add java doc

add little logging
minor fixes

2 files changed, 65 insertions, 66 deletions

diff --git a/id/server/moa-id-commons/src/main/java/com/datentechnik/moa/id/conf/persistence/Configuration.java b/id/server/moa-id-commons/src/main/java/com/datentechnik/moa/id/conf/persistence/Configuration.java
index 43f7d9454..873208aaf 100644
--- a/id/server/moa-id-commons/src/main/java/com/datentechnik/moa/id/conf/persistence/Configuration.java
+++ b/id/server/moa-id-commons/src/main/java/com/datentechnik/moa/id/conf/persistence/Configuration.java
@@ -3,53 +3,52 @@ package com.datentechnik.moa.id.conf.persistence;
 import java.util.List;
 
 /**
- *
+ * An interface for a key-value configuration.
  */
 public interface Configuration {
 
 	/**
-	 * 
-	 * @param key
-	 * @return
+	 * Get the value associated with the given key as {@link Object}.
+	 * @param key the key
+	 * @return the object associated with the given key or {@code null} if the key does not exist or does not have a value.
 	 */
 	Object get(String key);
 
 	/**
+	 * Get the object of type {@code T} associated with the given key.
 	 * 
-	 * @param key
-	 * @param clazz
-	 * @return
+	 * @param key the key
+	 * @param clazz the type of the requested object
+	 * @return the object associated with the given key or {@code null} if the key does not exist or does not have a value.
 	 */
 	<T> T get(String key, Class<T> clazz);
 
 	/**
+	 * Store an object associated with a key. If the given object is set to {@code null} then the entry associated with the key is deleted.
 	 * 
-	 * @param key
-	 * @param value
+	 * @param key the key under which the value is stored, respectively key determining the entry to be deleted.
+	 * @param value the object to store. if value is set to {@code null} then the entry associated with key {@code key} is deleted.
+	 * @return {@code true} if the operation was carried out successfully, {@code false} otherwise.
 	 */
 	boolean set(String key, Object value);
 
 	/**
+	 * Get the object of type {@code T} associated with the given key from the database. If the key does not exist or does not have a value, the given default
+	 * value is returned.
 	 * 
-	 * @param key
-	 * @param clazz
-	 * @param defaultValue
-	 * @return
+	 * @param key the key
+	 * @param clazz the type of the requested object
+	 * @param defaultValue the default value to return
+	 * @return the object associated with the given key or {@code defaultValue} if the key does not exist or does not have a value.
 	 */
 	<T> T get(String key, Class<T> clazz, Object defaultValue);
 
 	/**
-	 * 
-	 * @param key
-	 * @param clazz
-	 * @return
+	 * Get a list of objects associated with the given key. The list may be empty or contain only a single object.
+	 * @param key the key
+	 * @param clazz the type of the requested object
+	 * @return a list containing objects of type {@code T} or an empty list if no objects are associated with the key.
 	 */
 	<T> List<T> getList(String key, Class<T> clazz);
 
-	/**
-	 *
-	 * @param key
-	 * @return
-	 */
-	void delete(String key);
 }
\ No newline at end of file
diff --git a/id/server/moa-id-commons/src/main/java/com/datentechnik/moa/id/conf/persistence/ConfigurationImpl.java b/id/server/moa-id-commons/src/main/java/com/datentechnik/moa/id/conf/persistence/ConfigurationImpl.java
index eebecf509..6d05af791 100644
--- a/id/server/moa-id-commons/src/main/java/com/datentechnik/moa/id/conf/persistence/ConfigurationImpl.java
+++ b/id/server/moa-id-commons/src/main/java/com/datentechnik/moa/id/conf/persistence/ConfigurationImpl.java
@@ -4,6 +4,8 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Required;
 import org.springframework.stereotype.Component;
 
@@ -21,12 +23,14 @@ import com.fasterxml.jackson.databind.type.CollectionType;
 import com.fasterxml.jackson.databind.type.TypeFactory;
 
 /**
- * 
- *
+ * The implementation of a key-value configuration implementing the {@link Configuration} interface.
+ * It employs the {@link ConfigPropertyDao} to persist configuration data.
  */
 @Component
 public class ConfigurationImpl implements Configuration {
 
+	private final Logger log = LoggerFactory.getLogger(getClass());
+	
 	ConfigPropertyDao configPropertyDao;
 	private JsonMapper mapper = new JsonMapper();
 
