Question

我想自己制作一个非常纤细的rest框架，并且试图将路由列表和相应的动作传递给我的HttpServlet。

名为 RoutingServlet的HttpServlet必须在init（）方法中从Routes.getRoutes（）静态方法获取此路由列表，并将请求和响应参数传递给所传递的特定处理程序（< strong>就像使用Spring Controller的Dispatcher Servlet一样）

当我尝试将列表传递给我的RoutingServlet 时，除了doGet（）或doPost（）方法之外，没有任何错误，路由列表为空（即使之前已填充）。

here Utility类，用于静态存储路由列表

public class Routes {

  public static List<RouteMapper> routes = new ArrayList<RouteMapper>();

  public static void setRoute(RouteMapper route){
    routes.add(route);
  }

  public static List<RouteMapper> getRoutes(){
    return routes;
  }
}

Application.java：

public class Application {

  public static void main(String[] args) throws Exception{
    UserHandler userHandler = new UserHandler();
    Routes.setRoute(new RouteMapper("/user/1", (req, res) -> userHandler.firstMapping(req, res)));
    Routes.setRoute(new RouteMapper("/user",   (req, res) -> userHandler.secondMapping(req, res)));
    System.out.println("In main routes size: " + Routes.getRoutes().size());
    EmbeddedServer.startServer("8086");

  }
}

RoutingServlet.java：

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

  public static List<RouteMapper> routes = new ArrayList<RouteMapper>();

  @Override
  public void init(ServletConfig config) throws ServletException {
    super.init(config);
    routes = Routes.getRoutes();
    System.out.println("In oninit routes size: " + routes.size());
  }

  @Override
  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    Object response = null;
    String path = req.getRequestURI();

    for(RouteMapper route : routes){
        if(Objects.equals(route.getUrlPath(),path)){
            response = route.getRoute().action(req, resp);
        }
    }
    String jsonResponse = "";
    if(response != null){
        ObjectMapper mapper = new ObjectMapper();
        jsonResponse = mapper.writeValueAsString(response);
    }else{
        jsonResponse = "Http Request not mapped!";
    }

    ServletOutputStream out = resp.getOutputStream();
    out.write(jsonResponse.getBytes());
    out.flush();
    out.close();
  }

  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    doGet(req, resp);
  }

  @Override
  protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    doGet(req, resp);
  }

  @Override
  protected void doDelete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    doGet(req, resp);
  }

}

所以问题是：为什么我不能将任何对象传递给Servlet？我该怎么办？

我成功的唯一方法是在Application类中静态定义列表（不是在主类中，而是在类声明之后），然后通过调用Application.routes从init（）中的HttpServlet获取路由列表。我不想使用这种方法，因为我想将一个库中的Servlet和嵌入式Tomcat分开，并通过导入所需的所有库类在我的Application＃main中使用此库。

如何将对象传递给HttpServlet类

0 个答案: