@WebServlet("/DownloadServlet")
public class DownloadServlet extends HttpServlet {protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置请求编码request.setCharacterEncoding("utf-8");//获取需要下载的文件名String fileName = request.getParameter("fileName") ;System.out.println(fileName);//设置两个  响应头response.addHeader("content-Type", "application/octet-stream");//获取客户端的User-Agent  （判断用户用的什么浏览器）String browser = request.getHeader("User-Agent");if (-1 < browser.indexOf("MSIE 6.0") || -1 < browser.indexOf("MSIE 7.0")) {// IE6, IE7 浏览器response.addHeader("content-disposition","attachment;filename=" + new String(fileName.getBytes(), "ISO8859-1"));} else if (-1 < browser.indexOf("MSIE 8.0")) {// IE8response.addHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));} else if (-1 < browser.indexOf("MSIE 9.0")) {// IE9response.addHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));} else if (-1 < browser.indexOf("Chrome")) {// 谷歌response.addHeader("content-disposition","attachment;filename*=UTF-8''" + URLEncoder.encode(fileName, "UTF-8"));} else if (-1 < browser.indexOf("Safari")) {// 苹果response.addHeader("content-disposition","attachment;filename=" + new String(fileName.getBytes(), "ISO8859-1"));} else {// 火狐或者其他的浏览器response.addHeader("content-disposition","attachment;filename*=UTF-8''" + URLEncoder.encode(fileName, "UTF-8"));}
//		response.addHeader("content-Disposition", "attachment;filename="+fileName);//Servlet通过文件的地址将文件转为输入流  读到Servlet 中String path = "res/"+fileName ;(我这里是绝对位置，可根据自己的需要进行修改)InputStream in = getServletContext().getResourceAsStream(path) ;//通过输出流  将刚才已转为输入流的文件输出给用户ServletOutputStream out = response.getOutputStream();byte[] bs = new  byte[1024] ;int len = -1 ;while( ( len=in.read(bs) ) != -1 ) {out.write(bs,0,len);;}out.close();in.close();}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request, response);}}