org.springframework.scripting.support

Class ScriptFactoryPostProcessor

java.lang.Object

org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter

org.springframework.scripting.support.ScriptFactoryPostProcessor

All Implemented Interfaces:

Aware, BeanClassLoaderAware, BeanFactoryAware, BeanPostProcessor, InstantiationAwareBeanPostProcessor, SmartInstantiationAwareBeanPostProcessor, DisposableBean, ResourceLoaderAware, Ordered

public class ScriptFactoryPostProcessor
extends InstantiationAwareBeanPostProcessorAdapter
implements BeanClassLoaderAware, BeanFactoryAware, ResourceLoaderAware, DisposableBean, Ordered

BeanPostProcessor that handles ScriptFactory definitions, replacing each factory with the actual scripted Java object generated by it.

This is similar to the FactoryBean mechanism, but is specifically tailored for scripts and not built into Spring's core container itself but rather implemented as an extension.

NOTE: The most important characteristic of this post-processor is that constructor arguments are applied to the ScriptFactory instance while bean property values are applied to the generated scripted object. Typically, constructor arguments include a script source locator and potentially script interfaces, while bean property values include references and config values to inject into the scripted object itself.

The following ScriptFactoryPostProcessor will automatically be applied to the two ScriptFactory definitions below. At runtime, the actual scripted objects will be exposed for "bshMessenger" and "groovyMessenger", rather than the ScriptFactory instances. Both of those are supposed to be castable to the example's Messenger interfaces here.

<bean class="org.springframework.scripting.support.ScriptFactoryPostProcessor"/>

 <bean id="bshMessenger" class="org.springframework.scripting.bsh.BshScriptFactory">
   <constructor-arg value="classpath:mypackage/Messenger.bsh"/>
   <constructor-arg value="mypackage.Messenger"/>
   <property name="message" value="Hello World!"/>
 </bean>

 <bean id="groovyMessenger" class="org.springframework.scripting.groovy.GroovyScriptFactory">
   <constructor-arg value="classpath:mypackage/Messenger.groovy"/>
   <property name="message" value="Hello World!"/>
 </bean>

NOTE: Please note that the above excerpt from a Spring XML bean definition file uses just the <bean/>-style syntax (in an effort to illustrate using the ScriptFactoryPostProcessor itself). In reality, you would never create a <bean/> definition for a ScriptFactoryPostProcessor explicitly; rather you would import the tags from the 'lang' namespace and simply create scripted beans using the tags in that namespace... as part of doing so, a ScriptFactoryPostProcessor will implicitly be created for you.

The Spring reference documentation contains numerous examples of using tags in the 'lang' namespace; by way of an example, find below a Groovy-backed bean defined using the 'lang:groovy' tag.

 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns:lang="http://www.springframework.org/schema/lang">

   <!-- this is the bean definition for the Groovy-backed Messenger implementation -->
   <lang:groovy id="messenger" script-source="classpath:Messenger.groovy">
     <lang:property name="message" value="I Can Do The Frug" />
   </lang:groovy>

   <!-- an otherwise normal bean that will be injected by the Groovy-backed Messenger -->
   <bean id="bookingService" class="x.y.DefaultBookingService">
     <property name="messenger" ref="messenger" />
   </bean>

 </beans>

Since:

2.0

Author:

Juergen Hoeller, Rob Harrop, Rick Evans, Mark Fisher

Field Summary

Fields

Modifier and Type	Field and Description
static String	INLINE_SCRIPT_PREFIX The Resource-style prefix that denotes an inline script.
static String	LANGUAGE_ATTRIBUTE
protected Log	logger Logger available to subclasses
static String	PROXY_TARGET_CLASS_ATTRIBUTE
static String	REFRESH_CHECK_DELAY_ATTRIBUTE

Fields inherited from interface org.springframework.core.Ordered

HIGHEST_PRECEDENCE, LOWEST_PRECEDENCE

Constructor Summary

Constructors

Constructor and Description
ScriptFactoryPostProcessor()

