com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTypeConverted Maven / Gradle / Ivy
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/*
* Copyright 2011-2018 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;
/**
* Annotation to mark a property as using a custom type-converter.
*
* May be annotated on a user-defined annotation to pass additional
* properties to the {@link DynamoDBTypeConverter}.
*
*
* @CurrencyFormat(separator=" ") //<- user-defined annotation
* public Currency getCurrency()
*
*
* Where,
*
* public class Currency {
* private Double amount;
* private String unit;
*
* public Double getAmount() { return amount; }
* public void setAmount(Double amount) { this.amount = amount; }
*
* public String getUnit() { return unit; }
* public void setUnit(String unit) { this.unit = unit; }
* }
*
*
* And user-defined annotation,
*
* @Target({ElementType.METHOD})
* @Retention(RetentionPolicy.RUNTIME)
* @DynamoDBTypeConverted(converter=CurrencyFormat.Converter.class)
* public @interface CurrencyFormat {
*
* String separator() default " ";
*
* public static class Converter implements DynamoDBTypeConverter<String,Currency> {
* private final String separator;
* public Converter(final Class<Currency> targetType, final CurrencyFormat annotation) {
* this.separator = annotation.separator();
* }
* public Converter() {
* this.separator = "|";
* }
* @Override
* public String convert(final Currency o) {
* return String.valueOf(o.getAmount()) + separator + o.getUnit();
* }
* @Override
* public Currency unconvert(final String o) {
* final String[] strings = o.split(separator);
* final Currency currency = new Currency();
* currency.setAmount(Double.valueOf(strings[0]));
* currency.setUnit(strings[1]);
* return currency;
* }
* }
* }
*
*
* Alternately, the property/field may be annotated directly (which
* requires the converter to provide a default constructor or a constructor
* with only the {@code targetType}),
*
* @DynamoDBTypeConverted(converter=CurrencyFormat.Converter.class)
* public Currency getCurrency() { return currency; }
*
*
* All converters are null-safe, a {@code null} value will never be passed
* to {@link DynamoDBTypeConverter#convert}
* or {@link DynamoDBTypeConverter#unconvert}.
*
* Precedence for selecting a type-converter first goes to getter annotations,
* then field, then finally type.
*
* May be used in combination with {@link DynamoDBTyped} to specify the
* attribute type binding.
* Compatible with {@link DynamoDBAutoGeneratedTimestamp}
*
* May be used as a meta-annotation.
*/
@DynamoDB
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.FIELD, ElementType.METHOD, ElementType.ANNOTATION_TYPE})
public @interface DynamoDBTypeConverted {
/**
* The class of the converter for this property.
*/
@SuppressWarnings("rawtypes")
Class converter();
}