Get Raw Html From the controller Spring thymeleaf

I have a controller that create model attribute and passes to the view "partial.html" to generate output

partial.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Home page</title>
    <meta charset="UTF-8"/>
    <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
</head>
<body>
<p>
    <span th:text="'Today is: ' + ${message}"></span>
</p>
</body>
</html>

and inside a controller method

model.addAttribute("message", search);

How to do I get Htlm Output to a string inside controller method? like this

String htmlOutput="from partial.html";

Solution

Let's say you have a HTML file with two variable name and todayDate.
You want to process it and want to store it in a string / database / AWS S3.

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
    <head>
        <meta charset="UTF-8">
    </head>
    <body>
        <p>Hello</p>
        <p th:text="${name}"></p>
        <p th:text="${todayDate}"></p>
    </body>
</html>

Your HTML file location is src/main/resources/templates/home.html

By using the below function you can get the final processed HTML as:

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
    </head>
    <body>
        <p>Hello</p>
        <p>Manoj</p>
        <p>30 November 2019</p>
    </body>
</html>

import org.thymeleaf.context.Context;

@GetMapping("/")
    public void process() {
        SpringTemplateEngine templateEngine = new SpringTemplateEngine();
        ClassLoaderTemplateResolver templateResolver = new ClassLoaderTemplateResolver();
        templateResolver.setPrefix("templates/");
        templateResolver.setCacheable(false);
        templateResolver.setSuffix(".html");
        templateResolver.setTemplateMode("HTML");

        // https://github.com/thymeleaf/thymeleaf/issues/606
        templateResolver.setForceTemplateMode(true);

        templateEngine.setTemplateResolver(templateResolver);

        Context ctx = new Context();

        SimpleDateFormat dateFormat = new SimpleDateFormat("dd MMMM yyyy");
        Calendar cal = Calendar.getInstance();

        ctx.setVariable("todayDate", dateFormat.format(cal.getTime()));
        ctx.setVariable("name", "Manoj");
        final String result = templateEngine.process("home", ctx);
        System.out.println("result:" + result);
    }