001/*
002 * Copyright 2012-2017 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 *      http://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.boot.web.servlet;
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;
024
025import javax.servlet.annotation.WebFilter;
026import javax.servlet.annotation.WebListener;
027import javax.servlet.annotation.WebServlet;
028
029import org.springframework.context.annotation.Import;
030import org.springframework.core.annotation.AliasFor;
031
032/**
033 * Enables scanning for Servlet components ({@link WebFilter filters}, {@link WebServlet
034 * servlets}, and {@link WebListener listeners}). Scanning is only performed when using an
035 * embedded web server.
036 * <p>
037 * Typically, one of {@code value}, {@code basePackages}, or {@code basePackageClasses}
038 * should be specified to control the packages to be scanned for components. In their
039 * absence, scanning will be performed from the package of the class with the annotation.
040 *
041 * @author Andy Wilkinson
042 * @since 1.3.0
043 * @see WebServlet
044 * @see WebFilter
045 * @see WebListener
046 */
047@Target(ElementType.TYPE)
048@Retention(RetentionPolicy.RUNTIME)
049@Documented
050@Import(ServletComponentScanRegistrar.class)
051public @interface ServletComponentScan {
052
053        /**
054         * Alias for the {@link #basePackages()} attribute. Allows for more concise annotation
055         * declarations e.g.: {@code @ServletComponentScan("org.my.pkg")} instead of
056         * {@code @ServletComponentScan(basePackages="org.my.pkg")}.
057         * @return the base packages to scan
058         */
059        @AliasFor("basePackages")
060        String[] value() default {};
061
062        /**
063         * Base packages to scan for annotated servlet components. {@link #value()} is an
064         * alias for (and mutually exclusive with) this attribute.
065         * <p>
066         * Use {@link #basePackageClasses()} for a type-safe alternative to String-based
067         * package names.
068         * @return the base packages to scan
069         */
070        @AliasFor("value")
071        String[] basePackages() default {};
072
073        /**
074         * Type-safe alternative to {@link #basePackages()} for specifying the packages to
075         * scan for annotated servlet components. The package of each class specified will be
076         * scanned.
077         * @return classes from the base packages to scan
078         */
079        Class<?>[] basePackageClasses() default {};
080
081}