The Spring Framework

## org.springframework.ui.velocity
Class VelocityEngineFactory

    java.lang.Object
      org.springframework.ui.velocity.VelocityEngineFactory

Direct Known Subclasses:
  VelocityConfigurer, VelocityEngineFactoryBean

    public class VelocityEngineFactory

extends Object

Factory that configures a VelocityEngine. Can be used standalone, but typically you will either use `VelocityEngineFactoryBean` for preparing a VelocityEngine as bean reference, or `VelocityConfigurer` for web views.

The optional "configLocation" property sets the location of the Velocity properties file, within the current application. Velocity properties can be overridden via "velocityProperties", or even completely specified locally, avoiding the need for an external properties file.

The "resourceLoaderPath" property can be used to specify the Velocity resource loader path via Spring's Resource abstraction, possibly relative to the Spring application context.

If "overrideLogging" is true (the default), the VelocityEngine will be configured to log via Commons Logging, that is, using the Spring-provided `CommonsLoggingLogSystem` as log system.

The simplest way to use this class is to specify a `"resourceLoaderPath"`; the VelocityEngine typically then does not need any further configuration.

Author:
  Juergen Hoeller
See Also:
  `setConfigLocation(org.springframework.core.io.Resource)`, `setVelocityProperties(java.util.Properties)`, `setResourceLoaderPath(java.lang.String)`, `setOverrideLogging(boolean)`, `createVelocityEngine()`, `CommonsLoggingLogSystem`, `VelocityEngineFactoryBean`, `VelocityConfigurer`, `VelocityEngine`

Field Summary
`protected Log` `logger`

Constructor Summary
`VelocityEngineFactory()`

Method Summary
`VelocityEngine` `createVelocityEngine()` Prepare the VelocityEngine instance and return it.
`protected ResourceLoader` `getResourceLoader()` Return the Spring ResourceLoader to use for loading Velocity template files.
`protected void` `initSpringResourceLoader(VelocityEngine velocityEngine, String resourceLoaderPath)` Initialize a SpringResourceLoader for the given VelocityEngine.
`protected void` `initVelocityResourceLoader(VelocityEngine velocityEngine, String resourceLoaderPath)` Initialize a Velocity resource loader for the given VelocityEngine: either a standard Velocity FileResourceLoader or a SpringResourceLoader.
`protected boolean` `isPreferFileSystemAccess()` Return whether to prefer file system access for template loading.
`protected VelocityEngine` `newVelocityEngine()` Return a new VelocityEngine.
`protected void` `postProcessVelocityEngine(VelocityEngine velocityEngine)` To be implemented by subclasses that want to to perform custom post-processing of the VelocityEngine after this FactoryBean performed its default configuration (but before VelocityEngine.init).
`void` `setConfigLocation(Resource configLocation)` Set the location of the Velocity config file.
`void` `setOverrideLogging(boolean overrideLogging)` Set whether Velocity should log via Commons Logging, i.e. whether Velocity's log system should be set to CommonsLoggingLogSystem.
`void` `setPreferFileSystemAccess(boolean preferFileSystemAccess)` Set whether to prefer file system access for template loading.
`void` `setResourceLoader(ResourceLoader resourceLoader)` Set the Spring ResourceLoader to use for loading Velocity template files.
`void` `setResourceLoaderPath(String resourceLoaderPath)` Set the Velocity resource loader path via a Spring resource location.
`void` `setVelocityProperties(Properties velocityProperties)` Set Velocity properties, like "file.resource.loader.path".
`void` `setVelocityPropertiesMap(Map velocityPropertiesMap)` Set Velocity properties as Map, to allow for non-String values like "ds.resource.loader.instance".

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### logger

    protected final Log logger

Constructor Detail

### VelocityEngineFactory

    public VelocityEngineFactory()

Method Detail

### setConfigLocation

    public void setConfigLocation(Resource configLocation)

  Set the location of the Velocity config file. Alternatively, you can specify all properties locally.

  See Also:
    `setVelocityProperties(java.util.Properties)`, `setResourceLoaderPath(java.lang.String)`

### setVelocityProperties

    public void setVelocityProperties(Properties velocityProperties)

  Set Velocity properties, like "file.resource.loader.path". Can be used to override values in a Velocity config file, or to specify all necessary properties locally.

  Note that the Velocity resource loader path also be set to any Spring resource location via the "resourceLoaderPath" property. Setting it here is just necessary when using a non-file-based resource loader.

  See Also:
    `setVelocityPropertiesMap(java.util.Map)`, `setConfigLocation(org.springframework.core.io.Resource)`, `setResourceLoaderPath(java.lang.String)`

### setVelocityPropertiesMap

    public void setVelocityPropertiesMap(Map velocityPropertiesMap)

  Set Velocity properties as Map, to allow for non-String values like "ds.resource.loader.instance".

  See Also:
    `setVelocityProperties(java.util.Properties)`

### setResourceLoaderPath

    public void setResourceLoaderPath(String resourceLoaderPath)

  Set the Velocity resource loader path via a Spring resource location. Accepts multiple locations in Velocity's comma-separated path style.

  When populated via a String, standard URLs like "file:" and "classpath:" pseudo URLs are supported, as understood by ResourceLoader. Allows for relative paths when running in an ApplicationContext.

