Package org.apache.velocity.runtime

Class RuntimeInstance

  • All Implemented Interfaces:
    DeprecatedRuntimeConstants, RuntimeConstants, RuntimeServices
    public class RuntimeInstance
extends Object
implements RuntimeConstants, RuntimeServices

    This is the Runtime system for Velocity. It is the single access point for all functionality in Velocity. It adheres to the mediator pattern and is the only structure that developers need to be familiar with in order to get Velocity to perform.

    The Runtime will also cooperate with external systems, which can make all needed setProperty() calls before calling init().

     -----------------------------------------------------------------------
 N O T E S  O N  R U N T I M E  I N I T I A L I Z A T I O N
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 init()

 If init() is called by itself the RuntimeInstance will initialize
 with a set of default values.
 -----------------------------------------------------------------------
 init(String/Properties)

 In this case the default velocity properties are layed down
 first to provide a solid base, then any properties provided
 in the given properties object will override the corresponding
 default property.
 -----------------------------------------------------------------------
    Version:
    $Id$
    Author:
    Jason van Zyl, Jeff Bowden, Geir Magusson Jr.

    • Constructor Detail

      • RuntimeInstance

        public RuntimeInstance()
        Creates a new RuntimeInstance object.

    • Method Detail

      • init

        public void init()
        This is the primary initialization method in the Velocity Runtime. The systems that are setup/initialized here are as follows:
        • Logging System
        • ResourceManager
        • EventHandler
        • Parser Pool
        • Global Cache
        • Static Content Include System
        • Velocimacro System
        Specified by:
        init in interface RuntimeServices

      • reset

        public void reset()
        Resets the instance, so Velocity can be re-initialized again.
        Since:
        2.0.0

      • isInitialized

        public boolean isInitialized()
        Returns true if the RuntimeInstance has been successfully initialized.
        Specified by:
        isInitialized in interface RuntimeServices
        Returns:
        True if the RuntimeInstance has been successfully initialized.
        Since:
        1.5

      • setProperty

        public void setProperty​(String key,
                        Object value)
        Allows an external system to set a property in the Velocity Runtime.
        Specified by:
        setProperty in interface RuntimeServices
        Parameters:
        key - property key
        value - property value

      • setProperties

        public void setProperties​(String fileName)
        Add all properties contained in the file fileName to the RuntimeInstance properties
        Parameters:
        fileName -

      • setProperties

        public void setProperties​(Properties props)
        Add all the properties in props to the RuntimeInstance properties
        Parameters:
        props -

      • setConfiguration

        public void setConfiguration​(ExtProperties configuration)
        Allow an external system to set an ExtProperties object to use.
        Specified by:
        setConfiguration in interface RuntimeServices
        Parameters:
        configuration -
        Since:
        2.0

      • addProperty

        public void addProperty​(String key,
                        Object value)
        Add a property to the configuration. If it already exists then the value stated here will be added to the configuration entry. For example, if resource.loader = file is already present in the configuration and you addProperty("resource.loader", "classpath") Then you will end up with a Vector like the following: ["file", "classpath"]
        Specified by:
        addProperty in interface RuntimeServices
        Parameters:
        key -
        value -

      • clearProperty

        public void clearProperty​(String key)
        Clear the values pertaining to a particular property.
        Specified by:
        clearProperty in interface RuntimeServices
        Parameters:
        key - of property to clear

      • getProperty

        public Object getProperty​(String key)
        Allows an external caller to get a property. The calling routine is required to know the type, as this routine will return an Object, as that is what properties can be.
        Specified by:
        getProperty in interface RuntimeServices
        Parameters:
        key - property to return
        Returns:
        Value of the property or null if it does not exist.

      • init

        public void init​(Properties p)
        Initialize the Velocity Runtime with a Properties object.
        Specified by:
        init in interface RuntimeServices
        Parameters:
        p - Velocity properties for initialization

      • init

        public void init​(String configurationFile)
        Initialize the Velocity Runtime with a properties file path.
        Specified by:
        init in interface RuntimeServices
        Parameters:
        configurationFile -

      • addDirective

        public void addDirective​(Directive directive)
        Programatically add a directive.
        Parameters:
        directive -

      • removeDirective

        public void removeDirective​(String name)
        Remove a directive.
        Parameters:
        name - name of the directive.

      • loadDirective

        public void loadDirective​(String directiveClass)
        instantiates and loads the directive with some basic checks
        Parameters:
        directiveClass - classname of directive to load

      • createNewParser

        public Parser createNewParser()
        Returns a JavaCC generated Parser.
        Specified by:
        createNewParser in interface RuntimeServices
        Returns:
        Parser javacc generated parser

      • parse

        public SimpleNode parse​(Reader reader,
                        Template template)
                 throws ParseException
        Parse the input and return the root of AST node structure.

        In the event that it runs out of parsers in the pool, it will create and let them be GC'd dynamically, logging that it has to do that. This is considered an exceptional condition. It is expected that the user will set the PARSER_POOL_SIZE property appropriately for their application. We will revisit this.
        Specified by:
        parse in interface RuntimeServices
        Parameters:
        reader - Reader retrieved by a resource loader
        template - template being parsed
        Returns:
        A root node representing the template as an AST tree.
        Throws:
        ParseException - When the template could not be parsed.

