JSP与Servlet之间传递_jsp文件与servlet-优快云博客

本文链接：https://blog.youkuaiyun.com/Lk_Java_Idiot/article/details/66473245

本文介绍了一个简单的JSP应用示例，包括如何通过Servlet进行页面转发，并实现用户登录功能。示例中包含了LoginUIServlet和LoginServlet两个关键组件的实现细节。

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当把jsp文件在WEB-INF里面所以不能直接访问的到所以需要转发才能访问的到,如果直接子啊WebRoot下就不用转发了
1.jsp位置

2.整体关系图如下：

3.LoginUIServlet

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 * 专门用来转发用
 * @author Admin
 */
public class LoginUIServlet extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.getRequestDispatcher("/WEB-INF/pages/login.jsp").forward(request, response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

4.login.jsp代码

<%@ page import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>用户登录</title> 
  </head> 
  <body>
    <form action="${pageContext.request.contextPath }/servlet/LoginServlet" method="post">
        用户名：<input type="text" name="username"/><br/>
        密码：<input type="password" name="password"/><br/>
        <input type="submit" value="登录"/>
    </form>
  </body>
</html>

5.LoginServlet代码

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.itheima.domain.User;
import com.itheima.service.BusinessService;
import com.itheima.service.impl.BusinessServiceImpl;
public class LoginServlet extends HttpServlet {
    private BusinessService s = new BusinessServiceImpl();
    public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        String username = request.getParameter("username");
        String password = request.getParameter("password"); 
        User user = s.login(username, password);
        if(user==null){
            response.getWriter().write("错误的用户名或密码.2秒后转向登录页面");
            response.setHeader("Refresh", "2;URL="+request.getContextPath()+"/servlet/LoginUIServlet");
            return;
        }   
        request.getSession().setAttribute("user", user);
        response.getWriter().write("登录成功.2秒后转向主页");
        response.setHeader("Refresh", "2;URL="+request.getContextPath());       
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}