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！");
             }
         }

     }

 }