JDBC基础学习笔记_05_jdbc的程序优化_Dao

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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 stubPreparedStatement 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 stubString 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 stubPreparedStatement 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 exceptiontry {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。

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