前言：上一篇博文讲解了邮件发送的基础用法(数据是写死的)，然而在实际开发中，大多数情况下邮件内容都是根据业务来动态生成的。所以在此篇博文中，我们将讲解邮件发送携带数据的几种方案。
一、解析自定义占位符
实现方法： 通过解析自定义占位符，将传递到邮件中的数据，转换成html内容，进行发送。
1）占位符替换函数
/**
* Replaces place holder ("${}") string in template with values in Map
*
* @param template
* @param models
* @return
*/
public static String replacePlaceHolder(String template, Map<String, String> models) { if (template.indexOf("${") == -1) {
return template;
} while (true) { int start = template.indexOf("${");
int end = template.indexOf("}", start); if (start != -1 && end != -1) { String key = template.substring(start + 2, end); if (models.containsKey(key)) {
template = template.substring(0, start) + models.get(key) + template.substring(end + 1);
} } else {
break;
} } return template; }
2) 邮件发送Test-Case
// 1. Resolve html template to real text
String htmlTemplate = "<html lang='zh-cn'><head></head><body><h1>发送带模板数据的Email</h1><p>你好，${username}。本次您的验证码为${code}，请妥善保管</p></body></html>"; Map<String, String> models = new HashMap<String, String>();
models.put("username", "XXX");
models.put("code", "4551"); String text = StringUtils.replacePlaceHolder(htmlTemplate, models); // 2. send email
boolean result = mailHandler.sendText("收件人邮箱", "发送带模板数据的Email", text);
Assert.assertEquals(true, result);
二、使用Velocity模板
实现方法：借用VelocityEngineUtils合并Velocity模板和数据，得到要发送的Email， 进行发送。
1) 引入依赖jar包
<!-- velocity -->
<dependency>
<groupId>org.apache.velocity</groupId>
<artifactId>velocity</artifactId>
<version>1.7</version>
</dependency>
2) 配置Velocity模板引擎
<!-- Define velocity engine -->
<bean id="velocityEngine" class="org.springframework.ui.velocity.VelocityEngineFactoryBean">
<property name="configLocation" value="classpath:velocity.properties" />
</bean>
velocity.properties:
input.encoding=UTF-8
output.encoding=UTF-8
resource.loader=class
class.resource.loader.class=org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader
3) 发送邮件实现函数
// Get email content by velocity merge models
String content = VelocityEngineUtils.mergeTemplateIntoString(velocityEngine, template, encoding, models); // Send email
MimeMessage mimeMessage = mailSender.createMimeMessage();
MimeMessageHelper helper = new MimeMessageHelper(mimeMessage, true, encoding);
helper.setFrom(form); // set sender
helper.setTo(to); // set recipients
helper.setSubject(subject);
helper.setText(content, true); // Indicate the text included is HTML
mailSender.send(mimeMessage);
三、使用FreeMarker模板
实现方法：借用FreeMarkerTemplateUtils合并FreeMarker模板和数据，得到要发送的Email， 进行发送。
1) 引入依赖jar包
<dependency>
<groupId>org.freemarker</groupId>
<artifactId>freemarker</artifactId>
<version>2.3.23</version>
</dependency>
2）配置FreeMarker
<!-- Define freemarker configuration -->
<bean id="freeMarkerConfiguration" class="org.springframework.ui.freemarker.FreeMarkerConfigurationFactoryBean">
<property name="templateLoaderPath" value="classpath:template/freemarker" />
<property name="defaultEncoding" value="utf-8" />
<property name="freemarkerSettings">
<props>
<prop key="template_update_delay">10</prop>
<prop key="locale">zh_CN</prop>
<prop key="number_format">#.##</prop>
</props>
</property>
</bean>
3) 发送邮件实现函数
// Get email content by freeMarker template
Template realTemplate = freeMarkerConfigurer.getTemplate(template);
String content = FreeMarkerTemplateUtils.processTemplateIntoString(realTemplate, models);
// Send email
MimeMessage mimeMessage = mailSender.createMimeMessage();
MimeMessageHelper helper = new MimeMessageHelper(mimeMessage, true, encoding);
helper.setFrom(form); // set sender
helper.setTo(to); // set recipients
helper.setSubject(subject);
helper.setText(content, true); // Indicate the text included is HTML
mailSender.send(mimeMessage);