在此页面上，我们将探索如何使用 Spring Boot 和 FreeMarker 发送电子邮件。 FreeMarkerTemplateUtils 是一个用于使用 FreeMarker 模板发送电子邮件的实用程序类。

String htmlText= FreeMarkerTemplateUtils.processTemplateIntoString(Template template, Object model);

它以字符串的形式返回处理后的 HTML 并抛出：

IOException – 如果模板在指定路径上不可用。

TemplateException – 如果模板中指定错误，则解析异常。

请参阅与如何使用 Spring Boot 示例发送电子邮件不同的代码片段。

....

FreeMarkerConfigurer freemarkerConfig;

{
	Template t = freemarkerConfig.getConfiguration().getTemplate("/email/welcome.ftlh");

	String htmlText= FreeMarkerTemplateUtils.processTemplateIntoString(t, dataMap);
}
....

// We can also get a Template object like this...

...

Configuration config;

{
	Template t = config.getTemplate("/email/welcome.ftlh");
	
	String htmlText= FreeMarkerTemplateUtils.processTemplateIntoString(t, dataMap);	
}
...

注意： Spring Boot 最近将默认扩展名从 .ftl 更改为 .ftlh

使用的技术

查找此应用程序中使用的所有工具/技术的列表。

Spring Tool Suite 4
JDK 8
Spring Boot 2.2.6.RELEASE
FreeMarker 2.3.30
Java Mail 1.6.2
Maven 3.2

需要依赖

将以下依赖项添加到 pom.xml.
pom.xml

<!-- FreeMarker -->
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>

<!-- Java Mailer -->
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-mail</artifactId>
</dependency>

项目结构

我们在 STS 4 IDE 中的应用程序的最终项目结构如下所示：

邮件服务器属性

在 application.properties 文件中定义邮件服务器属性。
application.properties

# Mail server properties
spring.mail.host=smtp.gmail.com
spring.mail.port=587
spring.mail.username=XXXXXXXXXXX
spring.mail.password=xxxxxxx
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.connectiontimeout=5000
spring.mail.properties.mail.smtp.timeout=5000
spring.mail.properties.mail.smtp.writetimeout=5000
spring.mail.properties.mail.smtp.starttls.enable=true

EmailDTO

EmailDTO 对象用于作为参数传递给我们的 EmailService 以封装电子邮件的详细信息，如收件人电子邮件、电子邮件主题等。
电子邮件DTO.java

package org.websparrow.dto;

import java.util.Map;

public class EmailDTO {

	private String to;
	private String subject;
	private Map<String, Object> emailData;

	// Generate Getters and Setters...
}

EmailService

一个服务类，它实际将数据拉取到模板并将电子邮件发送到收件人地址。
EmailService.java

package org.websparrow.service;

import java.nio.charset.StandardCharsets;

import javax.mail.internet.MimeMessage;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.stereotype.Service;
import org.springframework.ui.freemarker.FreeMarkerTemplateUtils;
import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer;
import org.websparrow.dto.EmailDTO;

@Service
public class EmailService {

	@Autowired
	private JavaMailSender mailSender;
	@Autowired
	private FreeMarkerConfigurer freemarkerConfig;

	public void sendWelcomeEmail(EmailDTO emailDTO) {
		System.out.println("##### Started sending welcome email ####");

		MimeMessage mimeMessage = mailSender.createMimeMessage();
		try {

			MimeMessageHelper helper = new MimeMessageHelper(mimeMessage,
					MimeMessageHelper.MULTIPART_MODE_MIXED_RELATED,
					StandardCharsets.UTF_8.name());

			String templateContent = FreeMarkerTemplateUtils
					.processTemplateIntoString(freemarkerConfig.getConfiguration()
							.getTemplate("/email/welcome.ftlh"),
							emailDTO.getEmailData());

			helper.setTo(emailDTO.getTo());
			helper.setSubject(emailDTO.getSubject());
			helper.setText(templateContent, true);
			mailSender.send(mimeMessage);

			System.out.println("######## Welcome email sent ######");
		} catch (Exception e) {
			System.out.println("Sending welcome email failed, check log...");
			e.printStackTrace();
		}
	}
}

FreeMarker HTML 电子邮件模板

创建您漂亮的 HTML 电子邮件模板并将其放在 src/main/resources/templates/email 文件夹下。确保模板的文件扩展名必须是 .ftlh。
欢迎.ftlh

<!DOCTYPE html>
<html>
<head>
<title>Welcome Letter</title>
</head>
<body>
	<h3>Dear ${name},</h3>

	<p>A warm welcome and lots of good wishes on becoming part of our growing team.</p>
	<p>We are pleased to inform you that you will work with the following team members:</p>
	<ol>
		<#list teamMembers as teamMember>		
			<li>${teamMember}</li>			
		</#list>		
	</ol>	
	<p>Regards</p>
	<p>Websparrow.org Team</p>
	<p>Location: ${location}</p>
</body>
</html>

运行

创建一个EmailDTO对象并设置必要的数据，调用EmailService发送邮件。
SBFreeMarkerEmailApp.java

package org.websparrow;

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.websparrow.dto.EmailDTO;
import org.websparrow.service.EmailService;

@SpringBootApplication
public class SBFreeMarkerEmailApp implements CommandLineRunner {

	@Autowired
	private EmailService emailService;

	@Override
	public void run(String... args) throws Exception {
		System.out.println("###### Email sending initiated ######");

		EmailDTO email = new EmailDTO();

		email.setTo("websparrow.org@gmail.com");
		email.setSubject("Welcome Letter via Spring Boot + FreeMarker");

		// Populate the template data
		Map<String, Object> templateData = new HashMap<>();
		templateData.put("name", "Atul Rai");
		// List of team members...
		List<String> teamMembers = Arrays.asList("Tendulkar", "Manish", "Dhirendra");
		templateData.put("teamMembers", teamMembers);
		templateData.put("location", "India");
		email.setEmailData(templateData);

		// Calling email service
		emailService.sendWelcomeEmail(email);
	}

	public static void main(String[] args) {
		SpringApplication.run(SBFreeMarkerEmailApp.class, args);
	}
}

测试一下

通过执行上述类启动您的应用程序，如果一切配置正确，您将在提供的电子邮件地址上收到一封电子邮件。

Spring Boot- 使用 FreeMarker 发送电子邮件