Added abstraction layer to DataSources

src/main/java/de/rwu/easydrop/api/client/AbstractDataSource.java

@@ -0,0 +1,99 @@
+package de.rwu.easydrop.api.client;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.MalformedURLException;
+import java.net.URL;
+
+import de.rwu.easydrop.api.dto.ProductDTO;
+import de.rwu.easydrop.util.FormattingUtil;
+
+/**
+ * Helper class for shared data and functions between data sources.
+ *
+ * @since 0.2.0
+ */
+public abstract class AbstractDataSource implements DataSource {
+
+    /**
+     * Returns the data origin for the current source.
+     *
+     * @return Data source name
+     */
+    protected abstract String getDataOrigin();
+
+    /**
+     * Returns the data source's API key.
+     *
+     * @return Data source API key
+     */
+    protected abstract String getApiKey();
+
+    /**
+     * Enriches a ProductDTO with API-gathered data.
+     *
+     * @param product Unfinished ProductDTO
+     * @param json    Product data
+     * @return Finished ProductDTO
+     */
+    public abstract ProductDTO buildProductDTO(ProductDTO product, String json);
+
+    /**
+     * Overridable standard implementation.
+     */
+    @Override
+    public ProductDTO getProductDTOById(final String productIdentifier)
+            throws IllegalArgumentException {
+        StringBuilder response = new StringBuilder();
+        String dataOrigin = getDataOrigin();
+        String apiKey = getApiKey();
+        ProductDTO product = new ProductDTO(productIdentifier, dataOrigin);
+
+        try {
+            String urlReadyIdentifier = FormattingUtil.urlEncode(productIdentifier);
+            URL apiUrl = createApiUrl(urlReadyIdentifier);
+
+            HttpURLConnection connection = (HttpURLConnection) apiUrl.openConnection();
+            connection.setRequestMethod("GET");
+            connection.setRequestProperty("Credential", apiKey);
+
+            int responseCode = connection.getResponseCode();
+            BufferedReader reader;
+            if (responseCode == HttpURLConnection.HTTP_OK) {
+                reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
+            } else {
+                throw new IllegalArgumentException(
+                        "Nothing found: "
+                                + dataOrigin
+                                + " API responded with error code "
+                                + responseCode);
+            }
+
+            String line;
+            while ((line = reader.readLine()) != null) {
+                response.append(line);
+            }
+            reader.close();
+
+            buildProductDTO(product, response.toString());
+        } catch (IOException e) {
+            throw new IllegalArgumentException(
+                    "Couldn't fulfill "
+                            + dataOrigin
+                            + " API request");
+        }
+
+        return product;
+    }
+
+    /**
+     * Creates an URL object to connect to the API with.
+     *
+     * @param productIdentifier Product identifier
+     * @return URL object
+     * @throws MalformedURLException
+     */
+    protected abstract URL createApiUrl(String productIdentifier) throws MalformedURLException;
+}

src/main/java/de/rwu/easydrop/api/client/AmazonProductDataSource.java

@@ -1,9 +1,5 @@
 package de.rwu.easydrop.api.client;
 
-import java.io.BufferedReader;
-import java.io.IOException;
-import java.io.InputStreamReader;
-import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
 import java.net.URL;
 
@@ -18,7 +14,7 @@ import de.rwu.easydrop.api.dto.ProductDTO;
  *
  * @since 0.1.0
  */
-public final class AmazonProductDataSource implements DataSource {
+public final class AmazonProductDataSource extends AbstractDataSource {
     /**
      * Name of this data source.
      */
@@ -52,47 +48,6 @@ public final class AmazonProductDataSource implements DataSource {
     }
 
     @Override
-    public ProductDTO getProductDTOById(final String productId) throws IllegalArgumentException {
-        StringBuilder response = new StringBuilder();
-        ProductDTO product = new ProductDTO(productId, DATA_ORIGIN);
-
-        try {
-            URL apiUrl = createApiUrl(productId);
-
-            HttpURLConnection connection = (HttpURLConnection) apiUrl.openConnection();
-            connection.setRequestMethod("GET");
-            connection.setRequestProperty("Credential", apiKey);
-
-            int responseCode = connection.getResponseCode();
-            BufferedReader reader;
-            if (responseCode == HttpURLConnection.HTTP_OK) {
-                reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
-            } else {
-                throw new IllegalArgumentException(
-                        "Nothing found: Amazon API responded with error code " + responseCode);
-            }
-
-            String line;
-            while ((line = reader.readLine()) != null) {
-                response.append(line);
-            }
-            reader.close();
-
-            buildProductDTO(product, response.toString());
-        } catch (IOException e) {
-            throw new IllegalArgumentException("Couldn't fulfill Amazon API request");
-        }
-
-        return product;
-    }
-
-    /**
-     * Enriches a ProductDTO with API-gathered data.
-     *
-     * @param product Unfinished ProductDTO
-     * @param json    Product data
-     * @return Finished ProductDTO
-     */
     public ProductDTO buildProductDTO(final ProductDTO product, final String json) {
         String root = "$.featuredOffer.";
         ReadContext ctx = JsonPath.parse(json);
@@ -112,6 +67,9 @@ public final class AmazonProductDataSource implements DataSource {
         return product;
     }
 
+    /**
+     * @param productId ASIN
+     */
     @Override
     public URL createApiUrl(final String productId) throws MalformedURLException {
         return new URL(baseUrl
@@ -122,4 +80,14 @@ public final class AmazonProductDataSource implements DataSource {
                 + "&locale="
                 + LOCALE);
     }
+
+    @Override
+    protected String getDataOrigin() {
+        return DATA_ORIGIN;
+    }
+
+    @Override
+    protected String getApiKey() {
+        return this.apiKey;
+    }
 }

src/main/java/de/rwu/easydrop/api/client/DataSource.java

@@ -1,8 +1,5 @@
 package de.rwu.easydrop.api.client;
 
-import java.net.MalformedURLException;
-import java.net.URL;
-
 import de.rwu.easydrop.api.dto.ProductDTO;
 
 /**
@@ -12,17 +9,8 @@ public interface DataSource {
     /**
      * Retrieves product info from the data source.
      *
-     * @param productId ASIN
+     * @param productIdentifier Product identifier
      * @return ProductDTO
      */
-    ProductDTO getProductDTOById(String productId);
+    ProductDTO getProductDTOById(String productIdentifier);
-
-    /**
-     * Creates an URL object to connect to the API with.
-     *
-     * @param productId ASIN
-     * @return URL object
-     * @throws MalformedURLException
-     */
-    URL createApiUrl(String productId) throws MalformedURLException;
 }

src/main/java/de/rwu/easydrop/util/FormattingUtil.java

@@ -27,4 +27,14 @@ public final class FormattingUtil {
     public static String formatEuro(final double amount) {
         return String.format(Locale.GERMAN, "%,.2f", amount) + " €";
     }
+
+    /**
+     * Makes a string URL ready. For now, only spaces are replaced.
+     *
+     * @param str
+     * @return URL-ready string
+     */
+    public static String urlEncode(final String str) {
+        return str.replace(" ", "+");
+    }
 }