I am trying to develop a very simple client / server where the client converts a file to bytes, sends it to the server, and then converts the bytes back in to a file.
Currently the program just creates an empty file. I'm not a fantastic Java developer so any help much appreciated.
This is the server part that receives what the client sends.
ServerSocket serverSocket = null;
serverSocket = new ServerSocket(4444);
Socket socket = null;
socket = serverSocket.accept();
DataOutputStream out = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
DataInputStream in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
byte[] bytes = new byte[1024];
in.read(bytes);
System.out.println(bytes);
FileOutputStream fos = new FileOutputStream("C:\\test2.xml");
fos.write(bytes);
And here is the client part
Socket socket = null;
DataOutputStream out = null;
DataInputStream in = null;
String host = "127.0.0.1";
socket = new Socket(host, 4444);
out = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
File file = new File("C:\\test.xml");
//InputStream is = new FileInputStream(file);
// Get the size of the file
long length = file.length();
if (length > Integer.MAX_VALUE) {
System.out.println("File is too large.");
}
byte[] bytes = new byte[(int) length];
//out.write(bytes);
System.out.println(bytes);
out.close();
in.close();
socket.close();
The correct way to copy a stream in Java is as follows:
int count;
byte[] buffer = new byte[8192]; // or 4096, or more
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
Wish I had a dollar for every time I've posted that in a forum.
Thanks for the help. I've managed to get it working now so thought I would post so that the others can use to help them.
Server:
public class Server {
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = null;
try {
serverSocket = new ServerSocket(4444);
} catch (IOException ex) {
System.out.println("Can't setup server on this port number. ");
}
Socket socket = null;
InputStream in = null;
OutputStream out = null;
try {
socket = serverSocket.accept();
} catch (IOException ex) {
System.out.println("Can't accept client connection. ");
}
try {
in = socket.getInputStream();
} catch (IOException ex) {
System.out.println("Can't get socket input stream. ");
}
try {
out = new FileOutputStream("M:\\test2.xml");
} catch (FileNotFoundException ex) {
System.out.println("File not found. ");
}
byte[] bytes = new byte[16*1024];
int count;
while ((count = in.read(bytes)) > 0) {
out.write(bytes, 0, count);
}
out.close();
in.close();
socket.close();
serverSocket.close();
}
}
and the Client:
public class Client {
public static void main(String[] args) throws IOException {
Socket socket = null;
String host = "127.0.0.1";
socket = new Socket(host, 4444);
File file = new File("M:\\test.xml");
// Get the size of the file
long length = file.length();
byte[] bytes = new byte[16 * 1024];
InputStream in = new FileInputStream(file);
OutputStream out = socket.getOutputStream();
int count;
while ((count = in.read(bytes)) > 0) {
out.write(bytes, 0, count);
}
out.close();
in.close();
socket.close();
}
}
Here is the server
Open a stream to the file and send it overnetwork
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 SimpleFileServer {
public final static int SOCKET_PORT = 5501;
public final static String FILE_TO_SEND = "file.txt";
public static void main (String [] args ) throws IOException {
FileInputStream fis = null;
BufferedInputStream bis = null;
OutputStream os = null;
ServerSocket servsock = null;
Socket sock = null;
try {
servsock = new ServerSocket(SOCKET_PORT);
while (true) {
System.out.println("Waiting...");
try {
sock = servsock.accept();
System.out.println("Accepted connection : " + sock);
// send file
File myFile = new File (FILE_TO_SEND);
byte [] mybytearray = new byte [(int)myFile.length()];
fis = new FileInputStream(myFile);
bis = new BufferedInputStream(fis);
bis.read(mybytearray,0,mybytearray.length);
os = sock.getOutputStream();
System.out.println("Sending " + FILE_TO_SEND + "(" + mybytearray.length + " bytes)");
os.write(mybytearray,0,mybytearray.length);
os.flush();
System.out.println("Done.");
} catch (IOException ex) {
System.out.println(ex.getMessage()+": An Inbound Connection Was Not Resolved");
}
}finally {
if (bis != null) bis.close();
if (os != null) os.close();
if (sock!=null) sock.close();
}
}
}
finally {
if (servsock != null)
servsock.close();
}
}
}
Here is the client
Recive the file being sent overnetwork