      • evaluate

        public boolean evaluate​(Context context,
                        Writer out,
                        String logTag,
                        String instring)
        Renders the input string using the context into the output writer. To be used when a template is dynamically constructed, or want to use Velocity as a token replacer.
        Note! Macros defined in evaluate() calls are not persisted in memory so next evaluate() call does not know about macros defined during previous calls.
        Specified by:
        evaluate in interface RuntimeServices
        Parameters:
        context - context to use in rendering input string
        out - Writer in which to render the output
        logTag - string to be used as the template name for log messages in case of error
        instring - input string containing the VTL to be rendered
        Returns:
        true if successful, false otherwise. If false, see Velocity runtime log
        Throws:
        ParseErrorException - The template could not be parsed.
        MethodInvocationException - A method on a context object could not be invoked.
        ResourceNotFoundException - A referenced resource could not be loaded.
        Since:
        Velocity 1.6

      • evaluate

        public boolean evaluate​(Context context,
                        Writer writer,
                        String logTag,
                        Reader reader)
        Renders the input reader using the context into the output writer. To be used when a template is dynamically constructed, or want to use Velocity as a token replacer.
        Note! Macros defined in evaluate() calls are not persisted in memory so next evaluate() call does not know about macros defined during previous calls.
        Specified by:
        evaluate in interface RuntimeServices
        Parameters:
        context - context to use in rendering input string
        writer - Writer in which to render the output
        logTag - string to be used as the template name for log messages in case of error
        reader - Reader containing the VTL to be rendered
        Returns:
        true if successful, false otherwise. If false, see Velocity runtime log
        Throws:
        ParseErrorException - The template could not be parsed.
        MethodInvocationException - A method on a context object could not be invoked.
        ResourceNotFoundException - A referenced resource could not be loaded.
        Since:
        Velocity 1.6

      • render

        public boolean render​(Context context,
                      Writer writer,
                      String logTag,
                      SimpleNode nodeTree)

        Initializes and renders the AST SimpleNode using the context into the output writer.

        Note that the nodeTree argument should be a fresh AST tree obtained by the parse(Reader, Template) method.

        If you wish to reuse AST trees but bypass the resource loading mechanism, you should rely on the Template API, as follow:

        
      RuntimeInstance runtimeInstance = new RuntimeInstance();
      Template template = new Template();
      template.setName("my_template");
      template.setRuntimeServices(runtimeInstance);
      SimpleNode astTree = runtimeInstance.parse(new StringReader("Some template..."), template);
      template.setData(astTree);
      template.initDocument();

        You will then be able to render several times the template with template.render(context, writer).

        Parameters:
        context - context to use in rendering input string
        writer - Writer in which to render the output
        logTag - string to be used as the template name for log messages in case of error
        nodeTree - SimpleNode which is the root of the AST to be rendered
        Returns:
        true if successful, false otherwise. If false, see Velocity runtime log for errors
        Throws:
        ParseErrorException - The template could not be parsed.
        MethodInvocationException - A method on a context object could not be invoked.
        ResourceNotFoundException - A referenced resource could not be loaded.
        Since:
        Velocity 1.6

      • invokeVelocimacro

        public boolean invokeVelocimacro​(String vmName,
                                 String logTag,
                                 String[] params,
                                 Context context,
                                 Writer writer)
        Invokes a currently registered Velocimacro with the params provided and places the rendered stream into the writer.
        Note: currently only accepts args to the VM if they are in the context.
        Note: only macros in the global context can be called. This method doesn't find macros defined by templates during previous mergeTemplate calls if Velocity.VM_PERM_INLINE_LOCAL has been enabled.
        Specified by:
        invokeVelocimacro in interface RuntimeServices
        Parameters:
        vmName - name of Velocimacro to call
        logTag - string to be used for template name in case of error. if null, the vmName will be used
        params - keys for args used to invoke Velocimacro, in java format rather than VTL (eg "foo" or "bar" rather than "$foo" or "$bar")
        context - Context object containing data/objects used for rendering.
        writer - Writer for output stream
        Returns:
        true if Velocimacro exists and successfully invoked, false otherwise.
        Since:
        1.6

      • getLoaderNameForResource

        public String getLoaderNameForResource​(String resourceName)
        Determines if a template exists and returns name of the loader that provides it. This is a slightly less hokey way to support the Velocity.resourceExists() utility method, which was broken when per-template encoding was introduced. We can revisit this.
        Specified by:
        getLoaderNameForResource in interface RuntimeServices
        Parameters:
        resourceName - Name of template or content resource
        Returns:
        class name of loader than can provide it

      • getLog

        public org.slf4j.Logger getLog()
        Returns the configured logger.
        Specified by:
        getLog in interface RuntimeServices
        Returns:
        A Logger instance
        Since:
        1.5

