文件的下载

Posted 2020-10-08 知行合一

文件的下载:

1). 步骤:

I. 设置 contentType 响应头: 设置响应的类型是什么 ? 通知浏览器是个下载的文件

response.setContentType("application/x-msdownload");

II. 设置 Content-Disposition 响应头: 通知浏览器不再有浏览器来自行处理(或打开)要下载的文件, 而由用户手工完成

response.setHeader("Content-Disposition", "attachment;filename=abc.txt");

III. 具体的文件: 可以调用 response.getOutputStream 的方式, 以 IO 流的方式发送给客户端.

OutputStream out = response.getOutputStream();
String pptFileName = "C:\\Users\\Think Pad\\Desktop\\__正在上课__\\11.尚硅谷_JavaWEB_监听器.pptx";

InputStream in = new FileInputStream(pptFileName);

byte [] buffer = new byte[1024];
int len = 0;

while((len = in.read(buffer)) != -1){
out.write(buffer, 0, len);
}

in.close();

out不用关闭，是提供给用户的！

 1 import java.io.FileInputStream;
 2 import java.io.IOException;
 3 import java.io.InputStream;
 4 import java.io.OutputStream;
 5 import java.net.URLEncoder;
 6 
 7 import javax.servlet.ServletException;
 8 import javax.servlet.http.HttpServlet;
 9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 
12 /**
13  * Servlet implementation class DownloadServlet
14  */
15 public class DownloadServlet extends HttpServlet {
16     private static final long serialVersionUID = 1L;
17 
18     /**
19      * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
20      */
21     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
22         response.setContentType("application/x-msdownload"); 
23         
24         String fileName = "文件下载.pptx";
25         response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));
26         
27         OutputStream out = response.getOutputStream();
28         String pptFileName = "C:\\Users\\Think Pad\\Desktop\\__正在上课__\\JavaWEB_监听器.pptx";
29         
30         InputStream in = new FileInputStream(pptFileName);
31         
32         byte [] buffer = new byte[1024];
33         int len = 0;
34         
35         while((len = in.read(buffer)) != -1){
36             out.write(buffer, 0, len);
37         }
38         
39         in.close();
40     }
41 
42 }