/**
* Construct a frequency table from an InputStream. This will create a temporary file to copy the
* InputStream in.
*
* @param source the Input Stream
* @return an InputStream which is a copy of the source Stream, provided to re-Read the same Bytes
* for the actual compression process.
*/
public InputStream constructTable(InputStream source, boolean copy) {
freq = new int[TABLESIZE];
try {
File file = null;
FileOutputStream fos = null;
if (copy == true) {
file = File.createTempFile("huf", "tmp");
file.deleteOnExit();
fos = new FileOutputStream(file);
}
while (source.available() != 0) {
int c = source.read();
freq[c]++;
if (copy) fos.write(c);
}
source.close();
if (copy) {
fos.close();
return new FileInputStream(file);
}
return null;
} catch (Exception ex) {
ExHandler.handle(ex);
return null;
}
}
/**
* Reloads a frequency table as saved by saveTable
*
* @return the table
*/
public static int[] loadTable(InputStream in) {
try {
int l = in.read();
l |= (in.read() << 8);
byte[] tbl = new byte[l];
for (int i = 0; i < tbl.length; i++) {
tbl[i] = (byte) in.read();
}
return expandTable(tbl);
} catch (Exception ex) {
ExHandler.handle(ex);
return null;
}
}
/**
* Creates a compacted form of the actual frequency table and saves it into an OutputStream.
*
* @return true on success
*/
public boolean saveTable(OutputStream out) {
byte[] tbl = compactTable(freq);
try {
short l = (short) tbl.length;
out.write(l & 0xff);
out.write(l >> 8);
for (int i = 0; i < tbl.length; i++) {
out.write(tbl[i]);
}
return true;
} catch (Exception ex) {
ExHandler.handle(ex);
return false;
}
}
/** constructs a frequency table from a file */
public static int[] constructTable(RandomAccessFile file) {
int[] ret = new int[TABLESIZE];
try {
file.seek(0L);
long l = file.length();
for (long i = 0; i < l; i++) {
int c = file.read();
ret[c]++;
}
return ret;
} catch (Exception ex) {
ExHandler.handle(ex);
return null;
}
}
