在Java中，GB碼和Unicode碼的互轉問題，歡迎討論

    在Java中，編碼格式非常重要，下面是一段GB碼和Unicode碼互轉的代碼，歡迎指出優缺點及需要改進的地方。

/**
 * @author Administrator
 *
 */
import java.io.*;
import java.util.Hashtable;

class GBUnicode{
 byte high[]=new byte[6763],low[]=new byte[6763];
 char unichar[]=new char[6763];
 Hashtable UniGB;

 public GBUnicode(String table_file)throws IOException
 {
  //BufferedInputStream tables=new BufferedInputStream (new FileInputStream(table_file));
  DataInputStream tables=new DataInputStream (new FileInputStream(table_file));
  int i,n=0;
  byte b,bl,bh,num[]=new byte[20];

  UniGB=new Hashtable(7000,1);
  while (n<6763 ){
   do{
    bh=(byte)tables.read();
   }while ((char)bh<=' '); //find first non-blank char
   bl=(byte)tables.read();
   high[n]=bh;
   low[n]=bl;
   do{
    b=(byte)tables.read();
   }while (b!=(byte)':'); //find ':'
   do{
    b=(byte)tables.read();
   }while ((char)b<=' '); //find next non-blank char to read as number
   i=0;
   while ((char)b>='0' && (char)b<='9'){
    num[i++]=b;
    b=(byte)tables.read();
   }
   unichar[n]=(char)Integer.parseInt(new String(num,0,0,i));
   if (UniGB.get(new Character(unichar[n]))!= null)
    System.out.println("Duplicated : "+unichar[n]);
   UniGB.put(new Character(unichar[n]),new Integer(n));
   n=n+1;
  }
  tables.close();
 }

 private int getGBindex(byte high,byte low){
  int i,j;
  i=high-(byte)0xb0;
  j=low-(byte)0xa1;
  if (i <39) {// L1 Chinese
   if (j<0 || j>94)
    return -1;
   return (i*94+j);
  }
  else if (i==39) {//one of the last 89 L1 Chinese
   if (j<0 || j>89)
    return -1;
   return (i*94+j);
  }
  else {//L2 Chinese
   if (j<0 || j>94)
    return -1;
   return (i*94+j-5);
  }
 }

 public byte[] Uni2GB(char unicode) {

  Integer index=(Integer)UniGB.get(new Character(unicode));
  if (index==null)
   return null;
  byte ch[]=new byte[2];
  ch[0]=high[index.intValue()];
  ch[1]=low[index.intValue()];
  return ch;
 }

 public char GB2Uni(byte high, byte low) {
  int index=getGBindex(high,low);
  if (index ==-1) //not GB Chinese
   return 0;
  return(unichar[index]);
 }
}