在做excel导出时如何将excel直接写在输出流中

之前做excel导出时，我都是先将文件写在服务器上，然后再下载下来，后来发现原来可以直接将文件写在输出流里边。
下面是一个小demo:
package com.huaqin.fcstrp.util;

import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

import javax.servlet.http.HttpServletResponse;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;

public class Write {

private HSSFWorkbook workbook = null;
/**
*
* @param response 下载请求的response
*/
public void createExcel(HttpServletResponse response){

//创建workbook
workbook = new HSSFWorkbook();
//添加Worksheet（不添加sheet时生成的xls文件打开时会报错)
Sheet sheet1 = workbook.createSheet("sheet1");
OutputStream out = null;
try {
out = response.getOutputStream();
String fileName = "test.xls";// 文件名
response.setContentType("application/x-msdownload");
response.setHeader("Content-Disposition", "attachment; filename="
+ URLEncoder.encode(fileName, "UTF-8"));
Row row = workbook.getSheet("sheet1").createRow(0); //创建第一行
for(int i = 0;i < 10;i++){
Cell cell = row.createCell(i);
cell.setCellValue("测试数据"+i);
}
workbook.write(out);
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}

调用：/**
* 下载2
* @param request
* @param response
* @return
* @throws FileNotFoundException
*/
@RequestMapping(value = "/download2")
@ResponseBody
public void download2(HttpServletRequest request,
HttpServletResponse response) throws FileNotFoundException {
Write write = new Write();
write.createExcel(response);

}