How to use SpringTemplateEngine when using Spring Boot

Question

I am using Thymeleaf SpringTemplateEngine to create a HTML e-mail on my Spring application. When I was using pure Spring MVC everything was perfect. Now with Spring Boot the class can't find my .html template. I think the problem is with ServletContext that is not returning the right path, but I can't figure out how to resolve it. So should I use another Context to process the template? Which one?

This is my MailService working for pure Spring MVC.

@Service
public class MailService {

    private JavaMailSenderImpl mailSender;

    private SpringTemplateEngine templateEngine;

    public MailService() {
        mailSender = new JavaMailSenderImpl();
        //mailSender config

        templateEngine = new SpringTemplateEngine();
        Set<ITemplateResolver> templatesResolvers = new HashSet<ITemplateResolver>();

        ClassLoaderTemplateResolver emailTemplateResolver = new ClassLoaderTemplateResolver();
        emailTemplateResolver.setPrefix("mail/");
        emailTemplateResolver.setTemplateMode("HTML5");
        emailTemplateResolver.setCharacterEncoding("UTF-8");
        emailTemplateResolver.setOrder(1);
        templatesResolvers.add(emailTemplateResolver);

        ServletContextTemplateResolver webTemplateResolver = new ServletContextTemplateResolver();
        webTemplateResolver.setPrefix("/mail/");
        webTemplateResolver.setTemplateMode("HTML5");
        webTemplateResolver.setCharacterEncoding("UTF-8");
        webTemplateResolver.setOrder(2);
        templatesResolvers.add(webTemplateResolver);

        templateEngine.setTemplateResolvers(templatesResolvers);
    }

    public void sendReport(String nome, String email, String obra,
            long medicao, HttpServletRequest request,
            HttpServletResponse response, ServletContext context, Locale locale)
            throws MessagingException {

        String subject = "Novo relatório";

        final WebContext ctx = new WebContext(request, response, context,
                locale);
        ctx.setVariable("nome", nome);
        ctx.setVariable("obra", obra);
        ctx.setVariable("data", DataUtils.getInstance().getDataString(medicao));
        ctx.setVariable("logo", "logo.jpg");

        final MimeMessage mimeMessage = this.mailSender.createMimeMessage();
        final MimeMessageHelper message = new MimeMessageHelper(mimeMessage,
                true, "UTF-8");
        message.setSubject(subject);
        try {
            message.setFrom(new InternetAddress(mailSender.getUsername(),
                    "Sistema"));
        } catch (UnsupportedEncodingException e) {
        }
        message.setTo(email);

        final String htmlContent = this.templateEngine.process(
                "email-relatorio.html", ctx);
        message.setText(htmlContent, true);

        try {
            File file = new File(context.getRealPath("app/img/logo-pro.jpg"));
            InputStreamSource imageSource = new ByteArrayResource(
                    IOUtils.toByteArray(new FileInputStream(file)));
            message.addInline("logo.jpg", imageSource, "image/jpg");
        } catch (IOException e) {
            e.printStackTrace();
        }

        this.mailSender.send(mimeMessage);
    }
}

The error:

org.thymeleaf.exceptions.TemplateInputException: Error resolving template "email-relatorio.html", template might not exist or might not be accessible by any of the configured Template Resolvers
    at org.thymeleaf.TemplateRepository.getTemplate(TemplateRepository.java:246)
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1104)
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1060)
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1011)
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:924)
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:898)

Answer 1

You are using Spring Boot then let Spring Boot do the heavy lifting, which it already does. Remove your constructor and simply @Autowire the JavaMailSender and SpringTemplateEngine.

Add the mail configuration to the application.properties.

spring.mail.host=your-mail-server
spring.mail.port=
spring.mail.username
spring.mail.password

Add the thyme leaf configuration to the application.properties

# THYMELEAF (ThymeleafAutoConfiguration)
spring.thymeleaf.check-template-location=true
spring.thymeleaf.prefix=classpath:/templates/
spring.thymeleaf.excluded-view-names= # comma-separated list of view names   that should be excluded from resolution
spring.thymeleaf.view-names= # comma-separated list of view names that can be resolved
spring.thymeleaf.suffix=.html
spring.thymeleaf.mode=HTML5
spring.thymeleaf.encoding=UTF-8
spring.thymeleaf.content-type=text/html # ;charset=<encoding> is added
spring.thymeleaf.cache=true # set to false for hot refresh

If you have done that change your class

@Service
public class MailService {

    @Autowired
    private JavaMailSender mailSender;

    @Autowired
    private SpringTemplateEngine templateEngine;

    @Value("${spring.mail.username}")
    private String username;

    public void enviarRelatorio(String nome, String email, String obra,long medicao, Locale locale) throws MessagingException {

        String subject = "Novo relatório";

        final Context ctx = new Context(locale);
        ctx.setVariable("nome", nome);
        ctx.setVariable("obra", obra);
        ctx.setVariable("data", DataUtils.getInstance().getDataString(medicao));
        ctx.setVariable("logo", "logo.jpg");

        final MimeMessage mimeMessage = this.mailSender.createMimeMessage();
        final MimeMessageHelper message = new MimeMessageHelper(mimeMessage,true, "UTF-8");
        message.setSubject(subject);
        message.setTo(email);

        try {
            message.setFrom(new InternetAddress(username, "Sistema"));
        } catch (UnsupportedEncodingException e) {
        }

        final String htmlContent = this.templateEngine.process( "email-relatorio", ctx);
        message.setText(htmlContent, true);

        try {
            message.addInline("logo.jpg", new FileSystemResource("imgs/logo-pro.jpg"), "image/jpg");
        } catch (IOException e) {
            e.printStackTrace();
        }

        this.mailSender.send(mimeMessage);
    }
}