Method Summary

Modifier and Type	Method and Description
protected ScriptSource	convertToScriptSource(String beanName, String scriptSourceLocator, ResourceLoader resourceLoader) Convert the given script source locator to a ScriptSource instance.
protected Class<?>	createCompositeInterface(Class<?>[] interfaces) Create a composite interface Class for the given interfaces, implementing the given interfaces in one single Class.
protected Class<?>	createConfigInterface(BeanDefinition bd, Class<?>[] interfaces) Create a config interface for the given bean definition, defining setter methods for the defined property values as well as an init method and a destroy method (if defined).
protected Object	createRefreshableProxy(TargetSource ts, Class<?>[] interfaces, boolean proxyTargetClass) Create a refreshable proxy for the given AOP TargetSource.
protected BeanDefinition	createScriptedObjectBeanDefinition(BeanDefinition bd, String scriptFactoryBeanName, ScriptSource scriptSource, Class<?>[] interfaces) Create a bean definition for the scripted object, based on the given script definition, extracting the definition data that is relevant for the scripted object (that is, everything but bean class and constructor arguments).
protected BeanDefinition	createScriptFactoryBeanDefinition(BeanDefinition bd) Create a ScriptFactory bean definition based on the given script definition, extracting only the definition data that is relevant for the ScriptFactory (that is, only bean class and constructor arguments).
void	destroy() Destroy the inner bean factory (used for scripts) on shutdown.
int	getOrder() Get the order value of this object.
protected ScriptSource	getScriptSource(String beanName, String scriptSourceLocator) Obtain a ScriptSource for the given bean, lazily creating it if not cached already.
Object	postProcessBeforeInstantiation(Class<?> beanClass, String beanName) Apply this BeanPostProcessor before the target bean gets instantiated.
Class<?>	predictBeanType(Class<?> beanClass, String beanName) Predict the type of the bean to be eventually returned from this processor's InstantiationAwareBeanPostProcessor.postProcessBeforeInstantiation(java.lang.Class<?>, java.lang.String) callback.
protected void	prepareScriptBeans(BeanDefinition bd, String scriptFactoryBeanName, String scriptedObjectBeanName) Prepare the script beans in the internal BeanFactory that this post-processor uses.
protected boolean	resolveProxyTargetClass(BeanDefinition beanDefinition)
protected long	resolveRefreshCheckDelay(BeanDefinition beanDefinition) Get the refresh check delay for the given ScriptFactory BeanDefinition.
void	setBeanClassLoader(ClassLoader classLoader) Callback that supplies the bean class loader to a bean instance.
void	setBeanFactory(BeanFactory beanFactory) Callback that supplies the owning factory to a bean instance.
void	setDefaultProxyTargetClass(boolean defaultProxyTargetClass) Flag to signal that refreshable proxies should be created to proxy the target class not its interfaces.
void	setDefaultRefreshCheckDelay(long defaultRefreshCheckDelay) Set the delay between refresh checks, in milliseconds.
void	setResourceLoader(ResourceLoader resourceLoader) Set the ResourceLoader that this object runs in.

Methods inherited from class org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter

determineCandidateConstructors, getEarlyBeanReference, postProcessAfterInitialization, postProcessAfterInstantiation, postProcessBeforeInitialization, postProcessPropertyValues

Methods inherited from class java.lang.Object

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

Field Detail

INLINE_SCRIPT_PREFIX

public static final String INLINE_SCRIPT_PREFIX

The Resource-style prefix that denotes an inline script.

An inline script is a script that is defined right there in the (typically XML) configuration, as opposed to being defined in an external file.

See Also:

Constant Field Values

REFRESH_CHECK_DELAY_ATTRIBUTE

public static final String REFRESH_CHECK_DELAY_ATTRIBUTE

PROXY_TARGET_CLASS_ATTRIBUTE

public static final String PROXY_TARGET_CLASS_ATTRIBUTE

LANGUAGE_ATTRIBUTE

public static final String LANGUAGE_ATTRIBUTE

logger

protected final Log logger

Logger available to subclasses

Constructor Detail

ScriptFactoryPostProcessor

public ScriptFactoryPostProcessor()

Method Detail

setDefaultRefreshCheckDelay

public void setDefaultRefreshCheckDelay(long defaultRefreshCheckDelay)

Set the delay between refresh checks, in milliseconds. Default is -1, indicating no refresh checks at all.

Note that an actual refresh will only happen when the ScriptSource indicates that it has been modified.

See Also:

ScriptSource.isModified()

setDefaultProxyTargetClass

public void setDefaultProxyTargetClass(boolean defaultProxyTargetClass)

Flag to signal that refreshable proxies should be created to proxy the target class not its interfaces.

Parameters:

defaultProxyTargetClass - the flag value to set

setBeanClassLoader

public void setBeanClassLoader(ClassLoader classLoader)

Description copied from interface: BeanClassLoaderAware

Callback that supplies the bean class loader to a bean instance.

Invoked after the population of normal bean properties but before an initialization callback such as InitializingBean's InitializingBean.afterPropertiesSet() method or a custom init-method.

