modules/sca-api/src/main/java/org/oasisopen/sca/annotation/Property.java

/*
 * Copyright(C) OASIS(R) 2005,2010. All Rights Reserved.
 * OASIS trademark, IPR and other policies apply.
 */
package org.oasisopen.sca.annotation;

import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

/**
 * The @Property annotation is used to denote a Java class field,
 * a setter method, or a constructor parameter that is used to
 * inject an SCA property value. The type of the property injected,
 * which can be a simple Java type or a complex Java type, is defined
 * by the type of the Java class field or the type of the input
 * parameter of the setter method or constructor.
 *
 * The @Property annotation can be used on fields, on setter methods
 * or on a constructor method parameter. However, the @Property annotation
 * MUST NOT be used on a class field that is declared as final.
 *
 * Properties can also be injected via setter methods even when
 * the @Property annotation is not present.  However, the @Property
 * annotation must be used in order to inject a property onto a
 * non-public field.  In the case where there is no @Property
 * annotation, the name of the property is the same as the name of the
 * field or setter.
 *
 * Where there is both a setter method and a field for a property, the
 * setter method is used.
 */
@Target({METHOD, FIELD, PARAMETER})
@Retention(RUNTIME)
public @interface Property {

    /**
     * The name of the property.  For a field annotation, the default is
     * the name of the field of the Java class.  For a setter method annotation,
     * the default is the JavaBeans property name corresponding to the setter
     * method name.  For a constructor parameter annotation, there is no
     * default and the name attribute MUST be present.
     *
     * @return    the name of the property
     */
    String name() default "";

    /**
     * Specifies whether injection is required, defaults to true. For a
     * constructor parameter annotation, this attribute MUST have the value true.
     *
     * @return    true if injection is required
     */
    boolean required() default true;
}