JDBC基础学习笔记_05_jdbc的程序优化_Dao

一.什么是Dao？

dao是数据访问对象，用来封装对数据库的访问，用它将数据库中的表转换为DTO类，就是转化为我们上一节封装的用户类和地址类。

二.建一个接口：负责插入功能，更新功能和删除功能

package com.langzimingjian.dao;

import java.sql.Connection;

import com.langzimingjian.entity.User;

public interface UserDao {
/**
* 保存用戶信息的save方法
*/
public void save(Connection connection, User user) throws Exception;

public void update(Connection connection,long id, User user)throws Exception;

public void delete(Connection connection,User user) throws Exception;

}

三建个类实现接口：

<pre name="code" class="java">package com.langzimingjian.dao.impi;

import java.sql.Connection;
import java.sql.PreparedStatement;

import com.langzimingjian.dao.UserDao;
import com.langzimingjian.entity.User;

public class UserDaoimpi implements UserDao {

/**
* 保存用戶信息
*/
public void save(Connection connection, User user) throws Exception {
// TODO Auto-generated method stub
PreparedStatement ps = connection.prepareStatement("insert into tbl_user(name,password,email)values(?,?,?)");
ps.setString(1, user.getName());
ps.setString(2, user.getPassword());
ps.setString(3, user.getEmail());
ps.execute();

}

/**
* 根據指定的id更新用戶信息
*/
public void update(Connection connection, long id, User user)
throws Exception {
// TODO Auto-generated method stub
String updateSql = "update tbl_user set name=?,password=?,email=?where id=?";
PreparedStatement ps = connection.prepareStatement(updateSql);
ps.setString(1, user.getName());
ps.setString(2, user.getPassword());
ps.setString(3, user.getEmail());
ps.setLong(4, id);
ps.execute();
}

/**
* 刪除指定的用戶信息
*/
public void delete(Connection connection, User user) throws Exception {
// TODO Auto-generated method stub
PreparedStatement ps = connection.prepareStatement("delete form tbl_user where id = ?");
ps.setLong(1, user.getId());
ps.execute();

}

}

新建一个测试类：

package com.langzimingjian.test;

import java.sql.Connection;

import com.langzimingjian.dao.UserDao;
import com.langzimingjian.dao.impi.UserDaoimpi;
import com.langzimingjian.entity.User;
import com.langzimingjian.utils.ConnectionFactory;

public class UserDaoTest {
public static void main(String[] args) {
Connection connection = null;
try {
connection =  ConnectionFactory.getInstance().makeConnection();
connection.setAutoCommit(false);

UserDao userDao = new UserDaoimpi();
User katelin = new User();
katelin.setName("katelin");
katelin.setPassword("123456789");
katelin.setEmail("katelin@qq.com");

userDao.save(connection, katelin);
connection.commit();
} catch (Exception e) {
// TODO: handle exception
try {
connection.rollback();
if(connection!= null){
connection.close();
}
} catch (Exception e2) {
// TODO: handle exception
}

}
}
}

测试结果：



成功。看完之后感觉套路很深，明天从新看下原码，看下mvc。