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Java file transfer over Sockets trim last bytes

I have been trying to create a Messenger with file transfer capabilities, but I keep having too many null characters at the end. any time I use the file length to strip them, for some reason more of the file gets stripped and it just becomes a total mess. I'm not using any Java 7 or higher elements as I want it compatible with Java 6, and Windows 98 (grandma's PC).
I also get a lot of random null characters added into the file, im not sure how to avoid this
This is my code:
Transmit
package com.androdome.lunacoffee.management;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import com.androdome.lunacoffee.ErrorScreen;
import com.androdome.lunacoffee.SendScreen;
public class FileTransmitter implements Runnable{
String adds;
FileInputStream message;
int filecut = 4096;
byte[] fileName;
long fileSize;
SendScreen send;
public FileTransmitter(String address, FileInputStream msg, byte[] fnme, SendScreen snd, long l) {
adds = address;
send = snd;
message = msg;
fileName = fnme;
fileSize = l;
}
public void run()
{
try {
InetAddress add = InetAddress.getByName(adds);
Socket sock = new Socket(add, 11001);
DataOutputStream da = new DataOutputStream(sock.getOutputStream());
PrintWriter output = new PrintWriter(da);
da.write(fileName);
da.writeLong(message.getChannel().size());
byte[] filebuffer = new byte[filecut];
int g = 0;
int back = 0;
while((g = message.read(filebuffer)) != -1)
{
if(g != filecut && g > 0)
{
back = g;
}
da.write(filebuffer);
filebuffer = new byte[filecut];
}
da.writeInt(back);
System.out.print(back);
output.flush();
output.close();
send.incrementSent();
} catch (UnknownHostException e) {
send.incrementError();
// TODO Auto-generated catch block
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
new ErrorScreen("Unable to send file", "Your file was not able to send because the host \"" + adds + "\" was not availible!", sw.toString());
pw.close();
try {
sw.close();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
} catch (IOException e) {
send.incrementError();
// TODO Auto-generated catch block
new ErrorScreen("Unable to send file", "Your file was not able to send due to a bad output stream!", e.getMessage());
}
}
}
Recieve:
package com.androdome.lunacoffee.management;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Arrays;
import com.androdome.lunacoffee.ErrorScreen;
import com.androdome.lunacoffee.FileScreen;
import com.androdome.lunacoffee.Main;
public class FileReciever implements Runnable {
int bufferSize = 4096;
int headerSize = 32;
byte[] filebuffer = new byte[bufferSize];
byte[] fileheader = new byte[headerSize];
Main main;
File downloadfile = new File("tmp");
File transferFile = new File("dnl.ldf");
public FileReciever(Main mn)
{
main = mn;
}
static byte[] trim(byte[] bytes)
{
int i = bytes.length - 1;
while (i >= 0 && bytes[i] == 0)
{
--i;
}
return Arrays.copyOf(bytes, i + 1);
}
public void run() {
try {
ServerSocket recieveSocket = new ServerSocket(11001);
while (this != null) {
try{
downloadfile.createNewFile();
Socket connectionSocket = recieveSocket.accept();
DataInputStream reader = new DataInputStream(connectionSocket.getInputStream());
reader.read(fileheader);
long fileSize = reader.readLong();
System.out.println(bufferSize);
filebuffer = new byte[bufferSize];
String fileName = new String(fileheader);
fileheader = new byte[headerSize];
FileOutputStream fw = new FileOutputStream(downloadfile);
while(reader.read(filebuffer) != -1)
{
fw.write(filebuffer);
filebuffer = new byte[bufferSize];
}
//reader.readInt();
reader.close();
fw.close();
//RandomAccessFile file = new RandomAccessFile(downloadfile, "Rwd");
//file.setLength(fileSize); // Strip off the last _byte_, not the last character
//file.close();
connectionSocket.close();
FileScreen fs = new FileScreen(downloadfile, fileName, connectionSocket.getInetAddress().getHostName());
fs.setVisible(true);
fs.setLocationRelativeTo(null);
}
catch(Exception ex)
{}
}
} catch (IOException e) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
new ErrorScreen("Unable to start the File Recieve Thread", "Luna Messenger may already be running, or another program is using port 11001. Please close any program running on port 11001.", sw.toString());
pw.close();
try {
sw.close();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
}
}

