decompress.java

huffman字符编码的java实现

package Huffman;

import java.io.*;
import java.util.*;
import javax.imageio.stream.*;

public class Decompress{
	private byte [] output;
	private byte []table;//symbol table
	private int length,bytelength;//length of table  
	private int [] count;
	private File inname,outname;
	
	public Decompress(File in,File out){
		inname=in;
		outname=out;
	}
	
	private void readFile(){
		try{
			FileImageInputStream infile=new FileImageInputStream(inname);
			length=infile.readInt();
			//System.out.print(length+" ");
			
			table=new byte [length+1];
			count=new int [length+1];
			
			infile.read(table,1,length);//read table[]
			
			
			for(int i=1;i<=length;i++) //read count[]
			{
				count[i]=infile.readInt();
				//System.out.print(table[i]+" "+count[i]+" ");
			}
			
			bytelength=infile.readInt();
			//System.out.print(bytelength);
			
			output=new byte[bytelength+1];
			
			int n=length;//create hufftree
			int m=2*n-1;
			int i;
			//System.out.print(n+" "+m+" ");
			HTNode [] HT=new HTNode[m+1];
			for(i=1;i<=n;i++) HT[i]=new  HTNode(count[i],0,0,0);
			for(;i<=m;i++) HT[i]=new HTNode(0,0,0,0);
			
			for(i=n+1;i<=m;i++) {
				int s1=0,s2=0;
				int w1=10000,w2=10000;
				for(int j=1;j<=i-1;j++)
				{
					if(HT[j].parent==0)
					{
						if(HT[j].weight<w1) 
						{
							w2=w1;
							w1=HT[j].weight;
							s2=s1;
							s1=j;
							//System.out.print(j+" "+s1+","+w1+" ");
						}
							
						else if(HT[j].weight<w2)
						{
							s2=j;
							w2=HT[j].weight;
							//System.out.print("kk ");
						}
					}
				}
				//System.out.print(s1+","+s2+" ");
				HT[s1].parent=i;
				HT[s2].parent=i;
				HT[i].lchild=s1;
				HT[i].rchild=s2;
				HT[i].weight=HT[s1].weight+HT[s2].weight;
			}//create HuffTree
			
			int r;
			
			for(i=1;i<=bytelength;i++)
			{
				r=m;
				do
				{
					int b=infile.readBit();
					if(b==0)
					r=HT[r].lchild;
					else 
					r=HT[r].rchild;
				}
				while(HT[r].lchild!=0);
				output[i]=table[r];
			}
			
			}
		catch(FileNotFoundException e){
			}
		catch(IOException e){
		} 
	}
	

	private void write(){
		try{
		FileImageOutputStream outfile=new FileImageOutputStream(outname);
		outfile.write(output,1,bytelength);
		}
		catch(IOException e){
		} 
	}
	
	public void process(){
		readFile();
		write();
	}
	
	//public static void main(String [] args){
	//	Decompress c=new Decompress(new File("h.dat"),new File("sam2.txt"));
	//	c.process();
	//}
}