Develop Reference

How to read /write XORed txt file UTF8 in java?

what i did so far :
I read a file1 with text, XORed the bytes with a key and wrote it back to another file2.
My problem: I read for example 'H' from file1 , the byte value is 72;
72 XOR -32 = -88
Now i wrote -88 in to the file2.
when i read file2 i should get -88 as first byte, but i get -3.
public byte[] readInput(String File) throws IOException {
Path path = Paths.get(File);
byte[] data = Files.readAllBytes(path);
byte[]x=new byte[data.length ];
FileInputStream fis = new FileInputStream(File);
InputStreamReader isr = new InputStreamReader(fis);//utf8
Reader in = new BufferedReader(isr);
int ch;
int s = 0;
while ((ch = in.read()) > -1) {// read till EOF
x[s] = (byte) (ch);
}
in.close();
return x;
}
public void writeOutput(byte encrypted [],String file) {
try {
FileOutputStream fos = new FileOutputStream(file);
Writer out = new OutputStreamWriter(fos,"UTF-8");//utf8
String s = new String(encrypted, "UTF-8");
out.write(s);
out.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
public byte[]DNcryption(byte[]key,byte[] mssg){
if(mssg.length==key.length)
{
byte[] encryptedBytes= new byte[key.length];
for(int i=0;i<key.length;i++)
{
encryptedBytes[i]=Byte.valueOf((byte)(mssg[i]^key[i]));//XOR
}
return encryptedBytes;
}
else
{
return null;
}
}

You're not reading the file as bytes - you're reading it as characters. The encrypted data isn't valid UTF-8-encoded text, so you shouldn't try to read it as such.
Likewise, you shouldn't be writing arbitrary byte arrays as if they're UTF-8-encoded text.
Basically, your methods have signatures accepting or returning arbitrary binary data - don't use Writer or Reader classes at all. Just write the data straight to the stream. (And don't swallow the exception, either - do you really want to continue if you've failed to write important data?)
I would actually remove both your readInput and writeOutput methods entirely. Instead, use Files.readAllBytes and Files.write.

In writeOutput method you convert encrypted byte array into UTF-8 String which changes the actual bytes you are writing later to the file. Try this code snippet to see what is happening when you try to convert byte array with negative values to UTF-8 String:
final String s = new String(new byte[]{-1}, "UTF-8");
System.out.println(Arrays.toString(s.getBytes("UTF-8")));
It will print something like [-17, -65, -67]. Try using OutputStream to write bytes to the file.
new FileOutputStream(file).write(encrypted);

corrupted file text while reading

I have the following code:
BlobDomain blobDomain = null;
OutputStream out = null;
try {
blobDomain = new BlobDomain();
out = blobDomain.getBinaryOutputStream();
byte[] buffer = new byte[8192];
int bytesRead = 0;
while ((bytesRead = in.read(buffer, 0, 8192)) != -1) {
out.write(buffer, 0, bytesRead);
String line = (new String(buffer));
fullText += line;
}
} catch (Exception e) {
//do nothing
}finally{
if (out != null)
try {
out.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
when i print the fullText what i see for larger files is that end part of the text is added again to the fullText. So full text has some lines repeated in the end. any suggestions on what is wrong here?

The reason that you are getting this is that you are writing the entire buffer every time to your String. Thus, when you reach the end of the file you may not have read exactly the amount of bytes that your buffer is sized at. The old data is still in the buffer and will also be written to your String.
One option to solve this may be to write your data to a String first and then to write your String to the output stream. This should also be faster than adding to a String after each read.
Save inputStream to String:
java.util.Scanner s = new java.util.Scanner(in).useDelimiter("\\A");
fullText = s.hasNext() ? s.next() : "";
Write String to output stream:
out.write(fullText.getBytes());
If you want to keep you code as-is then perform a substring on the buffer and retrieve only the amount of bytes read. For example:
String line = (new String(buffer.substring(0,bytesRead));