@@ -42,10 +46,10 @@ public class ConfigurationImpl implements Configuration {
 	@Override
 	public Object get(String key) {
 		// return null if key does not exist
-
 		try {
-			return mapper.deserialize(getPropertyValue(key), null);
+			return mapper.deserialize(configPropertyDao.getProperty(key).getValue(), null);
 		} catch (Exception e) {
+			log.trace("Error while deserializing value of key '{}' to object.", key);
 			return null;
 		}
 	}
@@ -58,6 +62,7 @@ public class ConfigurationImpl implements Configuration {
 			try {
 				return clazz.cast(mapper.deserialize(property.getValue(), clazz));
 			} catch (IOException e) {
+				log.trace("Error while deserializing value of key '{}' to object of type {}.",key,clazz.getClass());
 				return null;
 			}
 		} else {
@@ -68,24 +73,27 @@ public class ConfigurationImpl implements Configuration {
 	@Override
 	public boolean set(String key, Object value) {
 
-		ConfigProperty keyValue = new ConfigProperty();
-		keyValue.setKey(key);
-		try {
-			keyValue.setValue(mapper.serialize(value));
-			// System.out.println(">> key - value: " + keyValue.getKey() + " - " + keyValue.getValue() + "\n");
-			configPropertyDao.saveProperty(keyValue);
+		if (value == null) {
+			configPropertyDao.delete(key);
 			return true;
-		} catch (JsonProcessingException e) {
-			// TODO do proper error handling
-			e.printStackTrace();
-			return false;
-		}
+		} else {
 
+			ConfigProperty keyValue = new ConfigProperty();
+			keyValue.setKey(key);
+			try {
+				keyValue.setValue(mapper.serialize(value));
+				configPropertyDao.saveProperty(keyValue);
+				return true;
+			} catch (JsonProcessingException e) {
+				log.trace("Error while serializing object for key '{}'.", key);
+				return false;
+			}
+		}
 	}
 
 	@Override
 	public <T> T get(String key, Class<T> clazz, Object defaultValue) {
-		// TODO complete the method
+
 		T value = get(key, clazz);
 		if (value != null) {
 			return value;
@@ -116,36 +124,30 @@ public class ConfigurationImpl implements Configuration {
 			}
 			return tmp;
 		} catch (IOException e) {
+			log.trace("Error while deserializing value for key '{}' to List<{}>.", key,clazz.getClass());
 			return new ArrayList<T>();
 		}
 	}
 
-	private String getPropertyValue(String key) {
-		ConfigProperty property = configPropertyDao.getProperty(key);
-		return property.getValue();
-	}
-
-	@Override
-	public void delete(String key) {
-		configPropertyDao.delete(key);
-	}
-
 
 	/**
-	 * 
+	 * Helper class to handle the JSON (de-)serialization.
 	 *
 	 */
 	private class JsonMapper {
 
 		private ObjectMapper mapper = new ObjectMapper();
 
+		/**
+		 * The default constructor where the default pretty printer is disabled.
+		 */
 		public JsonMapper() {
 			this(false);
 		}
 
 		/**
-		 * 
-		 * @param prettyPrint
+		 * The constructor.
+		 * @param prettyPrint enables or disables the default pretty printer
 		 */
 		public JsonMapper(boolean prettyPrint) {
 			mapper.setVisibility(PropertyAccessor.ALL, Visibility.NONE);
@@ -157,25 +159,26 @@ public class ConfigurationImpl implements Configuration {
 		}
 
 		/**
-		 * 
-		 * @param value
-		 * @return
-		 * @throws JsonProcessingException
+		 * Serialize an object to a JSON string.
+		 * @param value the object to serialize
+		 * @return a JSON string
+		 * @throws JsonProcessingException thrown when an error occurs during serialization
 		 */
 		public String serialize(Object value) throws JsonProcessingException {
 			return mapper.writeValueAsString(value);
 		}
 
 		/**
+		 * Deserialize a JSON string.
 		 * 
-		 * @param value
-		 * @param clazz
-		 * @return
-		 * @throws JsonParseException
-		 * @throws JsonMappingException
-		 * @throws IOException
+		 * @param value the JSON string to deserialize
+		 * @param clazz optional parameter that determines the type of the returned object. If not set, an {@link Object} is returned.
+		 * @return the deserialized JSON string as an object of type {@code clazz} or {@link Object}
+		 * @throws JsonParseException if the JSON string contains invalid content.
+		 * @throws JsonMappingException if the input JSON structure does not match structure expected for result type
+		 * @throws IOException if an I/O problem occurs (e.g. unexpected end-of-input)
 		 */
-		public <T> Object deserialize(String value, Class<T> clazz) throws JsonParseException, JsonMappingException, IOException {
+		public <T> Object deserialize(String value, Class<T> clazz) throws JsonParseException, JsonMappingException, IOException{
 
 			ObjectMapper mapper = new ObjectMapper();
 			if (clazz != null) {
@@ -184,10 +187,7 @@ public class ConfigurationImpl implements Configuration {
 			} else {
 				return mapper.readValue(value, Object.class);
 			}
-
 		}
-
 	};
 
-
 }