001/*
002 * Copyright 2002-2015 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.bind.annotation;
018
019import java.lang.annotation.Documented;
020import java.lang.annotation.ElementType;
021import java.lang.annotation.Retention;
022import java.lang.annotation.RetentionPolicy;
023import java.lang.annotation.Target;
024import java.util.Map;
025
026import org.springframework.core.annotation.AliasFor;
027
028/**
029 * Annotation which indicates that a method parameter should be bound to a web
030 * request parameter.
031 *
032 * <p>Supported for annotated handler methods in Servlet and Portlet environments.
033 *
034 * <p>If the method parameter type is {@link Map} and a request parameter name
035 * is specified, then the request parameter value is converted to a {@link Map}
036 * assuming an appropriate conversion strategy is available.
037 *
038 * <p>If the method parameter is {@link java.util.Map Map&lt;String, String&gt;} or
039 * {@link org.springframework.util.MultiValueMap MultiValueMap&lt;String, String&gt;}
040 * and a parameter name is not specified, then the map parameter is populated
041 * with all request parameter names and values.
042 *
043 * @author Arjen Poutsma
044 * @author Juergen Hoeller
045 * @author Sam Brannen
046 * @since 2.5
047 * @see RequestMapping
048 * @see RequestHeader
049 * @see CookieValue
050 * @see org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter
051 * @see org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter
052 * @see org.springframework.web.portlet.mvc.annotation.AnnotationMethodHandlerAdapter
053 */
054@Target(ElementType.PARAMETER)
055@Retention(RetentionPolicy.RUNTIME)
056@Documented
057public @interface RequestParam {
058
059        /**
060         * Alias for {@link #name}.
061         */
062        @AliasFor("name")
063        String value() default "";
064
065        /**
066         * The name of the request parameter to bind to.
067         * @since 4.2
068         */
069        @AliasFor("value")
070        String name() default "";
071
072        /**
073         * Whether the parameter is required.
074         * <p>Defaults to {@code true}, leading to an exception being thrown
075         * if the parameter is missing in the request. Switch this to
076         * {@code false} if you prefer a {@code null} value if the parameter is
077         * not present in the request.
078         * <p>Alternatively, provide a {@link #defaultValue}, which implicitly
079         * sets this flag to {@code false}.
080         */
081        boolean required() default true;
082
083        /**
084         * The default value to use as a fallback when the request parameter is
085         * not provided or has an empty value.
086         * <p>Supplying a default value implicitly sets {@link #required} to
087         * {@code false}.
088         */
089        String defaultValue() default ValueConstants.DEFAULT_NONE;
090
091}