Added product retriever with tests

src/main/java/de/rwu/easydrop/service/retriever/ProductRetriever.java

@@ -0,0 +1,67 @@
+package de.rwu.easydrop.service.retriever;
+
+import de.rwu.easydrop.api.client.AmazonProductDataSource;
+import de.rwu.easydrop.api.client.DataSourceFactory;
+import de.rwu.easydrop.api.client.EbayItemDataSource;
+import de.rwu.easydrop.api.dto.ProductDTO;
+import de.rwu.easydrop.model.Product;
+import de.rwu.easydrop.service.mapping.ProductMapper;
+import de.rwu.easydrop.service.validation.ProductValidator;
+
+/**
+ * Retrieves Product Objects from various data sources.
+ *
+ * @since 0.2.0
+ */
+public class ProductRetriever {
+    /**
+     * Data source factory.
+     */
+    private DataSourceFactory dataSourceFactory;
+
+    /**
+     * @param newDataSourceFactory the dataSourceFactory to set
+     */
+    public void setDataSourceFactory(final DataSourceFactory newDataSourceFactory) {
+        this.dataSourceFactory = newDataSourceFactory;
+    }
+
+    /**
+     * @param newDataSourceFactory
+     */
+    public ProductRetriever(final DataSourceFactory newDataSourceFactory) {
+        this.setDataSourceFactory(newDataSourceFactory);
+    }
+
+    /**
+     * Retrieves a product from Amazon.
+     *
+     * @param asin Product identifier
+     * @return Product from Amazon
+     */
+    public Product getProductFromAmazon(final String asin) {
+        AmazonProductDataSource dataSource = dataSourceFactory.createAmazonProductDataSource();
+        ProductDTO dto = dataSource.getProductDTOById(asin);
+
+        Product product = ProductMapper.mapProductFromDTO(dto);
+        ProductValidator.validate(product);
+
+        return product;
+    }
+
+    /**
+     * Retrieves a product from eBay.
+     *
+     * @param query Product search query
+     * @return Product from eBay
+     */
+    public Product getProductFromEbay(final String query) {
+        EbayItemDataSource dataSource = dataSourceFactory.createEbayItemDataSource();
+        ProductDTO dto = dataSource.getProductDTOById(query);
+
+        Product product = ProductMapper.mapProductFromDTO(dto);
+        ProductValidator.validate(product);
+
+        return product;
+    }
+}

src/main/java/de/rwu/easydrop/service/retriever/package-info.java

@@ -0,0 +1,6 @@
+/**
+ * Retrieves Objects from a data source.
+ *
+ * @since 0.2.0
+ */
+package de.rwu.easydrop.service.retriever;