1. 通过FileInputStream读取文件输入流

    public void export(String excelPath, String fileName) throws Exception{                    //将文件存到指定位置          //读取目标文件流，转换调用下载          File resultFile = new File(excelPath);          FileInputStream resultFileFi = new FileInputStream(resultFile);          long l = resultFile.length();          int k = 0;          byte abyte0[] = new byte[65000];                    // 调用下载          response.setContentType("application/x-msdownload");          response.setContentLength((int) l);          response.setHeader("Content-Disposition", "attachment; filename=" + fileName);          while ((long) k < l) {              int j;              j = resultFileFi.read(abyte0, 0, 65000);              k += j;              response.getOutputStream().write(abyte0, 0, j);          }          resultFileFi.close();                    //转换成功后，删除临时文件          resultFile.delete();      }

2. 注意getServletContext().getMimeType(fileName)，读取文件类型

    public void export1(String excelPath, String fileName){          if (request.getParameter("file") != null) {              fileName = request.getParameter("file");          }          System.out.println(ServletActionContext.getServletContext().getMimeType(fileName));          response.setContentType(ServletActionContext.getServletContext().getMimeType(fileName));          response.setHeader("Content-disposition","attachment; filename="+fileName);          BufferedInputStream bis = null;          BufferedOutputStream bos = null;          try {              bis = new BufferedInputStream( new FileInputStream(excelPath) );              bos = new BufferedOutputStream(response.getOutputStream());              byte[] buff = new byte[2048];              int bytesRead;              while(-1 != (bytesRead = bis.read(buff, 0, buff.length))) {                  bos.write(buff,0,bytesRead);              }           } catch(final IOException e) {              System.out.println ( "出现IOException." + e );           } finally {              if (bis != null)                  try {                      bis.close();                  } catch (IOException e) {                      e.printStackTrace();                  }              if (bos != null)                  try {                      bos.close();                  } catch (IOException e) {                      e.printStackTrace();                  }           }              }