Develop Reference

java array byte file to human readable

I have a byte array file with me which I am trying to convert into human readable. I tried below ways :
public static void main(String args[]) throws IOException
{
//System.out.println("Platform Encoding : " + System.getProperty("file.encoding"));
FileInputStream fis = new FileInputStream("<Path>");
// Using Apache Commons IOUtils to read file into byte array
byte[] filedata = IOUtils.toByteArray(fis);
String str = new String(filedata, "UTF-8");
System.out.println(str);
}
Another approach :
public static void main(String[] args) {
File file = new File("<Path>");
readContentIntoByteArray(file);
}
private static byte[] readContentIntoByteArray(File file) {
FileInputStream fileInputStream = null;
byte[] bFile = new byte[(int) file.length()];
try {
FileInputStream(file);
fileInputStream.read(bFile);
fileInputStream.close();
for (int i = 0; i < bFile.length; i++) {
System.out.print((char) bFile[i]);
}
} catch (Exception e) {
e.printStackTrace();
}
return bFile;
}
These codes are compiling but its not yielding output file in a human readable fashion. Excuse me if this is a repeated or basic question.
Could someone please correct me where I am going wrong here?

Your code (from the first snippet) for decoding a byte file into a UTF-8 text file looks correct to me (assuming FileInputStream fis = new FileInputStream("Path") is yielding the correct fileInputStream) .
If you're expecting a text file format but are not sure which encoding the file format is in (perhaps it's not UTF-8) , you can use a library like the below to find out.
https://code.google.com/archive/p/juniversalchardet/
or just explore some of the different Charsets in the Charset library and see what they produce in your String initialization line and what you produce:
new String(byteArray, Charset.defaultCharset()) // try other Charsets here.
The second method you show has associated catches with byte to char conversion , depending on the characters, as discussed here (Byte and char conversion in Java).
Chances are, if you cannot find a valid encoding for this file, it is not human readable to begin with, before byte conversion, or the byte array file being passed to you lost something that makes it decodeable along the way.

Gzip decompression adding one extra byte ... Why?

I've written a simple Java code snippet which takes a String, converts it to byte[], and then compresses it using Gzip. Then it decompresses the result to get back the byte[], which now contains one extra garbage value byte. Why is there a garbage value byte here ??
public static void main(String[] args) throws Exception {
String testString = "Sample String here";
byte[] originalBytes = testString.getBytes();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
GZIPOutputStream gzos = new GZIPOutputStream(baos);
gzos.write(originalBytes);
gzos.close();
byte[] compressedBytes = baos.toByteArray();
ByteArrayInputStream bais = new ByteArrayInputStream(compressedBytes);
GZIPInputStream gzis = new GZIPInputStream(bais);
ByteArrayOutputStream dbaos = new ByteArrayOutputStream();
while(gzis.available() > 0) {
dbaos.write(gzis.read());
}
byte[] decompressedBytes = dbaos.toByteArray();
String decompressedString = new String(decompressedBytes);
System.out.println(">>" + decompressedString + "<<");
System.out.println("Size of bytes before: " + originalBytes.length);
System.out.println("Size of bytes after: " + decompressedBytes.length);
}
Output:
>>Sample String here�<<
Size of bytes before: 18
Size of bytes after: 19
Can someone tell me why is there a garbage value byte ? How do I get rid of it WITHOUT changing the setup of the code above ??

You are using available() here, so you get one extra byte. You should be reading the stream and checking for a value less than 0. Change this
ByteArrayOutputStream dbaos = new ByteArrayOutputStream();
while(gzis.available() > 0) {
dbaos.write(gzis.read());
}
to something like
ByteArrayOutputStream dbaos = new ByteArrayOutputStream();
int b;
while ((b = gzis.read()) >= 0) {
dbaos.write(b);
}
and I get
>>Sample String here<<
Size of bytes before: 18
Size of bytes after: 18

Convert ZIP to byte array without saving the output to file

I have a ZIP file and when I convert it into byte array and encode it, I am unable to print the encoded format without writing it into file.
Could anyone help in solving this issue?
My code is
InputStream is = null;
OutputStream os = null;
is = new FileInputStream("C:/Users/DarkHorse/Desktop/WebServicesTesting/PolicyCredit.zip");
os = new FileOutputStream("D:/EclipseTestingFolder/EncodedFile1.txt");
int bytesRead = 0;
int chunkSize = 10000000;
byte[] chunk = new byte[chunkSize];
while ((bytesRead = is.read(chunk)) > 0)
{
byte[] ba = new byte[bytesRead];
for(int i=0;i<ba.length;i++)
{
ba[i] = chunk[i];
}
byte[] encStr = Base64.encodeBase64(ba);
os.write(encStr);
}
os.close();
is.close();
}
My Output in the file is
UEsDBBQAAAAIANGL/UboGxdAAQUAAK0WAAAQAAAAUG9saWN5Q3JlZGl0LnhtbJVY3Y6rNhC+r9R34AlqSPankSwkdtNskbLZKOk5Va8QC95d6wRIDZyeffszxgSMGUPKFcx8M/b8egwN87IWcZ6waF+cePLp//qLAw/d8BOL/mRxykRL6sk89T1KLq8adx1XLHp5i55YzkRc8SL3F6534y69O0oQpia6K6LiLTqwpBBpKdUPCRq
But when I am trying to print it on the screen, I am getting in this way
8569115686666816565656573657871764785981117112010065658185656575488765656581656565658571571159787785381517410890711084876110104116987486895189541147810467431145782515265108113838097110107831191071001167811510798769075791075386975681675753100541198273689012110110210211512212010383777185807570991205677479856101103119785655738799905411997704399101807611247471137665119471005666797647109821201211078276