In your above code,i think it makes following mistake.
The first,you should add a number which indicate the filename's length.like this:
da.writeInt(fileName.length); //the added code
da.write(fileName);
On the FileReciever,the receive code is :
int fileNameLength = reader.readInt();
fileheader=new byte[fileNameLength];
read(reader,fileheader,0,fileNameLength);
the read method can read up to length bytes from input stream into a array of bytes until the stream is end.
public static int read(InputStream in, byte[] b, int off, int len) throws IOException {
if (len < 0) {
throw new IndexOutOfBoundsException("len is negative");
}
int total = 0;
while (total < len) {
int result = in.read(b, off + total, len - total);
if (result == -1) {
break;
}
total += result;
}
return total;
}
The second,it is not correctly that the FileTransmitter translate the file date to the FileReciever,and should not add a number at end.The appropriate approach is just writing file data to socket outputstream in FileTransmitter,and don't do any other things.Like this:
while((g = message.read(filebuffer)) != -1)
{
da.write(filebuffer,0,g);
}
On the orther hand,and how many bytes should be readed depend on the length of bytes that your readed from the socket's inputstream ago, when you read the bytes from socket oupustream into filebuffer.the receiver code:
int readLength;
int sumLength=0;
while((readLength=reader.read(filebuffer,0,(int)(fileSize-sumLength>filebuffer.length?filebuffer.length:fileSize-sumLength))) != -1){
sumLength+=readLength;
fw.write(filebuffer,0,readLength);
if(sumLength==fileSize){
break;
}
}

Input Validation method for Java

I'm sort of new to Java and I'm learning about input validation methods but I'm struggling with an assignment that I'm trying to complete. Can someone help me? The following code is reading a file somewhere on your computer. I'm supposed to verify that the file path is correct with an input validation method. This is what I have so far:
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
public class readFile {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.print("Enter the name of your File: ");
String fileName = scan.nextLine();
File inputFile = new File(fileName);
BufferedReader reader = null;
try {
String sCurrentLine;
reader = new BufferedReader(new FileReader(inputFile));
while ((sCurrentLine = reader.readLine()) != null) {
System.out.println(sCurrentLine);
}
} catch (IOException e) {
e.printStackTrace();
System.out.print(e.getMessage());
} finally {
try {
if (reader != null)reader.close();
} catch (IOException ex) {
System.out.println(ex.getMessage());
ex.printStackTrace();
}
}
}
}

The easiest way to tell if the file path given is correct is to simply check if it exists:
if (inputFile.exists() && !inputFile.isDirectory()) {
// inputFile has a valid path.
}

Use following code checking.
File f = new File(filePathString);
if(f.exists() && !f.isDirectory()) {
// do something
}

How to use IO Scanner/System.out copying video and photos?

I use io scanner / System.out to copy text files. I tried using the same technique to copy pdf, video and image files. The result was that the files were copied, but they were corrupt (cannot open them). Also, the file size does not equal the original file size.
code
import java.awt.Desktop;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.Scanner;
public class ScannerTest {
public static void main(String[] args) throws IOException {
PrintStream out =System.out;
long start = System.currentTimeMillis();
copyFile(new File("H:\\a.pdf"), new File("H:\\b.pdf"));// 2 file input, output
System.setOut(out);
System.out.println(System.currentTimeMillis()-start);
}
static String text=null;
public static void copyFile(File input,File output) throws IOException{
//Scanner read file
Scanner in= new Scanner(new FileInputStream(input));
StringBuilder builder =new StringBuilder();
try {
while(in.hasNextLine()){
text=in.nextLine();
builder.append(text);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
in.close();
}
//System.out
try {
OutputStream outputStream = new FileOutputStream(output);
PrintStream printStream = new PrintStream(outputStream);
System.setOut(printStream);
System.out.println(new String(builder));
Desktop.getDesktop().open(output);
} catch (Exception e) {
e.printStackTrace();
}
}
}
p/s: Not use IO other.(ex: BufferedInput/OutputStream)

