如何在Java中访问HTTP会话

   <groupId>javax.servlet</groupId>
   <artifactId>javax.servlet-api</artifactId>
   <version>4.0.1</version>
   <scope>provided</scope>
</dependency>

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet("/accessSession")
public class AccessSessionServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession();
        // 访问或设置会话属性
        session.setAttribute("username", "JohnDoe");
        String username = (String) session.getAttribute("username");
        // ...
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // ...
    }
}

request.setAttribute("message", "Hello, World!");
request.getRequestDispatcher("nextServlet").forward(request, response);