通常velocity是配合spring mvc之类的框架在web中使用，但velocity本身其实对运行环境没有过多的限制，在单独的java application中也可以独立使用，下面演示了利用velocity模板引擎生成 『每日发货单』邮件内容：
一、先定义邮件内容模板：mail-template.vm
<string>用户，您好：</string>
<h2>以下是 $date.format('yyyy-MM-dd',$model.deliverDate,$convert.toLocale("en_US")) 的发货清单，请核对！</h2>
<ul>
#foreach ($item in $model.items)
<li>$velocityCount . $item.productName / $item.productNum 件</li>
#end
</ul>
这里面涉及到二个java类：Order(发货订单)及OrderItem(订单明细)
import java.util.Date;
import java.util.List;
public class Order {
private Date deliverDate;
private List<OrderItem> items;
public Date getDeliverDate() {
return deliverDate;
}
public void setDeliverDate(Date deliverDate) {
this.deliverDate = deliverDate;
}
public List<OrderItem> getItems() {
return items;
}
public void setItems(List<OrderItem> items) {
this.items = items;
}
}
及
public class OrderItem {
private String productName;
private int productNum;
public String getProductName() {
return productName;
}
public void setProductName(String productName) {
this.productName = productName;
}
public int getProductNum() {
return productNum;
}
public void setProductNum(int productNum) {
this.productNum = productNum;
}
}
二、使用示例
import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader;
import org.apache.velocity.tools.generic.ConversionTool;
import org.apache.velocity.tools.generic.DateTool;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Date;
public class VelocityTest {
public static void main(String[] args) {
VelocityEngine ve = new VelocityEngine();
//定义vm资源加载的路径为classpath所在目录
ve.setProperty(RuntimeConstants.RESOURCE_LOADER, "classpath");
ve.setProperty("classpath.resource.loader.class", ClasspathResourceLoader.class.getName());
ve.init();
//加载模板
Template t = ve.getTemplate("mail-template.vm", "utf-8");
VelocityContext ctx = new VelocityContext();
//加载velocity-tools
ctx.put("date", new DateTool());
ctx.put("convert", new ConversionTool());
//放入要绑定的对象
ctx.put("model", getOrder());
StringWriter sw = new StringWriter();
t.merge(ctx, sw);
//输出
System.out.println(sw.toString());
}
private static Order getOrder() {
Order o = new Order();
o.setDeliverDate(new Date());
o.setItems(new ArrayList<OrderItem>());
OrderItem item1 = new OrderItem();
item1.setProductName("iphone");
item1.setProductNum(1);
OrderItem item2 = new OrderItem();
item2.setProductName("mac pro");
item2.setProductNum(2);
o.getItems().add(item1);
o.getItems().add(item2);
return o;
}
}
运行的输出结果：
<string>用户 您好：</string>
<h2>以下是 2015-09-12 的发货清单，请核对！</h2>
<ul>
<li>1 . iphone / 1 件</li>
<li>2 . mac pro / 2 件</li>
</ul>
参考文章：
http://www.ibm.com/developerworks/cn/java/j-lo-velocity1/index.html
