servlet登录

package com.lxr.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.mail.SendFailedException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.lxr.dao.Dao;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;
import com.mysql.jdbc.jdbc2.optional.ConnectionWrapper;

@SuppressWarnings("serial")
public class AddAccount extends HttpServlet {

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


    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        String account = (String) request
                .getParameter("account");
        String password = (String) request
                .getParameter("password");
        Connection conn = null;
        PreparedStatement stmt = null;
        String     sql="";
        ResultSet rs = null;
        try {
            
//            sql="select * from account where account='"+account+"'+ and password='"+password+"'";
            sql="select account, password from account where account=? and password=? ";
            System.out.println("执行的sql语句"+sql);
            conn = Dao.getConnection();
//            stmt=conn.createStatement();
            stmt=conn.prepareStatement(sql);
            stmt.setString(1,account);
            stmt.setString(2,password);
            rs=stmt.executeQuery();
            if (rs.next()) {
                //request.getContextPath()返回的是当前的webapp的名字
                //而服务器内部跳转实在webapp里边,所以不用加request.getContextPath()
                //直接加jsp页面的名字就行
                //而请求重定向是默认不在webapp里边的  所以要加上webapp(request.getContextPath())的名字再加jsp页面名
                System.out.println("登录成功");
                request.getRequestDispatcher("/loginsuccess.jsp").forward(request, response);
//                response.sendRedirect("/plan/loginsuccess.jsp");
            }else {
                System.out.println("登录失败");
//                request.getRequestDispatcher("/login.jsp").forward(request, response);
                response.sendRedirect(request.getContextPath()+"/login.jsp");
                
                
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            try {
                if(rs!=null){
                    rs.close();
                }
                if(stmt!=null){
                    stmt.close();
                }
                if(conn!=null){
                    conn.close();
                }
            } catch (SQLException e2) {
                System.out.println("释放资源发生异常！");
            }
        }

    }


}