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我正在使用此处找到的设计模式。它有一个 FrontController、Command -> Service 和 Dao。

如果我在浏览器中加载此 URL(viewprofile 是 jsp 的名称):

http://localhost:8080/MyApplication/FrontController/viewprofile

我不知道如何自动调用ViewProfileCommand然后显示用户的详细信息。

目前我拥有它的方式是这样的,为了调用ViewProfileCommand我必须将它连接到 URL 上,例如:http://localhost:8080/MyApplication/FrontController/viewprofile?action=ViewProfile

如何将 jsp 映射到命令而不必将其连接到 URL?谢谢

前端控制器:

package com.secret.bookstore.servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
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 com.secret.bookstore.command.Command;
import com.secret.bookstore.command.CommandFactory;
import com.secret.bookstore.exceptions.CommandCreationException;
import com.sun.net.httpserver.Filter.Chain;

/*
 * Front Controller (Mediator Pattern)
 */
@WebServlet(urlPatterns={"/FrontController"})
public class FrontController extends HttpServlet {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public FrontController(){
        super();
    }

    protected void service(HttpServletRequest request, HttpServletResponse response){
        String action = request.getParameter("action");

        CommandFactory commandFactory = CommandFactory.getInstance();
        Command command = null;
        String view = null;

        view = request.getPathInfo().substring(1);

        if(action != null){
            try {
                command = commandFactory.createCommand(action);
                view = command.execute(request, response);
            } catch(CommandCreationException e) {
                e.printStackTrace();
            }
        }

        forwardToPage(request, response, view);
    }

    /**
     * Forward to server to the supplied page
     */
    private void forwardToPage(HttpServletRequest request, HttpServletResponse response, String view){

        //Get the request dispatcher object and forward the request to the appropriate JSP page...
        if(view.equals(request.getPathInfo().substring(1))){
                RequestDispatcher dispatcher = request.getRequestDispatcher("/WEB-INF/" + view + ".jsp");

                try {
                    dispatcher.forward(request, response);
                } catch (ServletException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
        } else {
            try {
                response.sendRedirect(view);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

    }

}
4

1 回答 1

2

您已经设计了前端控制器来根据请求参数而不是请求路径信息来确定操作。所以你真的必须提供一个请求参数才能调用一个动作。

链接答案中的前端控制器示例根据请求方法和请求路径信息确定操作,这也是一种更明智的方式。您需要执行相同的操作才能实现能够预处理 GET 请求的功能要求。

基本上:

command = commandFactory.createCommand(request.getMethod(), request.getPathInfo());

或者就像在给定的例子中一样:

command = commandFactory.createCommand(request);
于 2012-04-07T01:35:26.677 回答