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 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("[e-mail]");

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。