JAVAWEB登陆跳转后台

package dao;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import entry.user;
import util.DBUtil;

@SuppressWarnings("unused")
public class userDao {
    //
    
        
        
        public static boolean id(String id,String pwd) {
            boolean f = false;
            String sql = "select * from user3 where id = '" + id + "' and password = '"+pwd+"'";
            //
            Connection conn = DBUtil.getConn();
            Statement state = null;
            ResultSet rs = null;       
            try {
                state = conn.createStatement();
                rs = state.executeQuery(sql);
                if (rs.next()) {
                    f = true;
                }
            } catch (SQLException e) {
                e.printStackTrace();
            } finally {
                DBUtil.close(rs, state, conn);
            }
            return f;
        }
}
package entry;

public class user {
private String id;
private String password;



public String getId() {
    return id;
}
public void setId(String id) {
    this.id = id;
}
public String getPassword() {
    return password;
}
public void setPassword(String password) {
    this.password = password;
}

public user(){}
public user( String password) {
    
    this.password = password;
};
public user(String id, String password) {
    super();
    this.id = id;
    this.password = password;
    
}
}

package servlet;

import java.io.IOException;
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 dao.userDao;


/**
 * Servlet implementation class AddServlet
 */
@WebServlet("/AddServlet")
public class AddServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
   
        
        
        protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
             request.setCharacterEncoding("utf-8");
             //鑾峰彇鏁版嵁
             String id = request.getParameter("id");
             String password = request.getParameter("password");
             
           
             
            
              System.out.println(id);
             System.out.println(password);
             if(userDao.id(id,password)) {
                 request.setAttribute("message", "登录成功");
                 request.getRequestDispatcher("chenggong.jsp").forward(request,response);
             } else {
                 request.setAttribute("message", "登录失败");
                 request.getRequestDispatcher("houtai.jsp").forward(request,response);
             }
        }
        
        
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

            doGet(request, response);
        }

    


    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */


}
package util;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
 
/*
 * 鏁版嵁搴撹繛鎺ュ伐鍏�
 */
public class DBUtil {
     
    public static String db_url = "jdbc:mysql://localhost:3306/user?useSSL=false";
    public static String db_user = "root";
    public static String db_pass = "root";
     
    public static Connection getConn () {
        Connection conn = null;
         
        try {
            Class.forName("com.mysql.jdbc.Driver");//鍔犺浇椹卞姩
            conn = DriverManager.getConnection(db_url, db_user, db_pass);
        } catch (Exception e) {
            e.printStackTrace();
        }
         
        return conn;
    }
     
    /*10鍏抽棴杩炴帴*/
    public static void close (Statement state, Connection conn) {
        if (state != null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
         
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
     
    public static void close (ResultSet rs, Statement state, Connection conn) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
         
        if (state != null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
         
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
 
    public static void main(String[] args) throws SQLException {
        Connection conn = getConn();
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        String sql ="select * from user";
        pstmt = conn.prepareStatement(sql);
        rs = pstmt.executeQuery();
        if(rs.next()){
            System.out.println("绌�");
        }else{
            System.out.println("涓嶇┖");
        }
    }
}