ApplicationContext in Ant Task.

[stibrian]

I am trying to create an ApplicationContext (specifically a FileSystemXmlApplicationContext) in a custom Ant task I have written. It finds the XML file correctly, and then throws NoClassDefFoundException for a bean that is the DriverManagerDataSource....
Right before I init the context I can call Class.forName() for the driver manager class and it loads fine, so why won't the bean factory find it?
what classpath concept am I missing? I have pored through my Spring in Action book and these forums and still haven't a solution.
Any help would be greatly appreciated.

[jbetancourt]

I am trying to create an ApplicationContext (specifically a FileSystemXmlApplicationContext) in a custom Ant task I have written. It finds the XML file correctly, and then throws NoClassDefFoundException for a bean that is the DriverManagerDataSource....
Right before I init the context I can call Class.forName() for the driver manager class and it loads fine, so why won't the bean factory find it?
what classpath concept am I missing? I have pored through my Spring in Action book and these forums and still haven't a solution.
Any help would be greatly appreciated.

Did my article on integrating Spring into Ant help in any way?
See: http://www.javaworld.com/javaworld/j...antspring.html

[stibrian]

The article is nice, and I'm going to look at using your technique in the future (maybe this time if I keep having issues). I am actually working towards something much simpler though.
My Task:

private void setupBeanFactory() throws BeansException, FileNotFoundException, ClassNotFoundException{
        
        Class.forName("org.springframework.jdbc.datasource.DriverManagerDataSource");
        
        FileSystemXmlApplicationContext cp2 = new     FileSystemXmlApplicationContext("etc/config/config.xml");
      }
    
    /** 
     * The main point of entry when ant calls our custom task.
     */
    public void execute() throws BuildException {
        try {
            setupBeanFactory();
        } catch (Exception e) {
                        e.printStackTrace();
        }
    }

My config.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
"http&#58;//www.springframework.org/dtd/spring-beans.dtd">
<beans>
    <!--  our jndi datasource -->
	<bean id="dataSource"
		class="org.springframework.jdbc.datasource.DriverManagerDataSource">
		<property name="url">
			<value>jdbc&#58;mysql&#58;//localhost/dbName?autoReconnect=true</value>
		</property>
		<property name="username">
			<value>password</value>
		</property>
		<property name="password">
			<value>password</value>
		</property>
		<property name="driverClassName">
			<value>org.gjt.mm.mysql.Driver</value>
		</property>
	</bean>

	<!--  create the session factory with the correct dialect with our datasource -->
	<bean id="sessionFactory"
		class="org.springframework.orm.hibernate.LocalSessionFactoryBean">
		<property name="dataSource">
			<ref bean="dataSource" />
		</property>
		<property name="hibernateProperties">
			<props>
				<prop key="hibernate.dialect">
					net.sf.hibernate.dialect.MySQLDialect
				</prop>
			  <!-- <prop key="hibernate.show_sql">
			  	true
			  </prop>-->
			</props>
		</property>
		<property name="mappingDirectoryLocations">
			<list>
				<value>classpath&#58;my class mappings directory</value>
			</list>
		</property>
	</bean>

	<!--  create the hibernate template based on our session factory -->
	<bean id="hibernateTemplate"
		class="org.springframework.orm.hibernate.HibernateTemplate">
		<property name="sessionFactory">
			<ref bean="sessionFactory" />
		</property>
	</bean>
	
	
	
</beans>

Now when Ant executes I get this stack trace:

[exportDomainData] (xml.XmlBeanDefinitionReader         119 ) Loading XML bean definitions from file [C:\java\eclipse\workspace\hit\etc\config\config.xml]
[exportDomainData] org.springframework.beans.factory.BeanDefinitionStoreException: Error registering bean with name 'dataSource' defined in file [C:\java\eclipse\workspace\hit\etc\config\config.xml]: Bean class [org.springframework.jdbc.datasource.DriverManagerDataSource] not found; nested exception is java.lang.ClassNotFoundException: org.springframework.jdbc.datasource.DriverManagerDataSource
[exportDomainData] java.lang.ClassNotFoundException: org.springframework.jdbc.datasource.DriverManagerDataSource
[exportDomainData] at java.net.URLClassLoader$1.run(URLClassLoader.java:199)
[exportDomainData] at java.security.AccessController.doPrivileged(Native Method)
[exportDomainData] at java.net.URLClassLoader.findClass(URLClassLoader.java:187)
[exportDomainData] at java.lang.ClassLoader.loadClass(ClassLoader.java:289)
[exportDomainData] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:274)
[exportDomainData] at java.lang.ClassLoader.loadClass(ClassLoader.java:235)
[exportDomainData] at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:302)
[exportDomainData] at java.lang.Class.forName0(Native Method)
[exportDomainData] at java.lang.Class.forName(Class.java:219)
[exportDomainData] at org.springframework.beans.factory.support.BeanDefinitionReaderUtils.createBeanDefinition(BeanDefinitionReaderUtils.java:60)
[exportDomainData] at org.springframework.beans.factory.xml.DefaultXmlBeanDefinitionParser.parseBeanDefinition(DefaultXmlBeanDefinitionParser.java:306)
[exportDomainData] at org.springframework.beans.factory.xml.DefaultXmlBeanDefinitionParser.parseBeanDefinition(DefaultXmlBeanDefinitionParser.java:274)
[exportDomainData] at org.springframework.beans.factory.xml.DefaultXmlBeanDefinitionParser.registerBeanDefinitions(DefaultXmlBeanDefinitionParser.java:186)
[exportDomainData] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:175)
[exportDomainData] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:133)
[exportDomainData] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:99)
[exportDomainData] at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:102)
[exportDomainData] at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:70)
[exportDomainData] at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:87)
[exportDomainData] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:262)
&#91;exportDomainData&#93; at org.springframework.context.support.FileSystemXmlApplicationContext.<init>&#40;FileSystemXmlApplicationContext.java&#58;82&#41;
&#91;exportDomainData&#93; at org.springframework.context.support.FileSystemXmlApplicationContext.<init>&#40;FileSystemXmlApplicationContext.java&#58;67&#41;
&#91;exportDomainData&#93; at org.springframework.context.support.FileSystemXmlApplicationContext.<init>&#40;FileSystemXmlApplicationContext.java&#58;58&#41;
&#91;exportDomainData&#93; at com.sourceallies.hit.util.ant.DomainDataExportTask.setupBeanFactory&#40;Unknown Source&#41;
&#91;exportDomainData&#93; at com.sourceallies.hit.util.ant.DomainDataExportTask.execute&#40;Unknown Source&#41;
&#91;exportDomainData&#93; at org.apache.tools.ant.UnknownElement.execute&#40;UnknownElement.java&#58;275&#41;
&#91;exportDomainData&#93; at org.apache.tools.ant.Task.perform&#40;Task.java&#58;364&#41;
&#91;exportDomainData&#93; at org.apache.tools.ant.Target.execute&#40;Target.java&#58;341&#41;
&#91;exportDomainData&#93; at org.apache.tools.ant.Target.performTasks&#40;Target.java&#58;369&#41;
&#91;exportDomainData&#93; at org.apache.tools.ant.Project.executeTarget&#40;Project.java&#58;1214&#41;
&#91;exportDomainData&#93; at org.apache.tools.ant.Project.executeTargets&#40;Project.java&#58;1062&#41;
&#91;exportDomainData&#93; at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.run&#40;InternalAntRunner.java&#58;387&#41;
&#91;exportDomainData&#93; at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.main&#40;InternalAntRunner.java&#58;136&#41;

