From d853368f4c06a28f3f42448ceda631d0d08591e5 Mon Sep 17 00:00:00 2001
From: Marc Baloup <marc.baloup@laposte.net>
Date: Fri, 15 Mar 2019 19:09:11 +0100
Subject: [PATCH] Better management of DB connection + adding method in ORM to
 truncate table

---
 .../pandacube/java/util/orm/DBConnection.java | 25 +++++++++++++++----
 .../java/fr/pandacube/java/util/orm/ORM.java  | 13 ++++++++++
 2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/src/main/java/fr/pandacube/java/util/orm/DBConnection.java b/src/main/java/fr/pandacube/java/util/orm/DBConnection.java
index 6343099..2f74199 100644
--- a/src/main/java/fr/pandacube/java/util/orm/DBConnection.java
+++ b/src/main/java/fr/pandacube/java/util/orm/DBConnection.java
@@ -2,8 +2,8 @@ package fr.pandacube.java.util.orm;
 
 import java.sql.Connection;
 import java.sql.DriverManager;
+import java.sql.ResultSet;
 import java.sql.SQLException;
-import java.sql.Statement;
 
 public class DBConnection {
 	private Connection conn;
@@ -28,13 +28,28 @@ public class DBConnection {
 		connect();
 	}
 
-	public void reconnectIfNecessary() throws SQLException {
-		try(Statement stmt = conn.createStatement()) {
-		} catch (SQLException e) {
+	private void checkConnection() throws SQLException {
+		if (!isConnected()) {
 			close();
 			connect();
 		}
 	}
+	
+	public boolean isConnected()
+    {
+        boolean connected = false;
+
+        try (ResultSet rs = conn.createStatement().executeQuery("SELECT 1;"))
+        {
+            if (rs == null)
+                connected = false;
+            else if (rs.next())
+                connected = true;
+        } catch (Exception e) {
+            connected = false;
+        }
+        return connected;
+    }
 
 	public Connection getNativeConnection() throws SQLException {
 		if (conn.isClosed())
@@ -43,7 +58,7 @@ public class DBConnection {
 		if (timeOfLastCheck + 5000 > now) {
 			timeOfLastCheck = now;
 			if (!conn.isValid(1))
-				reconnectIfNecessary();
+				checkConnection();
 		}
 		return conn;
 	}
diff --git a/src/main/java/fr/pandacube/java/util/orm/ORM.java b/src/main/java/fr/pandacube/java/util/orm/ORM.java
index e309ee9..85fbe70 100644
--- a/src/main/java/fr/pandacube/java/util/orm/ORM.java
+++ b/src/main/java/fr/pandacube/java/util/orm/ORM.java
@@ -3,6 +3,7 @@ package fr.pandacube.java.util.orm;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
+import java.sql.Statement;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
@@ -163,6 +164,18 @@ public final class ORM {
 	}
 	
 	
+	
+	public static <E extends SQLElement<E>> boolean truncateTable(Class<E> elemClass) throws ORMException {
+		boolean success;
+        try (Statement stmt = connection.getNativeConnection().createStatement()) {
+            success = stmt.execute("TRUNCATE `" + elemClass.newInstance().tableName() + "`");
+        } catch(SQLException | ReflectiveOperationException e) {
+        	throw new ORMException(e);
+        }
+        return success;
+	}
+	
+	
 	public static ResultSet getCustomResult(String sql, List<Object> params) throws ORMException {
 		try {
 			PreparedStatement ps = connection.getNativeConnection().prepareStatement(sql);