javaWeb的servlet读取服务器文件并下载到浏览器

package com.tiglle.servlet;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class FileServlet extends HttpServlet {    /**     *      */    private static final long serialVersionUID = 1L;    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        resp.setContentType("application/octet-stream");        resp.setHeader("Content-Disposition", "attachment;filename=test.mp4");        File file = new File("C:\\test.txt");        FileInputStream fis = new FileInputStream(file);        byte[] b = new byte[1024];        int len = 0;        while((len=fis.read(b))!=-1){            resp.getOutputStream().write(b, 0, len);        }        fis.close();    }    @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        // TODO Auto-generated method stub        super.doPost(req, resp);    }}