Package org.dellroad.stuff.pobj

Class SpringPersistentObjectSchemaUpdater<T>

java.lang.Object

org.dellroad.stuff.schema.AbstractSchemaUpdater<PersistentFileTransaction,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:

PersistentObjectDelegate<T>, Aware, BeanFactoryAware, InitializingBean

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

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.
• The default value may be configured as an XML resource

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">

      <!-- Normal nested persistent object delegate. You supply the XML (un)marshaller (not shown). -->
      <bean id="normalDelegate" class="org.dellroad.stuff.pobj.SpringDelegate"
        p:marshaller-ref="marshaller" p:unmarshaller-ref="unmarshaller"/>

      <!-- Schema updating persistent object delegate; the updates below will be auto-detected. -->
      <bean id="updatingDelegate" class="org.dellroad.stuff.pobj.SpringPersistentObjectSchemaUpdater"
        p:marshaller-ref="marshaller" p:unmarshaller-ref="unmarshaller" p:defaultXML="classpath:default.xml">
          <constructor-arg ref="normalDelegate"/>
      </bean>

      <!-- Persistent object, configured to use our schema updating delegate -->
      <bean id="persistentObject" class="org.dellroad.stuff.pobj.PersistentObject"
        init-method="start" destroy-method="stop" p:file="/var/lib/pobj.xml" p:allowEmptyStart="true"
        p:numBackups="3" p:delegate-ref="updatingDelegate"/>

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

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

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

      <!-- Schema update #3: requires that update #1 be applied first -->
      <bean id="update3" depends-on="update1"
        class="org.dellroad.stuff.pobj.SpringXSLPersistentObjectSchemaUpdate"/>

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

  </beans>
 

Field Summary

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

delegate, NAMESPACE_URI, UPDATE_ELEMENT_NAME, UPDATES_ELEMENT_NAME, XML_PREFIX, XMLNS_ATTRIBUTE_NAME

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

log

Constructor Summary

Constructors

Constructor	Description
SpringPersistentObjectSchemaUpdater(PersistentObjectDelegate<T> delegate)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	afterPropertiesSet()
T	getDefaultValue()	Get the default 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	setDefaultXML(Resource resource)	Set the resource containing the default value, encoded as XML, to be used on an uninitialized persistent object.

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

commitTransaction, copy, databaseNeedsInitialization, deserialize, getAppliedUpdateNames, handleWritebackException, initializeDatabase, isSameGraph, openTransaction, recordUpdateApplied, rollbackTransaction, serialize, setTransformerFactory, validate

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

apply, applyInTransaction, generateMultiUpdateName, getAllUpdateNames, 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 Details

SpringPersistentObjectSchemaUpdater

public SpringPersistentObjectSchemaUpdater(PersistentObjectDelegate<T> delegate)

Constructor.

Parameters:

delegate - delegate that will be wrapped by this instance

Throws:

IllegalArgumentException - if delegate is null

See Also:

• PersistentObjectSchemaUpdater(org.dellroad.stuff.pobj.PersistentObjectDelegate<T>)

Method Details

setDefaultXML

public void setDefaultXML(Resource resource)

Set the resource containing the default value, encoded as XML, to be used on an uninitialized persistent object. This will override whatever default value is returned by the nested delegate.

Parameters:

resource - default database content

getDefaultValue

public T getDefaultValue()

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

The implementation in SpringPersistentObjectSchemaUpdater parses and returns the default value resource, if any; otherwise, the delegate provided to the constructor is queried for a default value.

Specified by:

getDefaultValue in interface PersistentObjectDelegate<T>

Overrides:

getDefaultValue in class PersistentObjectSchemaUpdater<T>

Returns:

root object initial value, or null if there is no default value

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

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<PersistentFileTransaction,PersistentFileTransaction>

Returns:

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