DAO设计模式

package com.pr.connection;

import java.sql.*;

public class DataBaseConnection {

    private final String DBDRIVER = "com.mysql.jdbc.Driver";

    private final String DBURL = "jdbc:mysql://localhost:3306/javaweb";

    private final String DBUSER = "root";

    private final String DBPASSWORD = "123456";

    private Connection conn = null;

    public DataBaseConnection(){

       try{

           Class.forName(DBDRIVER);

           this.conn = DriverManager.getConnection(DBURL,DBUSER,DBPASSWORD);

       }

       catch(Exception e){

           System.out.println("加载驱动失败");

       }

    }

    public Connection getConnection(){

       return conn;

    }

    public void close(){

       try{

           conn.close();

       }

       catch(Exception e){

           System.out.println("数据库连接关闭失败");

       }

    }

}

package com.pr.vo;

public class User {

    private int userid;

    private String username;

    private String password;

    public int getUserid() {

       return userid;

    }

    public void setUserid(int userid) {

       this.userid = userid;

    }

    public String getUsername() {

       return username;

    }

    public void setUsername(String username) {

       this.username = username;

    }

    public String getPassword() {

       return password;

    }

    public void setPassword(String password) {

       this.password = password;

    }

}

package com.pr.dao;

import java.util.List;

import com.pr.vo.User;

public interface IUser {

    public void insert(User user) throws Exception;

    public void update(User user) throws Exception;

    public void delete(int userId) throws Exception;

    public User queryById(int userId) throws Exception;

    public List<User> queryAll() throws Exception;

}

package com.pr.dao;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.util.ArrayList;

import java.util.List;

import com.pr.vo.User;

import com.pr.connection.DataBaseConnection;

public class UserImplement implements IUser {

    public void insert(User user) throws Exception {

       String sql = "insert into user(username,password) values (?,?)";

       PreparedStatement pstmt = null;

       DataBaseConnection dbc = null;

       try{

           dbc = new DataBaseConnection();

           pstmt = dbc.getConnection().prepareStatement(sql);

           pstmt.setString(1,user.getUsername());

           pstmt.setString(2,user.getPassword());

           pstmt.executeUpdate();

           pstmt.close();

       }

       catch(Exception e){

           throw new Exception("操作出现异常");

       }

       finally{

           dbc.close();

       }

    }

    public void update(User user) throws Exception {

       String sql = "update user set username=?,password=? where userid=?";

       PreparedStatement pstmt = null;

       DataBaseConnection dbc = null;

       try{

           dbc = new DataBaseConnection();

           pstmt = dbc.getConnection().prepareStatement(sql);

           pstmt.setString(1,user.getUsername());

           pstmt.setString(2,user.getPassword());

           pstmt.setInt(3,user.getUserid());

           pstmt.executeUpdate();

           pstmt.close();

       }

       catch(Exception e){

           throw new Exception("操作出现异常");

       }

       finally{

           dbc.close();

       }

    }

    public void delete(int userId) throws Exception {

       String sql = "delete from user where userid=?";

       PreparedStatement pstmt = null;

       DataBaseConnection dbc = null;

       try{

           dbc = new DataBaseConnection();

           pstmt = dbc.getConnection().prepareStatement(sql);

           pstmt.setInt(1,userId);

           pstmt.executeUpdate();

           pstmt.close();

       }

       catch(Exception e){

           throw new Exception("操作出现异常");

       }

       finally{

           dbc.close();

       }

    }

    public User queryById(int userId) throws Exception {

       User user = null;

       String sql = "select * from user where userid=?";

       PreparedStatement pstmt = null;

       DataBaseConnection dbc = null;

       try{

           dbc = new DataBaseConnection();

           pstmt = dbc.getConnection().prepareStatement(sql);

           pstmt.setInt(1,userId);

           ResultSet rs = pstmt.executeQuery();

           if(rs.next()){

              user = new User();

              user.setUserid(rs.getInt(1));

              user.setUsername(rs.getString(2));

              user.setPassword(rs.getString(3));

           }

           rs.close();

           pstmt.close();

       }

       catch(Exception e){

           throw new Exception("操作出现异常");

       }

       finally{

           dbc.close();

       }

       return user;

    }

    public List<User> queryAll() throws Exception {

       List<User> all = new ArrayList<User>();

       String sql = "select * from user";

       PreparedStatement pstmt = null;

       DataBaseConnection dbc = null;

       try{

           dbc = new DataBaseConnection();

           pstmt = dbc.getConnection().prepareStatement(sql);

           ResultSet rs = pstmt.executeQuery();

           while(rs.next()){

              User user = new User();

              user.setUserid(rs.getInt(1));

              user.setUsername(rs.getString(2));

              user.setPassword(rs.getString(3));

              all.add(user);

           }

           rs.close();

           pstmt.close();

       }

       catch(Exception e){

           throw new Exception("操作出现异常");

       }

       finally{

           dbc.close();

       }

       return all;

    }

}

package com.pr.dao;

public class DAOFactory {

    public static UserImplement getUserDAOInstance(){

       return new UserImplement();

    }

}