Specified by:

setBeanClassLoader in interface BeanClassLoaderAware

Parameters:

classLoader - the owning class loader; may be null in which case a default ClassLoader must be used, for example the ClassLoader obtained via ClassUtils.getDefaultClassLoader()

setBeanFactory

public void setBeanFactory(BeanFactory beanFactory)

Description copied from interface: BeanFactoryAware

Callback that supplies the owning factory to a bean instance.

Invoked after the population of normal bean properties but before an initialization callback such as InitializingBean.afterPropertiesSet() or a custom init-method.

Specified by:

setBeanFactory in interface BeanFactoryAware

Parameters:

beanFactory - owning BeanFactory (never null). The bean can immediately call methods on the factory.

See Also:

BeanInitializationException

setResourceLoader

public void setResourceLoader(ResourceLoader resourceLoader)

Description copied from interface: ResourceLoaderAware

Set the ResourceLoader that this object runs in.

This might be a ResourcePatternResolver, which can be checked through instanceof ResourcePatternResolver. See also the ResourcePatternUtils.getResourcePatternResolver method.

Invoked after population of normal bean properties but before an init callback like InitializingBean's afterPropertiesSet or a custom init-method. Invoked before ApplicationContextAware's setApplicationContext.

Specified by:

setResourceLoader in interface ResourceLoaderAware

Parameters:

resourceLoader - ResourceLoader object to be used by this object

See Also:

ResourcePatternResolver, ResourcePatternUtils.getResourcePatternResolver(org.springframework.core.io.ResourceLoader)

getOrder

public int getOrder()

Description copied from interface: Ordered

Get the order value of this object.

Higher values are interpreted as lower priority. As a consequence, the object with the lowest value has the highest priority (somewhat analogous to Servlet load-on-startup values).

Same order values will result in arbitrary sort positions for the affected objects.

Specified by:

getOrder in interface Ordered

Returns:

the order value

See Also:

Ordered.HIGHEST_PRECEDENCE, Ordered.LOWEST_PRECEDENCE

predictBeanType

public Class<?> predictBeanType(Class<?> beanClass,
                                String beanName)

Description copied from interface: SmartInstantiationAwareBeanPostProcessor

Predict the type of the bean to be eventually returned from this processor's InstantiationAwareBeanPostProcessor.postProcessBeforeInstantiation(java.lang.Class<?>, java.lang.String) callback.

Specified by:

predictBeanType in interface SmartInstantiationAwareBeanPostProcessor

Overrides:

predictBeanType in class InstantiationAwareBeanPostProcessorAdapter

Parameters:

beanClass - the raw class of the bean

beanName - the name of the bean

Returns:

the type of the bean, or null if not predictable

postProcessBeforeInstantiation

public Object postProcessBeforeInstantiation(Class<?> beanClass,
                                             String beanName)

Description copied from interface: InstantiationAwareBeanPostProcessor

Apply this BeanPostProcessor before the target bean gets instantiated. The returned bean object may be a proxy to use instead of the target bean, effectively suppressing default instantiation of the target bean.

If a non-null object is returned by this method, the bean creation process will be short-circuited. The only further processing applied is the BeanPostProcessor.postProcessAfterInitialization(java.lang.Object, java.lang.String) callback from the configured BeanPostProcessors.

This callback will only be applied to bean definitions with a bean class. In particular, it will not be applied to beans with a "factory-method".

Post-processors may implement the extended SmartInstantiationAwareBeanPostProcessor interface in order to predict the type of the bean object that they are going to return here.

Specified by:

postProcessBeforeInstantiation in interface InstantiationAwareBeanPostProcessor

Overrides:

postProcessBeforeInstantiation in class InstantiationAwareBeanPostProcessorAdapter

Parameters:

beanClass - the class of the bean to be instantiated

beanName - the name of the bean

Returns:

the bean object to expose instead of a default instance of the target bean, or null to proceed with default instantiation

See Also:

AbstractBeanDefinition.hasBeanClass(), AbstractBeanDefinition.getFactoryMethodName()

prepareScriptBeans

protected void prepareScriptBeans(BeanDefinition bd,
                                  String scriptFactoryBeanName,
                                  String scriptedObjectBeanName)

Prepare the script beans in the internal BeanFactory that this post-processor uses. Each original bean definition will be split into a ScriptFactory definition and a scripted object definition.