You need to create a string representation of Base 64 encoded data.
System.out.println( new String(encStr, Charset.forName("UTF-8")));
Here are some other examples Base 64 Print Question
String Class

Assuming your result array byte[] encStr = Base64.encodeBase64(ba) is actually the encoded string, try the following:
System.out.println(new String(bytes, Charset.defaultCharset());

If you are using JDK 7 you can use Files.readAllBytes(path)
Your code would be much simpler like below:
Path path = Paths.get("C:/Users/DarkHorse/Desktop/WebServicesTesting/PolicyCredit.zip");
byte[] data = Files.readAllBytes(path);
byte[] encStr = Base64.encodeBase64(data);
System.out.println( new String(encStr));
Your will be able to print on console.

Using Java Deflater/Inflater with custom dictionary causes IllegalArgumentException

The following code is based on the example given in the javadocs for java.util.zip.Deflater. The only changes I have made is to create a byte array called dict and then set the dictionary on both the Deflater and Inflater instances using the setDictionary(byte[]) method.
The problem I'm seeing is that when I call Inflater.setDictionary() with the exact same array as I used for the Deflater, I get an IllegalArgumentException.
Here is the code in question:
import java.util.zip.Deflater;
import java.util.zip.Inflater;
public class DeflateWithDictionary {
public static void main(String[] args) throws Exception {
String inputString = "blahblahblahblahblah??";
byte[] input = inputString.getBytes("UTF-8");
byte[] dict = "blah".getBytes("UTF-8");
// Compress the bytes
byte[] output = new byte[100];
Deflater compresser = new Deflater();
compresser.setInput(input);
compresser.setDictionary(dict);
compresser.finish();
int compressedDataLength = compresser.deflate(output);
// Decompress the bytes
Inflater decompresser = new Inflater();
decompresser.setInput(output, 0, compressedDataLength);
decompresser.setDictionary(dict); //IllegalArgumentExeption thrown here
byte[] result = new byte[100];
int resultLength = decompresser.inflate(result);
decompresser.end();
// Decode the bytes into a String
String outputString = new String(result, 0, resultLength, "UTF-8");
System.out.println("Decompressed String: " + outputString);
}
}
If I try deflating the same compressed bytes without setting the dictionary, I get no error but the result returned is zero bytes.
Is there anything special I need to do in order to use a custom dictionary with Deflater/Inflater?

I actually figured this out while formulating the question but thought I should post the question anyway so others might benefit from my struggles.
It turns out you have to call inflate() once after setting the input but before setting the dictionary. The value returned will be 0, and a call to needsDictionary() will then return true. After that you can set the dictionary and call inflate again.
The amended code is as follows:
import java.util.zip.Deflater;
import java.util.zip.Inflater;
public class DeflateWithDictionary {
public static void main(String[] args) throws Exception {
String inputString = "blahblahblahblahblah??";
byte[] input = inputString.getBytes("UTF-8");
byte[] dict = "blah".getBytes("UTF-8");
// Compress the bytes
byte[] output = new byte[100];
Deflater compresser = new Deflater();
compresser.setInput(input);
compresser.setDictionary(dict);
compresser.finish();
int compressedDataLength = compresser.deflate(output);
// Decompress the bytes
Inflater decompresser = new Inflater();
decompresser.setInput(output, 0, compressedDataLength);
byte[] result = new byte[100];
decompresser.inflate(result);
decompresser.setDictionary(dict);
int resultLength = decompresser.inflate(result);
decompresser.end();
// Decode the bytes into a String
String outputString = new String(result, 0, resultLength, "UTF-8");
System.out.println("Decompressed String: " + outputString);
}
}
This seems very counter intuitive and clunky from an API design perspective, so please enlighten me if there are any better alternatives.

Assigning to a byte array in Java

I have a byte array I want to assign as follows:
First byte specifies the length of the string: (byte)string.length()
2nd - Last bytes contain string data from string.getBytes()
Other than using a for loop, is there a quick way to initialize a byte array using bytes from two different variables?

You can use System.arrayCopy() to copy your bytes:
String x = "xx";
byte[] out = new byte[x.getBytes().length()+1];
out[0] = (byte) (0xFF & x.getBytes().length());
System.arraycopy(x.getBytes(), 0, out, 1, x.length());
Though using something like a ByteArrayOutputStream or a ByteBuffer like other people suggested is probably a cleaner approach and will be better for your in the long run :-)

How about ByteBuffer ?
Example :
ByteBuffer bb = ByteBuffer.allocate(string.getBytes().length +1 );
bb.put((byte) string.length());
bb.put(string.getBytes());

While ByteBuffer is generally the best way to build up byte arrays, given the OP's goals I think the following will be more robust:
public static void main(String[] argv)
throws Exception
{
String s = "any string up to 64k long";
ByteArrayOutputStream bos = new ByteArrayOutputStream();
DataOutputStream out = new DataOutputStream(bos);
out.writeUTF(s);
out.close();
byte[] bytes = bos.toByteArray();
ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
DataInputStream in = new DataInputStream(bis);
String s2 = in.readUTF();
}

How about ByteArrayOutputStream?