JAva Excelファイルのエクスポート

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import jxl.Workbook;
import jxl.write.Label;
import jxl.write.WritableSheet;
import jxl.write.WritableWorkbook;
import jxl.write.WriteException;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

	public void exportExcel(List list, String fileName, Map headName) throws WriteException,IOException{
    	OutputStream os = new FileOutputStream(new File(fileName));
        //     
        WritableWorkbook workbook = Workbook.createWorkbook(os);
        //      
        WritableSheet sheet = workbook.createSheet("  ",0);
        //      
        Map dataMap;
        int row = 0, cell = 0;
        if(headName == null){
        	headName = (Map)list.get(0);
        }
		for(String key : headName.keySet()){
			Label label = new Label(cell, row ,headName.get(key));
			sheet.addCell(label);
			cell++;
		}
		//    
    	for(row = 0;row < list.size();row++){
    		cell = 0;
    		dataMap = (Map)list.get(row);
    		for(String key : headName.keySet()){
    			Label label = new Label(cell, row + 1 ,dataMap.get(key).toString());
    			sheet.addCell(label);
    			cell++;
    		}
    	}
        workbook.write();
        workbook.close();
        os.close();
    }