velocity模板路径

遇到的velocity加载模板时的路径问题。

于是查阅资料解决。最后综合velocity自己带的例子的example1和example2，改写了一个例子。怎样解决的在例子的注释中已经说的很明确。对于初学velocity的同志来说，这个例子可以是你参照学习的良好实例

 /*
  * 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.BufferedWriter;
 import  java.io.OutputStreamWriter;
 import  java.io.StringWriter;
 import  java.util.ArrayList;
 import  java.util.Properties;

 import  org.apache.velocity.Template;
 import  org.apache.velocity.VelocityContext;
 import  org.apache.velocity.app.Velocity;
 import  org.apache.velocity.app.VelocityEngine;
 import  org.apache.velocity.exception.MethodInvocationException;
 import  org.apache.velocity.exception.ParseErrorException;

 /**
  * This class is a simple demonstration of how the Velocity Template Engine
  * can be used in a standalone application using the Velocity utility class.
  *
  * It demonstrates two of the 'helper' methods found in the org.apache.velocity.util.Velocity
  * class, mergeTemplate() and evaluate().
  *
  *
  * @author <a href="mailto:[email protected]">Geir Magnusson Jr.</a>
  * @version $Id: Example2.java 463298 2006-10-12 16:10:32Z henning $
  */

 public   class  Example2
 {

      public   static  ArrayList getNames()
         {
             ArrayList list = new  ArrayList();

             list.add("ArrayList element 1" );
             list.add("ArrayList element 2" );
             list.add("ArrayList element 3" );
             list.add("ArrayList element 4" );

             return  list;
         }

     public   static   void  main( String args[] )
     {
         /* first, we init the runtime engine.  Defaults are fine. */

         Properties p = new  Properties();
         //设置输入输出编码类型。和这次说的解决的问题无关
         p.setProperty(Velocity.INPUT_ENCODING, "UTF-8" );
         p.setProperty(Velocity.OUTPUT_ENCODING, "UTF-8" );
         //这里加载类路径里的模板而不是文件系统路径里的模板
         p.setProperty("file.resource.loader.class" ,  "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader" );
         //也可以用下面方法指定一个绝对路径，不过这样要求你所有的模板都放在该路径下，是有局限的
         //p.setProperty(Velocity.FILE_RESOURCE_LOADER_PATH, "模板路径");
         try
         {
             Velocity.init(p);
         }
         catch (Exception e)
         {
             System.out.println("Problem initializing Velocity : "  + e );
             return ;
         }

         /* lets make a Context and put data into it */

         VelocityContext context = new  VelocityContext();

         context.put("name" ,  "Velocity" );
         context.put("project" ,  "阿帕奇" );

         context.put("list" , getNames());

         /* lets render a template */

         StringWriter w = new  StringWriter();

         try
         {
             Velocity.mergeTemplate("example2.vm" ,  "UTF-8" , context, w );
         }
         catch  (Exception e )
         {
             System.out.println("Problem merging template : "  + e );
         }

         System.out.println(" template : "  + w );

         /*
          *  lets dynamically 'create' our template
          *  and use the evaluate() method to render it
          */

         //这个例子也同时告诉我们可以先从文件系统读取一个文件到字符串，然后进行我们想要的操作
         String s = "We are using $project $name to render this." ;
         w = new  StringWriter();

         try
         {
             Velocity.evaluate( context, w, "mystring" , s );
         }
         catch ( ParseErrorException pee )
         {
             /*
              * thrown if something is wrong with the
              * syntax of our template string
              */
             System.out.println("ParseErrorException : "  + pee );
         }
         catch ( MethodInvocationException mee )
         {
             /*
              *  thrown if a method of a reference
              *  called by the template
              *  throws an exception. That won't happen here
              *  as we aren't calling any methods in this
              *  example, but we have to catch them anyway
              */
             System.out.println("MethodInvocationException : "  + mee );
         }
         catch ( Exception e )
         {
             System.out.println("Exception : "  + e );
         }

         System.out.println(" string : "  + w );

         ///////////////////////////////////////////////////////
         //其他方法: 1分别指定路径，此方法可以设定不同的路径 （也可是相对的。在eclipse下是工程目录）
         try  {
             VelocityEngine velocityEngine = new  VelocityEngine();
             Properties properties = new  Properties();
             //也可以在这里指定绝对路径。当指定相对路径时， 在不同的环境下是有区别的。
             //比如把程序部署到tomcat以后，相对路径相对到哪里是个很恶心的事情。
             String basePath = "vm" ;
             //可设置绝对路径
             //String basePath = "F:/";
             properties.setProperty(Velocity.FILE_RESOURCE_LOADER_PATH, basePath);
             velocityEngine.init(properties);
             Template template = velocityEngine.getTemplate("example2.vm" );
             BufferedWriter writer = new  BufferedWriter(
                     new  OutputStreamWriter(System.out));
             template.merge(context, writer);
             writer.flush();
             writer.close();
         } catch  (Exception e) {
             e.printStackTrace();
         }
     }
 }

