jpa tutorial

The use of JPA also has a long time, the mystery of which is only used a little, the project does not have to think of the knowledge, really is now used to learn, this time encountered the problem is large text, in the database type is TEXT , but what to do when mapping?! Here is a brief introduction: to be honest, use JPA string , we also know that string mapped to a database with a maximum leng

The most common type of primary key is the single-field primary key, which uses two or more fields as the primary key, and is commonly used in a table where multiple fields can uniquely indicate a single record. For example, stock data sheets, stock codes, dates, and close prices as primary keys. Each stock, on a specific date, can have only one closing price. The database management system uses MySQL to create a table person with a combined primary key.The CREATE TABLE person (name VARCHAR (255

1. Dependent jar package: 2. configuration file: XML version = "1.0" encoding = "UTF-8" ?> Persistence Xmlns = Http://java.sun.com/xml/ns/persistence" Xmlns : Xsi = Http://www.w3.org/2001/XMLSchema-instance" Xsi : Schemalocation =Http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" Version = "1.0" > Persistence - Unit Name = "Hellojpapu" Transaction - Type = "Resource_local" > Provider > Org. hibernate. EJB.

Configure multiple data sources in JPA. You can configure multiple Of course, persistence-unit names cannot be repeated: Org. Apache. openjpa. Persistence. persistenceproviderimplOrg. Apache. openjpa. Persistence. persistenceproviderimpl Of course, you can also configure more data sources. Here I only have two. When calling, you only need to specify different unit-names for the entitymanager of JPA: @

1. Create a jpa test project using maven Mvn archetype: create-DgroupId = myjpa-DartifactId = myjpa 2. Add the packages that jpa depends on 3. Create two model classes Customer. java Package myjpa. model; Address. java Package myjpa. model; 4. Configure the persistence. xml file Create the META-INF directory under the src/main/resources Directory of the project, and create the persistence. xml file u

Programming at ordinary times, in addition to writing pages, it is also annoying to repeatedly write some SQL statements in dao. Recently, it was found that spring data jpa is very useful, it can minimize the number of times we write SQL statements. Some simple SQL statements can be automatically parsed into SQL statements based on the Interface Name, which greatly saves programming time, so that we can spend more time on the most important business l

In the JPA function, I used createnativequery to execute a query statement. This query statement uses union and left join. After the query result is displayed, the number of records is correct, however, the data of each record is exactly the same, and the query statement executed by the record is put in MySQL for query. The result is correct. Each record is a record, but after JPA is mapped to entity, it be

(). Commit (); em. Close (); factory. Close ();} 3. Update the query. The Code is as follows: @ TestPublic VoidUpdatequery () {entitymanagerfactory Factory= Persistence. createentitymanagerfactory ("learn_jpa"); Entitymanager em=Factory. createentitymanager (); em. gettransaction (). Begin ();//Query named ParametersQuery query = em. createquery ("Update person p set name =: name where P. ID =: ID"); Query. setparameter ("Name", "hwl"); Query. setparameter ("ID", 3); Query.exe cuteupdate (); e

1. Configure persistence. xml 2. In the j2se environment, only the entitymanager managed by the application can be used and transactions can be manually controlled. Public class testclient {public static void main (string [] ARGs) {entitymanagerfactory EMF = persistence. createentitymanagerfactory ("bookstorepu"); entitymanager em = EMF. createentitymanager (); try {// start em of the transaction. gettransaction (). begin ();/* entity operation * // transaction commit em. gettransaction (). co

Problem phenomenon:Pages that use the spring Webflow process need to query data from MySQL, show up in the foreground, and the page will not respond after several queries, and the last of the server's logs is Hibernate's SQL statement.Operating Environment:jre:1.8Spring Framework:4.3.8.releaseSpring Webflow:2.4.5.releaseSpring Data Jpa:1.11.4.releaseHibernate:5.2.5.finalmysql:5.7.14tomcat:8.0 (database connection pool using Tomcat)Problem Solving Proc

