Maven + Spring + Hibernate: hibernate3-maven-plugin hbm2ddl fails for reason "Caused by: java.lang.NullPointerException"

Question

I had to downgrade Hibernate from version 4 to version 3 (3.3.2.GA to be specific), due to current lack of support for Hibernate 4 within Spring, and now the project fails to build when it attempts to generate schema with hbm2ddl. The error is too vague, and Google-ing it hasn't yielded much.

Here's my pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="
         http://maven.apache.org/POM/4.0.0
         http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>example</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>Spring + Hibernate Example</name>
    <packaging>jar</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <spring.version>3.1.2.RELEASE</spring.version>
        <hibernate.version>3.3.2.GA</hibernate.version>
        <java.version>1.6</java.version>
    </properties>

    <build>
        <extensions>
            <extension>
                <groupId>org.hsqldb</groupId>
                <artifactId>hsqldb</artifactId>
                <version>2.0.0</version>
            </extension>
            <extension>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>1.2.17</version>
            </extension>
        </extensions>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.0.2</version>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                </configuration>
            </plugin>
            <plugin>
                <!-- Run "mvn hibernate3:hbm2ddl" to generate schema -->
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>hibernate3-maven-plugin</artifactId>
                <version>3.0</version>

                <executions>
                    <execution>
                        <id>generate-ddl</id>
                        <phase>process-classes</phase>
                        <goals>
                            <goal>hbm2ddl</goal>
                        </goals>
                    </execution>
                </executions>

                <configuration>
                    <hibernatetool destdir="${project.build.directory}/generated">
                        <annotationConfiguration configurationfile="hibernate.cfg.xml"/>

                        <hbm2ddl export="false" create="true" update="true"
                                 format="format" outputfilename="schemaDiff.ddl"/>

                    </hibernatetool>
                </configuration>

            </plugin>
        </plugins>
    </build>

    <dependencies>
        <!-- Inversion of Control: Spring Dependencies -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
            <exclusions>
                <!-- Exclude the problematic commons-logging -->
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>commons-dbcp</groupId>
            <artifactId>commons-dbcp</artifactId>
            <version>1.4</version>
        </dependency>

        <!-- Object Relational Mapping: Hibernate -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>javax.transaction</groupId>
            <artifactId>jta</artifactId>
            <version>1.1</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate.javax.persistence</groupId>
            <artifactId>hibernate-jpa-2.0-api</artifactId>
            <version>1.0.1.Final</version>
        </dependency>

        <!-- Hibernate Annotations Dependencies -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-annotations</artifactId>
            <version>3.5.6-Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-commons-annotations</artifactId>
            <version>3.3.0.ga</version>
        </dependency>

        <!-- Database: HSQLDB -->
        <dependency>
            <groupId>org.hsqldb</groupId>
            <artifactId>hsqldb</artifactId>
            <version>2.0.0</version>
        </dependency>

        <!-- Connection Pool: C3P0 -->
        <dependency>
            <groupId>c3p0</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.1.2</version>
        </dependency>

        <!-- Second-level caching: Ehcache -->
        <dependency>
            <groupId>ehcache</groupId>
            <artifactId>ehcache</artifactId>
            <version>1.2.3</version>
        </dependency>

        <!-- Logging: SLF4j & Log4J -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>jcl-over-slf4j</artifactId>
            <version>1.6.6</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.6.6</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.6.6</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
            <scope>runtime</scope>
        </dependency>

        <!-- Testing: JUnit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>

        <!-- Testing: Spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
        </dependency>

    </dependencies>

</project>

Running

mvn hibernate3:hbm2ddl

fails with

[ERROR] Failed to execute goal org.codehaus.mojo:hibernate3-maven-plugin:3.0:hbm2ddl
(default-cli) on project example: There was an error creating the AntRun task.
NullPointerException -> [Help 1]

The full stack trace is:

[ERROR] Failed to execute goal org.codehaus.mojo:hibernate3-maven-plugin:3.0:hbm2ddl (default-cli) on project example: There was an error creating the AntRun task. NullPointerException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.codehaus.mojo:hibernate3-maven-plugin:3.0:hbm2ddl (default-cli) on project example: There was an error creating the AntRun task.
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:217)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:319)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.maven.plugin.MojoExecutionException: There was an error creating the AntRun task.
    at org.codehaus.mojo.hibernate3.AbstractHibernateMojo.execute(AbstractHibernateMojo.java:84)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    ... 19 more
Caused by: java.lang.NullPointerException
    at org.codehaus.plexus.configuration.DefaultPlexusConfiguration.add(DefaultPlexusConfiguration.java:174)
    at org.codehaus.plexus.configuration.DefaultPlexusConfiguration.addChild(DefaultPlexusConfiguration.java:150)
    at org.codehaus.mojo.hibernate3.util.PlexusConfigurationUtils.setHibernateConfiguration(PlexusConfigurationUtils.java:289)
    at org.codehaus.mojo.hibernate3.util.PlexusConfigurationUtils.parseHibernateTool(PlexusConfigurationUtils.java:67)
    at org.codehaus.mojo.hibernate3.AbstractHibernateToolMojo.getConfiguration(AbstractHibernateToolMojo.java:60)
    at org.codehaus.mojo.hibernate3.AbstractHibernateMojo.execute(AbstractHibernateMojo.java:76)
    ... 21 more

Hopefully someone can shed some light on this!

