Check database connection before accessing it

This hopefully fixes #7

config.yml

@@ -60,6 +60,10 @@ database:
   # Either use 'SQLite' or 'MySQL'. Otherwise you will break the plugin!
   type: "SQLite"
 
+  # Set the amount of attempts, ShopChest tries to reconnect to the database,
+  # when the connection is lost, until giving up.
+  reconnect-attemps: 5
+
   # If the specified type is 'MySQL', here you configure the...
   # (You can leave this empty if you're using SQLite)
   mysql:

src/de/epiceric/shopchest/config/Config.java

@@ -32,6 +32,11 @@ public class Config {
     /** The database type used for ShopChest. **/
     public static Database.DatabaseType database_type = Database.DatabaseType.valueOf(plugin.getConfig().getString("database.type"));
 
+    /**
+     * The amount of attempts, ShopChest tries to reconnect to the database, when the connection is lost, until giving up
+     **/
+    public static int database_reconnect_attempts = plugin.getConfig().getInt("database.reconnect-attempts");
+
     /**
      * <p>The minimum prices for certain items</p>
      * This returns a key set, which contains e.g "STONE", "STONE:1", of the <i>minimum-prices</i> section in ShopChest's config.

src/de/epiceric/shopchest/listeners/ShopInteractListener.java

@@ -3,6 +3,7 @@ package de.epiceric.shopchest.listeners;
 import com.griefcraft.lwc.LWC;
 import com.griefcraft.model.Protection;
 import de.epiceric.shopchest.ShopChest;
+import de.epiceric.shopchest.config.Config;
 import de.epiceric.shopchest.config.Regex;
 import de.epiceric.shopchest.language.LanguageUtils;
 import de.epiceric.shopchest.language.LocalizedMessage;
@@ -234,7 +235,14 @@ public class ShopInteractListener implements Listener {
      * @param shopType  Type of the shop
      */
     private void create(Player executor, Location location, ItemStack product, double buyPrice, double sellPrice, ShopType shopType) {
-        Shop shop = new Shop(database.getNextFreeID(), plugin, executor, product, location, buyPrice, sellPrice, shopType);
+        int id = database.getNextFreeID(Config.database_reconnect_attempts);
+
+        if (id == 0) {
+            executor.sendMessage(LanguageUtils.getMessage(LocalizedMessage.Message.ERROR_OCCURRED, new LocalizedMessage.ReplacedRegex(Regex.ERROR, "Could not connect to database")));
+            return;
+        }
+
+        Shop shop = new Shop(id, plugin, executor, product, location, buyPrice, sellPrice, shopType);
 
         ShopUtils.addShop(shop, true);
         executor.sendMessage(LanguageUtils.getMessage(LocalizedMessage.Message.SHOP_CREATED));

src/de/epiceric/shopchest/sql/Database.java

@@ -1,6 +1,7 @@
 package de.epiceric.shopchest.sql;
 
 import de.epiceric.shopchest.ShopChest;
+import de.epiceric.shopchest.config.Config;
 import de.epiceric.shopchest.shop.Shop;
 import de.epiceric.shopchest.shop.Shop.ShopType;
 import de.epiceric.shopchest.utils.ShopUtils;
@@ -19,6 +20,8 @@ public abstract class Database {
     public ShopChest plugin;
     public Connection connection;
 
+    private int attempts = Config.database_reconnect_attempts;
+
     public Database(ShopChest plugin) {
         this.plugin = plugin;
         initialize();
@@ -65,14 +68,23 @@ public abstract class Database {
     }
 
