package org.springmodules.template.engine.velocity.extended;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
import java.io.*;
import java.util.Properties;
import org.apache.commons.collections.ExtendedProperties;
import org.apache.velocity.Template;
import org.apache.velocity.context.Context;
import org.apache.velocity.context.InternalContextAdapterImpl;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.exception.TemplateInitException;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.resource.ResourceManager;
import org.apache.velocity.runtime.log.Log;
import org.apache.velocity.runtime.parser.ParseException;
import org.apache.velocity.runtime.parser.node.SimpleNode;
import org.springframework.core.io.Resource;
/**
* <p/>
* This class provides a separate new-able instance of the
* Velocity template engine. The alternative model for use
* is using the Velocity class which employs the singleton
* model.
* </p>
* <p/>
* <p/>
* Please ensure that you call one of the init() variants.
* This is critical for proper behavior.
* </p>
* <p/>
* <p> Coming soon : Velocity will call
* the parameter-less init() at the first use of this class
* if the init() wasn't explicitly called. While this will
* ensure that Velocity functions, it almost certainly won't
* function in the way you intend, so please make sure to
* call init().
* </p>
*
* @version $Id: ExtendedVelocityEngine.java,v 1.2 2007/07/11 00:43:57 hueboness Exp $
*/
public class ExtendedVelocityEngine implements RuntimeConstants {
private ExtendedRuntimeInstance ri;
/**
* Init-less CTOR
*/
public ExtendedVelocityEngine(ResourceManager resourceManager) throws Exception {
this(new ExtendedRuntimeInstance(resourceManager));
}
public ExtendedVelocityEngine(ExtendedRuntimeInstance ri) throws Exception {
this.ri = ri;
}
/**
* initialize the Velocity runtime engine, using the default
* properties of the Velocity distribution
*
* @throws Exception
*/
public void init() throws Exception {
ri.init();
}
/**
* initialize the Velocity runtime engine, using default properties
* plus the properties in the properties file passed in as the arg
*
* @param propsFilename file containing properties to use to initialize
* the Velocity runtime
* @throws Exception
*/
public void init(String propsFilename) throws Exception {
ri.init(propsFilename);
}
/**
* initialize the Velocity runtime engine, using default properties
* plus the properties in the passed in java.util.Properties object
*
* @param p Proprties object containing initialization properties
* @throws Exception
*/
public void init(Properties p) throws Exception {
ri.init(p);
}
/**
* Set a Velocity Runtime property.
*
* @param key
* @param value
*/
public void setProperty(String key, Object value) {
ri.setProperty(key, value);
}
/**
* Add a Velocity Runtime property.
*
* @param key
* @param value
*/
public void addProperty(String key, Object value) {
ri.addProperty(key, value);
}
/**
* Clear a Velocity Runtime property.
*
* @param key of property to clear
*/
public void clearProperty(String key) {
ri.clearProperty(key);
}
/**
* Set an entire configuration at once. This is
* useful in cases where the parent application uses
* the ExtendedProperties class and the velocity configuration
* is a subset of the parent application's configuration.
*
* @param configuration
*/
public void setExtendedProperties(ExtendedProperties configuration) {
ri.setConfiguration(configuration);
}
/**
* Get a Velocity Runtime property.
*
* @param key property to retrieve
* @return property value or null if the property
* not currently set
*/
public Object getProperty(String key) {
return ri.getProperty(key);
}
/**
* 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.
*
* @param context context to use in rendering input string
* @param out Writer in which to render the output
* @param logTag string to be used as the template name for log
* messages in case of error
* @param instring input string containing the VTL to be rendered
* @return true if successful, false otherwise. If false, see
* Velocity runtime log
* @throws ParseErrorException
* @throws MethodInvocationException
* @throws ResourceNotFoundException
* @throws IOException
*/
public boolean evaluate(Context context, Writer out,
String logTag, String instring)
throws ParseErrorException, MethodInvocationException,
ResourceNotFoundException, IOException {
return evaluate(context, out, logTag, new BufferedReader(new StringReader(instring)));
}
/**
* Renders the input stream 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.
*
* @param context context to use in rendering input string
* @param writer Writer in which to render the output
* @param logTag string to be used as the template name for log messages
* in case of error
* @param instream input stream containing the VTL to be rendered
* @return true if successful, false otherwise. If false, see
* Velocity runtime log
* @throws ParseErrorException
* @throws MethodInvocationException
* @throws ResourceNotFoundException
* @throws IOException
* @deprecated
*/
public boolean evaluate(Context context, Writer writer,
String logTag, InputStream instream)
throws ParseErrorException, MethodInvocationException,
ResourceNotFoundException, IOException {
/*
* first, parse - convert ParseException if thrown
*/
BufferedReader br = null;
String encoding = null;
try {
encoding = ri.getString(INPUT_ENCODING, ENCODING_DEFAULT);
br = new BufferedReader(new InputStreamReader(instream, encoding));
}
catch (UnsupportedEncodingException uce) {
String msg = "Unsupported input encoding : " + encoding
+ " for template " + logTag;
throw new ParseErrorException(msg);
}
return evaluate(context, writer, logTag, br);
}
/**
* 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.
