Support BindParam annotation

Allows customizing the name of the request parameter to bind a
constructor parameter to.

Closes gh-30947

spring-web/src/main/java/org/springframework/web/bind/annotation/BindParam.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2002-2018 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
+ *
+ *      https://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.web.bind.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to bind values from a web request such as request parameters or
+ * path variables to fields of a Java object. Supported on constructor parameters
+ * of {@link ModelAttribute @ModelAttribute} controller method arguments
+ *
+ * @author Rossen Stoyanchev
+ * @since 6.1
+ * @see org.springframework.web.bind.WebDataBinder#construct
+ */
+@Target(ElementType.PARAMETER)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface BindParam {
+
+	/**
+	 * The lookup name to use for the bind value.
+	 */
+	String value() default "";
+
+}

spring-web/src/main/java/org/springframework/web/bind/support/BindParamNameResolver.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2002-2018 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
+ *
+ *      https://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.web.bind.support;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.util.StringUtils;
+import org.springframework.validation.DataBinder;
+import org.springframework.web.bind.annotation.BindParam;
+
+/**
+ * {@link org.springframework.validation.DataBinder.NameResolver} that determines
+ * the bind value name from a {@link BindParam @BindParam} method parameter
+ * annotation.
+ *
+ * @author Rossen Stoyanchev
+ * @since 6.1
+ */
+public final class BindParamNameResolver implements DataBinder.NameResolver {
+
+	@Override
+	public String resolveName(MethodParameter parameter) {
+		BindParam bindParam = parameter.getParameterAnnotation(BindParam.class);
+		if (bindParam != null) {
+			if (StringUtils.hasText(bindParam.value())) {
+				return bindParam.value();
+			}
+		}
+		return null;
+	}
+
+}

spring-web/src/main/java/org/springframework/web/bind/support/DefaultDataBinderFactory.java

@@ -91,6 +91,7 @@ public class DefaultDataBinderFactory implements WebDataBinderFactory {
 			@Nullable ResolvableType type) throws Exception {
 
 		WebDataBinder dataBinder = createBinderInstance(target, objectName, webRequest);
+		dataBinder.setNameResolver(new BindParamNameResolver());
 
 		if (target == null && type != null) {
 			dataBinder.setTargetType(type);
@@ -99,6 +100,7 @@ public class DefaultDataBinderFactory implements WebDataBinderFactory {
 		if (this.initializer != null) {
 			this.initializer.initBinder(dataBinder);
 		}
+
 		initBinder(dataBinder, webRequest);
 
 		if (this.methodValidationApplicable && type != null) {
@@ -112,7 +114,7 @@ public class DefaultDataBinderFactory implements WebDataBinderFactory {
 
 	/**
 	 * Extension point to create the WebDataBinder instance.
-	 * By default this is {@code WebRequestDataBinder}.
+	 * By default, this is {@code WebRequestDataBinder}.
 	 * @param target the binding target or {@code null} for type conversion only
 	 * @param objectName the binding target object name
 	 * @param webRequest the current request