Java fast stream copy with ISO-8859-1

I have the following code, which will read in files in ISO-8859-1, as thats what is required in this application,
private static String readFile(String filename) throws IOException {
String lineSep = System.getProperty("line.separator");
File f = new File(filename);
StringBuffer sb = new StringBuffer();
if (f.exists()) {
BufferedReader br =
new BufferedReader(
new InputStreamReader(
new FileInputStream(filename), "ISO-8859-1"));
String nextLine = "";
while ((nextLine = br.readLine()) != null) {
sb.append(nextLine+ " ");
// note: BufferedReader strips the EOL character.
// sb.append(lineSep);
}
br.close();
}
return sb.toString();
}
The problem is it is pretty slow. I have this function, which is MUCH faster, but I can not seem to find how to place the character encoding:
private static String fastStreamCopy(String filename)
{
String s = "";
FileChannel fc = null;
try
{
fc = new FileInputStream(filename).getChannel();
MappedByteBuffer byteBuffer = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
int size = byteBuffer.capacity();
if (size > 0)
{
byteBuffer.clear();
byte[] bytes = new byte[size];
byteBuffer.get(bytes, 0, bytes.length);
s = new String(bytes);
}
fc.close();
}
catch (FileNotFoundException fnfx)
{
System.out.println("File not found: " + fnfx);
}
catch (IOException iox)
{
System.out.println("I/O problems: " + iox);
}
finally
{
if (fc != null)
{
try
{
fc.close();
}
catch (IOException ignore)
{
}
}
}
return s;
}
Any one have an idea of where i should be putting the ISO encoding?

From the code you posted, you're not trying to "copy" the stream, but read it into a string.
You can simply provide the encoding in the String constructor:
s = new String(bytes, "ISO-88591-1");
Personally I'd just replace the whole method with a call to the Guava method Files.toString():
String content = Files.toString(new File(filename), StandardCharsets.ISO_8859_1);
If you're using Java 6 or earlier, you'll need to use the Guava field Charsets.ISO_8859_1 instead of StandardCharsets.ISO_8859_1 (which was only introduced in Java 7).
However your use of the term "copy" suggests that you want to write the result to some other file (or stream). If that is true, then you don't need to care about the encoding at all, since you can just handle the byte[] directly and avoid the (unnecessary) conversion to and from String.

where you are converting bytes to string e.g. s = new String(bytes, encoding); or vice versa.

special char Android (ø)

i have to retrieve some data from a txt file and then show those data inside my app.
My problem is that if i have the special char 'ø' inside my txt, this is not shown and a '?' is shown instead.
i tried to check data like
if(string.charAt(i) == 'ø') do sth
or
string.replace('ø' , 'O')
but none of them is working and i think that Java could not recognize that char at all.
Do you have any idea?
thanks
edit
this is how i read data
String[] obj = getText(getActivity(), myTXT.txt").split("\n");
where getText is:
public String getText(Context c, String fileName){
ByteArrayOutputStream outputStream = null;
try {
AssetManager am = c.getAssets();
InputStream is = am.open(fileName);
outputStream = new ByteArrayOutputStream();
byte buf[] = new byte[1024];
int len;
while ((len = is.read(buf)) != -1){
outputStream.write(buf,0,len);
}
outputStream.close();
is.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return outputStream.toString();
}

These chars must be in UTF-8 encoding, check for your file while its getting saved whether its incoding. Create an InputStreamReader instance that uses the constructor specifying encoding.
InputStreamReader r= new InputStreamReader(new FileInputStream(myFile),"UTF-8");
// read your contents here.
r.close();

Cannot get URL content as UTF-8

i'm trying to read content from a URL but it does return strange symbols instead of "è", "à", etc.
This is the code i'm using:
public static String getPageContent(String _url) {
URL url;
InputStream is = null;
BufferedReader dis;
String line;
String text = "";
try {
url = new URL(_url);
is = url.openStream();
//This line should open the stream as UTF-8
dis = new BufferedReader(new InputStreamReader(is, "UTF-8"));
while ((line = dis.readLine()) != null) {
text += line + "\n";
}
} catch (MalformedURLException mue) {
mue.printStackTrace();
} catch (IOException ioe) {
ioe.printStackTrace();
} finally {
try {
is.close();
} catch (IOException ioe) {
// nothing to see here
}
}
return text;
}
I saw other questions like this, and all of them were answered like
Declare your inputstream as
new InputStreamReader(is, "UTF-8")
But i can't get it to work.
For example, if my url content contains
è uno dei più
I get
è uno dei più
What am i missing?

Judging by your example. You do receive a multibyte UTF-8 byte stream but your text editor reads in as ISO-8859-1. Tell your editor to read bytes as UTF-8!

I don't really know why this should not work, however the Java 7 way would be to use StandardCharsets.UTF_8 see
http://docs.oracle.com/javase/7/docs/api/java/nio/charset/StandardCharsets.html
in the (new) Constructor InputStreamReader(InputStream in, Charset cs), see
http://docs.oracle.com/javase/7/docs/api/java/io/InputStreamReader.html.