Develop Reference

Display or download image through the browser

I have a server that displays what the user asks for from the browser, I am using linux and when i run the server and ask for a file like Image.png using this link localhost:9999/Image.png on FireFox i get this message:
The image "localhost:9999/Image.png" cannot be displayed because it
contains errors.
But when i change the variable fileName to an HTML file it works perfectly and i can visualize the html page.
What am I doing wrong??
This is my server:
import java.io.*;
import java.net.*;
import java.util.Scanner;
public class Server {
public static void main(String args[]) throws IOException {
// Declarem les variables a utilitzar
ServerSocket serverSocket = null;
Socket socket = null;
InputStream inS = null;
OutputStream outS = null;
try
{
serverSocket = new ServerSocket(9999);
while(true)
{
socket= serverSocket.accept();
inS = socket.getInputStream();
outS = socket.getOutputStream();
try{
BufferedReader br = new BufferedReader(new InputStreamReader(inS));
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(outS));
System.out.println("THis is what the user wants = " + br.readLine());
String fileName = "Image.png";
String extension= "";
int i = fileName.lastIndexOf('.');
if (i > 0) {
extension = fileName.substring(i+1);
}
String dataReturn = "";
if(extension.equals("png"))
{
bw.write("HTTP/1.0 200 OK\r\n");
bw.write("Content-Type: image/png\r\n");
bw.write("\r\n");
FileReader myFilepng = new FileReader(fileName);
Scanner scanner1 = new Scanner(myFilepng);
dataReturn = "";
while(scanner1.hasNextLine()) {
dataReturn = scanner1.nextLine();
System.out.println(dataReturn);
bw.write(dataReturn);
}
scanner1.close();
}else{
if(extension.equals("html"))
{
bw.write("HTTP/1.0 200 OK\r\n");
bw.write("Content-Type: text/html\r\n");
bw.write("\r\n");
bw.write("<TITLE>"+fileName+"/TITLE>");
FileReader myFile = new FileReader(fileName);
Scanner scanner = new Scanner(myFile);
dataReturn = "";
while(scanner.hasNextLine()) {
dataReturn = scanner.nextLine();
System.out.println(dataReturn);
bw.write(dataReturn);
}
scanner.close();
}
}
bw.close();
}catch(Exception e)
{
}
}
}catch (IOException e) {
System.out.println(e);
}
inS.close();
outS.close();
socket.close();
}
}

You are not writing the contents of your png file to your bw BufferedWriter. Instead you are only sending the header of the response to the client. As you are indicating your response is a png image and there is no data, your browser is telling you the image contains errors (in fact, it does not contains nothing at all).
Open the png filename, write the data to your "bw" buffer to send it to the client. That should be enough.
Edit:
To to that, try the following code for your "if" is image:
if(extension.equals("png"))
{
File file = new File(fileName);
FileInputStream fis = new FileInputStream(file);
byte[] data = new byte[(int) file.length()];
fis.read(data);
fis.close();
DataOutputStream binaryOut = new DataOutputStream(outS);
binaryOut.writeBytes("HTTP/1.0 200 OK\r\n");
binaryOut.writeBytes("Content-Type: image/png\r\n");
binaryOut.writeBytes("Content-Length: " + data.length);
binaryOut.writeBytes("\r\n\r\n");
binaryOut.write(data);
binaryOut.close();
}
Note the use of a binary stream in comparison to the text stream you use in case of html.

