JPA 环境搭建

JPA 核心配置文件

类路径 META-INF/persistence.xml：

<?xml version="1.0" encoding="UTF-8"?>
<!--
    persistence-unit（持久化单元）
        name：持久化单元名称
        transaction-type（事务类型）：
            JTA：分布式事务
            RESOURCE_LOCAL：本地事务
    -->
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="2.0">
    <persistence-unit name="myJpa" transaction-type="RESOURCE_LOCAL">
        <!--JPA实现方式-->
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <properties>
            <!--数据库信息-->
            <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="743216wm"/>
            <!--JPA实现方（Hibernate）信息-->
            <!--显示 SQL-->
            <property name="hibernate.show_sql" value="true"/>
            <!--格式化 SQL-->
            <property name="hibernate.format_sql" value="true"/>
            <!--
                hibernate.hbm2ddl.auto（自动创建数据库表）：
                    create：如果有表，先删除表再创建
                    update：如果有表，不会创建表；如果没表，就创建表
                    none：不会创建表
            -->
            <property name="hibernate.hbm2ddl.auto" value="update"/>
        </properties>
    </persistence-unit>
</persistence>

JPA 相关依赖

以 Hibernate 作为 JPA 的实现

<dependencies>
    <!-- junit -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>

    <!-- hibernate对jpa的支持包 -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>${project.hibernate.version}</version>
    </dependency>

    <!-- c3p0 -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-c3p0</artifactId>
        <version>${project.hibernate.version}</version>
    </dependency>

    <!-- log日志 -->
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
    </dependency>

    <!-- Mysql and MariaDB -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.6</version>
    </dependency>

    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
        <version>2.3.0</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-impl</artifactId>
        <version>2.3.0</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-core</artifactId>
        <version>2.3.0</version>
    </dependency>
    <dependency>
        <groupId>javax.activation</groupId>
        <artifactId>activation</artifactId>
        <version>1.1.1</version>
    </dependency>
</dependencies>