There are two problems (at least):
you use nextLine() which will read up to the next "\r\n"', '\n', '\r', '\u2028', '\u2029' or '\u0085' and discard what ever it found as line separator (one or two characters). As you are not even using append(text).append('\n') I doubt that this will correctly copy multi-line text, let alone binary files where each of the possible line-terminators may have a different meaning.
you use Scanner and StringBuilder which are not safe for binary data. As the Documentation on new Scanner(java.io.InputStream) states:
Bytes from the stream are converted into characters using the underlying platform's default charset.
If any byte-sequence in you input file is not valid as e.g. UTF-8 (which is a common default charset) it is silently replaced by a generic 'could not read input'-character. For text-files this can mean, that a 'ä' is converted to '�', for binary files this can render the whole file unusable.
If you want to copy arbitrary (possibly binary) files I would recommend not taking any chances and stick to byte[] APIs. You could however also use a charset which is known to accept all byte-sequences unchanged like ISO-8859-1 when creating Scanner and PrintStream; you would than still need to refrain from using line-APIs that suppress the found line-separator.
This should do the trick:
import java.awt.Desktop;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
/**
* Created for http://stackoverflow.com/a/25351502/1266906
*/
public class CopyFile {
public static void main(String[] args) {
long start = System.currentTimeMillis();
copyFile(new File("H:\\a.pdf"), new File("H:\\b.pdf"));// 2 file input, output
System.out.println(System.currentTimeMillis() - start);
}
public static void copyFile(File input, File output) {
try {
try (FileInputStream inputStream = new FileInputStream(input);
OutputStream outputStream = new FileOutputStream(output)) {
byte[] buffer = new byte[4096];
do {
int readBytes = inputStream.read(buffer);
if (readBytes < 1) {
// end of file
break;
} else {
outputStream.write(buffer, 0, readBytes);
}
} while (true);
}
// Open result
Desktop.getDesktop().open(output);
} catch (Exception e) {
e.printStackTrace();
}
}
}
pre Java 7 you need to use try-finally:
public static void copyFile(File input, File output) {
try {
FileInputStream inputStream = new FileInputStream(input);
try {
OutputStream outputStream = new FileOutputStream(output);
try {
byte[] buffer = new byte[4096];
do {
int readBytes = inputStream.read(buffer);
if (readBytes < 1) {
// end of file
break;
} else {
outputStream.write(buffer, 0, readBytes);
}
} while (true);
} finally {
outputStream.close();
}
} finally {
inputStream.close();
}
// Open result
Desktop.getDesktop().open(output);
} catch (Exception e) {
e.printStackTrace();
}
}

Reading video data and writing to another file java

I am reading a video file data in bytes and sending to another file but the received video file is not playing properly and is chattered.
Can anyone explain me why this is happening and a solution is appreciated.
My code is as follows
import java.io.*;
public class convert {
public static void main(String[] args) {
//create file object
File file = new File("B:/music/Billa.mp4");
try
{
//create FileInputStream object
FileInputStream fin = new FileInputStream(file);
byte fileContent[] = new byte[(int)file.length()];
fin.read(fileContent);
//create string from byte array
String strFileContent = new String(fileContent);
System.out.println("File content : ");
System.out.println(strFileContent);
File dest=new File("B://music//a.mp4");
BufferedWriter bw=new BufferedWriter(new FileWriter(dest));
bw.write(strFileContent+"\n");
bw.flush();
}
catch(FileNotFoundException e)
{
System.out.println("File not found" + e);
}
catch(IOException ioe)
{
System.out.println("Exception while reading the file " + ioe);
}
}
}

This question might be dead but someone might find this useful.
You can't handle video as string. This is the correct way to read and write (copy) any file using Java 7 or higher.
Please note that size of buffer is processor-dependent and usually should be a power of 2. See this answer for more details.
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
public class FileCopy {
public static void main(String args[]) {
final int BUFFERSIZE = 4 * 1024;
String sourceFilePath = "D:\\MyFolder\\MyVideo.avi";
String outputFilePath = "D:\\OtherFolder\\MyVideo.avi";
try(
FileInputStream fin = new FileInputStream(new File(sourceFilePath));
FileOutputStream fout = new FileOutputStream(new File(outputFilePath));
){
byte[] buffer = new byte[BUFFERSIZE];
while(fin.available() != 0) {
bytesRead = fin.read(buffer);
fout.write(buffer, 0, bytesRead);
}
}
catch(Exception e) {
System.out.println("Something went wrong! Reason: " + e.getMessage());
}
}
}

Hope this also helpful for you - This can read and write a file into another file (You can use any file type to do that)
import java.io.FileInputStream;
import java.io.FileOutputStream;
public class Copy {
public static void main(String[] args) throws Exception {
FileInputStream input = new FileInputStream("input.mp4"); //input file
byte[] data = input.readAllBytes();
FileOutputStream output = new FileOutputStream("output.mp4"); //output file
output.write(data);
output.close();
}
}

import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import javax.imageio.ImageIO;
public class Reader {
public Reader() throws Exception{
File file = new File("C:/Users/Digilog/Downloads/Test.mp4");
FileInputStream fin = new FileInputStream(file);
byte b[] = new byte[(int)file.length()];
fin.read(b);
File nf = new File("D:/K.mp4");
FileOutputStream fw = new FileOutputStream(nf);
fw.write(b);
fw.flush();
fw.close();
}
}

