SpringDataJPA 系列之 JPA 简介

<dependencies>
	<!-- hibernate 对 jpa 的支持包 -->
	<dependency>
		<groupId>org.hibernate</groupId>
		<artifactId>hibernate-entitymanager</artifactId>
		<version>5.0.7.Final</version>
	</dependency>
	
	<!-- c3p0 -->
	<dependency>
		<groupId>org.hibernate</groupId>
		<artifactId>hibernate-c3p0</artifactId>
		<version>5.0.7.Final</version>
	</dependency>
	
	<!-- log 日志 -->
	<dependency>
		<groupId>log4j</groupId>
		<artifactId>log4j</artifactId>
		<version>1.2.17</version>
	</dependency>
	
	<!-- Mysql 驱动 -->
	<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<version>5.1.6</version>
	</dependency>
</dependencies>

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/7/28
 * @description 学生类
 */
@Entity
public class Student implements Serializable {

    private static final long SerialVersionUID = 1L;

    @Id // 声明 id 为主键
    @GeneratedValue(strategy= GenerationType.IDENTITY) // 配置主键的生成策略
    private Long id;

    private String name;

    private Integer age;

    private Boolean sex;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Boolean getSex() {
        return sex;
    }

    public void setSex(Boolean sex) {
        this.sex = sex;
    }
}

<?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_2_0.xsd"
             version="2.0">
    <!-- 配置持久化单元
            name：持久化单元名称
            transaction-type：事务类型
                RESOURCE_LOCAL：本地事务管理
                JTA：分布式事务管理
    -->
    <persistence-unit name="myJpa" transaction-type="RESOURCE_LOCAL">
        <!--配置JPA规范的服务提供商 -->
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <properties>
            <!-- 数据库驱动 -->
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
            <!-- 数据库地址 -->
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/db"/>
            <!-- 数据库用户名 -->
            <property name="javax.persistence.jdbc.user" value="root"/>
            <!-- 数据库密码 -->
            <property name="javax.persistence.jdbc.password" value="root"/>

            <!-- jpa 提供者的可选配置：我们的JPA规范的提供者为 hibernate，所以 jpa 的核心配置中兼容 hibernate -->
            <property name="hibernate.show_sql" value="true"/>
            <property name="hibernate.format_sql" value="true"/>
            <property name="hibernate.hbm2ddl.auto" value="create"/>
        </properties>
    </persistence-unit>
</persistence>

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/7/28
 * @description 演示类
 */
public class Demo {
    public static void main(String[] args) {
        // 创建实体管理类工厂，借助 Persistence 的静态方法获取，其中传递的参数为持久化单元名称，需要 jpa 配置文件中指定
        EntityManagerFactory factory = Persistence.createEntityManagerFactory("myJpa");
        // 创建实体管理类
        EntityManager em = factory.createEntityManager();
        // 获取事务对象
        EntityTransaction tx = em.getTransaction();
        // 开启事务
        tx.begin();
        Student tbStudent = new Student();
        tbStudent.setName("张三");
        tbStudent.setAge(23);
        tbStudent.setSex(false);

        //保存操作
        em.persist(tbStudent);

        // 提交事务
        tx.commit();
        // 释放资源
        em.close();
        factory.close();
    }
}

mysql> select * from student;
+----+------+-----+-----+
| id | Name | age | sex |
+----+------+-----+-----+
|  1 | 张三 |  23 | 0   |
|  2 | 张三 |  23 | 0   |
|  3 | 张三 |  23 | 0   |
+----+------+-----+-----+
3 rows in set (0.02 sec)