     /**
+     * @param reconnectAttempts Attempts to reconnect to the database if not connected
      * @return Lowest possible ID which is not used (> 0)
      */
-    public int getNextFreeID() {
+    public int getNextFreeID(int reconnectAttempts) {
-        for (int i = 1; i < getHighestID() + 1; i++) {
+        if (!isConnected()) {
-            if (get(i, ShopInfo.X) == null) {
+            if (reconnectAttempts > 0) {
+                connection = getConnection();
+                plugin.getLogger().info("Reconnecting to database (" + reconnectAttempts + ") ...");
+                return getNextFreeID(reconnectAttempts - 1);
+            } else return 0;
+        }
+
+        for (int i = 1; i < getHighestID(attempts) + 1; i++) {
+            if (get(i, ShopInfo.X, attempts) == null) {
                 return i;
             } else {
-                if (i == getHighestID()) {
+                if (i == getHighestID(attempts)) {
                     return i + 1;
                 }
             }
@@ -84,7 +96,15 @@ public abstract class Database {
     /**
      * @return Highest ID which is used
      */
-    public int getHighestID() {
+    public int getHighestID(int reconnectAttempts) {
+        if (!isConnected()) {
+            if (reconnectAttempts > 0) {
+                connection = getConnection();
+                plugin.getLogger().info("Reconnecting to database (" + reconnectAttempts + ") ...");
+                return getHighestID(reconnectAttempts - 1);
+            } else return 0;
+        }
+
         PreparedStatement ps = null;
         ResultSet rs = null;
 
@@ -116,7 +136,16 @@ public abstract class Database {
      *
      * @param shop Shop to remove
      */
-    public void removeShop(Shop shop) {
+    public void removeShop(Shop shop, int reconnectAttempts) {
+        if (!isConnected()) {
+            if (reconnectAttempts > 0) {
+                connection = getConnection();
+                plugin.getLogger().info("Reconnecting to database (" + reconnectAttempts + ") ...");
+                removeShop(shop, reconnectAttempts - 1);
+                return;
+            } else return;
+        }
+
         PreparedStatement ps = null;
 
         try {
@@ -135,7 +164,15 @@ public abstract class Database {
      * @param shopInfo What to get
      * @return Value you wanted to get. This needs to be casted to the right type!
      */
-    public Object get(int id, ShopInfo shopInfo) {
+    public Object get(int id, ShopInfo shopInfo, int reconnectAttempts) {
+        if (!isConnected()) {
+            if (reconnectAttempts > 0) {
+                connection = getConnection();
+                plugin.getLogger().info("Reconnecting to database (" + reconnectAttempts + ") ...");
+                return get(id, shopInfo, reconnectAttempts - 1);
+            } else return null;
+        }
+
         PreparedStatement ps = null;
         ResultSet rs = null;
 
@@ -148,17 +185,17 @@ public abstract class Database {
 
                     switch (shopInfo) {
                         case SHOP:
-                            Shop shop = ShopUtils.getShop((Location) get(id, ShopInfo.LOCATION));
+                            Shop shop = ShopUtils.getShop((Location) get(id, ShopInfo.LOCATION, attempts));
                             if (shop != null)
                                 return shop;
                             else {
                                 return new Shop(id, plugin,
-                                        (OfflinePlayer) get(id, ShopInfo.VENDOR),
+                                        (OfflinePlayer) get(id, ShopInfo.VENDOR, attempts),
-                                        (ItemStack) get(id, ShopInfo.PRODUCT),
+                                        (ItemStack) get(id, ShopInfo.PRODUCT, attempts),
-                                        (Location) get(id, ShopInfo.LOCATION),
+                                        (Location) get(id, ShopInfo.LOCATION, attempts),
-                                        (double) get(id, ShopInfo.BUYPRICE),
+                                        (double) get(id, ShopInfo.BUYPRICE, attempts),
-                                        (double) get(id, ShopInfo.SELLPRICE),
+                                        (double) get(id, ShopInfo.SELLPRICE, attempts),
-                                        (ShopType) get(id, ShopInfo.SHOPTYPE));
+                                        (ShopType) get(id, ShopInfo.SHOPTYPE, attempts));
                             }
                         case VENDOR:
                             return Bukkit.getOfflinePlayer(UUID.fromString(rs.getString("vendor")));
@@ -173,7 +210,7 @@ public abstract class Database {
                         case Z:
                             return rs.getInt("z");
                         case LOCATION:
-                            return new Location((World) get(id, ShopInfo.WORLD), (int) get(id, ShopInfo.X), (int) get(id, ShopInfo.Y), (int) get(id, ShopInfo.Z));
+                            return new Location((World) get(id, ShopInfo.WORLD, attempts), (int) get(id, ShopInfo.X, attempts), (int) get(id, ShopInfo.Y, attempts), (int) get(id, ShopInfo.Z, attempts));
                         case BUYPRICE:
                             return rs.getDouble("buyprice");
                         case SELLPRICE:
@@ -184,14 +221,14 @@ public abstract class Database {
                             if (shoptype.equals("INFINITE")) {
 
