我已經在java中編寫了lzw算法的代碼。在解壓縮時它進入無限循環。以不同的方式讀取255以上的值。即時給予ma代碼的例子。在java中的lzw解壓縮
import java.io.*;
import java.util.*;
public class test_decom {
static final int BUFFERSIZE = 32;
static final int CHARSIZE = 12;
static long buffer; //32 bits of space, up to 16bit compression, only 24 bits used
static int bufferBits; //How many bits are stored in the buffer
static int bits = 12; //How many bits per code
static int lzwSize; // have writen dis value at the end of compression file but this
//also not writing..... **plz help for this also**
static int getCode(InputStream fp)
{
long temp;
while(bufferBits <=(BUFFERSIZE - CHARSIZE *2))//Never go over than size - or we loose data
{ //Also never use full 64 bits, to avoid issues
//No point reading anymore, files done :p
try
{
System.out.print("bufferBits : ");
if(fp.available() <= 0)
break;
//test = fp.read();
//buffer |= test << bufferBits;
buffer |= fp.read() <<(bufferBits);
bufferBits+= CHARSIZE; //Buffer now stores one more char.
System.out.println(buffer);
}
catch(IOException e)
{
System.out.println("Error in getCode" + e.getMessage());
}
}
temp = (buffer << (64-bits)) >>> (64-bits); //We remove the excess bits
buffer >>>= bits; //Remove the bits from buffer
bufferBits -= bits;
System.out.println("temp : "+temp);
return (int)temp; //we return the correct code
}
public static void main(String arg[]) throws IOException
{
// int prefix[] = new int[20];
//int nextCode = 0;
// String dict[] = new String [20];
lzwSize = (short)(1<<(bits)-1);
BufferedInputStream fileIn = null;
BufferedOutputStream fileOut = null;
try
{
fileIn = new BufferedInputStream (new FileInputStream ("C:\\Documents and Settings\\project\\LzwTut\\test1_test.txt"));
fileOut = new BufferedOutputStream(new FileOutputStream("C:\\Documents and Settings\\gauri\\project\\practice\\LzwTut\\test1_Test.txt"));
}
catch(IOException e)
{
System.out.println("Unable to load file " + e.getMessage());
}
ArrayList<Integer> input = new ArrayList<Integer>();
Dictionary dic = new Hashtable();
String val = null;
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int ab;
while((ab=getCode(fileIn))!=lzwSize){ //i tried putting -1 but that is also not working
//problem in this....
//initialization
input.add(ab);
}
// input.get(i) = Integer.parseInt(br.readLine());
for(int i=0;i<input.size()-1;i++)
//{
try{
if(input.get(i)<=255)
{
fileOut.write(input.get(i));
//System.out.println("output : "+input.get(i));
if(input.get(i+1)>255)
{
val = (String)dic.get(input.get(i+1)-256);
dic.put(i, input.get(i)+" "+val);
// System.out.println("dic.put("+i+", "+input[i]+" "+val+")");
}
else
{
dic.put(i, input.get(i)+" "+input.get(i+1));
//System.out.println("dic.put("+i+", "+input[i]+" "+input[i+1]+")");
}
// addDict(i,input[i],input[i+1]);//abhi tak out of bounds not solved
}
else
{
val = (String)dic.get(input.get(i)-256);
//System.out.print("output : ");
for(int k=0;k<val.length();k++)
{
if(val.charAt(k) == ' ')
continue;
else
{
fileOut.write(val.charAt(k));
// System.out.print(val.charAt(k));
}
}
// System.out.println();
if(input.get(i+1)>255)
{
String val1 = (String)dic.get(input.get(i+1)-256);
dic.put(i, val+" "+val1);
// System.out.println("dic.put("+i+", "+val+" "+val1+")");
}
else
{
dic.put(i, val+" "+input.get(i+1));
// System.out.println("dic.put("+i+", "+val+" "+input[i+1]+")");
}
}
}
catch(Exception e)
{}
if(input.get(input.size() - 1)>255)
{
//System.out.print("output : ");
for(int k=0;k<val.length();k++)
{
if(val.charAt(k) == ' ')
continue;
else
{
// System.out.print(val.charAt(k));
fileOut.write(val.charAt(k));
}
}
}
else{
//System.out.println("output : "+input.get(input.size() - 1));
fileOut.write(input.get(input.size() - 1));
}
try{
fileIn.close();
fileOut.close();
}
catch(Exception e)
{
}
// System.out.println("output : "+input[9]);
}
}
例如: txt文件test_test.txt包含: 堆棧溢出堆棧溢出.......... 壓縮後: 輸入:115 輸入:116輸出:115 輸入: 97輸出:116 輸入:99輸出:97 輸入:107輸出:99 輸入:32輸出:107 輸入:111輸出:32 輸入:118輸出:111 輸入:101輸出:118 輸入:114輸出:101 inpu T:102輸出:114 輸入:108輸出:102 輸入:111輸出:108 輸入:119輸出:111 輸入:32輸出:119 輸入:105輸出:32 輸入:115輸出:105 輸入:32輸出:115 輸入:98輸出:32 輸入:101安輸出:98 輸入:115輸出:101 輸入:116 輸入:32輸出:256 輸入:102輸出:32 輸入:111輸出: 102 輸入:114輸出:111 輸入:117輸出:114 輸入:109輸出:117 輸入:46輸出:109 輸入:32輸出:46 輸入:115輸出:32 輸入:116 輸入:97輸出:256 輸入:99 輸入:107輸出:258 輸入:32 輸入:111 輸出:260輸入:118 輸入:101輸出:262 輸入:114 輸入:102輸出:264 輸入:108 輸入:111輸出:266 輸入:119 輸入:46輸出:268 生成成功(總時間:0秒)//它應該寫入lzwSize但它不會寫入
解壓後: 輸出:115 輸出:116 輸出:97 輸出:99 輸出:107 輸出:32 輸出:111 輸出:118 輸出:101 輸出:114 輸出:102 輸出:108 輸出:111 輸出:119 輸出:32 輸出:105 輸出:115 輸出:32 輸出:98 輸出: 101
你的問題是什麼? – 2013-03-25 17:51:50