这是本人在项目中用到的，感觉还不错，在此分享一下：
/**
* 读取磁盘指定路径的文件，返回字节数组（可以写入输出流用来下载文件） * @param file 文件全路径 * @throws IOException 读写文件异常 * @return 下载文件的字节数组 */ public static byte[] readFileBytes(String file) throws IOException { File f = new File(file); if (!f.exists()) { DebugLogFactory.error(Tools.class, "error:file is not exsit "); return null; } BufferedInputStream bis = null; FileInputStream fis = null; ByteArrayOutputStream bos = null; byte[] fileBytes = null; try { fis = new FileInputStream(f); bis = new BufferedInputStream(fis); int dataSize = 1024; byte[] bt = new byte[dataSize]; bos = new ByteArrayOutputStream(); int readLen = 0; while ((readLen = bis.read(bt)) > 0) { bos.write(bt, 0, readLen); } fileBytes = bos.toByteArray(); } finally { if (null != bis) { try { bis.close(); } catch (Exception e) { DebugLogFactory.error(Tools.class, "close BufferedInputStream bis failed ", e); } bis = null; } if (null != fis) { try { fis.close(); } catch (Exception e) { DebugLogFactory.error(Tools.class, "close FileInputStream fis failed ", e); } fis = null; } if (null != bos) { try { bos.close(); } catch (Exception e) { DebugLogFactory.error(Tools.class, "close ByteArrayOutputStream bos failed ", e); } bos = null; } } return fileBytes; } /** * 将字节数组写入输出流下载文件 * @param downloadFileBytes 待写入的字节数组 * @param resp HttpServletResponse * @param out PrintWriter * @param resFileName 下载文件的命名 * @throws IOException 读写文件异常 */ public static void writeFileBytes(HttpServletResponse resp, PrintWriter out, byte[] downloadFileBytes, String resFileName) throws IOException { if (null != downloadFileBytes) { OutputStream opts = null; try { resp.reset(); resp.setContentType("application/x-msdownload"); resp.setHeader("Content-Disposition", "attachment;filename=" + resFileName); opts = resp.getOutputStream(); opts.write(downloadFileBytes); } catch (Exception e) { DebugLogFactory.error(Tools.class, "writeFileBytes() error", e); } finally { if (null != opts) { opts.close(); opts = null; } if (null != out) { out.close(); out = null; } } } }