Question

'greeter'是 WildFly 8 中的快速入门项目，用于演示基本的hibernate数据库和JPA功能作为教程。在项目中，我不明白何时以及如何在H2数据库中创建“USERS”数据库。这是用于数据库创建和设置的两个相关文件：

META-INF / persistence.xml中

<persistence version="2.0"
    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">
    <persistence-unit name="primary">
        <!-- If you are running in a production environment, add a managed 
            data source, this example data source is just for development and testing! -->
        <!-- The datasource is deployed as WEB-INF/greeter-quickstart-ds.xml, 
            you can find it in the source at src/main/webapp/WEB-INF/greeter-quickstart-ds.xml -->
        <jta-data-source>java:jboss/datasources/GreeterQuickstartDS</jta-data-source>
        <properties>
            <!-- Properties for Hibernate -->
            <property name="hibernate.hbm2ddl.auto" value="create-drop" />
            <property name="hibernate.show_sql" value="false" />
        </properties>
    </persistence-unit>
</persistence>

WEB-INF / greeter-quickstart-ds.xml

<datasources xmlns="http://www.jboss.org/ironjacamar/schema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.jboss.org/ironjacamar/schema http://docs.jboss.org/ironjacamar/schema/datasources_1_0.xsd">
    <!-- The datasource is bound into JNDI at this location. We reference 
        this in META-INF/persistence.xml -->
    <datasource jndi-name="java:jboss/datasources/GreeterQuickstartDS"
        pool-name="greeter-quickstart" enabled="true" use-java-context="true">
        <connection-url>jdbc:h2:mem:greeter-quickstart;DB_CLOSE_ON_EXIT=FALSE;DB_CLOSE_DELAY=-1</connection-url>
        <driver>h2</driver>
        <security>
            <user-name>sa</user-name>
            <password>sa</password>
        </security>
    </datasource>
</datasources>

/wildfly-greeter/src/main/resources/import.sql

INSERT INTO USERS (ID, USERNAME, FIRSTNAME, LASTNAME) VALUES (-1, 'jdoe', 'John', 'Doe');

INSERT INTO USERS (ID, USERNAME, FIRSTNAME, LASTNAME) VALUES (-2, 'emuster', 'Erika', 'Mustermann');

默认情况下，H2数据库系统没有USERS数据库，该数据库由演示使用。那么在这个演示项目中如何创建“USERS”？感谢。

Answer 1

由于persistence.xml中的以下设置，您在运行项目时会自动创建USERS数据库：

<property name="hibernate.hbm2ddl.auto" value="create-drop" />

Answer 2

数据库是由Hibernate在部署时设置的。为了构建数据库模式，Hibernate会扫描所有相关文件，而不仅仅是XML文件，还会扫描类，以获取所需的信息，这就是 Users 表的来源从

以下是greeter快速启动示例中的确切代码，该示例负责用户表：

@Entity
// User is a keyword in some SQL dialects!
@Table(name="Users")
public class User {
... etc.

所以，就是这样，他们只是用复数＆＃39; s ＆＃39;来称呼用户。避免与您选择的DBMS发生冲突。

Wildfly Greeter快速启动项目

2 个答案: