Spring 4 使用Freemarker模板发送邮件&添加附件

前言

Spring对Java的邮件发送提供了很好的支持，提供了超级简单的API，大大简化了Java邮件发送功能的开发。

Spring对Email的支持是基于JavaMail API开发的，所以，我们在使用Spring开发Java邮件发送功能时，需要引入javax.mail-api和其实现类mail包，如下：

        <!-- JavaMail -->
        <dependency>
            <groupId>javax.mail</groupId>
            <artifactId>javax.mail-api</artifactId>
            <version>1.5.5</version>
        </dependency>
        <dependency>
            <groupId>javax.mail</groupId>
            <artifactId>mail</artifactId>
            <version>1.4.7</version>
        </dependency>

另外，如果打算使用freemarker作为邮件主题的模板的话，还需引入freemarker：

        <dependency>
            <groupId>org.freemarker</groupId>
            <artifactId>freemarker</artifactId>
            <version>2.3.23</version>
        </dependency>

最后，添加其它依赖spring-context-support、spring-context等；

Bean配置——JavaMailSenderImpl

Spring提供了两个基础接口用于发送邮件：

MailSender：发送简单的邮件信息，提供基本功能，如‘from’, ’to’, ’cc’, ’bcc’, ’subject’ 以及其它邮件属性。

JavaMailSender：对MailSender进行扩展，提供专业的JavaMail特性，如对MIME消息的支持。

JavaMailSenderImpl是JavaMailSender接口的实现，一般我们都会使用它来进行邮件发送，如下是javaMailSender bean的配置：

比较简单，就不细说了，注意下端口的配置,密码是邮件账号的密码，我这里改成了XXXXXX。

    <bean id="javaMailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">  
        <property name="host" value="smtp.qq.com"></property>  
        <property name="port" value="25"></property>  
        <property name="username" value="928651551@qq.com"></property>  
        <property name="password" value="XXXXXX"></property>  
        <property name="defaultEncoding" value="UTF-8"></property>  
        <property name="javaMailProperties">  
            <props>
                <prop key="mail.transport.protocol">smtp</prop>
                <prop key="mail.smtp.auth">true</prop>
                <!-- true for Gamil 
                <prop key="mail.smtp.starttls.enable">false</prop>
                <prop key="mail.debug">true</prop>-->
            </props> 
        </property>
    </bean>

Bean配置——FreeMarkerConfigurationFactoryBean

因为我们使用了freemarker作为邮件主体的模板，所以这里对freeMarker做了下配置

    <bean id="freeMarkerConfiguration" class="org.springframework.ui.freemarker.FreeMarkerConfigurationFactoryBean">
       <property name="templateLoaderPath" value="classpath:emailtemplates" />
    </bean>

另外，我们使用的freeMarker模板如下：

<html>
    <body>
        <h3>User name: ${user.name} has been deleted.</h3>
        <h6>Detail:</h6>
        <div>
            <p>user id : ${user.id}.</p>
            <p>user address : ${user.address}.</p>
        </div>
        <span>Sent using FreeMarker Template</span>
    </body>
</html>

编写邮件发送Service

主要工作落在组装MIME消息，使用Freemarker模板生成邮件主体，另外我们还给邮件添加了一张图片作为附件，

package cn.edu.hdu.webbf.service.mail.impl;

import java.util.HashMap;
import java.util.Map;

import javax.mail.internet.MimeMessage;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.mail.MailException;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.mail.javamail.MimeMessagePreparator;
import org.springframework.stereotype.Service;
import org.springframework.ui.freemarker.FreeMarkerTemplateUtils;

import cn.edu.hdu.webbf.common.log.Logger;
import cn.edu.hdu.webbf.service.mail.IMailService;
import freemarker.template.Configuration;

@Service("mailService")
public class MailServiceImpl implements IMailService
{

    protected Logger logger = Logger.getLogger(this.getClass());

    @Autowired
    JavaMailSender mailSender;

    @Autowired
    Configuration freemarkerConfiguration;

    @Override
    public void sendEmail(Object obj)
    {

        MimeMessagePreparator preparator = getMessagePreparator(obj);

        try
        {
            mailSender.send(preparator);
            logger.info("mail send sesuccss.");
        }
        catch (MailException ex)
        {
            logger.error(ex.getMessage(), ex);
        }
    }

    private MimeMessagePreparator getMessagePreparator(final Object obj)
    {

        MimeMessagePreparator preparator = new MimeMessagePreparator()
        {

            @Override
            public void prepare(MimeMessage mimeMessage) throws Exception
            {
                MimeMessageHelper helper = new MimeMessageHelper(mimeMessage, true);
                helper.setFrom("928651551@qq.com");
                helper.setTo("928651551@qq.com");
                helper.setSubject("mail test.");
                Map<String, Object> model = new HashMap<String, Object>();
                model.put("user", obj);
                String text = geFreeMarkerTemplateContent(model);//Use Freemarker
                helper.setText(text, true);
                helper.addAttachment("userdel.png", new ClassPathResource("imgs/userdel.png"));
            }
        };
        return preparator;
    }

    public String geFreeMarkerTemplateContent(Map<String, Object> model)
    {
        StringBuffer content = new StringBuffer();
        try
        {
            content.append(FreeMarkerTemplateUtils.processTemplateIntoString(
                freemarkerConfiguration.getTemplate("fm_userDeleted.txt"), model));
            return content.toString();
        }
        catch (Exception e)
        {
            logger.error("Exception occured while processing fmtemplate:" + e.getMessage(), e);
        }
        return "";
    }

}

Controller调用

删除用户的时候，发送一封通知邮件，说明那个用户被删除了。

    @RequestMapping(value = "/{id}", method = RequestMethod.DELETE, produces = "application/json; charset=utf-8")
    public ResponseEntity<User> deleteUser(@PathVariable Long id)
    {
        User user = userService.findById(id);
        if (user == null)
        {
            return new ResponseEntity<User>(HttpStatus.NOT_FOUND);
        }
        userService.deleteUser(id);
        mailService.sendEmail(user);
        return new ResponseEntity<User>(HttpStatus.NO_CONTENT);
    }