Mapping Arbitrary Data Using the AWS SDK for Java Object Persistence Model

import java.io.IOException;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.PropertiesCredentials;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBAttribute;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBHashKey;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMarshaller;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMarshalling;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTable;

public class ObjectPersistenceMappingExample {
    
    static AmazonDynamoDBClient client;
    
    public static void main(String[] args) throws IOException {
        
        AWSCredentials credentials = new PropertiesCredentials(
                ObjectPersistenceMappingExample.class.getResourceAsStream("AwsCredentials.properties"));

        client = new AmazonDynamoDBClient(credentials);
        
        DimensionType dimType = new DimensionType();
        dimType.setHeight("8.00");
        dimType.setLength("11.0");
        dimType.setThickness("1.0");
        
        Book book = new Book();
        book.setId(502);
        book.setTitle("Book 502");
        book.setISBN("555-5555555555");
        book.setBookAuthors(new HashSet<String>(Arrays.asList("Author1", "Author2")));
        book.setDimensions(dimType);
        
        System.out.println(book);
        
        DynamoDBMapper mapper = new DynamoDBMapper(client);
        mapper.save(book);
        
        Book bookRetrieved = mapper.load(Book.class, 502);
        
        System.out.println(bookRetrieved);
        
        bookRetrieved.getDimensions().setHeight("9.0");
        bookRetrieved.getDimensions().setLength("12.0");
        bookRetrieved.getDimensions().setThickness("2.0");
        
        mapper.save(bookRetrieved);

        bookRetrieved = mapper.load(Book.class, 502);        
        System.out.println(bookRetrieved);

    }
        
    @DynamoDBTable(tableName="ProductCatalog")
    public static class Book {
        private int id;
        private String title;
        private String ISBN;
        private Set<String> bookAuthors;
        private DimensionType dimensionType;
        
        @DynamoDBHashKey(attributeName = "Id")
        public int getId() { return id; }
        public void setId(int id) { this.id = id; }
        
        @DynamoDBAttribute(attributeName = "Title")
        public String getTitle() { return title; }    
        public void setTitle(String title) { this.title = title; }
        
        @DynamoDBAttribute(attributeName="ISBN")
        public String getISBN() { return ISBN; }    
        public void setISBN(String ISBN) { this.ISBN = ISBN;}
        
        @DynamoDBAttribute(attributeName = "Authors")
        public Set<String> getBookAuthors() { return bookAuthors; }    
        public void setBookAuthors(Set<String> bookAuthors) { this.bookAuthors = bookAuthors; }
        
        @DynamoDBMarshalling(marshallerClass = DimensionTypeConverter.class) 
        public DimensionType getDimensions() { return dimensionType; }
        public void setDimensions(DimensionType dimensionType) { this.dimensionType = dimensionType; }
        
        @Override
        public String toString() {
            return "Book [ISBN=" + ISBN + ", bookAuthors=" + bookAuthors
            + ", dimensionType=" + dimensionType + ", Id=" + id
            + ", Title=" + title + "]";            
        }
    }
    static public class DimensionType {
        
        private String length;
        private String height;
        private String thickness;
        
        public String getLength() { return length; }
        public void setLength(String length) { this.length = length; }
        
        public String getHeight() { return height; }
        public void setHeight(String height) { this.height = height; }
        
        public String getThickness() { return thickness; }
        public void setThickness(String thickness) { this.thickness = thickness; }
    }
    
    // Converts the complex type DimensionType to a string and vice-versa.
    static public class DimensionTypeConverter implements DynamoDBMarshaller<DimensionType> {

        @Override
        public String marshall(DimensionType value) {
            DimensionType itemDimensions = (DimensionType)value;      
            String dimension = null;
            try {
                if (itemDimensions != null) {
                    dimension = String.format("%s x %s x %s", 
                            itemDimensions.getLength(),
                            itemDimensions.getHeight(),
                            itemDimensions.getThickness());
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return dimension; 
        }

        @Override
        public DimensionType unmarshall(Class<DimensionType> dimensionType, String value) {
          
            DimensionType itemDimension = new DimensionType();
            try {
                if (value != null && value.length() !=0 ) {
                    String[] data = value.split("x");
                    itemDimension.setLength(data[0].trim());
                    itemDimension.setHeight(data[1].trim());
                    itemDimension.setThickness(data[2].trim());
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            
            return itemDimension;
        }        
    }
}