How to receive plain Text through Socket in Java

I was trying to send plain text through Socket. So I found a post in StackOverflow, I followed it and I guess it that I did it write However, How can I accept that plain text as string in the client?
I used BufferedReader() and InputStreamReader() class, but exception has been thrown.
Exception : exception java.net.SocketException: Broken pipe
Here is the code:
Server:
OutputStreamWriter osw = new OutputStreamWriter(socket.getOutputStream(), "UTF-8");
osw.write(fileName, 0, fileName.length());
Client:
InputStream in = socket.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String fileName = br.readLine();
br.close();
Some help would be great. :) Thank you.
Client side code:
public void soc_client() throws Exception {
long time = System.currentTimeMillis();
long totalRecieved = 0;
try {
Socket sock = new Socket("172.16.27.106", 55000);
System.out.println("Hello Client");
InputStream in = sock.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String fileName = br.readLine();
File outputFile = new File(fileName + "");
br.close(); // CLOSING BufferedReader
FileOutputStream fileOutputStream = new FileOutputStream(outputFile);
byte[] buffer = new byte[100 * 1024];
int bytesRead = 0;
while ((bytesRead = in.read(buffer)) != -1) {
fileOutputStream.write(buffer, 0, bytesRead);
totalRecieved += bytesRead;
System.out.println("Recieved " + (totalRecieved / 1024)
+ " kilobytes in "
+ ((System.currentTimeMillis() - time) / 1000)
+ " seconds");
}
fileOutputStream.close();
sock.close();
} catch (Exception e) {
System.out.println("Exception " + e);
} finally {
System.out.println("Recieved " + totalRecieved + " bytes in "
+ (System.currentTimeMillis() - time) + "ms.");
}
}

You're reading a line but you aren't sending a line, and you aren't closing the OutputWriter either. So readLine() will block forever waiting for a line terminator or an EOS that is never coming.
Add a newline to the message.
Close the OutputWriter.

Well to use sockets to send and transfer text in client server fashion , i'm posting a simple basic code , which upon running send a HELLO WORLD response to client.
//Server Side
ServerSocket server= new ServerSocket(1166); // //1166 -port no. u can use any other too.
Socket s= server.accept(); // makes a connection whenever a client requests.
OutputStream os= socket.getOutputStream();
DataOutputStream dos = new DataOutputStream(os);
dos.writeUTF("Hello World");
dos.close();
// Client Side
Socket socket= new Socket("Ip address of you server" , 1166) ;
InputStream is= new InputStream();
DataInputStream dis = new DataInputStream(is);
String msg=dis.readUTF();
System.out.println(msg);
dis.close();
now after you run the code once on server computer , then run the client side code and the server will now respond you with Hello World.

how to stop socket keeps writing data in loop java

I have made server client application where server will send a file to client and client will receive it and save it in C:/ on any place.
I first send a string "File" in order to tell client to receive file and than server send file name and size to client and then start sending it.
Problem is that client doesnt receive file although it read in loop and get all bytes but doesnt write to required file object. Please have a look on client code I HAVE SHOWN WHERE IT STUCKS
Following is server code :
public void run(){
try{
System.out.println("Starting writing file");
objOut.writeObject("File");
objOut.flush();
File f= new File(filePath);
String name= f.getName();
int length =(int) f.length();
objOut.writeObject(name);
objOut.flush();
objOut.writeObject(length);
objOut.flush();
byte[] filebytes = new byte[(int)f.length()];
FileInputStream fin= new FileInputStream(f);
BufferedInputStream bin = new BufferedInputStream(fin);
bin.read(filebytes, 0, filebytes.length);
BufferedOutputStream bout = new BufferedOutputStream(objOut);
bout = new BufferedOutputStream(objOut);
bout.write(filebytes, 0, filebytes.length);
bout.flush();
System.out.println("File completelty sent");
}
catch(Exception ex)
{
System.out.println("error on writing file : "+ex.getMessage());
}
}
Following is client code :
while(true){
fobjIn = new ObjectInputStream(fileSock.getInputStream());
String str = (String) fobjIn.readObject();
if(str.equals("File"))
{
System.out.println("Starting receiving file");
ReceiveFile();
}
System.out.println(str);
}
public void ReceiveFile() throws Exception{
String name =(String)fobjIn.readObject();
File f = new File("C:/Temp/" +name);
f.createNewFile();
int length = (int) fobjIn.readObject();
FileOutputStream fout = new FileOutputStream(f);
BufferedOutputStream buffout = new BufferedOutputStream(fout);
byte[] filebyte = new byte[length];
int bytesRead=0,current=0;
bytesRead = fobjIn.read(filebyte, 0, filebyte.length);
do {
bytesRead = fobjIn.read(filebyte, current, (filebyte.length-current));
if(bytesRead > 0) {
current += bytesRead;
System.out.println("writting" + bytesRead);
}
else break;
} while(bytesRead > -1);
^^^^^^^IT DOESNT COMEOUT FROM LOOP while begugging^^^^^^^^
buffout.write(filebyte, 0 , current);
buffout.flush();
System.out.println("written");
}

