Package org.springframework.scripting.support

Class ScriptFactoryPostProcessor

java.lang.Object
org.springframework.scripting.support.ScriptFactoryPostProcessor
All Implemented Interfaces:
Aware, BeanClassLoaderAware, BeanFactoryAware, BeanPostProcessor, InstantiationAwareBeanPostProcessor, SmartInstantiationAwareBeanPostProcessor, DisposableBean, ResourceLoaderAware, Ordered
public class ScriptFactoryPostProcessor extends Object implements SmartInstantiationAwareBeanPostProcessor, 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, Sam Brannen

  • Field Details

    • 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:

    • REFRESH_CHECK_DELAY_ATTRIBUTE

      public static final String REFRESH_CHECK_DELAY_ATTRIBUTE
      The refreshCheckDelay attribute.

    • PROXY_TARGET_CLASS_ATTRIBUTE

      public static final String PROXY_TARGET_CLASS_ATTRIBUTE
      The proxyTargetClass attribute.

    • LANGUAGE_ATTRIBUTE

      public static final String LANGUAGE_ATTRIBUTE
      The language attribute.

    • logger

      protected final Log logger
      Logger available to subclasses.

  • Constructor Details

    • ScriptFactoryPostProcessor

      public ScriptFactoryPostProcessor()

  • Method Details

    • 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:

    • 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

    • 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:

    • 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 - the ResourceLoader object to be used by this object
      See Also:

    • 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:

    • predictBeanType

      @Nullable 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.

      The default implementation returns null. Specific implementations should try to predict the bean type as far as known/cached already, without extra processing steps.

      Specified by:
      predictBeanType in interface SmartInstantiationAwareBeanPostProcessor
      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

    • postProcessProperties

      public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName)
      Description copied from interface: InstantiationAwareBeanPostProcessor
      Post-process the given property values before the factory applies them to the given bean.

      The default implementation returns the given pvs as-is.

      Specified by:
      postProcessProperties in interface InstantiationAwareBeanPostProcessor
      Parameters:
      pvs - the property values that the factory is about to apply (never null)
      bean - the bean instance created, but whose properties have not yet been set
      beanName - the name of the bean
      Returns:
      the actual property values to apply to the given bean (can be the passed-in PropertyValues instance), or null to skip property population

    • postProcessBeforeInstantiation

      @Nullable 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 be applied to bean definitions with their bean class, as well as to factory-method definitions in which case the returned bean type will be passed in here.

      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.

      The default implementation returns null.

      Specified by:
      postProcessBeforeInstantiation in interface InstantiationAwareBeanPostProcessor
      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:

    • 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:

    • 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

      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, @Nullable 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:

    • 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:

    • createScriptedObjectBeanDefinition

      protected BeanDefinition createScriptedObjectBeanDefinition(BeanDefinition bd, String scriptFactoryBeanName, ScriptSource scriptSource, @Nullable 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:

    • createRefreshableProxy

      protected Object createRefreshableProxy(TargetSource ts, @Nullable 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:

    • destroy

      public void destroy()
      Destroy the inner bean factory (used for scripts) on shutdown.
      Specified by:
      destroy in interface DisposableBean