Basic database function

pom.xml

@@ -14,8 +14,8 @@
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <maven.compiler.source>1.7</maven.compiler.source>
-    <maven.compiler.target>1.7</maven.compiler.target>
+    <maven.compiler.source>1.8</maven.compiler.source>
+    <maven.compiler.target>1.8</maven.compiler.target>
   </properties>
 
   <dependencies>
@@ -96,6 +96,16 @@
         </plugin>
       </plugins>
     </pluginManagement>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <configuration>
+          <source>8</source>
+          <target>8</target>
+        </configuration>
+      </plugin>
+    </plugins>
   </build>
 
 </project>

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

@@ -78,5 +78,12 @@ public class App {
             return;
         }
         config.getDatabaseManager().initPool();
+        if(config.getDatabaseManager().checkConnection())
+            log.atInfo().log("Database connected!");
+        else{
+            log.atFatal().log("Unable to connect to database.");
+            System.exit(1);
+            return;
+        }
     }
 }

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

@@ -9,6 +9,7 @@ import java.io.IOException;
 import java.io.PrintStream;
 import java.io.PrintWriter;
 import java.util.*;
+import java.util.function.BiConsumer;
 
 public final class ConfigurationManager {
     private static ConfigurationManager instance;
@@ -116,4 +117,11 @@ public final class ConfigurationManager {
         prop.clear();
     }
 
+    public Object getOrDefault(Object key, Object defaultValue) {
+        return prop.getOrDefault(key, defaultValue);
+    }
+
+    public void forEach(BiConsumer<? super Object, ? super Object> action) {
+        prop.forEach(action);
+    }
 }

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

@@ -1,6 +1,13 @@
 package org.leolo.nrdatad.db;
 
+import java.sql.Connection;
+import java.sql.SQLException;
+
 public interface DatabaseManager {
 
     public void initPool();
+
+    public boolean checkConnection();
+
+    public Connection getConnection() throws SQLException;
 }

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

@@ -5,6 +5,8 @@ import org.apache.logging.log4j.Logger;
 import org.leolo.nrdatad.ConfigurationManager;
 import org.mariadb.jdbc.MariaDbPoolDataSource;
 
+import java.sql.*;
+
 public class DatabaseManager implements org.leolo.nrdatad.db.DatabaseManager{
     Logger logger = LogManager.getLogger();
     private MariaDbPoolDataSource ds;
@@ -26,5 +28,33 @@ public class DatabaseManager implements org.leolo.nrdatad.db.DatabaseManager{
                 ":"+conf.getProperty("db.port", "3306")+
                 "/"+conf.getProperty("db.name");
         logger.atDebug().log("URL={}",url);
+        try {
+            ds = new MariaDbPoolDataSource(url);
+            ds.setMinPoolSize(1);
+            ds.setMaxPoolSize(Integer.parseInt(conf.getOrDefault("db.poolsize", "20").toString()));
+            ds.setUser(conf.getProperty("db.user").toString());
+            ds.setPassword(conf.getProperty("db.pwd").toString());
+        } catch (SQLException e) {
+            logger.atFatal().withThrowable(e).log("Cannot connect to DB");
+            System.exit(-2);
+        }
+    }
+
+    @Override
+    public boolean checkConnection() {
+        try(
+                Connection conn = ds.getConnection();
+                Statement stmt = conn.createStatement();
+                ResultSet rs = stmt.executeQuery("SELECT 1")
+        ){
+            return rs.next();
+        }catch(SQLException e){
+            return false;
+        }
+    }
+
+    @Override
+    public Connection getConnection() throws SQLException{
+        return ds.getConnection();
     }
 }

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

@@ -1,8 +1,7 @@
 package org.leolo.nrdatad.db.test;
 
-public class DatabaseManager implements org.leolo.nrdatad.db.DatabaseManager {
+public class DatabaseManager {
 
-    @Override
     public void initPool() {
 
     }