Add spring.http.multipart.resolve-lazily

This commit adds the `spring.http.multipart.resolve-lazily`
property, in order to configure whether the multipart request
should be resolved lazily, as the parameters are accessed.

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/MultipartAutoConfiguration.java

@@ -43,6 +43,7 @@ import org.springframework.web.servlet.DispatcherServlet;
  *
  * @author Greg Turnquist
  * @author Josh Long
+ * @author Toshiaki Maki
  */
 @Configuration
 @ConditionalOnClass({ Servlet.class, StandardServletMultipartResolver.class,
@@ -66,7 +67,9 @@ public class MultipartAutoConfiguration {
 	@Bean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
 	@ConditionalOnMissingBean(MultipartResolver.class)
 	public StandardServletMultipartResolver multipartResolver() {
-		return new StandardServletMultipartResolver();
+		StandardServletMultipartResolver multipartResolver = new StandardServletMultipartResolver();
+		multipartResolver.setResolveLazily(multipartProperties.isResolveLazily());
+		return multipartResolver;
 	}
 
 }

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/MultipartProperties.java

@@ -42,6 +42,7 @@ import org.springframework.util.StringUtils;
  * {@literal String} variants that accept {@literal Kb} or {@literal Mb} suffixes.
  *
  * @author Josh Long
+ * @author Toshiaki Maki
  * @since 1.1.0
  */
 @ConfigurationProperties(prefix = "spring.http.multipart", ignoreUnknownFields = false)
@@ -75,6 +76,12 @@ public class MultipartProperties {
 	 */
 	private String fileSizeThreshold = "0";
 
+	/**
+	 * Whether to resolve the multipart request lazily at the time of file or parameter
+	 * access.
+	 */
+	private boolean resolveLazily = false;
+
 	public boolean getEnabled() {
 		return this.enabled;
 	}
@@ -115,6 +122,14 @@ public class MultipartProperties {
 		this.fileSizeThreshold = fileSizeThreshold;
 	}
 
+	public boolean isResolveLazily() {
+		return resolveLazily;
+	}
+
+	public void setResolveLazily(boolean resolveLazily) {
+		this.resolveLazily = resolveLazily;
+	}
+
 	/**
 	 * Create a new {@link MultipartConfigElement} using the properties.
 	 * @return a new {@link MultipartConfigElement} configured using there properties

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/MultipartAutoConfigurationTests.java

@@ -40,6 +40,7 @@ import org.springframework.http.client.ClientHttpRequest;
 import org.springframework.http.client.ClientHttpResponse;
 import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
 import org.springframework.stereotype.Controller;
+import org.springframework.test.util.ReflectionTestUtils;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.client.RestTemplate;
@@ -59,6 +60,7 @@ import static org.mockito.Mockito.mock;
  * @author Dave Syer
  * @author Josh Long
  * @author Ivan Sopov
+ * @author Toshiaki Maki
  */
 public class MultipartAutoConfigurationTests {
 
@@ -188,6 +190,20 @@ public class MultipartAutoConfigurationTests {
 				.isNotInstanceOf(StandardServletMultipartResolver.class);
 	}
 
+	@Test
+	public void configureResolveLazily() {
+		this.context = new AnnotationConfigEmbeddedWebApplicationContext();
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.http.multipart.resolve-lazily=true");
+		this.context.register(ContainerWithNothing.class, BaseConfiguration.class);
+		this.context.refresh();
+		StandardServletMultipartResolver multipartResolver = this.context
+				.getBean(StandardServletMultipartResolver.class);
+		boolean resolveLazily = (Boolean) ReflectionTestUtils.getField(multipartResolver,
+				"resolveLazily");
+		assertThat(resolveLazily).isTrue();
+	}
+
 	private void verify404() throws Exception {
 		HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
 		ClientHttpRequest request = requestFactory.createRequest(

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -283,6 +283,7 @@ content into your application; rather pick only the properties that you need.
 	spring.http.multipart.location= # Intermediate location of uploaded files.
 	spring.http.multipart.max-file-size=1Mb # Max file size. Values can use the suffixed "MB" or "KB" to indicate a Megabyte or Kilobyte size.
 	spring.http.multipart.max-request-size=10Mb # Max request size. Values can use the suffixed "MB" or "KB" to indicate a Megabyte or Kilobyte size.
+	spring.http.multipart.resolve-lazily=false # Whether to resolve the multipart request lazily at the time of file or parameter access.
 
 	# JACKSON ({sc-spring-boot-autoconfigure}/jackson/JacksonProperties.{sc-ext}[JacksonProperties])
 	spring.jackson.date-format= # Date format string or a fully-qualified date format class name. For instance `yyyy-MM-dd HH:mm:ss`.