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.Socket;
public class SimpleFileClient {
public final static int SOCKET_PORT = 5501;
public final static String SERVER = "127.0.0.1";
public final static String
FILE_TO_RECEIVED = "file-rec.txt";
public final static int FILE_SIZE = Integer.MAX_VALUE;
public static void main (String [] args ) throws IOException {
int bytesRead;
int current = 0;
FileOutputStream fos = null;
BufferedOutputStream bos = null;
Socket sock = null;
try {
sock = new Socket(SERVER, SOCKET_PORT);
System.out.println("Connecting...");
// receive file
byte [] mybytearray = new byte [FILE_SIZE];
InputStream is = sock.getInputStream();
fos = new FileOutputStream(FILE_TO_RECEIVED);
bos = new BufferedOutputStream(fos);
bytesRead = is.read(mybytearray,0,mybytearray.length);
current = bytesRead;
do {
bytesRead =
is.read(mybytearray, current, (mybytearray.length-current));
if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);
bos.write(mybytearray, 0 , current);
bos.flush();
System.out.println("File " + FILE_TO_RECEIVED
+ " downloaded (" + current + " bytes read)");
}
finally {
if (fos != null) fos.close();
if (bos != null) bos.close();
if (sock != null) sock.close();
}
}
}
To avoid the limitation of the file size , which can cause the Exception java.lang.OutOfMemoryError to be thrown when creating an array of the file size byte[] bytes = new byte[(int) length];, instead we could do
byte[] bytearray = new byte[1024*16];
FileInputStream fis = null;
try {
fis = new FileInputStream(file);
OutputStream output= socket.getOututStream();
BufferedInputStream bis = new BufferedInputStream(fis);
int readLength = -1;
while ((readLength = bis.read(bytearray)) > 0) {
output.write(bytearray, 0, readLength);
}
bis.close();
output.close();
}
catch(Exception ex ){
ex.printStackTrace();
} //Excuse the poor exception handling...
Rookie, if you want to write a file to server by socket, how about using fileoutputstream instead of dataoutputstream? dataoutputstream is more fit for protocol-level read-write. it is not very reasonable for your code in bytes reading and writing. loop to read and write is necessary in java io. and also, you use a buffer way. flush is necessary. here is a code sample: http://www.rgagnon.com/javadetails/java-0542.html
Adding up on EJP's answer; use this for more fluidity.
Make sure you don't put his code inside a bigger try catch with more code between the .read and the catch block, it may return an exception and jump all the way to the outer catch block, safest bet is to place EJPS's while loop inside a try catch, and then continue the code after it, like:
int count;
byte[] bytes = new byte[4096];
try {
while ((count = is.read(bytes)) > 0) {
System.out.println(count);
bos.write(bytes, 0, count);
}
} catch ( Exception e )
{
//It will land here....
}
// Then continue from here
EDIT: ^This happened to me cuz I didn't realize you need to put socket.shutDownOutput() if it's a client-to-server stream!
Hope this post solves any of your issues
Related
I want to receive text files through a socket connection in java, I set up the server end but before I continue with the client I would like to know if the code I made works, except I have no idea how to test this.
Any help would be much appreciated..
EDIT: I know the port is open and listening for requests, what i want is to test what happens if it receives anything, will it create a file from the input and can I test this by simulation(sending a file or bytes i dont know)?
public class Server {
private static int port = 8080;
private static int maxConnections = 100000;
// Listen for incoming connections and handle them
public static void startServer() {
int i = 0;
try {
ServerSocket listener = new ServerSocket(port);
Socket server;
System.out.println("Started server on port:" + port);
while ((i++ < maxConnections) || (maxConnections == 0)) {
RunServer connection;
server = listener.accept();
RunServer conn_c = new RunServer(server);
Thread t = new Thread(conn_c);
t.start();
System.out.println("Created new thread");
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
class RunServer implements Runnable {
private Socket server;
RunServer(Socket server) {
this.server = server;
}
public void run() {
int bytesRead;
int current = 0;
BufferedOutputStream bufferedOutputStream = null;
FileOutputStream fileOutputStream = null;
DataInputStream clientData = null;
File file = null;
try {
// creating connection.
