如何在不使用 HttpServletRequest session 的情況下更新 @SessionAttributes，使用 Spring MVC

Question

我正在嘗試像這樣更新我的@SessionAttributes ，但是當我的.jsp重新加載時，我的屬性會發生任何變化。 我不明白HttpServletRequest session 和HttpSession之間的區別，我唯一知道的是HttpSession是 30 分鍾，根據我的web.xml 。

@Controller
@ControllerAdvice
@SessionAttributes({"Usuario", "ImagenUsuario"})
public class UserController {

  private UsuarioServicio usuario_servicio;
    
  @Autowired(required=true)
  @Qualifier(value="UsuarioServicio")
  public void setUsuarioServicio(UsuarioServicio us){
    this.usuario_servicio = us;
  }
  
  @RequestMapping(value = "/ActualizarImagenPerfil", method = { RequestMethod.GET, RequestMethod.POST })
  public ModelAndView ActualizarImagenPerfil(HttpServletRequest request, HttpServletResponse response, HttpSession session) {
    ModelAndView mav = null;
    Usuario usuario = (Usuario) session.getAttribute("Usuario");
    Map<String, String> map = new HashMap<>();
    
    if(session.getAttribute("Usuario") != null) {
      if(request.getHeader("X-Requested-With") != null && request.getHeader("X-Requested-With").equals("XMLHttpRequest")) {
        map.put("redirect", "true");

        try{
          UsersProfileImage profile_image = new UsersProfileImage();
          profile_image.RemoveImage(usuario.getId() + ".");
          usuario.setImagenPerfil(profile_image.SaveImage(usuario.getId(), request.getParameter("imagebase64")));
          usuario_servicio.ActualizarFotoPerfil(usuario.getId(), usuario.getImagenPerfil());
          session.setAttribute("ImagenUsuario", profile_image.Base64ImageRetrieve(usuario.getImagenPerfil()));
          session.setAttribute("Usuario", usuario);
          
          map.put("url", request.getContextPath() + "/R_MProfile/1");
        } catch(Exception e) {
          map.put("url", request.getContextPath() + "/E_Login");
        }
        
        try {
          ObjectMapper mapper = new ObjectMapper();
          response.setContentType("text/html; charset=UTF-8");
          response.getWriter().write(mapper.writeValueAsString(map));
          response.getWriter().flush();
        } catch (IOException ex) {
          Logger.getLogger(ProfileController.class.getName()).log(Level.SEVERE, null, ex);
        }
          
      } else {
        mav = new ModelAndView("forward:/R_MProfile");
      }

    } else {
      
      mav = new ModelAndView("forward:/Login");
    }

    return mav;
  }
  
  @RequestMapping(value = "/BorrarImagenPerfil", method = RequestMethod.GET)
  public ModelAndView BorrarImagenPerfil(HttpServletRequest request, HttpServletResponse response, HttpSession session) {
    ModelAndView mav;
    Usuario usuario = (Usuario) session.getAttribute("Usuario");

    if(session.getAttribute("Usuario") != null) {
      try{
          UsersProfileImage profile_image = new UsersProfileImage();
          profile_image.RemoveImage(usuario.getId() + ".");
          usuario_servicio.BorrarFotoPerfil(usuario.getId());
          usuario.setImagenPerfil(null);
          
          mav = new ModelAndView("forward:/R_MProfile/2");
      } catch(Exception e) {
        mav = new ModelAndView("forward:/R_MProfile");
      }
      
    } else {
      mav = new ModelAndView("forward:/Login");
    }
    
    return mav;
  }

}```

Answer 1

@SessionAttributes 允許您在呈現視圖之前告訴 Spring 您的 model 屬性中的哪些屬性也將被復制到 HttpSession。

JSP scriptlet 以顯示 HttpSession 屬性。

<h3>Session Scope (key==values)</h3>
<%
  java.util.Enumeration<String> sessEnum = request.getSession()
    .getAttributeNames();
  while (sessEnum.hasMoreElements()) {
    String s = sessEnum.nextElement();
    out.print(s);
    out.println("==" + request.getSession().getAttribute(s));
%><br />
<%
  }
%>

Annotate controller class with @SessionAttributes to put the same model attribute (requestObject) in the Spring session.

@Controller
@SessionAttributes("requestObject")
public class MyController {
  ...
}