//用户登录处理方法，登录servlet的实现
package ch;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;


import java.util.Collection;

import utils.*;

public class Logon extends HttpServlet
{
    public void doPost(HttpServletRequest request,HttpServletResponse response)
    throws ServletException,IOException
    {
        //取得用户提交的用户名和密码
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        
        //进行用户合法性验证
        UserInfo user=UserBean.logon(username, password);..........................................(1)
        
        //对登录结果进行处理
        RequestDispatcher dispatcher=null;
        if(user!=null)
        {
            //验证通过
            HttpSession session=request.getSession();
            session.setAttribute("session_userinfo",user);
            
            //跳转到留言列表servlet
            dispatcher=request.getRequestDispatcher("/ch/ArticleList");
        }
        else
        {
            //设置错误提示信息
            request.setAttribute("msg","登录失败！可能是用户名密码输入错误或者账号被锁定！");
            
            //跳转到用户登录页面
            dispatcher=request.getRequestDispatcher("/logon.jsp");
        }
        dispatcher.forward(request,response);
    }
}
    
    

//用户注册方法
package ch;

import java.sql.*;

import utils.*;
public class UserBean
{
       //用户登录
    public static UserInfo logon(String username,String password)
    {
        Connection conn=null;
        Statement st=null;
        ResultSet rs=null;
        try
        {
            //得到数据库的连接
            conn=DatabaseBean.getConnection();
            st=conn.createStatement();
            
            //生成查询用户信息的语句
            String sql="SELECT userid,username,password,email,type,status"+"FROM userinfo WHERE username='"
                       +username+"' AND password='"+password+"' AND status="+UserInfo.STATUS_NORMAL;
            
            //执行查询语句
            rs=st.executeQuery(sql);....................................................(2)
            while(rs.next())
            {
                //得到查询结果
                UserInfo user=new UserInfo();
                user.setUserID(rs.getInt(1));
                user.setUsername(rs.getString(2));
                user.setPassword(rs.getString(3));
                user.setEmail(rs.getString(4));
                user.setType(rs.getInt(5));
                user.setStatus(rs.getInt(6));
                
                return user;
            }
        }
        catch(SQLException ex)
        {
            ex.printStackTrace(System.err);
        }
        finally
        {
            //关闭数据库的连接
            DatabaseBean.close(rs,st,conn);
        }
        return null;
    }
}