Answer 1

I faced the same problem while trying to make maven bootstrap a database from a hibernate model (issue described in Generate database schema (Hibernate) on maven test).

I got hbm2ddl working quite well with the following combination of versions: Hibernate (runtime): 4.1.7.Final hibernate3-maven-plugin: 3.6.10.Final, specified plugin version 2.2 hibernate3-maven-plugin's hibernate-validator dependency: 4.2.0.Final

Below the relevant parts of the pom:

Versions:

<properties>

    <org.hibernate.version>4.1.7.Final</org.hibernate.version>
    <hibernate.maven.plugin.version>3.6.10.Final</hibernate.maven.plugin.version>

</properties>

hibernate3-maven-plugin's definition:

<build>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>hibernate3-maven-plugin</artifactId>
            <version>2.2</version>
            <configuration>
                <components>
                    <component>
                        <name>hbm2ddl</name>
                        <implementation>jpaconfiguration</implementation>
                    </component>

                </components>

                <componentProperties>
                    <outputfilename>schema.ddl</outputfilename>
                    <create>true</create>
                    <export>false</export>
                    <format>true</format>
                    <drop>false</drop>
                    <jdk5>true</jdk5>
                    <propertyfile>target/test-classes/application.properties</propertyfile>
                    <skip>${skipTests}</skip>
                </componentProperties>
            </configuration>
            <executions>
                <execution>
                    <phase>process-classes</phase>
                    <goals>
                        <goal>hbm2ddl</goal>
                    </goals>
                </execution>
            </executions>
            <dependencies>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-entitymanager</artifactId>
                    <version>${hibernate.maven.plugin.version}</version>
                    <exclusions>
                        <exclusion>
                            <groupId>cglib</groupId>
                            <artifactId>cglib</artifactId>
                        </exclusion>
                        <exclusion>
                            <groupId>commons-logging</groupId>
                            <artifactId>commons-logging</artifactId>
                        </exclusion>
                    </exclusions>
                </dependency>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-core</artifactId>
                    <version>${hibernate.maven.plugin.version}</version>
                    <exclusions>
                        <exclusion>
                            <groupId>cglib</groupId>
                            <artifactId>cglib</artifactId>
                        </exclusion>
                        <exclusion>
                            <groupId>commons-logging</groupId>
                            <artifactId>commons-logging</artifactId>
                        </exclusion>
                    </exclusions>
                </dependency>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-validator</artifactId>
                    <version>4.2.0.Final</version>
                </dependency>

            </dependencies>
        </plugin>

    </plugins>
</build>

Runtime dependencies:

<dependencies>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>${org.hibernate.version}</version>
    </dependency>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>${org.hibernate.version}</version>
    </dependency>
</dependencies>

I hope this helps.

Answer 2

For a large project (more than 250 Entities), I use the following pom.xml witch works fine and generate the schema during the compile phase. Note : persistence.xml specifies the database dialect.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>test</groupId>
<artifactId>jpa</artifactId>
<version>1.0-SNAPSHOT</version>

<dependencies>
    <!-- java EE (for annotations) -->
    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-api</artifactId>
        <version>6.0</version>
        <scope>provided</scope>
    </dependency>
</dependencies>

<build>
    <plugins>

        <!-- hibernate hmb2ddl plugin configuration -->
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>hibernate3-maven-plugin</artifactId>
            <version>3.0</version>
            <executions>
                <execution>
                    <id>generate.database.schema.from.ejb.annotation</id>
                    <phase>compile</phase>
                    <goals>
                        <goal>run</goal>
                    </goals>
                    <configuration>
                        <hibernatetool>
                            <classpath><path location="src/main/java"/></classpath>
                            <hbm2ddl console="false" export="false" update="false"
                                drop="false" create="true" outputfilename="create.sql" format="false"
                                haltonerror="true">
                                <jpaconfiguration persistenceunit="persist" />
                            </hbm2ddl>
                        </hibernatetool>
                    </configuration>
                </execution>
            </executions>
            <dependencies>
                <!-- hibernate tools -->
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-core</artifactId>
                    <version>3.6.10.Final</version>
                </dependency>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-entitymanager</artifactId>
                    <version>3.6.10.Final</version>
                </dependency>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-validator</artifactId>
                    <version>4.1.0.Final</version>
                </dependency>
                <dependency>
                    <groupId>javassist</groupId>
                    <artifactId>javassist</artifactId>
                    <version>3.4.GA</version>
                </dependency>
            </dependencies>
        </plugin>

    </plugins>
</build>