Example of downloading file from the server in servlet

For downloading a file from the server, here is the simple example. I am supposing you have home.jsp file in E drive that you want to download. If there is any jar or zip file, you can direct provide a link to that file. So there is no need to write the program to download. But if there is any java file or jsp file etc, you need to create a program to download that file.

Example of downloading file from the server in servlet

In this example, we are creating three files:

• index.html
• DownloadServlet.java
• web.xml

---

index.html

This file provides a link to download the file.

1. <a href="servlet/DownloadServlet">download the jsp file</a>  

---

DownloadServlet.java

This is the servlet file that reads the content of the file and writes it into the stream to send as a response. For this purpose, we need to inform the server, so we are setting the content type as APPLICATION/OCTET-STREAM .

1. import java.io.*;  
2. import javax.servlet.ServletException;  
3. import javax.servlet.http.*;  
4.   
5. public class DownloadServlet extends HttpServlet {  
6.   
7. public void doGet(HttpServletRequest request, HttpServletResponse response)  
8.             throws ServletException, IOException {  
9.   
10. response.setContentType("text/html");  
11. PrintWriter out = response.getWriter();  
12. String filename = "home.jsp";   
13. String filepath = "e:\\";   
14. response.setContentType("APPLICATION/OCTET-STREAM");   
15. response.setHeader("Content-Disposition","attachment; filename=\"" + filename + "\"");   
16.   
17. FileInputStream fileInputStream = new FileInputStream(filepath + filename);  
18.             
19. int i;   
20. while ((i=fileInputStream.read()) != -1) {  
21. out.write(i);   
22. }   
23. fileInputStream.close();   
24. out.close();   
25. }  
26.   
27. }  

---

web.xml file

This configuration file provides informations to the server about the servlet.

1. <web-app>  
2.   
3. <servlet>  
4. <servlet-name>DownloadServlet</servlet-name>  
5. <servlet-class>DownloadServlet</servlet-class>  
6. </servlet>  
7.   
8. <servlet-mapping>  
9. <servlet-name>DownloadServlet</servlet-name>  
10. <url-pattern>/servlet/DownloadServlet</url-pattern>  
11. </servlet-mapping>  
12.   
13. </web-app>