Introduce Ordered Filter and WebFilter interfaces

Add `Ordered` variants of `javax.servlet.Filter` and
`org.springframework.web.server.WebFilter` mainly so that we can
deprecate `FilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER`.

Closes gh-14793

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/SecurityProperties.java

@@ -25,7 +25,7 @@ import java.util.UUID;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.web.servlet.DispatcherType;
-import org.springframework.boot.web.servlet.FilterRegistrationBean;
+import org.springframework.boot.web.servlet.filter.OrderedFilter;
 import org.springframework.core.Ordered;
 import org.springframework.util.StringUtils;
 
@@ -58,7 +58,7 @@ public class SecurityProperties implements SecurityPrerequisite {
 	 * other filters registered with the container). There is no connection between this
 	 * and the {@code @Order} on a WebSecurityConfigurer.
 	 */
-	public static final int DEFAULT_FILTER_ORDER = FilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER
+	public static final int DEFAULT_FILTER_ORDER = OrderedFilter.REQUEST_WRAPPER_FILTER_MAX_ORDER
 			- 100;
 
 	private final Filter filter = new Filter();

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/servlet/SecurityAutoConfigurationTests.java

@@ -32,7 +32,7 @@ import org.springframework.boot.autoconfigure.orm.jpa.test.City;
 import org.springframework.boot.test.context.runner.WebApplicationContextRunner;
 import org.springframework.boot.test.rule.OutputCapture;
 import org.springframework.boot.web.servlet.DelegatingFilterProxyRegistrationBean;
-import org.springframework.boot.web.servlet.FilterRegistrationBean;
+import org.springframework.boot.web.servlet.filter.OrderedFilter;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -85,8 +85,7 @@ public class SecurityAutoConfigurationTests {
 						.getBean("securityFilterChainRegistration",
 								DelegatingFilterProxyRegistrationBean.class)
 						.getOrder()).isEqualTo(
-								FilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER
-										- 100));
+								OrderedFilter.REQUEST_WRAPPER_FILTER_MAX_ORDER - 100));
 	}
 
 	@Test
@@ -126,8 +125,7 @@ public class SecurityAutoConfigurationTests {
 						.getBean("securityFilterChainRegistration",
 								DelegatingFilterProxyRegistrationBean.class)
 						.getOrder()).isEqualTo(
-								FilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER
-										- 100));
+								OrderedFilter.REQUEST_WRAPPER_FILTER_MAX_ORDER - 100));
 	}
 
 	@Test

spring-boot-project/spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -3063,7 +3063,7 @@ If a specific order is required, you should avoid configuring a Filter that read
 request body at `Ordered.HIGHEST_PRECEDENCE`, since it might go against the character
 encoding configuration of your application. If a Servlet filter wraps the request, it
 should be configured with an order that is less than or equal to
-`FilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER`.
+`OrderedFilter.REQUEST_WRAPPER_FILTER_MAX_ORDER`.
 
 
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/filter/OrderedHiddenHttpMethodFilter.java

@@ -26,12 +26,12 @@ import org.springframework.web.filter.reactive.HiddenHttpMethodFilter;
  * @since 2.0.5
  */
 public class OrderedHiddenHttpMethodFilter extends HiddenHttpMethodFilter
-		implements Ordered {
+		implements OrderedWebFilter {
 
 	/**
 	 * The default order is high to ensure the filter is applied before Spring Security.
 	 */
-	public static final int DEFAULT_ORDER = -10000;
+	public static final int DEFAULT_ORDER = REQUEST_WRAPPER_FILTER_MAX_ORDER - 10000;
 
 	private int order = DEFAULT_ORDER;
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/filter/OrderedWebFilter.java

@@ -0,0 +1,35 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.web.reactive.filter;
+
+import org.springframework.core.Ordered;
+import org.springframework.web.server.WebFilter;
+
+/**
+ * An {@link Ordered} {@link org.springframework.web.server.WebFilter}.
+ *
+ * @author Phillip Webb
+ * @since 2.1.0
+ */
+public interface OrderedWebFilter extends WebFilter, Ordered {
+
+	/**
+	 * Filters that wrap the request should be ordered less than or equal to this.
+	 */
+	int REQUEST_WRAPPER_FILTER_MAX_ORDER = 0;
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/AbstractFilterRegistrationBean.java

@@ -48,7 +48,10 @@ public abstract class AbstractFilterRegistrationBean<T extends Filter>
 
 	/**
 	 * Filters that wrap the servlet request should be ordered less than or equal to this.
+	 * @deprecated since 2.1.0 in favor of
+	 * {@code OrderedFilter.REQUEST_WRAPPER_FILTER_MAX_ORDER}
 	 */
+	@Deprecated
 	protected static final int REQUEST_WRAPPER_FILTER_MAX_ORDER = 0;
 
 	private final Log logger = LogFactory.getLog(getClass());

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/FilterRegistrationBean.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.
@@ -45,7 +45,10 @@ public class FilterRegistrationBean<T extends Filter>
 
