文件下载

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();                }         }            }