You should probably close your stream on the server side when you are done sending, so that the client can be notified that the server is done sending. Or else it'll just sit there waiting for more data.

Java TCP Server read file name

I want to create small client-server TCP file transfer program. And I have problem with one thing. When I send file from Client to Server, for example a txt file: omg.txt, I want the Server to read the incoming file name.
So - Client send omg.txt, Server says "New file recived: omg.txt". I tried to use BufferedReader (Server) and DataOutputStream (Client, because you have to write name of the file to send it) but it didnt work.
EDIT:
Client:
Socket sock = new Socket("localhost",13267);
System.out.println("Wait...");
Scanner input = new Scanner(System.in);
while(true){
// wysylanie
System.out.println("Filename");
String p = input.nextLine();
File myFile = new File (p);
boolean exists = (new File(p)).exists();
if (exists) {
byte [] mybytearray = new byte [(int)myFile.length()];
FileInputStream fis = new FileInputStream(myFile);
BufferedInputStream bis = new BufferedInputStream(fis);
BufferedOutputStream out = new BufferedOutputStream(sock.getOutputStream());
bis.read(mybytearray,0,mybytearray.length);
OutputStream os = sock.getOutputStream();
System.out.println("Wait...");
os.write(mybytearray,0,mybytearray.length);
os.flush();
System.out.println("Done");
sock.close();
}
Server:
int filesize=6022386;
int bytesRead;
int current = 0;
ServerSocket servsock = new ServerSocket(13267);
Scanner input = new Scanner(System.in);
while (true) {
System.out.println("Wait...");
Socket sock = servsock.accept();
System.out.println("OK : " + sock);
// odbior pliku
byte [] mybytearray = new byte [filesize];
InputStream is = sock.getInputStream();
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);
System.out.println("New filename");
String p = input.nextLine();
File plik = new File(p);
FileOutputStream fos = new FileOutputStream(plik);
BufferedOutputStream bos = new BufferedOutputStream(fos);
bos.write(mybytearray, 0 , current);
bos.flush();
System.out.println("File saved");
bos.close();
sock.close();
And I tried to do something like that:
Client addon:
DataOutputStream outToServer = new DataOutputStream(sock.getOutputStream());
sentence = input.nextLine();
outToServer.writeBytes(sentence);
Server addon:
BufferedReader inFromClient = new BufferedReader(new InputStreamReader(sock.getInputStream()));
clientSentence = inFromClient.readLine();
System.out.println(clientSentence);
...but unfortunetly I have "Wait.." all the time for Client

TCP just transfers raw data. If you want to send files with a filename, you may want to use a higher level protocol, such as FTP or TFTP.
If you really want to use plain TCP, you'll need to encode the filename in your message somehow. You could, for example, send the filename as the first line of the message, and then have the other end turn the rest of the message into a file with that name.
This may be helpful to you: http://www.adp-gmbh.ch/blog/2004/november/15.html