*
* @param context context to use in rendering input string
* @param writer Writer in which to render the output
* @param logTag string to be used as the template name for log messages
* in case of error
* @param reader Reader containing the VTL to be rendered
* @return true if successful, false otherwise. If false, see
* Velocity runtime log
* @throws ParseErrorException
* @throws MethodInvocationException
* @throws ResourceNotFoundException
* @throws IOException
* @since Velocity v1.1
*/
public boolean evaluate(Context context, Writer writer,
String logTag, Reader reader)
throws ParseErrorException, MethodInvocationException,
ResourceNotFoundException, IOException {
SimpleNode nodeTree = null;
try {
nodeTree = ri.parse(reader, logTag);
}
catch (ParseException pex) {
throw new ParseErrorException(pex);
}
catch (TemplateInitException pex) {
throw new ParseErrorException(pex);
}
/*
* now we want to init and render
*/
if (nodeTree != null) {
InternalContextAdapterImpl ica =
new InternalContextAdapterImpl(context);
ica.pushCurrentTemplateName(logTag);
try {
try {
nodeTree.init(ica, ri);
}
catch (TemplateInitException pex) {
throw new ParseErrorException(pex);
}
/**
* pass through application level runtime exceptions
*/
catch (RuntimeException e) {
throw e;
}
catch (Exception e) {
getLog().error("Velocity.evaluate() : init exception for tag = "
+ logTag, e);
}
/*
* now render, and let any exceptions fly
*/
nodeTree.render(ica, writer);
}
finally {
ica.popCurrentTemplateName();
}
return true;
}
return false;
}
/**
* Invokes a currently registered Velocimacro with the parms provided
* and places the rendered stream into the writer.
* <p/>
* Note : currently only accepts args to the VM if they are in the context.
*
* @param vmName name of Velocimacro to call
* @param logTag string to be used for template name in case of error
* @param params args used to invoke Velocimacro. In context key format :
* eg "foo","bar" (rather than "$foo","$bar")
* @param context Context object containing data/objects used for rendering.
* @param writer Writer for output stream
* @return true if Velocimacro exists and successfully invoked, false otherwise.
* @throws Exception
*/
public boolean invokeVelocimacro(String vmName, String logTag,
String params[], Context context,
Writer writer)
throws Exception {
/*
* check parms
*/
if (vmName == null || params == null || context == null
|| writer == null || logTag == null) {
getLog().error("VelocityEngine.invokeVelocimacro() : invalid parameter");
return false;
}
/*
* does the VM exist?
*/
if (!ri.isVelocimacro(vmName, logTag)) {
getLog().error("VelocityEngine.invokeVelocimacro() : VM '" + vmName
+ "' not registered.");
return false;
}
/*
* now just create the VM call, and use evaluate
*/
StringBuffer construct = new StringBuffer("#");
construct.append(vmName);
construct.append("(");
for (int i = 0; i < params.length; i++) {
construct.append(" $");
construct.append(params[i]);
}
construct.append(" )");
try {
boolean retval = evaluate(context, writer,
logTag, construct.toString());
return retval;
}
/**
* pass through application level runtime exceptions
*/
catch (RuntimeException e) {
throw e;
}
catch (Exception e) {
getLog().error("VelocityEngine.invokeVelocimacro() : error ", e);
throw e;
}
}
/**
* Merges a template and puts the rendered stream into the writer.
* The default encoding that Velocity uses to read template files is defined in
* the property input.encoding and defaults to ISO-8859-1.
*
* @param templateName name of template to be used in merge
* @param context filled context to be used in merge
* @param writer writer to write template into
* @return true if successful, false otherwise. Errors
* logged to velocity log.
* @throws ResourceNotFoundException
* @throws ParseErrorException
* @throws MethodInvocationException
* @throws Exception
* @deprecated
*/
public boolean mergeTemplate(String templateName,
Context context, Writer writer)
throws ResourceNotFoundException, ParseErrorException, MethodInvocationException, Exception {
return mergeTemplate(templateName, ri.getString(INPUT_ENCODING, ENCODING_DEFAULT),
context, writer);
}
/**
* merges a template and puts the rendered stream into the writer
*
* @param templateName name of template to be used in merge
* @param encoding encoding used in template
* @param context filled context to be used in merge
* @param writer writer to write template into
* @return true if successful, false otherwise. Errors
* logged to velocity log
* @throws ResourceNotFoundException
* @throws ParseErrorException
* @throws MethodInvocationException
* @throws Exception
* @since Velocity v1.1
*/
public boolean mergeTemplate(String templateName, String encoding,
Context context, Writer writer)
throws ResourceNotFoundException, ParseErrorException, MethodInvocationException, Exception {
Template template = ri.getTemplate(templateName, encoding);
if (template == null) {
getLog().error("Velocity.mergeTemplate() was unable to load template '"
+ templateName + "'");
return false;
} else {
template.merge(context, writer);
return true;
}
}
/**
* Returns a <code>Template</code> from the Velocity
* resource management system.
