@Configuration
class RouterRouterConfiguration {

    @Bean
    fun mainRouter(userHandler: UserHandler) = router {
        accept(TEXT_HTML).nest {
            GET("/") { ok().render("index") }
            GET("/sse") { ok().render("sse") }
            GET("/users", userHandler::findAllView)
        }
        "/api".nest {
            accept(APPLICATION_JSON).nest {
                GET("/users", userHandler::findAll)
            }
            accept(TEXT_EVENT_STREAM).nest {
                GET("/users", userHandler::stream)
            }
        }
        resources("/**", ClassPathResource("static/"))
    }
}

val mockMvc: MockMvc = ...
mockMvc.get("/person/{name}", "Lee") {
    secure = true
    accept = APPLICATION_JSON
    headers {
        contentLanguage = Locale.FRANCE
    }
    principal = Principal { "foo" }
}.andExpect {
    status { isOk }
    content { contentType(APPLICATION_JSON) }
    jsonPath("$.name") { value("Lee") }
    content { json("""{"someBoolean": false}""", false) }
}.andDo {
    print()
}

dependencies {
        runtime("org.jetbrains.kotlin:kotlin-scripting-jsr223:${kotlinVersion}")
}

@Configuration
class KotlinScriptConfiguration {

    @Bean
    fun kotlinScriptConfigurer() = ScriptTemplateConfigurer().apply {
        engineName = "kotlin"
        setScripts("scripts/render.kts")
        renderFunction = "render"
        isSharedEngine = false
    }

    @Bean
    fun kotlinScriptViewResolver() = ScriptTemplateViewResolver().apply {
        setPrefix("templates/")
        setSuffix(".kts")
    }
}

dependencies {

    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:${coroutinesVersion}")
    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-reactor:${coroutinesVersion}")
}

@RestController
class CoroutinesRestController(client: WebClient, banner: Banner) {

    @GetMapping("/suspend")
    suspend fun suspendingEndpoint(): Banner {
        delay(10)
        return banner
    }

    @GetMapping("/flow")
    fun flowEndpoint() = flow {
        delay(10)
        emit(banner)
        delay(10)
        emit(banner)
    }

    @GetMapping("/deferred")
    fun deferredEndpoint() = GlobalScope.async {
        delay(10)
        banner
    }

    @GetMapping("/sequential")
    suspend fun sequential(): List<Banner> {
        val banner1 = client
                .get()
                .uri("/suspend")
                .accept(MediaType.APPLICATION_JSON)
                .awaitExchange()
                .awaitBody<Banner>()
        val banner2 = client
                .get()
                .uri("/suspend")
                .accept(MediaType.APPLICATION_JSON)
                .awaitExchange()
                .awaitBody<Banner>()
        return listOf(banner1, banner2)
    }

    @GetMapping("/parallel")
    suspend fun parallel(): List<Banner> = coroutineScope {
        val deferredBanner1: Deferred<Banner> = async {
            client
                    .get()
                    .uri("/suspend")
                    .accept(MediaType.APPLICATION_JSON)
                    .awaitExchange()
                    .awaitBody<Banner>()
        }
        val deferredBanner2: Deferred<Banner> = async {
            client
                    .get()
                    .uri("/suspend")
                    .accept(MediaType.APPLICATION_JSON)
                    .awaitExchange()
                    .awaitBody<Banner>()
        }
        listOf(deferredBanner1.await(), deferredBanner2.await())
    }

    @GetMapping("/error")
    suspend fun error() {
        throw IllegalStateException()
    }

    @GetMapping("/cancel")
    suspend fun cancel() {
        throw CancellationException()
    }

}

@Controller
class CoroutinesViewController(banner: Banner) {

    @GetMapping("/")
    suspend fun render(model: Model): String {
        delay(10)
        model["banner"] = banner
        return "index"
    }
}

@Configuration
class RouterConfiguration {

    @Bean
    fun mainRouter(userHandler: UserHandler) = coRouter {
        GET("/", userHandler::listView)
        GET("/api/user", userHandler::listApi)
    }
}

class UserHandler(builder: WebClient.Builder) {

    private val client = builder.baseUrl("...").build()

    suspend fun listView(request: ServerRequest): ServerResponse =
            ServerResponse.ok().renderAndAwait("users", mapOf("users" to
            client.get().uri("...").awaitExchange().awaitBody<User>()))

    suspend fun listApi(request: ServerRequest): ServerResponse =
                ServerResponse.ok().contentType(MediaType.APPLICATION_JSON).bodyAndAwait(
                client.get().uri("...").awaitExchange().awaitBody<User>())
}

import org.springframework.transaction.reactive.executeAndAwait

class PersonRepository(private val operator: TransactionalOperator) {

    suspend fun initDatabase() = operator.executeAndAwait {
        insertPerson1()
        insertPerson2()
    }

    private suspend fun insertPerson1() {
        // INSERT SQL statement
    }

    private suspend fun insertPerson2() {
        // INSERT SQL statement
    }
}

import org.springframework.transaction.reactive.transactional

class PersonRepository(private val operator: TransactionalOperator) {

    fun updatePeople() = findPeople().map(::updatePerson).transactional(operator)

    private fun findPeople(): Flow<Person> {
        // SELECT SQL statement
    }

    private suspend fun updatePerson(person: Person): Person {
        // UPDATE SQL statement
    }
}

class Person(val name: String, val age: Int)

data class Person(val name: String, val age: Int)

val jack = Person(name = "Jack", age = 1)
val olderJack = jack.copy(age = 2)

