Hibernate JPA无法生成数据库Schema脚本问题求助

我已配置jakarta.persistence.schema-generation.scripts.create-target属性以生成指定文件名的SQL脚本，但在MacOS上使用find命令搜索整个主目录后，未找到该文件。尝试过foo.sql、./foo.sql和/tmp/foo.sql三种路径，主目录和/tmp目录中均无结果。数据库表确实已创建，且运行日志中无报错信息。

相关代码文件 #

persistence.xml

<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">
    <persistence-unit name="foo">
        <class>Foo</class>
        <properties>
            <property name="jakarta.persistence.jdbc.url" value="jdbc:postgresql:///main" />
            <property name="jakarta.persistence.jdbc.user" value="main" />
            <property name="jakarta.persistence.jdbc.password" value="big1704cloudmain" />
            <property name="hibernate.default_schema" value="foo" />
            <property name="jakarta.persistence.schema-generation.database.action" value="validate" />
            <property name="jakarta.persistence.schema-generation.scripts.create-target" value="foo.sql" />
        </properties>
    </persistence-unit>
</persistence>

Main.kt

import jakarta.persistence.Entity
import jakarta.persistence.Id
import jakarta.persistence.Persistence

@Entity
data class Foo (@Id val n: Int)

fun main() {
    Persistence.createEntityManagerFactory("foo")
    println("Hello World!")
}

build.gradle.kts

plugins {
    kotlin("jvm") version "latest.release"
    application
}

repositories {
    mavenCentral()
}

dependencies {
    implementation("org.postgresql:postgresql:latest.release")
    implementation("org.hibernate:hibernate-core:latest.release")
}

application {
    mainClass.set("MainKt")
}

java {
    toolchain {
        languageVersion.set(JavaLanguageVersion.of(18))
    }
}

运行输出

3:15:36 PM: Executing 'run'...

> Task :compileKotlin UP-TO-DATE
> Task :compileJava NO-SOURCE
> Task :processResources UP-TO-DATE
> Task :classes UP-TO-DATE

> Task :run
Hello World!

BUILD SUCCESSFUL in 737ms
3 actionable tasks: 1 executed, 2 up-to-date
May 13, 2023 3:15:36 PM org.hibernate.jpa.internal.util.LogHelper logPersistenceUnitInformation
INFO: HHH000204: Processing PersistenceUnitInfo [name: foo]
May 13, 2023 3:15:36 PM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate ORM core version 6.2.2.Final
May 13, 2023 3:15:36 PM org.hibernate.cfg.Environment <clinit>
INFO: HHH000406: Using bytecode reflection optimizer
May 13, 2023 3:15:36 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure
WARN: HHH10001002: Using built-in connection pool (not intended for production use)
May 13, 2023 3:15:36 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001005: Loaded JDBC driver class: org.postgresql.Driver
May 13, 2023 3:15:36 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001012: Connecting with JDBC URL [jdbc:postgresql:///main]
May 13, 2023 3:15:36 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001001: Connection properties: {password=****, user=main}
May 13, 2023 3:15:36 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001003: Autocommit mode: false
May 13, 2023 3:15:36 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections <init>
INFO: HHH10001115: Connection pool size: 20 (min=1)
May 13, 2023 3:15:36 PM org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl logSelectedDialect
INFO: HHH035001: Using dialect: org.hibernate.dialect.PostgreSQLDialect, version: org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$DialectResolutionInfoImpl@72ade7e3
May 13, 2023 3:15:36 PM org.hibernate.bytecode.internal.BytecodeProviderInitiator buildBytecodeProvider
INFO: HHH000021: Bytecode provider name : bytebuddy
May 13, 2023 3:15:36 PM org.hibernate.metamodel.internal.EntityInstantiatorPojoStandard resolveConstructor
INFO: HHH000182: No default (no-argument) constructor for class: Foo (class must be instantiated by Interceptor)
May 13, 2023 3:15:36 PM org.hibernate.engine.transaction.jta.platform.internal.JtaPlatformInitiator initiateService
INFO: HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]
May 13, 2023 3:15:36 PM org.hibernate.resource.transaction.backend.jdbc.internal.DdlTransactionIsolatorNonJtaImpl getIsolatedConnection
INFO: HHH10001501: Connection obtained from JdbcConnectionAccess [org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess@7ff35a3f] for (non-JTA) DDL execution was not in auto-commit mode; the Connection 'local transaction' will be committed and the Connection will be set into auto-commit mode.
3:15:36 PM: Execution finished 'run'.

核心原因 #

你设置的jakarta.persistence.schema-generation.database.action属性值为validate，这个模式下Hibernate仅会验证数据库现有结构与实体类定义是否匹配，不会执行创建表的DDL操作，因此也不会生成对应的创建脚本。你提到数据库表已存在，大概率是之前其他操作（比如曾经设置过create模式）生成的，本次运行只是验证步骤。

解决步骤 #

1. 修改DDL执行模式
   将persistence.xml中的jakarta.persistence.schema-generation.database.action值改为create或create-drop：

   <property name="jakarta.persistence.schema-generation.database.action" value="create" />
   

   • create：每次启动时创建表，若表已存在则覆盖
   • create-drop：启动时创建表，关闭EntityManagerFactory时删除表

2. 确认脚本生成路径

   • 若使用相对路径（如foo.sql），脚本默认生成在项目根目录（即执行./gradlew run的目录），而非用户主目录，直接去项目根目录查找即可。
   • 若需要指定绝对路径，可直接写全路径，比如：

     <property name="jakarta.persistence.schema-generation.scripts.create-target" value="/Users/你的用户名/foo.sql" />
     

内容的提问来源于stack exchange，提问作者user2297550