Parameters:

bd - the original bean definition in the main BeanFactory

scriptFactoryBeanName - the name of the internal ScriptFactory bean

scriptedObjectBeanName - the name of the internal scripted object bean

resolveRefreshCheckDelay

protected long resolveRefreshCheckDelay(BeanDefinition beanDefinition)

Get the refresh check delay for the given ScriptFactory BeanDefinition. If the BeanDefinition has a metadata attribute under the key REFRESH_CHECK_DELAY_ATTRIBUTE which is a valid Number type, then this value is used. Otherwise, the defaultRefreshCheckDelay value is used.

Parameters:

beanDefinition - the BeanDefinition to check

Returns:

the refresh check delay

resolveProxyTargetClass

protected boolean resolveProxyTargetClass(BeanDefinition beanDefinition)

createScriptFactoryBeanDefinition

protected BeanDefinition createScriptFactoryBeanDefinition(BeanDefinition bd)

Create a ScriptFactory bean definition based on the given script definition, extracting only the definition data that is relevant for the ScriptFactory (that is, only bean class and constructor arguments).

Parameters:

bd - the full script bean definition

Returns:

the extracted ScriptFactory bean definition

See Also:

ScriptFactory

getScriptSource

protected ScriptSource getScriptSource(String beanName,
                                       String scriptSourceLocator)

Obtain a ScriptSource for the given bean, lazily creating it if not cached already.

Parameters:

beanName - the name of the scripted bean

scriptSourceLocator - the script source locator associated with the bean

Returns:

the corresponding ScriptSource instance

See Also:

convertToScriptSource(java.lang.String, java.lang.String, org.springframework.core.io.ResourceLoader)

convertToScriptSource

protected ScriptSource convertToScriptSource(String beanName,
                                             String scriptSourceLocator,
                                             ResourceLoader resourceLoader)

Convert the given script source locator to a ScriptSource instance.

By default, supported locators are Spring resource locations (such as "file:C:/myScript.bsh" or "classpath:myPackage/myScript.bsh") and inline scripts ("inline:myScriptText...").

Parameters:

beanName - the name of the scripted bean

scriptSourceLocator - the script source locator

resourceLoader - the ResourceLoader to use (if necessary)

Returns:

the ScriptSource instance

createConfigInterface

protected Class<?> createConfigInterface(BeanDefinition bd,
                                         Class<?>[] interfaces)

Create a config interface for the given bean definition, defining setter methods for the defined property values as well as an init method and a destroy method (if defined).

This implementation creates the interface via CGLIB's InterfaceMaker, determining the property types from the given interfaces (as far as possible).

Parameters:

bd - the bean definition (property values etc) to create a config interface for

interfaces - the interfaces to check against (might define getters corresponding to the setters we're supposed to generate)

Returns:

the config interface

See Also:

InterfaceMaker, BeanUtils.findPropertyType(java.lang.String, java.lang.Class<?>...)

createCompositeInterface

protected Class<?> createCompositeInterface(Class<?>[] interfaces)

Create a composite interface Class for the given interfaces, implementing the given interfaces in one single Class.

The default implementation builds a JDK proxy class for the given interfaces.

Parameters:

interfaces - the interfaces to merge

Returns:

the merged interface as Class

See Also:

Proxy.getProxyClass(java.lang.ClassLoader, java.lang.Class<?>...)

createScriptedObjectBeanDefinition

protected BeanDefinition createScriptedObjectBeanDefinition(BeanDefinition bd,
                                                            String scriptFactoryBeanName,
                                                            ScriptSource scriptSource,
                                                            Class<?>[] interfaces)

Create a bean definition for the scripted object, based on the given script definition, extracting the definition data that is relevant for the scripted object (that is, everything but bean class and constructor arguments).

Parameters:

bd - the full script bean definition

scriptFactoryBeanName - the name of the internal ScriptFactory bean

scriptSource - the ScriptSource for the scripted bean

interfaces - the interfaces that the scripted bean is supposed to implement

Returns:

the extracted ScriptFactory bean definition

See Also:

ScriptFactory.getScriptedObject(org.springframework.scripting.ScriptSource, java.lang.Class<?>...)

createRefreshableProxy

protected Object createRefreshableProxy(TargetSource ts,
                                        Class<?>[] interfaces,
                                        boolean proxyTargetClass)

Create a refreshable proxy for the given AOP TargetSource.

Parameters:

ts - the refreshable TargetSource

interfaces - the proxy interfaces (may be null to indicate proxying of all interfaces implemented by the target class)

Returns:

the generated proxy

See Also:

RefreshableScriptTargetSource

destroy

public void destroy()

Destroy the inner bean factory (used for scripts) on shutdown.

Specified by:

destroy in interface DisposableBean