Generate DDL script at MAVEN build with Hibernate4

问题:

It seems like the hibernate3-maven-plugin used to generate DDL create/drop scripts is not compatible any more with Hibernate 4.3 and newer versions (using JPA 2.1).

I use this plugin configuration :

            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>hibernate3-maven-plugin</artifactId>
                <version>3.0</version>
                <executions>
                    <execution>
                        <id>generate-sql-schema</id>
                        <phase>process-sources</phase>
                        <goals>
                            <goal>hbm2ddl</goal>
                        </goals>
                        <configuration>
                            <hibernatetool>
                                <jpaconfiguration persistenceunit="${persistenceUnitName}" />
                                <hbm2ddl update="true" create="true" export="false"
                                    outputfilename="src/main/sql/schema.sql" format="true"
                                    console="true" />
                            </hibernatetool>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

But I get the following error :

[ERROR] Failed to execute goal org.codehaus.mojo:hibernate3-maven-plugin:3.0:hbm2ddl (generate-sql-schema) on project my-project: There was an error creating the AntRun task.
An Ant BuildException has occured: java.lang.NoClassDefFoundError: org/hibernate/util/ReflectHelper: org.hibernate.util.ReflectHelper -> [Help 1]

This class as migrated to a new package : org.hibernate.internal.util.ReflectHelper

However i found no clear way to keep generating DDL create scripts at MAVEN build.

There is no hibernate4-maven-plugin, or any other official way to do it.

So what ? Isn't it a main feature that should be supported ? How to do it ?

回答1:

As Hibernate 4.3+ now implements JPA 2.1 the appropriate way to generate DDL scripts is to use following set of JPA 2.1 properties :

<property name="javax.persistence.schema-generation.scripts.action" value="create"/>
<property name="javax.persistence.schema-generation.create-source" value="metadata"/>
<property name="javax.persistence.schema-generation.scripts.create-target" value="target/jpa/sql/create-schema.sql"/>

A nice summary of others properties and context of schema generation in JPA 2.1 can be found here : https://blogs.oracle.com/arungupta/entry/jpa_2_1_schema_generation

And official JPA 2.1 specifications here : https://jcp.org/aboutJava/communityprocess/final/jsr338/index.html

As this will be generated at runtime, you may want to execute this DDL generation at build.

Here is the JPA 2.1 approach to generate this script programmatically :

import java.io.IOException;
import java.util.Properties;

import javax.persistence.Persistence;

import org.hibernate.jpa.AvailableSettings;

public class JpaSchemaExport {

    public static void main(String[] args) throws IOException {
        execute(args[0], args[1]);
        System.exit(0);
    }

    public static void execute(String persistenceUnitName, String destination) {
        System.out.println("Generating DDL create script to : " + destination);

        final Properties persistenceProperties = new Properties();

        // XXX force persistence properties : remove database target
        persistenceProperties.setProperty(org.hibernate.cfg.AvailableSettings.HBM2DDL_AUTO, "");
        persistenceProperties.setProperty(AvailableSettings.SCHEMA_GEN_DATABASE_ACTION, "none");

        // XXX force persistence properties : define create script target from metadata to destination
        // persistenceProperties.setProperty(AvailableSettings.SCHEMA_GEN_CREATE_SCHEMAS, "true");
        persistenceProperties.setProperty(AvailableSettings.SCHEMA_GEN_SCRIPTS_ACTION, "create");
        persistenceProperties.setProperty(AvailableSettings.SCHEMA_GEN_CREATE_SOURCE, "metadata");
        persistenceProperties.setProperty(AvailableSettings.SCHEMA_GEN_SCRIPTS_CREATE_TARGET, destination);

        Persistence.generateSchema(persistenceUnitName, persistenceProperties);
    }

}

As you can see it's very simple !

Now you can use this in an AntTask, or MAVEN build like this (for MAVEN) :

<plugin>
    <artifactId>maven-antrun-plugin</artifactId>
    <version>1.7</version>
    <executions>
        <execution>
            <id>generate-ddl-create</id>
            <phase>process-classes</phase>
            <goals>
                <goal>run</goal>
            </goals>
            <configuration>
                <target>
                    <!-- ANT Task definition -->
                    <java classname="com.orange.tools.jpa.JpaSchemaExport"
                        fork="true" failonerror="true">
                        <arg value="${persistenceUnitName}" />
                        <arg value="target/jpa/sql/schema-create.sql" />
                        <!-- reference to the passed-in classpath reference -->
                        <classpath refid="maven.compile.classpath" />
                    </java>
                </target>
            </configuration>

        </execution>
    </executions>
</plugin>

Note that the official hibernate-maven-plugin also may, or may not, do the trick in some way :

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-maven-plugin</artifactId>
    <version>4.3.1.Final</version>
</dependency>

Enjoy ! :)

回答2:

I might be a little late but Andrew Thompson has another solution that doesn't involve a persistence.xml or a real database although it is specific to Hibernate.

http://jandrewthompson.blogspot.com/2009/10/how-to-generate-ddl-scripts-from.html

Sadly, it involves a little bit of code but its very flexible.