login.java

一个相对比较简单的留言簿！功能还比较齐全！

package com.pure35.servlet;

import java.io.IOException;


import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.pure35.database.UserDao;

//该servlet控制器(Login)是由login.jsp页面中登陆按扭的action（）方法调用其映射
//通过该servlet控制器(Login)调用数据操作类UserDao中的login方法验证用户的合法性，然后进行页面的跳转 

public class Login extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doPost(request, response);
	}
	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {	
		//	设置编码格式
		request.setCharacterEncoding("GBK");
		
		UserDao userDao=new UserDao();
		String sql=null;
		boolean isLogin=false;
		
		//得到从登陆页面中输入的用户名和密码
		String userName=request.getParameter("userName");
		String password=request.getParameter("password");
		
		//编写检验该用户存在的SQL语句字符串
		sql="select count(*) as mycount from user where username='"+userName+"'  and password='"+password+"' ";
		
		//调用UserVo中的login(sql)方法得到用户的验证结果
		isLogin=userDao.login(sql);
		
		//判断登陆验证是否通过
		if(isLogin)
		{	//验证通过将跳转到显示留言信息页面；
			//同时将该用户名保存在session中
			System.out.println("denglu");
			request.setAttribute("pageCount", "1");
			HttpSession hs=request.getSession(true);
			hs.setAttribute("userName", userName);	
			request.getRequestDispatcher("/ShowMessage").forward(request, response);		
		}
		else{
			//验证未通过将跳转到登陆页面；
			request.getRequestDispatcher("login.jsp").forward(request, response);
		}	
	}
}