Added connection manager

Signed-off-by: Jim Martens <github@2martens.de>

07/src/de.dis2017/data/db/DB2ConnectionManager.java

@@ -0,0 +1,73 @@
+package de.dis2017.data.db;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.Properties;
+
+/**
+ * Singleton for management of database connections
+ *
+ * @author Michael von Riegen
+ * @version April 2009
+ */
+class DB2ConnectionManager {
+    
+    // instance of Driver Manager
+    private static DB2ConnectionManager _instance = null;
+    
+    // DB2 connection
+    private Connection _con;
+    
+    /**
+     * Initializes database connection
+     */
+    private DB2ConnectionManager() {
+        try {
+            // load properties from db2.properties file
+            Properties      properties = new Properties();
+            URL             url        = ClassLoader.getSystemResource("db2.properties");
+            FileInputStream stream     = new FileInputStream(new File(url.toURI()));
+            properties.load(stream);
+            stream.close();
+            
+            String jdbcUser = properties.getProperty("jdbc_user");
+            String jdbcPass = properties.getProperty("jdbc_pass");
+            String jdbcUrl  = properties.getProperty("jdbc_url");
+            
+            // created connection to DB2 database
+            Class.forName("com.ibm.db2.jcc.DB2Driver");
+            _con = DriverManager.getConnection(jdbcUrl, jdbcUser, jdbcPass);
+            
+        } catch (IOException | ClassNotFoundException | SQLException | URISyntaxException e) {
+            e.printStackTrace();
+        }
+        
+    }
+    
+    /**
+     * Returns the instance of the connection manager
+     *
+     * @return DB2ConnectionManager
+     */
+    static DB2ConnectionManager getInstance() {
+        if (_instance == null) {
+            _instance = new DB2ConnectionManager();
+        }
+        return _instance;
+    }
+    
+    /**
+     * Returns the connection to the DB2 database
+     *
+     * @return Connection
+     */
+    Connection getConnection() {
+        return _con;
+    }
+}