jsp文件下载功能实现代码

小蚂蚁

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)
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持CodeAE代码之家。