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Script Views

The Spring Framework has a built-in integration for using Spring MVC with any templating library that can run on top of the JSR-223 Java scripting engine. We have tested the following templating libraries on different script engines:

Scripting Library	Scripting Engine
Handlebars	Nashorn
Mustache	Nashorn
React	Nashorn
EJS	Nashorn
ERB	JRuby
String templates	Jython
Kotlin Script templating	Kotlin

Scripting Library

Scripting Engine

Kotlin Script templating

Kotlin

The basic rule for integrating any other script engine is that it must implement the ScriptEngine and Invocable interfaces.

Requirements

See equivalent in the Reactive stack

You need to have the script engine on your classpath, the details of which vary by script engine:

The Nashorn JavaScript engine is provided with Java 8+. Using the latest update release available is highly recommended.
JRuby should be added as a dependency for Ruby support.
Jython should be added as a dependency for Python support.
org.jetbrains.kotlin:kotlin-script-util dependency and a META-INF/services/javax.script.ScriptEngineFactory file containing a org.jetbrains.kotlin.script.jsr223.KotlinJsr223JvmLocalScriptEngineFactory line should be added for Kotlin script support. See this example for more details.

You need to have the script templating library. One way to do that for JavaScript is through WebJars.

Script Templates

See equivalent in the Reactive stack

You can declare a ScriptTemplateConfigurer bean to specify the script engine to use, the script files to load, what function to call to render templates, and so on. The following example uses Mustache templates and the Nashorn JavaScript engine:

Java
Kotlin

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

	@Override
	public void configureViewResolvers(ViewResolverRegistry registry) {
		registry.scriptTemplate();
	}

	@Bean
	public ScriptTemplateConfigurer configurer() {
		ScriptTemplateConfigurer configurer = new ScriptTemplateConfigurer();
		configurer.setEngineName("nashorn");
		configurer.setScripts("mustache.js");
		configurer.setRenderObject("Mustache");
		configurer.setRenderFunction("render");
		return configurer;
	}
}

@Configuration
@EnableWebMvc
class WebConfig : WebMvcConfigurer {

	override fun configureViewResolvers(registry: ViewResolverRegistry) {
		registry.scriptTemplate()
	}

	@Bean
	fun configurer() = ScriptTemplateConfigurer().apply {
		engineName = "nashorn"
		setScripts("mustache.js")
		renderObject = "Mustache"
		renderFunction = "render"
	}
}

The following example shows the same arrangement in XML:

<mvc:annotation-driven/>

<mvc:view-resolvers>
	<mvc:script-template/>
</mvc:view-resolvers>

<mvc:script-template-configurer engine-name="nashorn" render-object="Mustache" render-function="render">
	<mvc:script location="mustache.js"/>
</mvc:script-template-configurer>

The controller would look no different for the Java and XML configurations, as the following example shows:

Java
Kotlin

@Controller
public class SampleController {

	@GetMapping("/sample")
	public String test(Model model) {
		model.addAttribute("title", "Sample title");
		model.addAttribute("body", "Sample body");
		return "template";
	}
}

@Controller
class SampleController {

	@GetMapping("/sample")
	fun test(model: Model): String {
		model["title"] = "Sample title"
		model["body"] = "Sample body"
		return "template"
	}
}

The following example shows the Mustache template:

<html>
	<head>
		<title>{{title}}</title>
	</head>
	<body>
		<p>{{body}}</p>
	</body>
</html>

The render function is called with the following parameters:

String template: The template content
Map model: The view model
RenderingContext renderingContext: The RenderingContext that gives access to the application context, the locale, the template loader, and the URL (since 5.0)

Mustache.render() is natively compatible with this signature, so you can call it directly.

If your templating technology requires some customization, you can provide a script that implements a custom render function. For example, Handlerbars needs to compile templates before using them and requires a polyfill to emulate some browser facilities that are not available in the server-side script engine.

The following example shows how to do so:

Java
Kotlin

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

	@Override
	public void configureViewResolvers(ViewResolverRegistry registry) {
		registry.scriptTemplate();
	}

	@Bean
	public ScriptTemplateConfigurer configurer() {
		ScriptTemplateConfigurer configurer = new ScriptTemplateConfigurer();
		configurer.setEngineName("nashorn");
		configurer.setScripts("polyfill.js", "handlebars.js", "render.js");
		configurer.setRenderFunction("render");
		configurer.setSharedEngine(false);
		return configurer;
	}
}

@Configuration
@EnableWebMvc
class WebConfig : WebMvcConfigurer {

	override fun configureViewResolvers(registry: ViewResolverRegistry) {
		registry.scriptTemplate()
	}

	@Bean
	fun configurer() = ScriptTemplateConfigurer().apply {
		engineName = "nashorn"
		setScripts("polyfill.js", "handlebars.js", "render.js")
		renderFunction = "render"
		isSharedEngine = false
	}
}

Setting the sharedEngine property to false is required when using non-thread-safe script engines with templating libraries not designed for concurrency, such as Handlebars or React running on Nashorn. In that case, Java SE 8 update 60 is required, due to this bug, but it is generally recommended to use a recent Java SE patch release in any case.

polyfill.js defines only the window object needed by Handlebars to run properly, as follows:

var window = {};

This basic render.js implementation compiles the template before using it. A production-ready implementation should also store any reused cached templates or pre-compiled templates. You can do so on the script side (and handle any customization you need — managing template engine configuration, for example). The following example shows how to do so:

function render(template, model) {
	var compiledTemplate = Handlebars.compile(template);
	return compiledTemplate(model);
}

Check out the Spring Framework unit tests, Java, and resources, for more configuration examples.