Register ApplicationConversionService for context

Update `SpringApplication` to automatically register the shared
`ApplicationConversionService` instance with the `BeanFactory` and
`Environment`.

Closes gh-12148

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplication.java

@@ -45,6 +45,7 @@ import org.springframework.boot.Banner.Mode;
 import org.springframework.boot.context.properties.bind.Bindable;
 import org.springframework.boot.context.properties.bind.Binder;
 import org.springframework.boot.context.properties.source.ConfigurationPropertySources;
+import org.springframework.boot.convert.ApplicationConversionService;
 import org.springframework.boot.web.reactive.context.StandardReactiveWebEnvironment;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextInitializer;
@@ -214,6 +215,8 @@ public class SpringApplication {
 
 	private boolean addCommandLineProperties = true;
 
+	private boolean addConversionService = true;
+
 	private Banner banner;
 
 	private ResourceLoader resourceLoader;
@@ -397,7 +400,6 @@ public class SpringApplication {
 			logStartupInfo(context.getParent() == null);
 			logStartupProfileInfo(context);
 		}
-
 		// Add boot specific singleton beans
 		ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
 		beanFactory.registerSingleton("springApplicationArguments", applicationArguments);
@@ -503,6 +505,10 @@ public class SpringApplication {
 	 */
 	protected void configureEnvironment(ConfigurableEnvironment environment,
 			String[] args) {
+		if (this.addConversionService) {
+			environment.setConversionService(
+					ApplicationConversionService.getSharedInstance());
+		}
 		configurePropertySources(environment, args);
 		configureProfiles(environment, args);
 	}
@@ -644,6 +650,10 @@ public class SpringApplication {
 						.setClassLoader(this.resourceLoader.getClassLoader());
 			}
 		}
+		if (this.addConversionService) {
+			context.getBeanFactory().setConversionService(
+					ApplicationConversionService.getSharedInstance());
+		}
 	}
 
 	/**
@@ -1046,6 +1056,16 @@ public class SpringApplication {
 		this.addCommandLineProperties = addCommandLineProperties;
 	}
 
+	/**
+	 * Sets if the {@link ApplicationConversionService} should be added to the application
+	 * context's {@link Environment}.
+	 * @param addConversionService if the application conversion service should be added
+	 * @since 2.1.0
+	 */
+	public void setAddConversionService(boolean addConversionService) {
+		this.addConversionService = addConversionService;
+	}
+
 	/**
 	 * Set default environment properties which will be used in addition to those in the
 	 * existing {@link Environment}.

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/builder/SpringApplicationBuilder.java

@@ -31,11 +31,13 @@ import org.springframework.beans.factory.support.BeanNameGenerator;
 import org.springframework.boot.Banner;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.WebApplicationType;
+import org.springframework.boot.convert.ApplicationConversionService;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextInitializer;
 import org.springframework.context.ApplicationListener;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.env.Environment;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.util.StringUtils;
 
@@ -370,6 +372,19 @@ public class SpringApplicationBuilder {
 		return this;
 	}
 
+	/**
+	 * Flag to indicate if the {@link ApplicationConversionService} should be added to the
+	 * application context's {@link Environment}.
+	 * @param addConversionService if the conversion service should be added.
+	 * @return the current builder
+	 * @since 2.1.0
+	 */
+	public SpringApplicationBuilder setAddConversionService(
+			boolean addConversionService) {
+		this.application.setAddConversionService(addConversionService);
+		return this;
+	}
+
 	/**
 	 * Default properties for the environment in the form {@code key=value} or
 	 * {@code key:value}.

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/ApplicationConversionService.java

@@ -57,7 +57,7 @@ public class ApplicationConversionService extends FormattingConversionService {
 	 * building it once needed.
 	 * @return the shared {@code ConversionService} instance (never {@code null})
 	 */
-	public static ConversionService getSharedInstance() {
+	public static ApplicationConversionService getSharedInstance() {
 		ApplicationConversionService sharedInstance = ApplicationConversionService.sharedInstance;
 		if (sharedInstance == null) {
 			synchronized (ApplicationConversionService.class) {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/SpringApplicationTests.java

@@ -56,6 +56,7 @@ import org.springframework.boot.context.event.ApplicationReadyEvent;
 import org.springframework.boot.context.event.ApplicationStartedEvent;
 import org.springframework.boot.context.event.ApplicationStartingEvent;
 import org.springframework.boot.context.event.SpringApplicationEvent;
+import org.springframework.boot.convert.ApplicationConversionService;
 import org.springframework.boot.testsupport.rule.OutputCapture;
 import org.springframework.boot.web.embedded.netty.NettyReactiveWebServerFactory;
 import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
@@ -597,6 +598,28 @@ public class SpringApplicationTests {
 				matchingPropertySource(PropertySource.class, "commandLineArgs"));
 	}
 
+	@Test
+	public void contextUsesApplicationConversionService() {
+		SpringApplication application = new SpringApplication(ExampleConfig.class);
+		application.setWebApplicationType(WebApplicationType.NONE);
+		this.context = application.run();
+		assertThat(this.context.getBeanFactory().getConversionService())
+				.isInstanceOf(ApplicationConversionService.class);
+		assertThat(this.context.getEnvironment().getConversionService())
+				.isInstanceOf(ApplicationConversionService.class);
+	}
+
+	@Test
+	public void contextWhenHasAddConversionServiceFalseUsesRegularConversionService() {
+		SpringApplication application = new SpringApplication(ExampleConfig.class);
+		application.setWebApplicationType(WebApplicationType.NONE);
+		application.setAddConversionService(false);
+		this.context = application.run();
+		assertThat(this.context.getBeanFactory().getConversionService()).isNull();
+		assertThat(this.context.getEnvironment().getConversionService())
+				.isNotInstanceOf(ApplicationConversionService.class);
+	}
+
 	@Test
 	public void runCommandLineRunnersAndApplicationRunners() {
 		SpringApplication application = new SpringApplication(CommandLineRunConfig.class);

spring-boot-samples/spring-boot-sample-simple/src/main/java/sample/simple/service/HelloWorldService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2013 the original author or authors.
+ * Copyright 2012-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
 
 package sample.simple.service;
 
+import java.time.Duration;
+
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Component;
 
@@ -25,8 +27,15 @@ public class HelloWorldService {
 	@Value("${name:World}")
 	private String name;
 
+	@Value("${duration:10s}")
+	private Duration duration;
+
 	public String getHelloMessage() {
-		return "Hello " + this.name;
+		return "Hello " + this.name + " for " + this.duration.getSeconds() + " seconds";
+	}
+
+	public Duration getDuration() {
+		return this.duration;
 	}
 
 }

spring-boot-samples/spring-boot-sample-simple/src/test/java/sample/simple/SampleSimpleApplicationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -62,9 +62,9 @@ public class SampleSimpleApplicationTests {
 
 	@Test
 	public void testCommandLineOverrides() throws Exception {
-		SampleSimpleApplication.main(new String[] { "--name=Gordon" });
+		SampleSimpleApplication.main(new String[] { "--name=Gordon", "--duration=1m" });
 		String output = this.outputCapture.toString();
-		assertThat(output).contains("Hello Gordon");
+		assertThat(output).contains("Hello Gordon for 60 seconds");
 	}
 
 }