/*
 * 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.BufferedWriter;
import java.io.OutputStreamWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Properties;

import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;

/**
 * This class is a simple demonstration of how the Velocity Template Engine
 * can be used in a standalone application using the Velocity utility class.
 *
 * It demonstrates two of the 'helper' methods found in the org.apache.velocity.util.Velocity
 * class, mergeTemplate() and evaluate().
 *
 *
 * @author <a href="mailto:[email protected]">Geir Magnusson Jr.</a>
 * @version $Id: Example2.java 463298 2006-10-12 16:10:32Z henning $
 */

public class Example2
{
	
	 public static ArrayList getNames()
	    {
	        ArrayList list = new ArrayList();

	        list.add("ArrayList element 1");
	        list.add("ArrayList element 2");
	        list.add("ArrayList element 3");
	        list.add("ArrayList element 4");

	        return list;
	    }
	
    public static void main( String args[] )
    {
        /* first, we init the runtime engine.  Defaults are fine. */

    	Properties p = new Properties();
    	//设置输入输出编码类型。和这次说的解决的问题无关
        p.setProperty(Velocity.INPUT_ENCODING, "UTF-8");
        p.setProperty(Velocity.OUTPUT_ENCODING, "UTF-8");
        //这里加载类路径里的模板而不是文件系统路径里的模板
        p.setProperty("file.resource.loader.class", "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader");
        //也可以用下面方法指定一个绝对路径，不过这样要求你所有的模板都放在该路径下，是有局限的
        //p.setProperty(Velocity.FILE_RESOURCE_LOADER_PATH, "模板路径");
        try
        {
            Velocity.init(p);
        }
        catch(Exception e)
        {
            System.out.println("Problem initializing Velocity : " + e );
            return;
        }

        /* lets make a Context and put data into it */

        VelocityContext context = new VelocityContext();

        context.put("name", "Velocity");
        context.put("project", "阿帕奇");
        
        context.put("list", getNames());

        /* lets render a template */

        StringWriter w = new StringWriter();

        try
        {
            Velocity.mergeTemplate("example2.vm", "UTF-8", context, w );
        }
        catch (Exception e )
        {
            System.out.println("Problem merging template : " + e );
        }

        System.out.println(" template : " + w );

        /*
         *  lets dynamically 'create' our template
         *  and use the evaluate() method to render it
         */

        //这个例子也同时告诉我们可以先从文件系统读取一个文件到字符串，然后进行我们想要的操作
        String s = "We are using $project $name to render this.";
        w = new StringWriter();

        try
        {
            Velocity.evaluate( context, w, "mystring", s );
        }
        catch( ParseErrorException pee )
        {
            /*
             * thrown if something is wrong with the
             * syntax of our template string
             */
            System.out.println("ParseErrorException : " + pee );
        }
        catch( MethodInvocationException mee )
        {
            /*
             *  thrown if a method of a reference
             *  called by the template
             *  throws an exception. That won't happen here
             *  as we aren't calling any methods in this
             *  example, but we have to catch them anyway
             */
            System.out.println("MethodInvocationException : " + mee );
        }
        catch( Exception e )
        {
            System.out.println("Exception : " + e );
        }

        System.out.println(" string : " + w );
        
        ///////////////////////////////////////////////////////
        //其他方法: 1分别指定路径，此方法可以设定不同的路径 （也可是相对的。在eclipse下是工程目录）
        try {
	        VelocityEngine velocityEngine = new VelocityEngine();
	        Properties properties = new Properties();
	        //也可以在这里指定绝对路径。当指定相对路径时， 在不同的环境下是有区别的。
	        //比如把程序部署到tomcat以后，相对路径相对到哪里是个很恶心的事情。
	        String basePath = "vm";
	        //可设置绝对路径
	        //String basePath = "F:/";
	        properties.setProperty(Velocity.FILE_RESOURCE_LOADER_PATH, basePath);
	        velocityEngine.init(properties);
	        Template template = velocityEngine.getTemplate("example2.vm");
	        BufferedWriter writer = new BufferedWriter(
	                new OutputStreamWriter(System.out));
	        template.merge(context, writer);
	        writer.flush();
            writer.close();
        } catch (Exception e) {
        	e.printStackTrace();
        }
    }
}

 

#         Properties p = new Properties(); 
#         //设置输入输出编码类型。和这次说的解决的问题无关 
#         p.setProperty(Velocity.INPUT_ENCODING, "UTF-8"); 
#         p.setProperty(Velocity.OUTPUT_ENCODING, "UTF-8"); 
#         //这里加载类路径里的模板而不是文件系统路径里的模板 
#         p.setProperty("file.resource.loader.class", "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader"); 

就这几个参数，花了半个小时才把类路径连上．多谢楼主了．