Skeleton code to initialize the DatabaseManager

src/main/java/org/leolo/nrdatad/App.java

@@ -4,8 +4,10 @@ package org.leolo.nrdatad;
 import org.apache.commons.cli.*;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.leolo.nrdatad.db.DatabaseManager;
 
 import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
 
 /**
  * Hello world!
@@ -14,6 +16,8 @@ import java.io.IOException;
 public class App {
 
     Logger log = LogManager.getLogger();
+
+    private ConfigurationManager config = ConfigurationManager.getInstance();
     public static void main( String[] args ) {
         Option confFile = Option.builder()
                 .required(false)
@@ -38,23 +42,38 @@ public class App {
 
     private void run(String configPath){
         log.always().log("System Started.");
+
         try {
-            ConfigurationManager.getInstance().loadConfiguration(configPath);
+            config.loadConfiguration(configPath);
         } catch (IOException e) {
             log.atError().withThrowable(e).log("Unable to load confog file");
             return;
         }
 //        log.atDebug()
-        if(ConfigurationManager.getInstance().getProperty("general.debug","false").equals("true")){
-            for(String key:ConfigurationManager.getInstance().stringPropertyNames()){
+        if(config.getProperty("general.debug","false").equals("true")){
+            for(String key:config.stringPropertyNames()){
                 if(key.endsWith("pwd")){
-                    log.atDebug().log("Config: {} : ****({} chars)", key, ConfigurationManager.getInstance().getProperty(key).length());
+                    log.atDebug().log("Config: {} : ****({} chars)", key, config.getProperty(key).length());
 
                 }else{
-                    log.atDebug().log("Config: {} : {}", key, ConfigurationManager.getInstance().getProperty(key));
+                    log.atDebug().log("Config: {} : {}", key, config.getProperty(key));
 
                 }
             }
         }
+        String databaseManagerClass = config.getProperty("db.manager","org.leolo.nrdatad.db.DatabaseManager");
+        log.atInfo().log("Creating database manager {}", databaseManagerClass);
+        try {
+            config.setDatabaseManager((DatabaseManager) Class.forName(databaseManagerClass).getConstructor().newInstance());
+        } catch (
+                InstantiationException|IllegalAccessException|InvocationTargetException|
+                NoSuchMethodException|ClassNotFoundException e
+        ) {
+            log.atFatal().log("Unable to create instance of {}", databaseManagerClass);
+            System.exit(1);
+        } catch (ClassCastException e){
+            log.atFatal().log("{} is not a DatabaseManager", databaseManagerClass);
+            System.exit(1);
+        }
     }
 }

src/main/java/org/leolo/nrdatad/ConfigurationManager.java

@@ -2,6 +2,7 @@ package org.leolo.nrdatad;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.leolo.nrdatad.db.DatabaseManager;
 
 import java.io.FileReader;
 import java.io.IOException;
@@ -13,7 +14,17 @@ public final class ConfigurationManager {
     private static ConfigurationManager instance;
     Logger logger = LogManager.getLogger();
     Properties prop = new Properties();
-    
+
+    private DatabaseManager databaseManager;
+
+    public DatabaseManager getDatabaseManager() {
+        return databaseManager;
+    }
+
+    public void setDatabaseManager(DatabaseManager databaseManager) {
+        this.databaseManager = databaseManager;
+    }
+
     public synchronized static ConfigurationManager getInstance(){
         if(instance==null){
             instance = new ConfigurationManager();

src/main/java/org/leolo/nrdatad/db/DatabaseManager.java

@@ -1,4 +1,6 @@
 package org.leolo.nrdatad.db;
 
 public interface DatabaseManager {
+
+    public void initPool();
 }

src/main/java/org/leolo/nrdatad/db/mariadb/DatabaseManager.java

@@ -1,5 +1,8 @@
 package org.leolo.nrdatad.db.mariadb;
 
 public class DatabaseManager implements org.leolo.nrdatad.db.DatabaseManager{
+    @Override
+    public void initPool() {
 
+    }
 }

src/test/java/org/leolo/nrdatad/db/test/DatabaseManager.java

@@ -1,4 +1,9 @@
 package org.leolo.nrdatad.db.test;
 
 public class DatabaseManager implements org.leolo.nrdatad.db.DatabaseManager {
+
+    @Override
+    public void initPool() {
+
+    }
 }