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一.JPA的概念
为了节省时间，更加具体的解释我们就略过吧。
二.在IDEA中使用JPA
2.1.添加JAP依赖
添加相关的maven依赖
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
<hibernate.version>5.2.17.Final</hibernate.version>
<goda.time.version>2.9.9</goda.time.version>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<!-- jdbc驱动包 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.37</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>4.3.10.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>4.3.10.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate.javax.persistence</groupId>
<artifactId>hibernate-jpa-2.1-api</artifactId>
<version>1.0.0.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate.common</groupId>
<artifactId>hibernate-commons-annotations</artifactId>
<version>4.0.5.Final</version>
</dependency>
<!--持久化依赖-->
<dependency>
<groupId>joda-time</groupId>
<artifactId>joda-time</artifactId>
<version>${goda.time.version}</version>
</dependency>
<dependency>
<groupId>org.jadira.usertype</groupId>
<artifactId>usertype.core</artifactId>
<version>6.0.1.GA</version>
</dependency>
<dependency>
<groupId>antlr</groupId>
<artifactId>antlr</artifactId>
<version>2.7.7</version>
</dependency>
<dependency>
<groupId>dom4j</groupId>
<artifactId>dom4j</artifactId>
<version>1.6.1</version>
</dependency>
<dependency>
<groupId>org.jboss</groupId>
<artifactId>jandex</artifactId>
<version>1.1.0.Final</version>
</dependency>
<dependency>
<groupId>org.javassist</groupId>
<artifactId>javassist</artifactId>
<version>3.18.1-GA</version>
</dependency>
<dependency>
<groupId>org.jboss.logging</groupId>
<artifactId>jboss-logging</artifactId>
<version>3.1.4.GA</version>
</dependency>
<dependency>
<groupId>org.jboss.logging</groupId>
<artifactId>jboss-logging-annotations</artifactId>
<version>1.2.0.Beta1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.jboss.spec.javax.transaction</groupId>
<artifactId>jboss-transaction-api_1.1_spec</artifactId>
<version>1.0.0.Final</version>
</dependency>
<dependency>
<groupId>javax.ejb</groupId>
<artifactId>ejb-api</artifactId>
<version>3.0</version>
</dependency>
</dependencies> |
2.2.配置JPA运行环境
在IDEA中，resources文件夹下，也就是资源文件夹下，创建META-INF文件夹，在该文件夹下创建persistence.xml文件，添加以下配置。
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1"
xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="MyJPA" transaction-type="RESOURCE_LOCAL">
<properties>
<property name="javax.persistence.jdbc.driver"
value="com.mysql.jdbc.Driver" />
<property name="javax.persistence.jdbc.url"
value="jdbc:mysql://localhost:3306/jpa" />
<property name="javax.persistence.jdbc.user" value="root" />
<property name="javax.persistence.jdbc.password" value="root" />
<property name="hibernate.dialect"
value="org.hibernate.dialect.MySQL5Dialect" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.hbm2ddl.auto" value="update" />
</properties>
</persistence-unit>
</persistence> |
如下：
2.3.创建表
CREATE TABLE `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(255) DEFAULT NULL,
`password` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8; |
2.4.在IDEA中配置数据源
在IDEA的右边有Database，按以下步骤操作即可。
这里也可以不配置，配置之后，可以在IDEA中直接看到数据库中的表，并且之后再IDEA中写的代码也不用有警告。
添加你的数据库名字，第一次配置下边会提示你下载插件，很具提示即可。
2.5.测试
创建User类
package com.hly.jpa.model.oneToOne;
import javax.persistence.*;
/**
* @author :hly
* @github :github.com/SiriusHly
* @blog :blog.csdn.net/Sirius_hly
* @date :2018/9/27
*/
@Entity
//指定表名，指定唯一约束
@Table(name = "user",uniqueConstraints = {@UniqueConstraint(columnNames = {"id","name"})})
public class User {
@Id//指定主键
@GeneratedValue
private int id;
@Column
private String name;
@Column
private String password;
//一对一映射
@OneToOne(optional = true, cascade = CascadeType.ALL)
@JoinColumn(name = "articleId", unique = true)
public Article article;
//省略了getter和setter
}
/**
* 获取应用管理的EntityManager
*/
@Test
public void testApplicationEntityManager() {
EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("MyJPA");
EntityManager em = entityManagerFactory.createEntityManager();
em.getTransaction().begin();
User user = new User();
user.setName("hly");
//以上两行为新建状态
//托管状态
em.persist(user);
//事务提交或调用flush()方法后会同步到数据库
em.getTransaction().commit();
//根据主键获取对象
//System.err.println(em.find(User.class,1));
//System.err.println(em.getReference(User.class,1));
em.close();
entityManagerFactory.close();
} |
数据库中插入数据则成功。
2.6.EntityManager接口
2.7.实体类中注解的含义
本文转自：https://blog.csdn.net/Sirius_hly/article/details/82903041
程序猿的技术大观园：www.javathinker.net
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