> For the complete documentation index, see [llms.txt](https://hantsy.gitbook.io/java-ee-8-by-example/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hantsy.gitbook.io/java-ee-8-by-example/servlet/servlet-push.md).
# Server Push
One highlight feature of HTTP/2 is Server Push. Servlet 4.0 add `PushBuilder` to handle push.
An example of enabling Servlet Push.
```java
@WebServlet(urlPatterns="")
@ServletSecurity(httpMethodConstraints={
@HttpMethodConstraint(value="GET", transportGuarantee=CONFIDENTIAL) })
public class PushServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse res)
throws IOException, ServletException {
PushBuilder pushBuilder = req.newPushBuilder().
path("main.css");
pushBuilder.push();
res.getWriter().println("HTTP2 TestHello Servlet Push!!!");
}
}
```
Run this application on Glassfish v5 in NetBeans IDE, it will open in browser instead of [http://localhost:8080/servlet-push/](https://localhost:8080/servlet-push/).
There is a warning flag on the HTTPS icon of address bar, the SSL certificate in Glassfish v5 is not recognized by Firefox. Click it and add `localhost` to the exception and make Firefox trust it.
In the Network tab of developer tools, you will the *main.css* is initialized by Push.
Grab the [source codes](https://github.com/hantsy/ee8-sandbox) from my GitHub account, and have a try.