001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
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006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
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011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.annotation;
014
015import static java.lang.annotation.ElementType.*;
016import static java.lang.annotation.RetentionPolicy.*;
017
018import java.lang.annotation.*;
019
020import org.apache.juneau.*;
021
022/**
023 * Maps constructor arguments to property names on beans with read-only properties.
024 *
025 * <p>
026 * This annotation can be used in the case of beans with properties whose values can only be set by passing them in
027 * through a constructor on the class.
028 * <br>Since method parameter names are lost during compilation, this annotation essentially redefines them so that they
029 * are available at runtime.
030 *
031 * <p>
032 * This annotation can only be applied to constructors and can only be applied to one constructor per class.
033 *
034 * <p>
035 * When present, bean instantiation is delayed until the call to {@link BeanMap#getBean()}.
036 * Until then, bean property values are stored in a local cache until <code>getBean()</code> is called.
037 * Because of this additional caching step, parsing into read-only beans tends to be slower and use more memory than
038 * parsing into beans with writable properties.
039 *
040 * <p>
041 * Attempting to call {@link BeanMap#put(String,Object)} on a read-only property after calling {@link BeanMap#getBean()}
042 * will result in a {@link BeanRuntimeException} being thrown.
043 * Multiple calls to {@link BeanMap#getBean()} will return the same bean instance.
044 *
045 * <h5 class='section'>See Also:</h5>
046 * <ul>
047 *    <li class='link'>{@doc juneau-marshall.Transforms.BeanConstructorAnnotation}
048 * </ul>
049 */
050@Documented
051@Target(CONSTRUCTOR)
052@Retention(RUNTIME)
053@Inherited
054public @interface BeanConstructor {
055
056   /**
057    * The names of the properties of the constructor arguments.
058    *
059    * <p>
060    * The number of properties listed must match the number of arguments in the constructor.
061    */
062   String properties() default "";
063}