//首先编写实体类 User

//然后编写通用工具类 JDBCUtils

//然后编写操作数据库表的 UserDao

//现在编写一个测试类，测试UserDao中登录方法是否有效

//然后编写 LoginServlet 用于请求处理、判断和转发
package cn.figo.web.servlet;import cn.figo.web.dao.UserDao;
import cn.figo.web.domain.User;
import org.apache.commons.beanutils.BeanUtils;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 java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {req.setCharacterEncoding("utf-8");/*//获取请求参数String username = req.getParameter("username");String password = req.getParameter("password");//封装User对象User loginUser = new User();loginUser.setUsername(username);loginUser.setPassword(password);*///使用开源的beanutils简化对象的封装Map<String,String[]> map = req.getParameterMap();User loginUser = new User();try {BeanUtils.populate(loginUser,map);} catch (IllegalAccessException e) {e.printStackTrace();} catch (InvocationTargetException e) {e.printStackTrace();}UserDao dao = new UserDao();User user = dao.login(loginUser);//如果登录成功，转发到成功页，否则转发到失败页if (user == null){req.getRequestDispatcher("/failServlet").forward(req,resp);}else {req.setAttribute("user",user);req.getRequestDispatcher("/successServlet").forward(req,resp);}}@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {super.doPut(req, resp);}
}

// SuccessServlet
package cn.figo.web.servlet;import cn.figo.web.domain.User;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 java.io.IOException;@WebServlet("/successServlet")
public class SuccessServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {User user = (User) request.getAttribute("user");if (user != null){response.setContentType("text/html;charset=utf-8");response.getWriter().write("登录成功，" + user.getUsername() + "欢迎您");}}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

// failServlet
package cn.figo.web.servlet;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 java.io.IOException;@WebServlet("/failServlet")
public class FailServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType("text/html;charset=utf-8");response.getWriter().write("登录失败，用户名或密码错误");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

/*