org.dellroad.stuff.pobj
Class SpringPersistentObjectSchemaUpdater<T>

java.lang.Object
  org.dellroad.stuff.schema.AbstractSchemaUpdater<File,PersistentFileTransaction>
      org.dellroad.stuff.pobj.PersistentObjectSchemaUpdater<T>
          org.dellroad.stuff.pobj.SpringPersistentObjectSchemaUpdater<T>

Type Parameters:

T - type of the root persistent object

All Implemented Interfaces:

BeanFactoryAware, DisposableBean, InitializingBean

public class SpringPersistentObjectSchemaUpdater<T>
extends PersistentObjectSchemaUpdater<T>
implements BeanFactoryAware, InitializingBean, DisposableBean

PersistentObjectSchemaUpdater optimized for use with Spring:

• getOrderingTieBreaker() is overridden to break ties by ordering updates in the same order as they are defined in the bean factory.
• This class implements InitializingBean and verifies all required properties are set.
• If no updates are explicitly configured, then all SpringPersistentObjectSchemaUpdates found in the containing bean factory are automatically configured; this requires that all of the schema updates are defined in the same ListableBeanFactory.

An example of how this class can be combined with custom XML to define an updater and all its updates:

  <beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="
      http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

      <!-- Persistent object delegate; you supply the XML (un)marshaller -->
      <bean id="delegate" class="org.dellroad.stuff.pobj.SpringDelegate"
          p:marshaller-ref="marshaller" p:unmarshaller-ref="unmarshaller"/>

      <!-- Persistent object schema updater -->
      <bean id="schemaUpdater" class="org.dellroad.stuff.pobj.SpringPersistentObjectSchemaUpdater"
          p:file="/var/example/pobj.xml" p:delegate-ref="delegate"
          p:initialXML="classpath:com/example/initial-pobj.xml"/>

      <!-- Persistent object bean -->
      <bean scope="prototype" factory-bean="schemaUpdater" factory-method="getPersistentObject"/>

      <!-- Define a common location for our schema update XSLTs -->
      <bean class="org.dellroad.stuff.pobj.SpringXSLUpdateTransformConfigurer"
          p:prefix="classpath:updates/" p:suffix=".xsl"/>

      <!-- Schema update #1 -->
      <bean id="update1" class="org.dellroad.stuff.pobj.SpringXSLPersistentObjectSchemaUpdate"
        transform="file:///usr/share/updates/SomeUpdate.xsl"/>

      <!-- Schema update #2: uses "classpath:updates/update2.xsl" thanks to TransformConfigurer -->
      <bean id="update2" class="org.dellroad.stuff.pobj.SpringXSLPersistentObjectSchemaUpdate"/>

      <!-- Add more schema updates over time as needed and everything just works... -->

  </beans>
 

The PersistentObject itself, fully updated, is accessible via PersistentObjectSchemaUpdater.getPersistentObject(). or, in the above example, via the persistentObject bean.

Field Summary

Fields inherited from class org.dellroad.stuff.pobj.PersistentObjectSchemaUpdater

allowEmptyStart, checkInterval, DEFAULT_CHECK_INTERVAL, delegate, file, NAMESPACE_URI, numBackups, UPDATE_ELEMENT_NAME, UPDATES_ELEMENT_NAME, writeDelay, XML_PREFIX, XMLNS_ATTRIBUTE_NAME

Fields inherited from class org.dellroad.stuff.schema.AbstractSchemaUpdater

log

Constructor Summary

SpringPersistentObjectSchemaUpdater()

Method Summary

void	afterPropertiesSet()
void	destroy()
protected T	getInitialValue() Get the initial value for the persistent object when no persistent file is found.
protected Comparator<SchemaUpdate<PersistentFileTransaction>>	getOrderingTieBreaker() Get the preferred ordering of two updates that do not have any predecessor constraints (including implied indirect constraints) between them.
void	setBeanFactory(BeanFactory beanFactory)
void	setInitialValue(T initialValue) Set the initial value to be used on an uninitialized persistent object.
void	setInitialXML(Resource resource) Set the resource containing the initial value, encoded as XML, to be used on an uninitialized persistent object.

Methods inherited from class org.dellroad.stuff.pobj.PersistentObjectSchemaUpdater

commitTransaction, databaseNeedsInitialization, getAppliedUpdateNames, getPersistentObject, initializeDatabase, openTransaction, recordUpdateApplied, rollbackTransaction, setAllowEmptyStart, setCheckInterval, setDelegate, setFile, setNumBackups, setWriteDelay, start, stop

Methods inherited from class org.dellroad.stuff.schema.AbstractSchemaUpdater

apply, applyInTransaction, generateMultiUpdateName, getUpdates, initializeAndUpdateDatabase, isIgnoreUnrecognizedUpdates, isValidUpdateName, setIgnoreUnrecognizedUpdates, setUpdates

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SpringPersistentObjectSchemaUpdater

public SpringPersistentObjectSchemaUpdater()

Method Detail

setInitialValue

public void setInitialValue(T initialValue)

Set the initial value to be used on an uninitialized persistent object.

Either this or a initial XML resource should be configured to handle the case that no persistent file exists yet.

setInitialXML

public void setInitialXML(Resource resource)

Set the resource containing the initial value, encoded as XML, to be used on an uninitialized persistent object. This can be used as an alternative to setInitialValue(T).

Either this or an explicit initial value should be configured to handle the case that no persistent file exists yet.

getInitialValue

protected T getInitialValue()

Get the initial value for the persistent object when no persistent file is found.

The implementation in SpringPersistentObjectSchemaUpdater returns the initial value, if any, otherwise it falls back to decoding the initial value from the initial value resource, if any. If neither property is configured, null is returned.

Overrides:

getInitialValue in class PersistentObjectSchemaUpdater<T>

setBeanFactory

public void setBeanFactory(BeanFactory beanFactory)

Specified by:

setBeanFactory in interface BeanFactoryAware

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Specified by:

afterPropertiesSet in interface InitializingBean

Throws:

Exception

destroy

public void destroy()

Specified by:

destroy in interface DisposableBean

getOrderingTieBreaker

protected Comparator<SchemaUpdate<PersistentFileTransaction>> getOrderingTieBreaker()

Get the preferred ordering of two updates that do not have any predecessor constraints (including implied indirect constraints) between them.

In the case no schema updates are explicitly configured, the Comparator returned by the implementation in SpringPersistentObjectSchemaUpdater sorts updates in the same order that they appear in the containing ListableBeanFactory. Otherwise, the superclass method is used.

Overrides:

getOrderingTieBreaker in class AbstractSchemaUpdater<File,PersistentFileTransaction>

Returns:

a Comparator that sorts incomparable updates in the order they should be applied