray.length);
os.flush();
socket.close();
System.out.println("File transfer complete");
}
}
And this is my server.java class
package ftppackage;
import java.net.*;
import java.io.*;
public class Server {
public static void main (String [] args ) throws IOException {
int filesize=1022386;
int bytesRead;
int currentTot = 0;
ServerSocket serverSocket = new ServerSocket(15123);
Socket socket = serverSocket.accept();
System.out.println("Accepted connection : " + socket);
byte [] bytearray = new byte [filesize];
InputStream is = socket.getInputStream();
FileOutputStream fos = new FileOutputStream("E:\\0\\"); // it is creating new file not copying the one from client
BufferedOutputStream bos = new BufferedOutputStream(fos);
bytesRead = is.read(bytearray,0,bytearray.length);
currentTot = bytesRead;
do {
bytesRead = is.read(bytearray, currentTot, (bytearray.length-currentTot));
if(bytesRead >= 0)
currentTot += bytesRead;
} while(bytesRead > -1);
bos.write(bytearray, 0 , currentTot);
bos.flush();
bos.close();
socket.close();
}
}
Plus, guide me how do add progress bar in it with percentage. I read about SwingWorker here but unable to implement it as I'm totally new with threading concepts.
Thank you for considering my questions.

FileNotFoundException is something you will get if you point the File Object to some File which is not existing in that path. it means what ever the file you are trying to upload in not there in the specified path. SO make sure you give a valid path.

Java: Transfer a file from server to client and from client to server

I am a newbie and I want to accomplish file transfer from server to client "do something with it" and then send the file back to the server. The most basic code I am using is here:
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
public class Main {
public static void main(String[] args) throws IOException {
ServerSocket servsock = new ServerSocket(123456);
File myFile = new File("s.pdf");
while (true) {
Socket sock = servsock.accept();
byte[] mybytearray = new byte[(int) myFile.length()];
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(myFile));
bis.read(mybytearray, 0, mybytearray.length);
OutputStream os = sock.getOutputStream();
os.write(mybytearray, 0, mybytearray.length);
os.flush();
sock.close();
}
}
}
The client module
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.Socket;
public class Main {
public static void main(String[] argv) throws Exception {
Socket sock = new Socket("127.0.0.1", 123456);
byte[] mybytearray = new byte[1024];
InputStream is = sock.getInputStream();
FileOutputStream fos = new FileOutputStream("s.pdf");
BufferedOutputStream bos = new BufferedOutputStream(fos);
int bytesRead = is.read(mybytearray, 0, mybytearray.length);
bos.write(mybytearray, 0, bytesRead);
bos.close();
sock.close();
}
}
Got it from this website: http://www.java2s.com/Code/Java/Network-Protocol/TransferafileviaSocket.htm
I understand how this works but I don't know how to send a file back to the server.
Please help.

I've written a file transfer class in the past, you can use it both in your client and server (by making an instance) and use the methods to send and receive files as much as you want.
import java.io.*;
import java.net.Socket;
public class FileTransferProcessor {
Socket socket;
InputStream is;
FileOutputStream fos;
BufferedOutputStream bos;
int bufferSize;
FileTransferProcessor(Socket client) {
socket = client;
is = null;
fos = null;
bos = null;
bufferSize = 0;
}
void receiveFile(String fileName) {
try {
is = socket.getInputStream();
bufferSize = socket.getReceiveBufferSize();
System.out.println("Buffer size: " + bufferSize);
fos = new FileOutputStream(fileName);
bos = new BufferedOutputStream(fos);
byte[] bytes = new byte[bufferSize];
int count;
while ((count = is.read(bytes)) >= 0) {
bos.write(bytes, 0, count);
}
bos.close();
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
void sendFile(File file) {
FileInputStream fis;
BufferedInputStream bis;
BufferedOutputStream out;
byte[] buffer = new byte[8192];
try {
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
out = new BufferedOutputStream(socket.getOutputStream());
int count;
while ((count = bis.read(buffer)) > 0) {
out.write(buffer, 0, count);
}
out.close();
fis.close();
bis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

Image file not fully copied

I am using following program to get file from server:
public static void main(String[] argv) throws Exception {
Socket sock = new Socket("127.0.0.1", 12345);
byte[] mybytearray = new byte[1024];
InputStream is = sock.getInputStream();
FileOutputStream fos = new FileOutputStream("E://cy.jpg");
BufferedOutputStream bos = new BufferedOutputStream(fos);
int bytesRead = is.read(mybytearray, 0, mybytearray.length);
bos.write(mybytearray, 0, bytesRead);
bos.close();
sock.close();
}
This is creating the file but only a few contents of the image are being copied.
Can someone please explain what is wrong with this code and how to fix it?

You are reading only 1024 bytes from InputStream. You need wrap reading by while loop:
int bytesRead ;
while ((bytesRead = is.read(mybytearray)) != -1) {
bos.write(mybytearray, 0, bytesRead);
}

Try this one.
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.Socket;
import org.apache.commons.io.IOUtils;
public class Test
{
public static void main(String[] argv) throws Exception {
Socket sock = new Socket("127.0.0.1", 12345);
InputStream is = sock.getInputStream();
FileOutputStream fos = new FileOutputStream("E://cy.jpg");
IOUtils.copy(is, fos);
IOUtils.closeQuietly(fos);
sock.close();
}
}
This code uses IOUtils from Commons IO

transfer String and file through socket

i would like to transfer file from server to client. before that i want to send file names from specific directory. the file is not transferring as the read is returning -1. can any one correct me where i am going wrong?
My client code goes like this.
import java.io.*;
import java.net.*;
class PC1Client {
public static void main(String args[]) throws UnknownHostException, IOException
{
byte[] aByte = new byte[1];
int bytesRead;
Socket sock = new Socket("localhost",3000);
InputStream is1 = sock.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is1));
String st = br.readLine();
System.out.println(st);
InputStream is = sock.getInputStream();
FileOutputStream fos = null;
fos = new FileOutputStream("F:\\ANI1.TXT");
ByteArrayOutputStream baos = new ByteArrayOutputStream();
BufferedOutputStream bos = new BufferedOutputStream(fos);
bytesRead = is.read(aByte, 0, aByte.length);
System.out.println(bytesRead);
do {
System.out.println("s");
baos.write(aByte);
bytesRead = is.read(aByte);
} while (bytesRead != -1);
bos.write(baos.toByteArray());
bos.flush();
bos.close();
sock.close();
}
}
My server code goes like this.
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
public class PC1Server {
public static void main(String[] args) throws IOException
{
ServerSocket serversocket = new ServerSocket(3000);
try
{
while(true)
{
String str="";
Socket socket = serversocket.accept();
File file = new File("D:\\ani");
for(File fi : file.listFiles() )
{
str=str+fi.getName()+";";
}
PrintWriter outname = new PrintWriter(socket.getOutputStream());
outname.println(str);
outname.flush();
outname.close();
System.out.println("hello der");
BufferedOutputStream out = new BufferedOutputStream(socket.getOutputStream() );
File myfile = new File("d:/hello.txt");
byte[] mybyte = new byte[(int)myfile.length()];
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(myfile));
bis.read(mybyte, 0, mybyte.length);
out.write(mybyte, 0, mybyte.length);
out.flush();
out.close();
}
}
catch(Exception e)
{
}
}
}

Few notes:
byte[] aByte = new byte[1]; is pointless - it forces you to read the file 1 byte at a time.
InputStream is = sock.getInputStream(); what is the point of opening the same input stream second time?
outname.close(); in your server code is what causes your problem.
Why do you close your output stream just to reopen it again?