velocityengine.java

velocity 的脚本语言的全部代码集合

package org.apache.velocity.app;

/*
 * Copyright 2000-2001,2004 The Apache Software Foundation.
 * 
 * Licensed 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 java.io.InputStream;
import java.io.IOException;
import java.io.Reader;
import java.io.BufferedReader;
import java.io.StringReader;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

import org.apache.velocity.context.Context;
import org.apache.velocity.Template;
import org.apache.velocity.context.InternalContextAdapterImpl;
import org.apache.velocity.runtime.RuntimeInstance;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.parser.node.SimpleNode;
import org.apache.velocity.runtime.configuration.Configuration;

import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.MethodInvocationException;

import org.apache.velocity.runtime.parser.ParseException;

import org.apache.commons.collections.ExtendedProperties;

/**
 * <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>
 * Please ensure that you call one of the init() variants. 
 * This is critical for proper behavior.  
 * </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>
 *
 * @author <a href="mailto:[e-mail]">Geir Magnusson Jr.</a>
 * @version $Id: VelocityEngine.java,v 1.6.4.1 2004/03/03 23:22:53 geirm Exp $
 */
public class VelocityEngine implements RuntimeConstants
{
    private RuntimeInstance ri = new RuntimeInstance();

    /**
     *  initialize the Velocity runtime engine, using the default 
     *  properties of the Velocity distribution
     */
    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
     */
    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
     *
     */
    public void init( Properties p )
        throws Exception
    {      
        ri.init( p ); 
    }
    
    /**
     * Set a Velocity Runtime property.
     *
     * @param String key
     * @param Object value
     */
    public void setProperty(String key, Object value)
    {
        ri.setProperty(key,value);
    }

    /**
     * Add a Velocity Runtime property.
     *
     * @param String key
     * @param Object 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 Configuration class and the velocity configuration
     * is a subset of the parent application's configuration.
     *
     * @param Configuration configuration
     *
     * @deprecated Use
     *  {@link #setExtendedProperties( ExtendedProperties  ) }
     */
    public void setConfiguration(Configuration configuration)
    {
        /*
         *  Yuk. We added a little helper to Configuration to 
         *  help with deprecation.  The Configuration class
         *  contains a 'shadow' ExtendedProperties
         */

        ExtendedProperties ep = configuration.getExtendedProperties();

        ri.setConfiguration( ep );
    }

    /**
     * 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 ExtendedProperties 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
     */
    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 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 instream input stream containing the VTL to be rendered
     *
     *  @return true if successful, false otherwise.  If false, see 
     *               Velocity runtime log
     *  @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 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 reader Reader containing the VTL to be rendered
     *
     *  @return true if successful, false otherwise.  If false, see 
     *               Velocity runtime log
     *
     *  @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.getMessage() );
        }                
     
        /*
         * now we want to init and render
         */