ScriptFactoryPostProcessor (Spring Framework 3.2.1.RELEASE API)
Date: 2013-01-24

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.bsh.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

    Methods
    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()` Return the order value of this object, with a higher value meaning greater in terms of sorting.
    `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`
      Return the order value of this object, with a higher value meaning greater in terms of sorting.

      Normally starting with 0, with `Integer.MAX_VALUE` indicating the greatest value. Same order values will result in arbitrary positions for the affected objects.

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

      Specified by:
        `getOrder` in interface `Ordered`
      Returns:
        the order value

    - #### 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 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`