Socket Programming file upload issues?Complete file not uploading

Hi i am using the following code for uploding my file from android phone to the server bt the file does not upload completely..e.g i uploded a 11kb file and got only 8kb file at the server.What am i doing wrong?
Client side
Socket skt = new Socket"112.***.*.**", 3000);
String FileName=fil.getName();
PrintWriter out2 = new PrintWriter(new BufferedWriter(new OutputStreamWriter(skt.getOutputStream())),true);
out2.println("Upload");
out2.println(FileName);
out2.println(spinindx);
out2.println(singleton.arrylst_setngs.get(0).toString());
out2.println(singleton.arrylst_setngs.get(1).toString());
out2.println(singleton.arrylst_setngs.get(2).toString());
out2.println(singleton.arrylst_setngs.get(3).toString());
out2.println(singleton.arrylst_setngs.get(4).toString());
out2.flush();
//Create a file input stream and a buffered input stream.
FileInputStream fis = new FileInputStream(fil);
BufferedInputStream in = new BufferedInputStream(fis);
BufferedOutputStream out = new BufferedOutputStream(skt.getOutputStream());
//Write the file to the server socket
int i;
byte[] buf = new byte[512];
while ((i = in.read(buf)) != -1) {
out.write(buf,0,i);
publishProgress(in.available());
System.out.println(i);
}
//Close the writers,readers and the socket.
in.close();
out.flush();
out.close();
out2.close();
skt.close();
}
catch( Exception e ) {
System.out.println(e);
}
The server side
InputStream inStream = socket.getInputStream();
BufferedReader inm = new BufferedReader(new InputStreamReader(inStream));
String Request=inm.readLine();
if(Request.equals("Upload")){
fileName = inm.readLine();
chosn = inm.readLine();
lt=inm.readLine();
cs = inm.readLine();
om = inm.readLine();
o = inm.readLine();
check=inm.readLine();
//Read, and write the file to the socket
BufferedInputStream in = new BufferedInputStream(inStream);
int i=0;
File f=new File("D:/data/"+filePrefx+fileName);
if(!f.exists()){
f.createNewFile();
}
FileOutputStream fos = new FileOutputStream("D:/data/"+filePrefx+fileName);
BufferedOutputStream out = new BufferedOutputStream(fos);
byte[] buf = new byte[512];
while ((i = in.read(buf)) != -1) {
System.out.println(i);
out.write(buf,0,i);
System.out.println("Receiving data...");
}
in.close();
inStream.close();
out.close();
fos.close();
socket.close();

Looks like you are using both a BufferedReader and a BufferedInputStream on the same underlying socket at the server side, and two kinds of output stream/writer at the client. So your BufferedReader is buffering, which is what it's supposed to do, and thus 'stealing' some of the data you're expecting to read with the BufferedInputStream. Moral: you can't do that. Use DataInputStream & DataOutputStream only, and writeUTF()/readUTF() for the 8 lines you are reading from the client before the file.

You shared the same underlying InputStream between your BufferedReader and bufferedInputStream.
What happened is, when you do the reading through BufferedReader, it reads more than the a few lines you requested from the underlying InputStream into its own internal buffer. And when you create the BufferedInputStream, the data has already been read by the BufferedReader. So Apart from what EJP suggested not to use any buffered class, you can create the BufferedInputStream, and then create the Reader on Top of it. The code is something like this:
BufferedInputStream in = new BufferedInputStream(inStream);
Reader inm = new InputStreamReader(in);
Add it to the beginning of your server code and remove this line:
BufferedInputStream in = new BufferedInputStream(inStream);

See this, i never tried though
void read() throws IOException {
log("Reading from file.");
StringBuilder text = new StringBuilder();
String NL = System.getProperty("line.separator");
Scanner scanner = new Scanner(new FileInputStream(fFileName), fEncoding);
try {
while (scanner.hasNextLine()){
text.append(scanner.nextLine() + NL);
}
}
finally{
scanner.close();
}
log("Text read in: " + text);
}
Shamelessly copied from
http://www.javapractices.com/topic/TopicAction.do?Id=42