*
* @param name The file name of the desired template.
* @return The template.
* @throws ResourceNotFoundException if template not found
* from any available source.
* @throws ParseErrorException if template cannot be parsed due
* to syntax (or other) error.
* @throws Exception if an error occurs in template initialization
*/
public Template getTemplate(String name)
throws ResourceNotFoundException, ParseErrorException, Exception {
return ri.getTemplate(name);
}
/**
* Returns a <code>Template</code> from the Velocity
* resource management system.
*
* @param name The file name of the desired template.
* @param encoding The character encoding to use for the template.
* @return The template.
* @throws ResourceNotFoundException if template not found
* from any available source.
* @throws ParseErrorException if template cannot be parsed due
* to syntax (or other) error.
* @throws Exception if an error occurs in template initialization
* @since Velocity v1.1
*/
public Template getTemplate(String name, String encoding)
throws ResourceNotFoundException, ParseErrorException, Exception {
return ri.getTemplate(name, encoding);
}
//============================================== START EXTENSION ===================================================
/**
* Creates and returns a {@link SpecialTemplate specail template} from the given resource and encoding.
*
* @param resource The resouce from which the template will be created.
* @param encoding The encoding of the template.
* @return The created special template.
*/
public SpecialTemplate getSpecialTemplate(Resource resource, String encoding) {
try {
return getSpecialTemplate(new InputStreamReader(resource.getInputStream()), encoding, resource.getDescription());
} catch (IOException e) {
throw new RuntimeException(e);
}
}
/**
* Creates and returns a {@link SpecialTemplate specail template} from the given reader and encoding.
*
* @param reader The reader from which the template will be created.
* @param encoding The encoding of the template.
* @param name A name associated with the template that will be used in log messages.
* @return The created special template.
*/
public SpecialTemplate getSpecialTemplate(Reader reader, String encoding, String name) {
return ri.getSpecialTemplate(reader, encoding, name);
}
//=============================================== END EXTENSION ====================================================
/**
* Determines if a resource is accessable via the currently
* configured resource loaders.
* <br><br>
* Note that the current implementation will <b>not</b>
* change the state of the system in any real way - so this
* cannot be used to pre-load the resource cache, as the
* previous implementation did as a side-effect.
* <br><br>
* The previous implementation exhibited extreme lazyness and
* sloth, and the author has been flogged.
*
* @param resourceName name of the resource to search for
* @return true if found, false otherwise
*/
public boolean resourceExists(String resourceName) {
return (ri.getLoaderNameForResource(resourceName) != null);
}
/**
* @param resourceName
* @return True if the template exists.
* @see #resourceExists(String)
* @deprecated Use resourceExists(String) instead.
*/
public boolean templateExists(String resourceName) {
return resourceExists(resourceName);
}
/**
* Returns a convenient Log instance that wraps the current LogChute.
* Use this to log error messages. It has the usual methods you'd expect.
*
* @return A log object.
*/
public Log getLog() {
return ri.getLog();
}
/**
* @param message
* @deprecated Use getLog() and call warn() on it.
*/
public void warn(Object message) {
getLog().warn(message);
}
/**
* @param message
* @deprecated Use getLog() and call warn() on it.
*/
public void info(Object message) {
getLog().info(message);
}
/**
* @param message
* @deprecated Use getLog() and call warn() on it.
*/
public void error(Object message) {
getLog().error(message);
}
/**
* @param message
* @deprecated Use getLog() and call warn() on it.
*/
public void debug(Object message) {
getLog().debug(message);
}
/**
* <p/>
* Sets an application attribute (which can be any Object) that will be
* accessible from any component of the system that gets a
* RuntimeServices. This allows communication between the application
* environment and custom pluggable components of the Velocity engine,
* such as ResourceLoaders and LogChutes.
* </p>
* <p/>
* <p/>
* Note that there is no enforcement or rules for the key
* used - it is up to the application developer. However, to
* help make the intermixing of components possible, using
* the target Class name (e.g. com.foo.bar ) as the key
* might help avoid collision.
* </p>
*
* @param key object 'name' under which the object is stored
* @param value object to store under this key
*/
public void setApplicationAttribute(Object key, Object value) {
ri.setApplicationAttribute(key, value);
}
/**
* <p/>
* Return an application attribute (which can be any Object)
* that was set by the application in order to be accessible from
* any component of the system that gets a RuntimeServices.
* This allows communication between the application
* environment and custom pluggable components of the
* Velocity engine, such as ResourceLoaders and LogChutes.
* </p>
*
* @param key object 'name' under which the object is stored
* @return value object to store under this key
*/
public Object getApplicationAttribute(Object key) {
return ri.getApplicationAttribute(key);
}
}