      • getLog

        public org.slf4j.Logger getLog​(String childNamespace)
        Get a logger for the specified child namespace. If a logger was configured using the runtime.log.instance configuration property, returns this instance. Otherwise, uses SLF4J LoggerFactory on baseNamespace '.' childNamespace.
        Specified by:
        getLog in interface RuntimeServices
        Parameters:
        childNamespace -
        Returns:
        child namespace logger

      • getLogContext

        public LogContext getLogContext()
        Get the LogContext object used to tack locations in templates.
        Specified by:
        getLogContext in interface RuntimeServices
        Returns:
        LogContext object
        Since:
        2.2

      • getString

        public String getString​(String key,
                        String defaultValue)
        String property accessor method with default to hide the configuration implementation.
        Specified by:
        getString in interface RuntimeServices
        Parameters:
        key - property key
        defaultValue - default value to return if key not found in resource manager.
        Returns:
        value of key or default

      • getVelocimacro

        public Directive getVelocimacro​(String vmName,
                                Template renderingTemplate,
                                Template template)
        Returns the appropriate VelocimacroProxy object if vmName is a valid current Velocimacro.
        Specified by:
        getVelocimacro in interface RuntimeServices
        Parameters:
        vmName - Name of velocimacro requested
        renderingTemplate - Template we are currently rendering. This information is needed when VM_PERM_ALLOW_INLINE_REPLACE_GLOBAL setting is true and template contains a macro with the same name as the global macro library.
        template - Template which acts as the host for the macro
        Returns:
        VelocimacroProxy

      • addVelocimacro

        public boolean addVelocimacro​(String name,
                              Node macro,
                              List<Macro.MacroArg> macroArgs,
                              Template definingTemplate)
        Adds a new Velocimacro. Usually called by Macro only while parsing.
        Specified by:
        addVelocimacro in interface RuntimeServices
        Parameters:
        name - Name of velocimacro
        macro - root AST node of the parsed macro
        macroArgs - Array of macro arguments, containing the #macro() arguments and default values. the 0th is the name.
        definingTemplate - Template containing the source of the macro
        Returns:
        boolean True if added, false if rejected for some reason (either parameters or permission settings)

      • isVelocimacro

        public boolean isVelocimacro​(String vmName,
                             Template template)
        Checks to see if a VM exists
        Specified by:
        isVelocimacro in interface RuntimeServices
        Parameters:
        vmName - Name of the Velocimacro.
        template - Template on which to look for the Macro.
        Returns:
        True if VM by that name exists, false if not

      • getString

        public String getString​(String key)
        String property accessor method to hide the configuration implementation
        Specified by:
        getString in interface RuntimeServices
        Parameters:
        key - property key
        Returns:
        value of key or null

      • getInt

        public int getInt​(String key)
        Int property accessor method to hide the configuration implementation.
        Specified by:
        getInt in interface RuntimeServices
        Parameters:
        key - Property key
        Returns:
        value

      • getInt

        public int getInt​(String key,
                  int defaultValue)
        Int property accessor method to hide the configuration implementation.
        Specified by:
        getInt in interface RuntimeServices
        Parameters:
        key - property key
        defaultValue - The default value.
        Returns:
        value

      • getBoolean

        public boolean getBoolean​(String key,
                          boolean def)
        Boolean property accessor method to hide the configuration implementation.
        Specified by:
        getBoolean in interface RuntimeServices
        Parameters:
        key - property key
        def - The default value if property not found.
        Returns:
        value of key or default value

      • getConfiguration

        public ExtProperties getConfiguration()
        Return the velocity runtime configuration object.
        Specified by:
        getConfiguration in interface RuntimeServices
        Returns:
        Configuration object which houses the Velocity runtime properties.

      • getApplicationAttribute

        public Object getApplicationAttribute​(Object key)
        Gets the application attribute for the given key
        Specified by:
        getApplicationAttribute in interface RuntimeServices
        Parameters:
        key -
        Returns:
        The application attribute for the given key.

      • setApplicationAttribute

        public Object setApplicationAttribute​(Object key,
                                      Object o)
        Sets the application attribute for the given key
        Specified by:
        setApplicationAttribute in interface RuntimeServices
        Parameters:
        key -
        o - The new application attribute.
        Returns:
        The old value of this attribute or null if it hasn't been set before.

      • getUberspect

        public Uberspect getUberspect()
        Returns the Uberspect object for this Instance.
        Specified by:
        getUberspect in interface RuntimeServices
        Returns:
        The Uberspect object for this Instance.

      • useStringInterning

        public boolean useStringInterning()
        Whether to use string interning
        Specified by:
        useStringInterning in interface RuntimeServices
        Returns:
        boolean

      • isHyphenAllowedInIdentifiers

        public boolean isHyphenAllowedInIdentifiers()
        get whether hyphens are allowed in identifiers
        Specified by:
        isHyphenAllowedInIdentifiers in interface RuntimeServices
        Returns:
        configured boolean flag

      • isScopeControlEnabled

        public boolean isScopeControlEnabled​(String scopeName)
        Get whether to provide a scope control object for this scope
        Specified by:
        isScopeControlEnabled in interface RuntimeServices
        Parameters:
        scopeName -
        Returns:
        scope control enabled
        Since:
        2.1