com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBAutoGeneratedKey Maven / Gradle / Ivy

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The AWS SDK for Java with support for OSGi. The AWS SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).

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/*
 * Copyright 2011-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *    http://aws.amazon.com/apache2.0
 *
 * This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
 * OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and
 * limitations under the License.
 */
package com.amazonaws.services.dynamodbv2.datamodeling;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.util.UUID;

/**
 * Annotation for marking a hash key or range key property in a class to
 * auto-generate this key. Only String typed keys can be auto generated, and are
 * given a random UUID. The annotation can be applied to either the getter
 * method or the class field for the auto-generated key property. If the
 * annotation is applied directly to the class field, the corresponding getter
 * and setter must be declared in the same class. This annotation can be applied
 * to both primary and index keys.
 *
 * @see UUID
 */
@DynamoDBAutoGenerated(generator=DynamoDBAutoGeneratedKey.Generator.class)
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD})
public @interface DynamoDBAutoGeneratedKey {

    /**
     * Default generator.
     */
    static final class Generator implements DynamoDBAutoGenerator {
        private final DynamoDBTypeConverter converter;

        public Generator(final Class targetType, final DynamoDBAutoGeneratedKey annotation) {
            this.converter = StandardTypeConverters.Scalar.UUID.getConverter(targetType);
        }

        @Override
        public final DynamoDBAutoGenerateStrategy getGenerateStrategy() {
            return DynamoDBAutoGenerateStrategy.CREATE;
        }

        @Override
        public final T generate(final T currentValue) {
            return converter.unconvert(UUID.randomUUID());
        }
    }

}