In addition to Jakub Orsula's answer, one needs to check the result of read operation to prevent garbage being written to end of file in last iteration.
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
public class FileCopy {
public static void main(String args[]) {
final int BUFFERSIZE = 4 * 1024;
String sourceFilePath = "D:\\MyFolder\\MyVideo.avi";
String outputFilePath = "D:\\OtherFolder\\MyVideo.avi";
try(
FileInputStream fin = new FileInputStream(new File(sourceFilePath));
FileOutputStream fout = new FileOutputStream(new File(outputFilePath));
){
byte[] buffer = new byte[BUFFERSIZE];
int bytesRead;
while(fin.available() != 0) {
bytesRead = fin.read(buffer);
fout.write(buffer, 0, bytesRead);
}
}
catch(Exception e) {
System.out.println("Something went wrong! Reason: " + e.getMessage());
}
}
}

Why does the integer written to a file get read as a different value?

I've got a program where I need to generate an integer, write it to a text file and read it back the next time the program runs. After some anomalous behavior, I've stripped it down to setting an integer value, writing it to a file and reading it back for debugging.
totScore, is set to 25 and when I print to the console prior to writing to the file, I see a value of 25. However, when I read the file and print to the console I get three values...25, 13, and 10. Viewing the text file in notepad gives me a character not on the keyboard, so I suspect that the file is being stored in something other that int.
Why do I get different results from my write and read steps?
Is it not being written as an int? How are these values being stored in the file? Do I need to cast the read value as something else and convert it to an integer?
Consider:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.nio.file.*;
import java.nio.file.StandardOpenOption.*;
//
public class HedgeScore {
public static void main(String[] args) {
int totScore = 25;
OutputStream outStream = null; ///write
try {
System.out.println("totscore="+totScore);
BufferedWriter bw = new BufferedWriter(new FileWriter(new File("hedgescore.txt")));
bw.write(totScore);
bw.write(System.getProperty("line.separator"));
bw.flush();
bw.close();
}
catch(IOException f) {
System.out.println(f.getMessage());
}
try {
InputStream input = new FileInputStream("hedgescore.txt");
int data = input.read();
while(data != -1) {
System.out.println("data being read from file :"+ data);
data = input.read();
int prevScore = data;
}
input.close();
}
catch(IOException f) {
System.out.println(f.getMessage());
}
}
}

You're reading/writing Strings and raw data, but not being consistent. Why not instead read in Strings (using a Reader of some sort) and then convert to int by parsing the String? Either that or write out your data as bytes and read it in as bytes -- although that can get quite tricky if the file must deal with different types of data.
So either:
import java.io.*;
public class HedgeScore {
private static final String FILE_PATH = "hedgescore.txt";
public static void main(String[] args) {
int totScore = 25;
BufferedWriter bw = null;
try {
System.out.println("totscore=" + totScore);
bw = new BufferedWriter(new FileWriter(new File(
FILE_PATH)));
bw.write(totScore);
bw.write(System.getProperty("line.separator"));
bw.flush();
} catch (IOException f) {
System.out.println(f.getMessage());
} finally {
if (bw != null) {
try {
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
InputStream input = null;
try {
input = new FileInputStream(FILE_PATH);
int data = 0;
while ((data = input.read()) != -1) {
System.out.println("data being read from file :" + data);
}
input.close();
} catch (IOException f) {
System.out.println(f.getMessage());
} finally {
if (input != null) {
try {
input.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
or:
import java.io.*;
public class HedgeScore2 {
private static final String FILE_PATH = "hedgescore.txt";
public static void main(String[] args) {
int totScore = 25;
PrintWriter pw = null;
try {
System.out.println("totscore=" + totScore);
pw = new PrintWriter(new FileWriter(new File(FILE_PATH)));
pw.write(String.valueOf(totScore));
pw.write(System.getProperty("line.separator"));
pw.flush();
} catch (IOException f) {
System.out.println(f.getMessage());
} finally {
if (pw != null) {
pw.close();
}
}
BufferedReader reader = null;
try {
reader = new BufferedReader(new FileReader(FILE_PATH));
String line = null;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
} catch (IOException f) {
System.out.println(f.getMessage());
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}