radium226/ApplicationController.java

## ApplicationController.java
package radium226;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
import org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.Context;
import org.thymeleaf.context.IContext;
import org.thymeleaf.expression.Sets;
import org.thymeleaf.spring5.SpringTemplateEngine;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;

@Controller
public class ApplicationController {

    @Autowired
    private TemplateEngine templateEngine;

    @RequestMapping("/")
    public String index(Model model) {
        List<String> items = new ArrayList<>();
        items.add("Initial Ping");
        items.add("Initial Pong");
        model.addAttribute("items", items);
        return "index";
    }

    @RequestMapping(path = "/sse", method = RequestMethod.GET)
    public SseEmitter sse() {
        SseEmitter sseEmitter = new SseEmitter();
        AtomicBoolean shouldContinue = new AtomicBoolean(true);
        Thread thread = new Thread(() -> {
            int i = 0;
            while (shouldContinue.get()) {
                try {
                    Thread.sleep(1000);

                    Context context = new Context();
                    context.setVariable("item", i++ % 2 == 0 ? "Ping" : "Pong");

                    Set<String> fragments = new HashSet<>();
                    fragments.add("item");

                    String html = templateEngine.process("index.html", fragments, context);
                    System.out.println(html);
                    sseEmitter.send(html, MediaType.TEXT_HTML);
                } catch (IOException | InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });

        thread.start();

        sseEmitter.onCompletion(() -> {
            shouldContinue.set(false);
        });

        return sseEmitter;
    }

}

## index.html
<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>SSE with Thymeleaf Fragment</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <script src="/webjars/jquery/3.3.1-1/jquery.min.js"></script>
    <script th:src="@{/scripts/jquery-sse.min.js}"></script>
    <script type="text/javascript">
        $(document).ready(function() {
            var items = $("#items")
            var sse = $.SSE("/sse", {
                onMessage: function(message) {
                    var html = message.data;
                    var item = $(html);
                    item.appendTo(items);

                }
            });
            sse.start();
        });
    </script>
</head>
<body>
    <ul id="items">
        <th:block th:each="item : ${items}">
            <li th:fragment="item" th:text="${item}">Item</li>
        </th:block>
    </ul>
</body>
</html>

## pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>radium226</groupId>
    <artifactId>sse-thymeleaf-fragments</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
    </parent>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>jquery</artifactId>
            <version>3.3.1-1</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- Package as an executable jar/war -->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>
	package radium226;

	import org.springframework.beans.factory.annotation.Autowired;
	import org.springframework.http.MediaType;
	import org.springframework.stereotype.Controller;
	import org.springframework.ui.Model;
	import org.springframework.web.bind.annotation.RequestMapping;
	import org.springframework.web.bind.annotation.RequestMethod;
	import org.springframework.web.bind.annotation.ResponseBody;
	import org.springframework.web.servlet.ModelAndView;
	import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
	import org.thymeleaf.TemplateEngine;
	import org.thymeleaf.context.Context;
	import org.thymeleaf.context.IContext;
	import org.thymeleaf.expression.Sets;
	import org.thymeleaf.spring5.SpringTemplateEngine;

	import java.io.IOException;
	import java.util.ArrayList;
	import java.util.HashSet;
	import java.util.List;
	import java.util.Set;
	import java.util.concurrent.atomic.AtomicBoolean;

	@Controller
	public class ApplicationController {

	@Autowired
	private TemplateEngine templateEngine;

	@RequestMapping("/")
	public String index(Model model) {
	List<String> items = new ArrayList<>();
	items.add("Initial Ping");
	items.add("Initial Pong");
	model.addAttribute("items", items);
	return "index";
	}

	@RequestMapping(path = "/sse", method = RequestMethod.GET)
	public SseEmitter sse() {
	SseEmitter sseEmitter = new SseEmitter();
	AtomicBoolean shouldContinue = new AtomicBoolean(true);
	Thread thread = new Thread(() -> {
	int i = 0;
	while (shouldContinue.get()) {
	try {
	Thread.sleep(1000);

	Context context = new Context();
	context.setVariable("item", i++ % 2 == 0 ? "Ping" : "Pong");

	Set<String> fragments = new HashSet<>();
	fragments.add("item");

	String html = templateEngine.process("index.html", fragments, context);
	System.out.println(html);
	sseEmitter.send(html, MediaType.TEXT_HTML);
	} catch (IOException \| InterruptedException e) {
	e.printStackTrace();
	}
	}
	});

	thread.start();

	sseEmitter.onCompletion(() -> {
	shouldContinue.set(false);
	});

	return sseEmitter;
	}

	}
	<!DOCTYPE HTML>
	<html xmlns:th="http://www.thymeleaf.org">
	<head>
	<title>SSE with Thymeleaf Fragment</title>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
	<script src="/webjars/jquery/3.3.1-1/jquery.min.js"></script>
	<script th:src="@{/scripts/jquery-sse.min.js}"></script>
	<script type="text/javascript">
	$(document).ready(function() {
	var items = $("#items")
	var sse = $.SSE("/sse", {
	onMessage: function(message) {
	var html = message.data;
	var item = $(html);
	item.appendTo(items);

	}
	});
	sse.start();
	});
	</script>
	</head>
	<body>
	<ul id="items">
	<th:block th:each="item : ${items}">
	<li th:fragment="item" th:text="${item}">Item</li>
	</th:block>
	</ul>
	</body>
	</html>
	<?xml version="1.0" encoding="UTF-8"?>
	<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>radium226</groupId>
	<artifactId>sse-thymeleaf-fragments</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>2.0.0.RELEASE</version>
	</parent>

	<properties>
	<java.version>1.8</java.version>
	</properties>

	<dependencies>
	<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
	</dependency>
	<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-thymeleaf</artifactId>
	</dependency>
	<dependency>
	<groupId>org.webjars</groupId>
	<artifactId>jquery</artifactId>
	<version>3.3.1-1</version>
	</dependency>
	</dependencies>

	<build>
	<plugins>
	<!-- Package as an executable jar/war -->
	<plugin>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-maven-plugin</artifactId>
	</plugin>
	</plugins>
	</build>

	</project>