In the JPA criteria Dynamic query, there is a "meta-model", which is a class dynamically generated from the "Entity" class, and its main function is to implement the "type safety" of the JPA criteria query.This article explains how to automatically generate a meta-model in the eclipse environment. The development environment shown in this article is MyEclipse, and the project is a MAVEN project.1. Right-cli

First, the beginning of the new project import jar package Antlr-2.7.7.jarC3p0-0.9.2.1.jarCom.springsource.net.sf.cglib-2.2.0.jarCom.springsource.org.aopalliance-1.0.0.jarCom.springsource.org.aspectj.weaver-1.6.8.release.jarCommons-logging-1.1.3.jarDom4j-1.6.1.jarEhcache-core-2.4.3.jarHibernate-c3p0-4.2.4.final.jarHibernate-commons-annotations-4.0.2.final.jarHibernate-core-4.2.4.final.jarHibernate-ehcache-4.2.4.final.jarHibernate-entitymanager-4.2.4.final.jarHibernate-

In spring Engineering, when you create an entity object, you can identify the database field @Column by using the JPA @entity identity entity and the database table's corresponding relationship. There are annotations that identify the relationship between two entities: @OneToOne, @OneToMany, @ManyToOne, and @manytomany, each identifying a pair of one or one-to-many, many-to-one, and many-to-many. Here, simply record the use of @onetoone and @onetomany

About integrating JPA in spring MVC is based on my last article on Spring MVC Basic configuration, so let's take a look at my previous post: http://blog.csdn.net/u012116457/article/details/43528111Next, you need to add some new files:Jdbc.properties:jdbc.driverclassname=com.mysql.jdbc.driverjdbc.url=jdbc\:mysql\://localhost\:3306/tmos?useunicode\=true characterencoding\=utf-8autoreconnect\=truejdbc.user=rootjdbc.password=rootjdbc.dialect= org.hibernat

Private specificationReference:Http://docs.spring.io/spring-data/data-jpa/docs/1.0.x/api/org/springframework/data/jpa/domain/Specification.htmlHttp://docs.oracle.com/javaee/5/api/javax/persistence/package-summary.htmlHttp://wenku.baidu.com/view/190e385c3b3567ec102d8a40.html?re=viewSpring Data JPA Specification Query

Web. xml file Configuration Configuration SPRINGMVC: Scan package, parser, load static function and annotation function Configure Spring Files: Scan packages, configure DataSource, accessories japentityfactory, etc... JPA basic configuration, transaction, JPA Manager, Springdata 　　SPRINGMVC, Spring, JPA, springdata integrated configuration

("-------------------------------------------"); System. out. println ("Create a Sort object by creating a collection of Sort.order objects"); ListNewArraylist(); Orders.add (NewSort.order (Sort.Direction.DESC,"ID")); Orders.add (NewSort.order (Sort.Direction.ASC,"FirstName")); List"Bauer",NewSort (orders)); for(Customer customer:result3) {System. out. println (Customer.tostring ()); } System. out. println ("-------------------------------------------");}A total of four sorting methods are lis

sorting functions.@NoRepositoryBean public Interface pagingandsortingrepository Iterable3, Jparepository interface.The interface inherits the Pagingandsortingrepository interface.Also inherit the Querybyexampleexecutor interface, this is an "instance" to query the interface, follow-up and write the article detailed description. @NoRepositoryBeanpublic Interface jparepositoryA few notes:(1) Several query, and batch save method, compared with Crudrepository interface, return is List, use more

1. Use Maven to create a JPA test project MVN ARCHETYPE:CREATE-DGROUPID=MYJPA-DARTIFACTID=MYJPA 2. Add the packages that JPA relies on 3. Create two model classes Customer.java Package Myjpa.model; Import java.io.Serializable; Import java.util.ArrayList; Import Java.util.Date; Import java.util.List; Import javax.persistence.Entity; Import Javax.persistence.GeneratedValue; Import Javax.persistence.Genera

As part of EJB3.0, JPA is a good thing. Its simple configuration and powerful default configuration support, make it easy and free to exist between light weight and weight, if your Java EE project now chooses lightweight or heavyweight architecture, if the persistence layer does not choose to use JPA, it uses some ORM frameworks (such as Hibernate, TopLink) Special API, then one day in the future will certa