juneau-core/juneau-marshall/src/main/java/org/apache/juneau/json/annotation/Json.java

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package org.apache.juneau.json.annotation;

import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.*;

import java.lang.annotation.*;

/**
 * Annotation for specifying various JSON options for the JSON serializers and parsers.
 *
 * <p>
 * Can be applied to Java types.
 *
 * <p>
 * Can be used for the following:
 * <ul class='spaced-list'>
 * 	<li>
 * 		Wrap bean instances inside wrapper object (e.g. <c>{'wrapperAttr':bean}</c>).
 * </ul>
 */
@Documented
@Target({TYPE,METHOD,FIELD})
@Retention(RUNTIME)
@Inherited
public @interface Json {

	/**
	 * Dynamically apply this annotation to the specified classes/methods/fields.
	 *
	 * <p>
	 * Used in conjunction with the {@link JsonConfig#applyJson()}.
	 * It is ignored when the annotation is applied directly to classes/methods/fields.
	 *
	 * <h5 class='section'>Valid patterns:</h5>
	 * <ul class='spaced-list'>
	 *  <li>Classes:
	 * 		<ul>
	 * 			<li>Fully qualified:
	 * 				<ul>
	 * 					<li><js>"com.foo.MyClass"</js>
	 * 				</ul>
	 * 			<li>Fully qualified inner class:
	 * 				<ul>
	 * 					<li><js>"com.foo.MyClass$Inner1$Inner2"</js>
	 * 				</ul>
	 * 			<li>Simple:
	 * 				<ul>
	 * 					<li><js>"MyClass"</js>
	 * 				</ul>
	 * 			<li>Simple inner:
	 * 				<ul>
	 * 					<li><js>"MyClass$Inner1$Inner2"</js>
	 * 					<li><js>"Inner1$Inner2"</js>
	 * 					<li><js>"Inner2"</js>
	 * 				</ul>
	 * 		</ul>
	 * 	<li>Methods:
	 * 		<ul>
	 * 			<li>Fully qualified with args:
	 * 				<ul>
	 * 					<li><js>"com.foo.MyClass.myMethod(String,int)"</js>
	 * 					<li><js>"com.foo.MyClass.myMethod(java.lang.String,int)"</js>
	 * 					<li><js>"com.foo.MyClass.myMethod()"</js>
	 * 				</ul>
	 * 			<li>Fully qualified:
	 * 				<ul>
	 * 					<li><js>"com.foo.MyClass.myMethod"</js>
	 * 				</ul>
	 * 			<li>Simple with args:
	 * 				<ul>
	 * 					<li><js>"MyClass.myMethod(String,int)"</js>
	 * 					<li><js>"MyClass.myMethod(java.lang.String,int)"</js>
	 * 					<li><js>"MyClass.myMethod()"</js>
	 * 				</ul>
	 * 			<li>Simple:
	 * 				<ul>
	 * 					<li><js>"MyClass.myMethod"</js>
	 * 				</ul>
	 * 			<li>Simple inner class:
	 * 				<ul>
	 * 					<li><js>"MyClass$Inner1$Inner2.myMethod"</js>
	 * 					<li><js>"Inner1$Inner2.myMethod"</js>
	 * 					<li><js>"Inner2.myMethod"</js>
	 * 				</ul>
	 * 		</ul>
	 * 	<li>Fields:
	 * 		<ul>
	 * 			<li>Fully qualified:
	 * 				<ul>
	 * 					<li><js>"com.foo.MyClass.myField"</js>
	 * 				</ul>
	 * 			<li>Simple:
	 * 				<ul>
	 * 					<li><js>"MyClass.myField"</js>
	 * 				</ul>
	 * 			<li>Simple inner class:
	 * 				<ul>
	 * 					<li><js>"MyClass$Inner1$Inner2.myField"</js>
	 * 					<li><js>"Inner1$Inner2.myField"</js>
	 * 					<li><js>"Inner2.myField"</js>
	 * 				</ul>
	 * 		</ul>
	 * 	<li>A comma-delimited list of anything on this list.
	 * </ul>
	 *
	 * <ul class='seealso'>
	 * 	<li class='link'>{@doc juneau-marshall.DynamicallyAppliedAnnotations}
	 * </ul>
	 */
	String on() default "";

	/**
	 * Wraps beans in a JSON object with the specified attribute name.
	 *
	 * <p>
	 * Applies only to {@link ElementType#TYPE}.
	 *
	 * <p>
	 * This annotation can be applied to beans as well as other objects serialized to other types (e.g. strings).
	 *
	 * <h5 class='figure'>Example:</h5>
	 * <p class='bcode w800'>
	 * 	<ja>@Json</ja>(wrapperAttr=<js>"myWrapper"</js>)
	 * 	<jk>public class</jk> MyBean {
	 * 		<jk>public int</jk> f1 = 123;
	 * 	}
	 * </p>
	 *
	 * <p>
	 * Without the <ja>@Json</ja> annotations, serializing this bean as JSON would have produced the following...
	 * <p class='bcode w800'>
	 * 	{
	 * 		f1: 123
	 * 	}
	 * </p>
	 *
	 * <p>
	 * With the annotations, serializing this bean as JSON produces the following...
	 * <p class='bcode w800'>
	 * 	{
	 * 		myWrapper: {
	 * 			f1: 123
	 * 		}
	 * 	}
	 * </p>
	 */
	String wrapperAttr() default "";
}