  Will define a path for the default Velocity resource loader with the name "file". If the specified resource cannot be resolved to a `java.io.File`, a generic SpringResourceLoader will be used under the name "spring", without modification detection.

  Note that resource caching will be enabled in any case. With the file resource loader, the last-modified timestamp will be checked on access to detect changes. With SpringResourceLoader, the resource will be cached forever (for example for class path resources).

  To specify a modification check interval for files, use Velocity's standard "file.resource.loader.modificationCheckInterval" property. By default, the file timestamp is checked on every access (which is surprisingly fast). Of course, this just applies when loading resources from the file system.

  To enforce the use of SpringResourceLoader, i.e. to not resolve a path as file system resource in any case, turn off the "preferFileSystemAccess" flag. See the latter's javadoc for details.

  See Also:
    `setResourceLoader(org.springframework.core.io.ResourceLoader)`, `setVelocityProperties(java.util.Properties)`, `setPreferFileSystemAccess(boolean)`, `SpringResourceLoader`, `FileResourceLoader`

### setResourceLoader

    public void setResourceLoader(ResourceLoader resourceLoader)

  Set the Spring ResourceLoader to use for loading Velocity template files. The default is DefaultResourceLoader. Will get overridden by the ApplicationContext if running in a context.

  See Also:
    `DefaultResourceLoader`, `ApplicationContext`

### getResourceLoader

    protected ResourceLoader getResourceLoader()

  Return the Spring ResourceLoader to use for loading Velocity template files.

### setPreferFileSystemAccess

    public void setPreferFileSystemAccess(boolean preferFileSystemAccess)

  Set whether to prefer file system access for template loading. File system access enables hot detection of template changes.

  If this is enabled, VelocityEngineFactory will try to resolve the specified "resourceLoaderPath" as file system resource (which will work for expanded class path resources and ServletContext resources too).

  Default is "true". Turn this off to always load via SpringResourceLoader (i.e. as stream, without hot detection of template changes), which might be necessary if some of your templates reside in an expanded classes directory while others reside in jar files.

  See Also:
    `setResourceLoaderPath(java.lang.String)`

### isPreferFileSystemAccess

    protected boolean isPreferFileSystemAccess()

  Return whether to prefer file system access for template loading.

### setOverrideLogging

    public void setOverrideLogging(boolean overrideLogging)

  Set whether Velocity should log via Commons Logging, i.e. whether Velocity's log system should be set to CommonsLoggingLogSystem. Default value is true.

  See Also:
    `CommonsLoggingLogSystem`

### createVelocityEngine

    public VelocityEngine createVelocityEngine()
                                        throws IOException,
                                               VelocityException

  Prepare the VelocityEngine instance and return it.

  Returns:
    the VelocityEngine instance
  Throws:
    `IOException` - if the config file wasn't found
    `VelocityException` - on Velocity initialization failure

### newVelocityEngine

    protected VelocityEngine newVelocityEngine()
                                        throws IOException,
                                               VelocityException

  Return a new VelocityEngine. Subclasses can override this for custom initialization, or for using a mock object for testing.

  Called by `createVelocityEngine()`.

  Returns:
    the VelocityEngine instance
  Throws:
    `IOException` - if a config file wasn't found
    `VelocityException` - on Velocity initialization failure
  See Also:
    `createVelocityEngine()`

### initVelocityResourceLoader

    protected void initVelocityResourceLoader(VelocityEngine velocityEngine,
                                              String resourceLoaderPath)

  Initialize a Velocity resource loader for the given VelocityEngine: either a standard Velocity FileResourceLoader or a SpringResourceLoader.

  Called by `createVelocityEngine()`.

  Parameters:
    `velocityEngine` - the VelocityEngine to configure
    `resourceLoaderPath` - the path to load Velocity resources from
  See Also:
    `FileResourceLoader`, `SpringResourceLoader`, `initSpringResourceLoader(org.apache.velocity.app.VelocityEngine, java.lang.String)`, `createVelocityEngine()`

### initSpringResourceLoader

    protected void initSpringResourceLoader(VelocityEngine velocityEngine,
                                            String resourceLoaderPath)

  Initialize a SpringResourceLoader for the given VelocityEngine.

  Called by `initVelocityResourceLoader`.

  Parameters:
    `velocityEngine` - the VelocityEngine to configure
    `resourceLoaderPath` - the path to load Velocity resources from
  See Also:
    `SpringResourceLoader`, `initVelocityResourceLoader(org.apache.velocity.app.VelocityEngine, java.lang.String)`

### postProcessVelocityEngine

    protected void postProcessVelocityEngine(VelocityEngine velocityEngine)
                                      throws IOException,
                                             VelocityException

  To be implemented by subclasses that want to to perform custom post-processing of the VelocityEngine after this FactoryBean performed its default configuration (but before VelocityEngine.init).

  Called by `createVelocityEngine()`.

  Parameters:
    `velocityEngine` - the current VelocityEngine
  Throws:
    `IOException` - if a config file wasn't found
    `VelocityException` - on Velocity initialization failure
  See Also:
    `createVelocityEngine()`, `VelocityEngine.init()`

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