Note the call to Class.forName() that loads the same class right before I try to load the ApplicationContext. It succeeds, and you can see from the stack trace that my Spring configuration file is being propertly loaded and read, but barfs when trying to instantiate the DriverManager. Why?

I'm a relative Spring newbie, and I'm pretty sure there's something fundamental I'm missing here, but what is it?

BTW - nice article. I've bookmarked it for future use as I wish to do more Ant/Spring stuff, but this is a quick and dirty and I can't make that work.

Why won't the FileSystemXmlApplicationContext load a class from the same classpath that the code on the preceding line is using?

Thanks again for the help.

Brian

[jbetancourt]

I haven't looked closely at your stack traces (I'm at work right now), however, when working on the Ant project, I did run into class loader issues. The way Ant does classloader stuff does not allow straightforward reuse. I used a technique I found in the Ant mailing list. Not sure if this is applicable to your exact problem.

[stibrian]

I'll look at your code more closely to see what you're talking about, but if it is an ant classloader issue then why can I load the class with Class.forName() but not with the ApplicationContext? I'm not a classloading genius so maybe I'm missing a subtlety here.... i'm rather confused.

[manifoldronin]

Class.forName() uses the classloader that loaded the current class, while I think ApplicationContext's implementations use the current thread context classloader. That might be what caused the different behavior (not sure how exactly though).

[stibrian]

I can't say as I understand the difference between the classloader that loaded the current class and the thread context classloader. I have a single thread of execution, why aren't they the same? As I said, I'm not a classloader guru, but am now more confused than ever.
If these 2 classloaders are in fact different, this begs the question: how do I tell Spring to use the classload that loaded the class I'm CALLING SPRING FROM, rather than some other one. I don't see how that behavior would make sense, but I'm always looking to be schooled, or at least pointed in the right direction.

[jbetancourt]

Classloader limitations are the floppy disk of the 21st century.

In my Ant implementation's AbstractAntTask I have:

        // code to handle cnf issues with taskdef classloader
        AntClassLoader2 antClassLoader = null;
        Object obj = this.getClass().getClassLoader();
        if (obj instanceof AntClassLoader2) {
            antClassLoader = (AntClassLoader2) obj;
            antClassLoader.setThreadContextLoader();
        }
        // end code to handle classnotfound issue

But, my issue was that the unit tests would not run in both command line and Eclipse. Anyway, I'm not a classloader expert.

[manifoldronin]

I can't say as I understand the difference between the classloader that loaded the current class and the thread context classloader. I have a single thread of execution, why aren't they the same? As I said, I'm not a classloader guru, but am now more confused than ever.

I don't understand how exactly it didn't work either. Why don't you print out the class names of the two classloaders - even just for the sake of knowing?

If these 2 classloaders are in fact different, this begs the question: how do I tell Spring to use the classload that loaded the class I'm CALLING SPRING FROM, rather than some other one. I don't see how that behavior would make sense, but I'm always looking to be schooled, or at least pointed in the right direction.

Have you tried using setContextClassLoader as jbetancourt pointed out?

[stibrian]

Having gotten a fix (thanks a million jbetancourt ), I plan to do more more investigation/education about classloaders in general. the code from teh abstract ant task that jbetancourt posted did the trick, but I hate to use even asnippet of code if I don't understand why its there - that's just prgramming by coincidence. :evil:

Funny thing, this same snippet of code was used to modify the Jasperreports ant compiler task.... now I REALLY have to understand what's going on.

Thanks for all the help, and I'll post any other information relevant to this topic here.

Brian