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A simplified velocity implementation for code generation.
package com.github.pfmiles.org.apache.velocity.app;
/*
* 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.Writer;
import java.util.Properties;
import com.github.pfmiles.org.apache.commons.collections.ExtendedProperties;
import com.github.pfmiles.org.apache.velocity.Template;
import com.github.pfmiles.org.apache.velocity.context.Context;
import com.github.pfmiles.org.apache.velocity.exception.MethodInvocationException;
import com.github.pfmiles.org.apache.velocity.exception.ParseErrorException;
import com.github.pfmiles.org.apache.velocity.exception.ResourceNotFoundException;
import com.github.pfmiles.org.apache.velocity.runtime.RuntimeConstants;
import com.github.pfmiles.org.apache.velocity.runtime.RuntimeInstance;
import com.github.pfmiles.org.apache.velocity.runtime.log.Log;
/**
*
* 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.
*
*
* 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 probably won't function in the way you intend, so it is
* strongly recommended that you call an init() method yourself if you use the
* default constructor.
*
*
* @version $Id: VelocityEngine.java 894920 2009-12-31 18:35:25Z nbubna $
*/
public class VelocityEngine implements RuntimeConstants {
private RuntimeInstance ri = new RuntimeInstance();
/**
* Init-less CTOR
*/
public VelocityEngine() {
// do nothing
}
/**
* Construct a VelocityEngine with the initial properties defined in the
* file propsFilename
*/
public VelocityEngine(String propsFilename) {
ri.setProperties(propsFilename);
}
/**
* Construct a VelocityEngine instance with the specified initial
* properties.
*/
public VelocityEngine(Properties p) {
ri.setProperties(p);
}
/**
* initialize the Velocity runtime engine, using the default properties of
* the Velocity distribution
*/
public void init() {
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
*/
public void init(String propsFilename) {
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
*/
public void init(Properties p) {
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 The template could not be parsed.
// * @throws MethodInvocationException A method on a context object could
// not be invoked.
// * @throws ResourceNotFoundException A referenced resource could not be
// loaded.
// */
// public boolean evaluate( Context context, Writer out,
// String logTag, String instring )
// throws ParseErrorException, MethodInvocationException,
// ResourceNotFoundException
// {
// return ri.evaluate(context, out, logTag, 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 Use
// * {@link #evaluate( Context context, Writer writer,
// * String logTag, Reader reader ) }
// */
// 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 The template could not be parsed.
// * @throws MethodInvocationException A method on a context object could
// not be invoked.
// * @throws ResourceNotFoundException A referenced resource could not be
// loaded.
// * @since Velocity v1.1
// */
// public boolean evaluate(Context context, Writer writer,
// String logTag, Reader reader)
// throws ParseErrorException, MethodInvocationException,
// ResourceNotFoundException
// {
// return ri.evaluate(context, writer, logTag, reader);
// }
// /**
// * 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.
// *
// * @param vmName name of Velocimacro to call
// * @param logTag string to be used for template name in case of error. if
// null,
// * the vmName will be used
// * @param params keys for args used to invoke Velocimacro, in java format
// * rather than VTL (eg "foo" or "bar" rather than "$foo" or "$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.
// */
// public boolean invokeVelocimacro( String vmName, String logTag,
// String params[], Context context,
// Writer writer )
// {
// return ri.invokeVelocimacro(vmName, logTag, params, context, writer);
// }
// /**
// * 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 UTF-8.
// *
// * @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
// * @deprecated Use
// * {@link #mergeTemplate( String templateName, String encoding,
// * Context context, Writer writer )}
// */
// public boolean mergeTemplate( String templateName,
// Context context, Writer writer )
// throws ResourceNotFoundException, ParseErrorException,
// MethodInvocationException
// {
// 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
* @since Velocity v1.1
*/
public boolean mergeTemplate(String templateName, String encoding, Context context, Writer writer) throws ResourceNotFoundException,
ParseErrorException, MethodInvocationException {
Template template = ri.getTemplate(templateName, encoding);
if (template == null) {
String msg = "VelocityEngine.mergeTemplate() was unable to load template '" + templateName + "'";
getLog().error(msg);
throw new ResourceNotFoundException(msg);
} else {
template.merge(context, writer);
return true;
}
}
/**
* Returns a Template 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.
*/
public Template getTemplate(String name) throws ResourceNotFoundException, ParseErrorException {
return ri.getTemplate(name);
}
/**
* Returns a Template 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.
* @since Velocity v1.1
*/
public Template getTemplate(String name, String encoding) throws ResourceNotFoundException, ParseErrorException {
return ri.getTemplate(name, encoding);
}
// /**
// * Determines if a resource is accessable via the currently
// * configured resource loaders.
// *
// * Note that the current implementation will not
// * 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.
// *
// * 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
// * @since 1.5
// */
// 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.
* @since 1.5
*/
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);
}
/**
*
* 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.
*
*
*
* 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.
*
*
* @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);
}
/**
*
* 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.
*
*
* @param key
* object 'name' under which the object is stored
* @return value object to store under this key
* @since 1.5
*/
public Object getApplicationAttribute(Object key) {
return ri.getApplicationAttribute(key);
}
/**
* Remove a directive.
*
* @param name
* name of the directive.
*/
public void removeDirective(String name) {
ri.removeDirective(name);
}
/**
* Instantiates and loads the directive with some basic checks.
*
* @param directiveClass
* classname of directive to load
*/
public void loadDirective(String directiveClass) {
ri.loadDirective(directiveClass);
}
public void init(ExtendedProperties props) {
ri.init(props);
}
/**
* merge String常量形式的模板
*/
public void mergeLiteralTemplate(String templateString, Context ctx, Writer out) {
Template template = ri.getStringTemplate(templateString);
template.merge(ctx, out);
}
/**
* 将传入String类型的模板内容parse为template对象
*
* @param templateString
* @return
*/
public Template parseStringTemplate(String templateString) {
return ri.getStringTemplate(templateString);
}
/**
* 渲染模板, 输出到指定的writer
*
* @param temp
* 模板对象
* @param ctx
* 上下文
* @param out
* 输出writer
*/
public void mergeTemplate(Template temp, Context ctx, Writer out) {
temp.merge(ctx, out);
}
}
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