@Component
class YourBean(
    private val mongoTemplate: MongoTemplate,
    private val solrClient: SolrClient
)

@Component
class YourBean {

    @Autowired
    lateinit var mongoTemplate: MongoTemplate

    @Autowired
    lateinit var solrClient: SolrClient
}

@Bean
fun propertyConfigurer() = PropertySourcesPlaceholderConfigurer().apply {
    setPlaceholderPrefix("%{")
}

@Bean
fun kotlinPropertyConfigurer() = PropertySourcesPlaceholderConfigurer().apply {
    setPlaceholderPrefix("%{")
    setIgnoreUnresolvablePlaceholders(true)
}

@Bean
fun defaultPropertyConfigurer() = PropertySourcesPlaceholderConfigurer()

public @interface RequestMapping {

    @AliasFor("path")
    String[] value() default {};

    @AliasFor("value")
    String[] path() default {};

    RequestMethod[] method() default {};

    // ...
}

package org.springframework.scripting;

public interface Calculator {

    int add(int x, int y);
}

// from the file 'calculator.groovy'
package org.springframework.scripting.groovy

class GroovyCalculator implements Calculator {

    int add(int x, int y) {
        x + y
    }
}

<!-- from the file 'beans.xml' -->
<beans>
    <lang:groovy id="calculator" script-source="classpath:calculator.groovy"/>
</beans>

package org.springframework.scripting;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {

    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
        Calculator calc = ctx.getBean("calculator", Calculator.class);
        System.out.println(calc.add(2, 8));
    }
}

BeanShell is a small, free, embeddable Java source interpreter with dynamic language
features, written in Java. BeanShell dynamically runs standard Java syntax and
extends it with common scripting conveniences such as loose types, commands, and method
closures like those in Perl and JavaScript.

package org.springframework.scripting;

public interface Messenger {

    String getMessage();
}

String message;

String getMessage() {
    return message;
}

void setMessage(String aMessage) {
    message = aMessage;
}

<lang:bsh id="messageService" script-source="classpath:BshMessenger.bsh"
    script-interfaces="org.springframework.scripting.Messenger">

    <lang:property name="message" value="Hello World!" />
</lang:bsh>

// from the file '/WEB-INF/groovy/FortuneController.groovy'
package org.springframework.showcase.fortune.web

import org.springframework.showcase.fortune.service.FortuneService
import org.springframework.showcase.fortune.domain.Fortune
import org.springframework.web.servlet.ModelAndView
import org.springframework.web.servlet.mvc.Controller

import javax.servlet.http.HttpServletRequest
import javax.servlet.http.HttpServletResponse

class FortuneController implements Controller {

    @Property FortuneService fortuneService

    ModelAndView handleRequest(HttpServletRequest request,
            HttpServletResponse httpServletResponse) {
        return new ModelAndView("tell", "fortune", this.fortuneService.tellFortune())
    }
}

<lang:groovy id="fortune"
        refresh-check-delay="3000"
        script-source="/WEB-INF/groovy/FortuneController.groovy">
    <lang:property name="fortuneService" ref="fortuneService"/>
</lang:groovy>

import org.springframework.validation.Validator
import org.springframework.validation.Errors
import org.springframework.beans.TestBean

class TestBeanValidator implements Validator {

    boolean supports(Class clazz) {
        return TestBean.class.isAssignableFrom(clazz)
    }

    void validate(Object bean, Errors errors) {
        if(bean.name?.trim()?.size() > 0) {
            return
        }
        errors.reject("whitespace", "Cannot be composed wholly of whitespace.")
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:lang="http://www.springframework.org/schema/lang"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/lang https://www.springframework.org/schema/lang/spring-lang.xsd">

    <lang:groovy id="messenger" script-source="classpath:Messenger.groovy" scope="prototype">
        <lang:property name="message" value="I Can Do The RoboCop" />
    </lang:groovy>

    <bean id="bookingService" class="x.y.DefaultBookingService">
        <property name="messenger" ref="messenger" />
    </bean>

</beans>

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:lang="http://www.springframework.org/schema/lang"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/lang https://www.springframework.org/schema/lang/spring-lang.xsd">

    <!-- bean definitions here -->

</beans>