Velocity demo

package org.demo;

import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.app.VelocityEngine;
import org.demo.bean.Student;

public class Test {
    public static void main(String[] args) throws Exception {
        /* first, get and initialize an engine */
        VelocityEngine ve = new VelocityEngine();

        // 设置类路径加载模板
        ve.setProperty(Velocity.RESOURCE_LOADER, "class");
        ve.setProperty("class.resource.loader.class",
                "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader");

        ve.init();

        /* next, get the Template */
        Template t = ve.getTemplate("org/demo/hello.vm");

        // Example 1
        /* create a context and add data */
        VelocityContext context = new VelocityContext();
        context.put("name", "sunny");
        context.put("site", "http://cutesunshineriver.iteye.com");
        context.put("date", (new Date()).toString());

        // Example 2
        /* fill the context with a list */
        List<String> temp = new ArrayList<String>();
        temp.add("1");
        temp.add("2");
        context.put("list", temp);

        // Example 3
        /* fill the context with hashmap */
        Map<String, Integer> map = new HashMap<String, Integer>();
        map.put("key1", 3);
        map.put("key2", 4);
        context.put("map", map);

        // Example 4
        /* fill the context with javabean list */
        List<Student> students = new ArrayList<Student>();
        students.add(new Student(5, "broadway 26"));
        students.add(new Student(6, "sunset avenue 26"));
        context.put("students", students);

        /* now render the template into a StringWriter */
        StringWriter writer = new StringWriter();
        t.merge(context, writer);
        /* show the World */
        System.out.println(writer.toString());
    }
}

2、vm文件 

#set($aVar = "good!")
Hello $name! Welcome to $site world!
today is $date.
$aVar
====================================
Logic below:
#set($admin = "admin")
#set($user = "user")
#if ($admin == $user)
Welcome admin!
#else
Welcome user!
#end
====================================
List below:
#foreach( $product in $list )
$product
#end
====================================
Map below:
#foreach($key in $map.keySet())
$key's value: $map.get($key)
#end
====================================
student beans below:
#foreach ($s in $students)
<$velocityCount> No: $s.no; Address: $s.address
#end
====================================
#macro ( tablerows $color $somelist )
  #foreach ( $something in $somelist )
    <tr><td bgcolor=$color>$something</td</tr>
  #end
#end
#set ( $greatlakes = [ "Superior", "Michigan", "Huron", "Erie", "Ontario" ] )
#set ( $color = "blue" )
<table>
  #tablerows( $color $greatlakes )
</table>
====================================
#foreach ( $bar in [2..-2] )
  $bar
#end

3、输出 
Hello sunny! Welcome to http://cutesunshineriver.iteye.com world! 
today is Sun Apr 10 09:09:12 CST 2011. 
good! 
==================================== 
Logic below: 
Welcome user! 
==================================== 
List below: 
1 
2 
==================================== 
Map below: 
key2's value: 4 
key1's value: 3 
==================================== 
student beans below: 
<1> No: 5; Address: broadway 26 
<2> No: 6; Address: sunset avenue 26 
==================================== 
<table> 
        <tr><td bgcolor=blue>Superior</td</tr> 
      <tr><td bgcolor=blue>Michigan</td</tr> 
      <tr><td bgcolor=blue>Huron</td</tr> 
      <tr><td bgcolor=blue>Erie</td</tr> 
      <tr><td bgcolor=blue>Ontario</td</tr> 
  </table> 
==================================== 
  2 
  1 
  0 
  -1 
  -2