jsp文件下载功能实现代码

本文实例为大家分享了jsp实现文件下载功能的3种方法，供大家参考，具体内容如下

第一种、采用转发的方式：

package cn.jbit.download.servlet;import java.io.IOException;import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;public class DownloadServlet extends HttpServlet {private static final long serialVersionUID = 6765085208899952414L;public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); }public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String filedownload = "/upload/1/10213.jpg";//即将下载的文件的相对路径 String filedisplay = "10213.jpg";//下载文件时显示的文件保存名称 response.setContentType("application/x-download");//设置为下载application/x-download //response.setContentType("application/x-msdownload");//设置为下载application/x-msdownload //response.setContentType("application/octet-stream");//设置为下载application/octet-stream response.addHeader("Content-Disposition", "attachment;filename=" + filedisplay);try { RequestDispatcher rd = request.getRequestDispatcher(filedownload); if(rd != null) { rd.forward(request,response); } response.flushBuffer(); } catch (Exception e) { e.printStackTrace(); } } } 

二、通过输出流的方式：

package cn.jbit.download.servlet;import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream;import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;public class DownloadOfIOServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); }public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String basePath = request.getSession().getServletContext().getRealPath("/upload");String filedisplay = "helloworld.jpg"; String filedownload = basePath + File.separator + "helloworld.jpg"; response.setContentType("applicaiton/x-download"); response.addHeader("Content-Disposition", "attachment;filename="+filedisplay);InputStream is = null; OutputStream os = null; BufferedInputStream bis = null; BufferedOutputStream bos = null;is = new FileInputStream(new File(filedownload)); bis = new BufferedInputStream(is); os = response.getOutputStream(); bos = new BufferedOutputStream(os);byte[] b = new byte[1024]; int len = 0; while((len = bis.read(b)) != -1){ bos.write(b,0,len); }bis.close(); is.close(); bos.close(); os.close(); } } 

第三种、通过超链接的方式(注意不推荐，因为会暴露下载文件的位置)