上QQ阅读APP看书，第一时间看更新

How to do it...

You need to perform the following steps to try this recipe:

We will create a servlet:

@WebServlet(name = "ServerPush", urlPatterns = {"/ServerPush"})
public class ServerPush extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, 
    HttpServletResponse 
    response) throws ServletException, IOException {

        PushBuilder pb = request.newPushBuilder();
        if (pb != null) {
            pb.path("images/javaee-logo.png")
              .addHeader("content-type", "image/png")
              .push();
        }

        try (PrintWriter writer = response.getWriter();) {
            StringBuilder html = new StringBuilder();
            html.append("<html>");
            html.append("<center>");
            html.append("<img src='images/javaee-logo.png'><br>");
            html.append("<h2>Image pushed by ServerPush</h2>");
            html.append("</center>");
            html.append("</html>");
            writer.write(html.toString());
        }
    }
}

To try it, run the project in a Jakarta EE 8 server and open this URL:

https://localhost:8181/ch01-servlet/ServerPush

Let's now see how this works.