 	/**
 	 * Filters that wrap the servlet request should be ordered less than or equal to this.
+	 * @deprecated since 2.1.0 in favor of
+	 * {@code OrderedFilter.REQUEST_WRAPPER_FILTER_MAX_ORDER}
 	 */
+	@Deprecated
 	public static final int REQUEST_WRAPPER_FILTER_MAX_ORDER = AbstractFilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER;
 
 	private T filter;

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/filter/OrderedCharacterEncodingFilter.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.
@@ -26,7 +26,7 @@ import org.springframework.web.filter.CharacterEncodingFilter;
  * @since 2.0.0
  */
 public class OrderedCharacterEncodingFilter extends CharacterEncodingFilter
-		implements Ordered {
+		implements OrderedFilter {
 
 	private int order = Ordered.HIGHEST_PRECEDENCE;
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/filter/OrderedFilter.java

@@ -0,0 +1,36 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.web.servlet.filter;
+
+import javax.servlet.Filter;
+
+import org.springframework.core.Ordered;
+
+/**
+ * An {@link Ordered} {@link javax.servlet.Filter}.
+ *
+ * @author Phillip Webb
+ * @since 2.1.0
+ */
+public interface OrderedFilter extends Filter, Ordered {
+
+	/**
+	 * Filters that wrap the servlet request should be ordered less than or equal to this.
+	 */
+	int REQUEST_WRAPPER_FILTER_MAX_ORDER = 0;
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/filter/OrderedFormContentFilter.java

@@ -16,7 +16,6 @@
 
 package org.springframework.boot.web.servlet.filter;
 
-import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.core.Ordered;
 import org.springframework.web.filter.FormContentFilter;
 
@@ -27,13 +26,12 @@ import org.springframework.web.filter.FormContentFilter;
  * @author Brian Clozel
  * @since 2.1.0
  */
-public class OrderedFormContentFilter extends FormContentFilter implements Ordered {
+public class OrderedFormContentFilter extends FormContentFilter implements OrderedFilter {
 
 	/**
 	 * Higher order to ensure the filter is applied before Spring Security.
 	 */
-	public static final int DEFAULT_ORDER = FilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER
-			- 9900;
+	public static final int DEFAULT_ORDER = REQUEST_WRAPPER_FILTER_MAX_ORDER - 9900;
 
 	private int order = DEFAULT_ORDER;
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/filter/OrderedHiddenHttpMethodFilter.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.
@@ -16,7 +16,6 @@
 
 package org.springframework.boot.web.servlet.filter;
 
-import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.core.Ordered;
 import org.springframework.web.filter.HiddenHttpMethodFilter;
 
@@ -27,13 +26,12 @@ import org.springframework.web.filter.HiddenHttpMethodFilter;
  * @since 2.0.0
  */
 public class OrderedHiddenHttpMethodFilter extends HiddenHttpMethodFilter
-		implements Ordered {
+		implements OrderedFilter {
 
 	/**
 	 * The default order is high to ensure the filter is applied before Spring Security.
 	 */
-	public static final int DEFAULT_ORDER = FilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER
-			- 10000;
+	public static final int DEFAULT_ORDER = REQUEST_WRAPPER_FILTER_MAX_ORDER - 10000;
 
 	private int order = DEFAULT_ORDER;
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/filter/OrderedRequestContextFilter.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.
@@ -16,7 +16,6 @@
 
 package org.springframework.boot.web.servlet.filter;
 
-import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.core.Ordered;
 import org.springframework.web.filter.RequestContextFilter;
 
@@ -26,10 +25,11 @@ import org.springframework.web.filter.RequestContextFilter;
  * @author Phillip Webb
  * @since 2.0.0
  */
-public class OrderedRequestContextFilter extends RequestContextFilter implements Ordered {
+public class OrderedRequestContextFilter extends RequestContextFilter
+		implements OrderedFilter {
 
 	// Order defaults to after Spring Session filter
-	private int order = FilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER - 105;
+	private int order = REQUEST_WRAPPER_FILTER_MAX_ORDER - 105;
 
 	@Override
 	public int getOrder() {

src/checkstyle/checkstyle-suppressions.xml

@@ -7,6 +7,8 @@
 	<suppress files=".+Configuration\.java" checks="HideUtilityClassConstructor" />
 	<suppress files=".+Application\.java" checks="HideUtilityClassConstructor" />
 	<suppress files="SignalUtils\.java" checks="IllegalImport" />
+	<suppress files="OrderedFilter\.java" checks="InterfaceIsType" />
+	<suppress files="OrderedWebFilter\.java" checks="InterfaceIsType" />
 	<suppress files="[\\/]src[\\/]test[\\/]java[\\/]cli[\\/]command[\\/]" checks="ImportControl" />
 	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]sample[\\/]" checks="ImportControl" />
 	<suppress files="[\\/]src[\\/]test[\\/]java[\\/]sample[\\/]" checks="ImportControl" />