when the string u is not a enlgish or number sentence,the file data have 
problem.

FileOutputStream  out = new FileOutputStream ("C:/workbook.xls");		
HSSFWorkbook wb = new HSSFWorkbook();
HSSFRow r = null;
HSSFCell c = null;
r = s.createRow((short)0);
c = r.createCell((short)0);	
String u="‘ªŽŽŒÜ˜ZŽµ";
c.setCellValue(u);
c.setCellType( HSSFCell.CELL_TYPE_STRING );
c.setEncoding(HSSFCell.ENCODING_COMPRESSED_UNICODE);
wb.write(out);