hibernate

Hibernate active transaction

由 好久不见. 提交于 2021-01-26 07:52:44
问题 In my service class I would like to have something like: class ClientService { // Authorize // Returns true: Authorization successful // Returns false: Authorization failed public boolean authorize(String id, String password) { //Here I would like to check if an active transaction exists. //If it exists, use that one, else create a new session and start //a new transaction. //For example: Session session = HibernateUtil.getSessionFactory().getCurrentSession(); if(!session.SOMEMETHOD_CHECK_IF

Hibernate active transaction

由 孤街浪徒 提交于 2021-01-26 07:51:17
问题 In my service class I would like to have something like: class ClientService { // Authorize // Returns true: Authorization successful // Returns false: Authorization failed public boolean authorize(String id, String password) { //Here I would like to check if an active transaction exists. //If it exists, use that one, else create a new session and start //a new transaction. //For example: Session session = HibernateUtil.getSessionFactory().getCurrentSession(); if(!session.SOMEMETHOD_CHECK_IF

MySQL学习（四）深入理解乐观锁与悲观锁

由 亡梦爱人 提交于 2021-01-26 04:38:44
转载自：http://www.hollischuang.com/archives/934 在 数据库的锁机制 中介绍过，数据库管理系统（DBMS）中的并发控制的任务是确保在多个事务同时存取数据库中同一数据时不破坏事务的隔离性和统一性以及数据库的统一性。 乐观并发控制(乐观锁)和悲观并发控制（悲观锁）是并发控制主要采用的技术手段。 无论是悲观锁还是乐观锁，都是人们定义出来的概念，可以认为是一种思想。其实不仅仅是关系型数据库系统中有乐观锁和悲观锁的概念，像memcache、hibernate、tair等都有类似的概念。 针对于不同的业务场景，应该选用不同的并发控制方式。所以， 不要把乐观并发控制和悲观并发控制狭义的理解为DBMS中的概念，更不要把他们和数据中提供的锁机制（行锁、表锁、排他锁、共享锁）混为一谈。其实，在DBMS中，悲观锁正是利用数据库本身提供的锁机制来实现的。 下面来分别学习一下悲观锁和乐观锁。 悲观锁 在关系数据库管理系统里，悲观并发控制（又名“悲观锁”，Pessimistic Concurrency Control，缩写“PCC”）是一种并发控制的方法。它可以阻止一个事务以影响其他用户的方式来修改数据。如果一个事务执行的操作都某行数据应用了锁，那只有当这个事务把锁释放，其他事务才能够执行与该锁冲突的操作。 悲观并发控制主要用于数据争用激烈的环境

Hibernate LAZY loading and spring's UserDetails

由 北战南征 提交于 2021-01-25 08:06:08
问题 I have a stateless REST backend. So no HTML views. Just JSON and REST endpoints. Authentication is done with Json Web Tokens. The client sends a JWT in each request. My backend takes the user's email from the subject claim in this JWT. Then it loads the UserModel from the database in class LiquidoUserDetailsService implements UserDetailsService { ...} Each user is part of a team. But the Team is a big entity with a lot of information in it. So teams are only loaded lazily, when necessary:

Hibernate LAZY loading and spring's UserDetails

由 蹲街弑〆低调 提交于 2021-01-25 08:05:00
问题 I have a stateless REST backend. So no HTML views. Just JSON and REST endpoints. Authentication is done with Json Web Tokens. The client sends a JWT in each request. My backend takes the user's email from the subject claim in this JWT. Then it loads the UserModel from the database in class LiquidoUserDetailsService implements UserDetailsService { ...} Each user is part of a team. But the Team is a big entity with a lot of information in it. So teams are only loaded lazily, when necessary:

Will HQL query use Hibernate second-level cache

由 允我心安 提交于 2021-01-23 07:04:11
问题 I would like to clarify some points regarding the secondary level cache of hibernate. The point to clarify is, will the HQL queries always hit the database (at least for getting ids). Consider we have entities class Customer { long id; // Primary key String name; set <Address> addressList; // One to many relationship } class Address{ long id; // Primary key String houseName; } The database table for the Address has a foreign key reference to the Customer (id) to support one to many

Will HQL query use Hibernate second-level cache

由 a 夏天 提交于 2021-01-23 07:04:09
问题 I would like to clarify some points regarding the secondary level cache of hibernate. The point to clarify is, will the HQL queries always hit the database (at least for getting ids). Consider we have entities class Customer { long id; // Primary key String name; set <Address> addressList; // One to many relationship } class Address{ long id; // Primary key String houseName; } The database table for the Address has a foreign key reference to the Customer (id) to support one to many

Spring Data REST HATEOS : not lazy loading

由 ≯℡__Kan透↙ 提交于 2021-01-22 05:21:12
问题 Problem I have two entities defined: School and District . A district can have many schools and a school can belong to one district. When executing a GET request against this endpoint http://localhost:8080/districts I would like to get a list of all the districts WITHOUT fetching each district's set of associated schools. But it seems like no matter what I do, hibernate is making DB calls to fetch data for each school individually. Entities School @Getter @Setter @NoArgsConstructor @Entity

JPA Criteria api with oracle12c JSON_VALUE function

由 放肆的年华 提交于 2021-01-21 11:29:05
问题 I'm trying to crete Criteria API query with JSON_VALUE function() is Oracle12c: select * from orderswhere (JSON_VALUE(duty, '$.department') in ( ? , ? , ? ,? , ? , ? , ?)); MODEL: @Entity @Table(name = "orders") @EntityListeners(AuditingEntityListener.class) public class Trade implements Serializable { @Convert(converter = JpaConverterJson.class) private Map<String, Object> duty; ..... } private Specification<InvoicePurchase> reportFormToSpec(Map<String, Object> params) { return (root, query,

SSM框架启动报 org.apache.bval.jsr303.ConfigurationImpl.getDefaultParameterNameProvider

由 情到浓时终转凉″ 提交于 2021-01-21 08:13:33
今天在做项目，在启动的时候报了一个错。错误信息是org.apache.bval.jsr303.ConfigurationImpl.getDefaultParameterNameProvider。 原因：使用了bval-jsr303.jar这个jar包。而Spring4.0之后不再支持这个jar包了。出现了该错误。 解决办法：把bval-jsr303这个jar换成hibernate-validator。Maven依赖如下： 删除该依赖 <dependency> <groupId>org.apache.bval</groupId> <artifactId>bval-jsr303</artifactId> <version>0.5</version> </dependency> 添加此依赖 <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-validator</artifactId> <version>5.2.4.Final</version> </dependency> 来源： oschina 链接： https://my.oschina.net/u/4276314/blog/3533093
订阅 hibernate