                                 Shop newShop = new Shop(id, plugin,
-                                        (OfflinePlayer) get(id, ShopInfo.VENDOR),
+                                        (OfflinePlayer) get(id, ShopInfo.VENDOR, attempts),
-                                        (ItemStack) get(id, ShopInfo.PRODUCT),
+                                        (ItemStack) get(id, ShopInfo.PRODUCT, attempts),
-                                        (Location) get(id, ShopInfo.LOCATION),
+                                        (Location) get(id, ShopInfo.LOCATION, attempts),
-                                        (double) get(id, ShopInfo.BUYPRICE),
+                                        (double) get(id, ShopInfo.BUYPRICE, attempts),
-                                        (double) get(id, ShopInfo.SELLPRICE),
+                                        (double) get(id, ShopInfo.SELLPRICE, attempts),
                                         ShopType.ADMIN);
 
-                                addShop(newShop);
+                                addShop(newShop, attempts);
 
                                 return ShopType.ADMIN;
                             }
@@ -213,7 +250,16 @@ public abstract class Database {
      * Adds a shop to the database
      * @param shop Shop to add
      */
-    public void addShop(Shop shop) {
+    public void addShop(Shop shop, int reconnectAttempts) {
+        if (!isConnected()) {
+            if (reconnectAttempts > 0) {
+                connection = getConnection();
+                plugin.getLogger().info("Reconnecting to database (" + reconnectAttempts + ") ...");
+                addShop(shop, reconnectAttempts - 1);
+                return;
+            } else return;
+        }
+
         PreparedStatement ps = null;
 
         try {
@@ -238,6 +284,28 @@ public abstract class Database {
         }
     }
 
+    /**
+     * @return Whether ShopChest is connected to the database
+     */
+    private boolean isConnected() {
+        PreparedStatement ps = null;
+        ResultSet rs = null;
+
+        boolean connected = false;
+
+        try {
+            ps = connection.prepareStatement("SELECT * FROM shop_list");
+            rs = ps.executeQuery();
+            connected = true;
+        } catch (SQLException e) {
+            connected = false;
+        } finally {
+            close(ps, rs);
+        }
+
+        return connected;
+    }
+
     /**
      * Closes a {@link PreparedStatement} and a {@link ResultSet}
      * @param ps {@link PreparedStatement} to close

src/de/epiceric/shopchest/utils/ShopUtils.java

@@ -81,7 +81,7 @@ public class ShopUtils {
         }
 
         if (addToDatabase)
-            plugin.getShopDatabase().addShop(shop);
+            plugin.getShopDatabase().addShop(shop, Config.database_reconnect_attempts);
 
     }
 
@@ -108,7 +108,7 @@ public class ShopUtils {
             shop.removeHologram();
 
             if (removeFromDatabase)
-                plugin.getShopDatabase().removeShop(shop);
+                plugin.getShopDatabase().removeShop(shop, Config.database_reconnect_attempts);
     }
 
     /**
@@ -212,10 +212,10 @@ public class ShopUtils {
         }
 
         int count = 0;
-        for (int id = 1; id < plugin.getShopDatabase().getHighestID() + 1; id++) {
+        for (int id = 1; id < plugin.getShopDatabase().getHighestID(Config.database_reconnect_attempts) + 1; id++) {
 
             try {
-                Shop shop = (Shop) plugin.getShopDatabase().get(id, Database.ShopInfo.SHOP);
+                Shop shop = (Shop) plugin.getShopDatabase().get(id, Database.ShopInfo.SHOP, Config.database_reconnect_attempts);
                 ShopUtils.addShop(shop, false);
             } catch (NullPointerException e) {
                 continue;