dao

Strategy for many DAOs in Spring Java

由 China☆狼群 提交于 2019-12-21 04:51:44
问题 We have many DAOs in an existing project (currently with no interfaces, but that can change). Rather than wiring a Spring-managed bean for each DAO class and injecting them into the service layer, we have a DAO "factory" of sorts that looks like this: public class DAOFactory { private static DAOFactory daoFac; static{ daoFac = new DAOFactory(); } private DAOFactory(){} public static DAOFactory getInstance(){ return daoFac; } public MyDAO1 getMyDAO1(){ return new MyDAO1(); } public MyDAO2

Strategy for many DAOs in Spring Java

由 笑着哭i 提交于 2019-12-21 04:51:11
问题 We have many DAOs in an existing project (currently with no interfaces, but that can change). Rather than wiring a Spring-managed bean for each DAO class and injecting them into the service layer, we have a DAO "factory" of sorts that looks like this: public class DAOFactory { private static DAOFactory daoFac; static{ daoFac = new DAOFactory(); } private DAOFactory(){} public static DAOFactory getInstance(){ return daoFac; } public MyDAO1 getMyDAO1(){ return new MyDAO1(); } public MyDAO2

How to create a DAO for join tables?

由 寵の児 提交于 2019-12-20 20:03:32
问题 I'm currently on learning on using Dao pattern in my project. I know, one Table is equivalent to one Dao , am I right? just like StudentDao , SubjectDao . Each Dao performs CRUD operations in their associated tables, but my question is, how am I going to create a DAO for joined tables? lets say I have a query to join student and subject table, then how do I create a DAO for that? Should I place it to the StudentDao ? or to SubjectDao ? or there's a good practice in that kind of situation? 回答1

ssm整合——Mybatis配置（1）

由 笑着哭i 提交于 2019-12-20 19:38:21
文章目录 mybatis搭建-基于注解 1. 环境准备 1.1 新建maven的webapp项目 1.2 新建必要的目录和文件 1.3 文件配置 2. 编写程序 2.1 User.java 2.2 IUserDao.java 2.3 测试程序 mybatis搭建-基于配置 1. 环境准备 1.1 新建maven的webapp项目 1.2 新建必要的目录和文件 1.3 文件配置 2.1 编写程序-类和表字段一致 2.1 User.java 2.2 IUserDao.java 2.3 IUserDao.xml 2.3 测试程序 2.2 编写程序-类和表字段不一致 2.1 User.java 2.2 IUserDao.java 2.3 IUserDao.xml 2.3 测试程序 mybatis搭建-基于注解 1. 环境准备 1.1 新建maven的webapp项目 1.2 新建必要的目录和文件 1.3 文件配置 pom.xml junit默认创建是4.11，手动改成4.12 < dependency > <!-- 单元测试，这里将原先的4.11版本改为了4.12--> < groupId > junit </ groupId > < artifactId > junit </ artifactId > < version > 4.12 </ version > < scope >

call service vs dao from another service

由 和自甴很熟 提交于 2019-12-20 12:44:42
问题 I have User And Role entities and Service, DAO layers for them. I need Role list from UserService. Which layer should I use from UserService? Call list method of RoleService vs RoleDAO ? Which one is common use and why? 回答1: Normally DAO layer is close to database, Service layer is encapsulating your business logic, performing any transactions or other things rather than just calling DAO. Service calling another service is more common because Your RoleService can have some business code

What is the difference between DAL, DTO and DAO in a 3 tier architecture style including with MVC

由 可紊 提交于 2019-12-20 11:59:20
问题 Recently I was learning about ORM (Object Relational Mapping) and the 3 tier architecture style (presentation,business and data persistence ). If I understand correctly, I can separate the data persistence layer into DTO and DAO layer. I would like to understand, how the following parts works together in a data persistence layer. DAL (Data Access Layer) DTO (Data Transfer Object) DAO (Data Access Object) In a top of that I learnt that In larger applications MVC is the presentation tier only

Why put a DAO layer over a persistence layer (like JDO or Hibernate)

由 浪子不回头ぞ 提交于 2019-12-20 09:05:11
问题 Data Access Objects (DAOs) are a common design pattern, and recommended by Sun. But the earliest examples of Java DAOs interacted directly with relational databases -- they were, in essence, doing object-relational mapping (ORM). Nowadays, I see DAOs on top of mature ORM frameworks like JDO and Hibernate, and I wonder if that is really a good idea. I am developing a web service using JDO as the persistence layer, and am considering whether or not to introduce DAOs. I foresee a problem when

Copying to/from Dbase data using Access

由 走远了吗. 提交于 2019-12-20 07:31:08
问题 I am stuck with some legacy back ends using dBase IV, and would like to be able to copy records from one table to another using an Access front end. The simple answer would be to link to the source and destination tables and run an INSERT query or similar. However, in my situation, the back end is not a single DBF file, but there are several hundred files that I need to dynamically link to for the copy operation. Currently I have to change and refresh the link definition using the TableDefs

MS Access DAO Connection Discard Changes On Exit

由 穿精又带淫゛_ 提交于 2019-12-20 07:05:35
问题 So I have this Access form where I use this VBA code with a DAO connection to a MySQL database. Everything works great but if the user closes the form without clicking save button the new record is saved anyway. So what I'm looking for is if there's any way the on the on close event I can stop the new record being saved to the database? The code I have, Private Sub Form_Load() 'Set Form Recordset Dim db As DAO.Database Dim rs As DAO.Recordset Dim SQL As String Set db = OpenDatabase("", False,

General or specific DAO to record delivery with information from multiple tables?

由 柔情痞子 提交于 2019-12-20 05:02:42
问题 I am creating a web application that lets the user store and retrieve information from a DB through a GUI using spring and hibernate. I have gotten stuck when it comes to creating the DAO and service layer. I want to create a method that can add a new delivery. In my delivery table i have Product Id and Customer Id which both are mapped to their own tables that contain Product Name, Product Type and Customer Name, Customer Country respectively. The part that I have trouble with is that I want
订阅 dao