dao

Does anyone have a good example for how to do a findByExample in JPA that will work within a generic DAO via reflection for any entity type? I know I can do it via my provider (Hibernate), but I don't want to break with neutrality... Seems like the criteria API might be the way to go....but I am not sure how to handle the reflection part of it. Actually, Query By Example (QBE) has been considered for inclusion in the JPA 2.0 specification but is not included, even if major vendors support it. Quoting Mike Keith: I'm sorry to say that we didn't actually get to do QBE in JPA 2.0. Criteria API

My problem is as follows. I need a class that works as a single point to a database connection in a web system, so to avoid having one user with two open connections. I need it to be as optimal as possible and it should manage every transaction in the system. In other words only that class should be able to instantiate DAOs. And to make it better, it should also use connection pooling! What should I do? Carlos Vergara You will need to implement a DAO Manager . I took the main idea from this website , however I made my own implementation that solves some few issues. Step 1: Connection pooling

dbcBaseDao接口，内容如下： package com.sun4j.core.jdbc.dao; import java.io.Serializable; import java.util.List; import java.util.Map; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.jdbc.support.rowset.SqlRowSet; public interface JdbcBaseDao<T> { void save(T entity); void update(T entity); void delete(T entity); void delete(Serializable id); void deleteAll(); T findById(Serializable id); List<T> findAll(); void batchDelete(Serializable[] ids); void batchUpdate(List<T> list); void batchSave(List<T> list); Map<String, Object> findOne(String sql, Object... args); List<Map

好处 将被依赖类的创建代码从 依赖类中移出，不用显式的写new。 可以单独维护 被依赖类的创建 过程。 方便该类的被共享。 如果该类初始化时，所需属性很多，使用配置，远比硬代码编写简单。 比如DataSource配置 数据库连接池时。 有多层依赖时，依赖关系的移出，事实上简化了 依赖关系的查看和维护。 因为对每个类而言，只需要关心这个类的依赖。 以WEB项目为例，Controller层只需要关心Service层，Service层只需要关心Dao层。 有可能一个Service中使用了N多的Dao，来实现一个方法中的逻辑。 但是Controller只要引用这个Service，调用这个方法。 1、自己去造。用java的话说就是调用者创建被调用者（IDAO dao=new DAO()） 2、你可以要找到生产锤子的工厂，向工厂购买即可。对应java的工厂模式。 3、你可以打电话找到卖锤子的商店，让人把锤子送货上门。对应spring的依赖注入 转载于:https://www.cnblogs.com/JAYIT/p/4871133.html 来源： https://blog.csdn.net/weixin_30917213/article/details/99814779

Someone know how to add a another datasource in hibernate configuration and how to configure Spring to that datasource its autoinject in my respective DAO? This is my code with one datasource, that run perfectly, but i don't know how add another datasource. I want to add another data source that is a database with different tables than the actual database. HIBERNATE CONF <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName"> <value>com.mysql.jdbc.Driver</value> </property> <property name="url" value="jdbc:mysql://localhost

JDBC简介 1、什么是JDBC？ 　　 JDBC（Java DataBase Connectivity,java数据库连接）是一种用于执行SQL语句的Java API（工具）。JDBC是Java访问数据库的标准规范。 　　规范：在java中的直接体现是接口 　　作用：为不同关系型数据库提供统一的访问，由一组用java语言编写的接口和工具类组成，由各大数据库厂商实现对应接口 2、连接数据库时要先加载驱动 　　什么是驱动？ 　　两个设备要进行通信时，需要满足一定通信数据格式，数据格式由设备提供商规定，设备提供商为设备提供驱动软件，通过软件可以与该设备进行通信。 　　 Java和数据库要想进行链接，必须提前规定一些数据格式，格式由数据库厂商实现。 　　mysql连接工具下载地址： https://dev.mysql.com/downloads/connector/j/ 3、J DBC是接口，而JDBC驱动才是接口的实现，没有驱动无法完成数据库连接！每个数据库厂商都有自己的驱动，用来连接自己公司的数据库。 JDBC连接详解 1.通过JDBC连接数据库需要五步 import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement;

I am developing a Java Desktop Application but have some confusions in choosing a technology for my persistence layer. Till now, I have been using JDBC for DB operations. Now, Recently I learnt Hibernate and JPA but still I am a novice on these technologies. Now my question is What to use for my Java Desktop Application from the following? JPA Hibernate JDBC DAO any other suggestion from you... I know that there is no best choice from them and it totally depends on the complexity and the requeirements of the project so below are the requirements of my project It's not a complex application. It