利用Velocity结合Spring发email

在spring中发mail是一件容易的事，如果利用Velocity做mail的模板来发送就更得心应手了。

首先，还是简单描述sping中的配置，发mail需要一个mail的engin：

<bean id="mailEngine" class="com.aodragon.jdt.backend.service.impl.MailEngineImpl">

<property name="mailSender">

<ref local="mailSender"/>

</property>

<property name="velocityEngine">

<ref local="velocityEngine"/>

</property>

</bean>

实现的类如下：

package com.aodragon.jdt.backend.service.impl;

import java.util.Map;

import javax.mail.MessagingException;

import javax.mail.internet.MimeMessage;

import org.apache.commons.logging.*;

import org.apache.velocity.app.VelocityEngine;

import org.apache.velocity.exception.VelocityException;

import org.springframework.core.io.ClassPathResource;

import org.springframework.mail.*;

import org.springframework.mail.javamail.*;

import org.springframework.ui.velocity.VelocityEngineUtils;

import com.aodragon.jdt.backend.service.MailEngine;

public class MailEngineImpl implements MailEngine {

protected static final Log log = LogFactory.getLog(MailEngineImpl.class);

private MailSender mailSender;

private VelocityEngine velocityEngine;

public void setMailSender(MailSender mailSender) {

this.mailSender = mailSender;

}

public void setVelocityEngine(VelocityEngine velocityEngine) {

this.velocityEngine = velocityEngine;

}

public void sendMessage(SimpleMailMessage msg, String templateName,

Map model) {

String result = null;

try {

result =                VelocityEngineUtils.mergeTemplateIntoString(velocityEngine, templateName, model);

} catch (VelocityException e) {

e.printStackTrace();

}

msg.setText(result);

send(msg);

}

public void sendMessage(SimpleMailMessage msg, String templateName, String encoding, Map model) {

String result = null;

try {

result =                VelocityEngineUtils.mergeTemplateIntoString(velocityEngine, templateName, encoding,model);

} catch (VelocityException e) {

e.printStackTrace();

}

msg.setText(result);

send(msg);

}

public void send(SimpleMailMessage msg) {

try {

mailSender.send(msg);

} catch (MailException ex) {

//log it and go on

log.error(ex.getMessage());

}

}

public void sendMessage(String[] emailAddresses,

ClassPathResource resource, String bodyText,

String subject, String attachmentName)

throws MessagingException {

MimeMessage message =

((JavaMailSenderImpl) mailSender).createMimeMessage();

// use the true flag to indicate you need a multipart message

MimeMessageHelper helper = new MimeMessageHelper(message, true);

helper.setTo(emailAddresses);

helper.setText(bodyText);

helper.setSubject(subject);

helper.addAttachment(attachmentName, resource);

((JavaMailSenderImpl) mailSender).send(message);

}

}

这个engin实现了4个方法，在需要的时候调用，这里也需要两个对象：

private MailSender mailSender;

private VelocityEngine velocityEngine;

所以在配置的时候需要注意有：

<bean id="mailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">

<property name="host">

<value>${email.host}</value>

</property>

<property name="username">

<value>${email.username}</value>

</property>

<property name="password">

<value>${email.password}</value>

</property>

</bean>

<bean id="velocityEngine" class="org.springframework.ui.velocity.VelocityEngineFactoryBean">

<property name="velocityProperties">

<props>

<prop key="resource.loader">class</prop>

<prop key="class.resource.loader.class">org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader</prop>

<prop key="velocimacro.library"/>

</props>

</property>

</bean>

这样配置是完成了，下面给一个在Action中发mail的调用示例

public ActionForward save(ActionMapping actionMapping,

ActionForm actionForm,

HttpServletRequest httpServletRequest,

HttpServletResponse httpServletRresponse) throws

Exception {

String toEmail = "…"

HashMap model = new HashMap();

this.smm.setTo(toEmail);

this.smm.setSubject("谢谢您的关注");

model.put("content","………….. ");

MessageResources resources = getResources(httpServletRequest);

this.mailEngin.sendMessage(this.smm,resources.getMessage(_locale,"velocity.email.bookproduct"),model);

return list(actionMapping, actionForm, httpServletRequest,

httpServletRresponse);

} // end save

这里需要说明的就是调用sendMessage中的第2个参数为resources.getMessage(_locale,"velocity.email.bookproduct")，这里是为了适应多语言版本，调用对应的vm文件，velocity.email.bookproduct是保存在ApplicationResource.properties各个版本中的vm文件对应的路径。其中_locale = (Locale)request.getSession().getAttribute(Globals.LOCALE_KEY)。

这样，简单的Velocity结合Spring发送email就完成了，还可以添加一个TASK来管理邮件的队列，让系统定时发送队列中的邮件；在线管理mailSender中的各个参数等等。