System.out.println("connected.");
// receive file
byte[] byteArray = new byte[6022386];
System.out.println("Please wait downloading file");
// reading file from socket
InputStream inputStream = server.getInputStream();
file = new File("toread.txt");
clientData = new DataInputStream(inputStream);
fileOutputStream = new FileOutputStream(file);
bufferedOutputStream = new BufferedOutputStream(fileOutputStream);
bytesRead = inputStream.read(byteArray, 0, byteArray.length);
current = bytesRead;
do {
bytesRead = inputStream.read(byteArray, current, (byteArray.length - current));
if (bytesRead >= 0)
current += bytesRead;
} while (bytesRead > -1);
bufferedOutputStream.write(byteArray, 0, current);
bufferedOutputStream.flush();
ReaderHelper.readTextFile(file);
} catch (IOException e) {
e.printStackTrace();
} catch (NumberFormatException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (fileOutputStream != null)
fileOutputStream.close();
if (bufferedOutputStream != null)
bufferedOutputStream.close();
if (clientData != null)
clientData.close();
if (server != null)
server.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Well, your socket will be up on port 8080 right?
You can open your browser and type: http://localhost:8080. The browser will create a connection and the line
server = listener.accept();
will "unlock". If you just wanna test if the socket is listenning it will do. Reading the stream you will see the first message of the HTTP protocol.
At first you have a possible error in a reading loop
byte[] byteArray = new byte[6022386];
//some code
do {
bytesRead = inputStream.read(byteArray, current, (byteArray.length - current));
if (bytesRead >= 0)
current += bytesRead;
} while (bytesRead > -1);
If file length is more than byteArray.length which is possible, then (byteArray.length - current) would be negative.
I suggest you to use smaller array, e.g. byte[] byteArray = new byte[8192]; and read file like this
while ((bytesRead = in.read(byteArray)) > 0 ) {
current += bytesRead;
bufferedOutputStream.write(byteArray, 0, bytesRead);
}
storing it into disk chunk by chunk. And after exiting while loop current will hold total number of read bytes.
Send file from another thread, which will connect to server
Socket clientSocket = new Socket("localhost", Server.port);
BufferedReader input = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
DataOutputStream output = new DataOutputStream(clientSocket.getOutputStream());
FileInputStream fileInput = new FileInputStream("fileName");
byte[] buffer = new byte[8192];
while(fileInput.read(buffer) != -1){
output.write(buffer, 0, length);
}
//close resources
I have been fixing my server many times and now i'm stuck ones again.
So I have been trying to send pictures through my clientGUI to a server, So the person can see the file im sending. I dont really know how to explain this. but however. Im just trying to send a file so the other client can accept it and save it. BUT as fast as I press the button picture (It should automatic send a picture to a desktop that I have placed) it does work,
Connection is accepted; localhost/127.0.0.1 - 1500
Sending C:/Users/Barry/Desktop/Ceo/Cao6.jpg(15306 bytes)
Server has closed the connection
but i'm not getting anything in the desktop and in my ServerGUI, I can see that it says :
Exception reading Streams: java.io.StreamCorruptedException: invalid type code: FF
which I have no idea how to fix it and I need some ideas how I can fix this.
Sendpic.java
public void SendPic() throws IOException {
JFileChooser chooser = new JFileChooser();
String FILESEND = "C:/Users/Barry/Desktop/Ceo/Cao6.jpg";
FileInputStream fis = null;
BufferedInputStream bis = null;
OutputStream os = null;
try {
// send file
File myFile = new File (FILESEND);
byte [] mybytearray = new byte [(int)myFile.length()];
fis = new FileInputStream(myFile);
bis = new BufferedInputStream(fis);
bis.read(mybytearray,0,mybytearray.length);
os = socket.getOutputStream();
System.out.println("Sending " + FILESEND + "(" + mybytearray.length + " bytes)");
os.write(mybytearray,0,mybytearray.length);
} catch (IOException e) {
e.printStackTrace();
}
}
getPic.Java
final static int FILE_SIZE = 6022386;
public void getPic() throws IOException {
JFileChooser chooser = new JFileChooser();
String FILETORECEIVED = "C:/Users/Barry/Desktop/";
int bytesRead;
int current = 0;
FileOutputStream fos = null;
BufferedOutputStream bos = null;
try {
byte [] mybytearray = new byte [FILE_SIZE];
InputStream is = socket.getInputStream();
fos = new FileOutputStream(FILETORECEIVED);
bos = new BufferedOutputStream(fos);
bytesRead = is.read(mybytearray,0,mybytearray.length);
current = bytesRead;
do {
bytesRead =
is.read(mybytearray, current, (mybytearray.length-current));
if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);
bos.write(mybytearray, 0 , current);
bos.flush();
System.out.println("File " + FILE_SIZE
+ " downloaded (" + current + " bytes read)");
}
finally {
if (fos != null) fos.close();
if (bos != null) bos.close();
}
}
ActionPerformed`
public void actionPerformed(ActionEvent e) {
Object button = e.getSource();
if (button == btnPicture) {
try {
controller.SendPic();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
return;
}`
i would like to know if it was possible in to do this in java. This is my code :
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.Socket;
public class SimpleFileClient {
public final static int SOCKET_PORT = 13267; // you may change this
public final static String SERVER = "192.168.0.36"; // localhost
public final static String
FILE_TO_RECEIVED = "c:/temps/source-downloaded.mp3"; // you may change this, I give a
// different name because i don't want to
// overwrite the one used by server...
public final static int FILE_SIZE = 6022386; // file size temporary hard coded
// should bigger than the file to be downloaded
public static void main (String [] args ) throws IOException {
int bytesRead;
int current = 0;
FileOutputStream fos = null;
BufferedOutputStream bos = null;
Socket sock = null;
try {
sock = new Socket(SERVER, SOCKET_PORT);
System.out.println("Connecting...");
// receive file
byte [] mybytearray = new byte [FILE_SIZE];
InputStream is = sock.getInputStream();
fos = new FileOutputStream(FILE_TO_RECEIVED);
bos = new BufferedOutputStream(fos);
bytesRead = is.read(mybytearray,0,mybytearray.length);
current = bytesRead;
do {
bytesRead =
is.read(mybytearray, current, (mybytearray.length-current));
if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);
bos.write(mybytearray, 0 , current);
bos.flush();
System.out.println("File " + FILE_TO_RECEIVED
+ " downloaded (" + current + " bytes read)");
}
finally {
if (fos != null) fos.close();
if (bos != null) bos.close();
if (sock != null) sock.close();
}
}
}
And i would like to know if it was possible for the file to open AFTER the transfer has been done. Thank you for your answers.
I have a server and client connection using sockets to transfer files, but if I want to be able to send strings to the server from the client upon user JButton actions, it throws socket closed errors (Because I used dos.close() in the Sender() constructor). The problem is, if I don't use dos.close(), the client program won't run/init the UI frame. What am I doing wrong? I need to be able to send files when the program first runs then send data later.
Sender:
public Sender(Socket socket) {
List<File> files = new ArrayList<File>();
files.add(new File(Directory.getDataPath("default.docx")));
files.add(new File(Directory.getDataPath("database.db")));
try {
BufferedOutputStream bos = new BufferedOutputStream(socket.getOutputStream());
DataOutputStream dos = new DataOutputStream(bos);
dos.writeInt(files.size());
for (File file : files) {
dos.writeLong(file.length());
dos.writeUTF(file.getName());
FileInputStream fis = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(fis);
int theByte = 0;
while ((theByte = bis.read()) != -1) {
bos.write(theByte);
}
bis.close();
}
dos.close(); // If this is disabled, the program won't work.
} catch (Exception e) {
e.printStackTrace();
}
}
Downloader:
public static byte[] document;
public Downloader(Socket socket) {
try {
BufferedInputStream bis = new BufferedInputStream(socket.getInputStream());
DataInputStream dis = new DataInputStream(bis);
int filesCount = dis.readInt();
for (int i = 0; i < filesCount; i++) {
long size = dis.readLong();
String fileName = dis.readUTF();
if (fileName.equals("database.db")) {
List<String> data = new ArrayList<String>();
BufferedReader reader = new BufferedReader(new InputStreamReader(bis));
String line;
while ((line = reader.readLine()) != null) {
if (line.trim().length() > 0) {
data.add(line);
}
}
reader.close();
parse(data);
} else if (fileName.equals("default.docx")) {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
for (int x = 0; x < size; x++) {
bos.write(bis.read());
}
bos.close();
document = bos.toByteArray();
}
}
//dis.close();
} catch (Exception e) {
e.printStackTrace();
}
}
Your first receive loop in the client terminates at EOS, which only happens when you close the socket in the sender, which you don't want to do. You're sending the length ahead of the file in each case so the receiving code should look like this in both cases:
long total = 0;
while ((total < size && (count = in.read(buffer, 0, size-total > buffer.length ? buffer.length : (int)(size-total))) > 0)
{
total += count;
out.write(buffer, 0, count);
}
out.close();
That loop reads exactly size bytes from the socket input stream and writes it to the OutputStream out, whatever out happens to be: in the first case, a FileOutputStream, in the second, a ByteArrayOutputStream.
My client can send Images normally to server, but when it comes to text files they arrive empty. Any ideas what am I doing wrong? I'd really appreciate help, because I have been trying to make this work for many days now. Thanks.
Here is the server code:
class TheServer {
public void setUp() throws IOException { // this method is called from Main class.
ServerSocket serverSocket = new ServerSocket(1991);
System.out.println("Server setup and listening...");
Socket connection = serverSocket.accept();
System.out.println("Client connect");
System.out.println("Socket is closed = " + serverSocket.isClosed());
BufferedReader rd = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String str = rd.readLine();
System.out.println("Recieved: " + str);
rd.close();
InputStream is = connection.getInputStream();
int bufferSize = connection.getReceiveBufferSize();
FileOutputStream fos = new FileOutputStream("C:/" + str);
BufferedOutputStream bos = new BufferedOutputStream(fos);
byte[] bytes = new byte[bufferSize];
int count;
while ((count = is.read(bytes)) > 0) {
bos.write(bytes, 0, count);
}
bos.flush();
bos.close();
is.close();
connection.close();
serverSocket.close();
}
}
and here is the client code:
public class TheClient {
public void send(File file) throws UnknownHostException, IOException { // this method is called from Main class.
Socket socket = null;
String host = "127.0.0.1";
socket = new Socket(host, 1991);
// Get the size of the file
long length = file.length();
if (length > Integer.MAX_VALUE) {
System.out.println("File is too large.");
}
BufferedWriter wr = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
wr.write(file.getName());
wr.newLine();
wr.flush();
byte[] bytes = new byte[(int) length];
FileInputStream fis = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(fis);
BufferedOutputStream out = new BufferedOutputStream(socket.getOutputStream());
int count;
while ((count = bis.read(bytes)) > 0) {
out.write(bytes, 0, count);
}
out.flush();
out.close();
fis.close();
bis.close();
socket.close();
}
}
You are prematurely closing BufferedReader on server side before reading all the data. This essentially closes the connection.
You should not use Reader or Writer for non-character streams like binary image data. And you should not mix BufferedReader with any other stream wrapper for the same stream since it may read as many data as it fills in buffer.