added database

made prefixes database-stored

src/main/java/Bot.java

@@ -8,6 +8,8 @@ import javax.security.auth.login.LoginException;
 import java.io.File;
 import java.nio.file.Files;
 import java.nio.file.Paths;
+import java.sql.ResultSet;
+import java.sql.SQLException;
 import java.util.HashMap;
 import java.util.Scanner;
 
@@ -15,6 +17,7 @@ public class Bot {
     static HashMap<Long, String> prefixes = new HashMap<>();
 
     private static ShardManager shardManager;
+    private static Database database = null;
 
     public static void main(String[] args) throws LoginException {
         String token = null;
@@ -22,7 +25,8 @@ public class Bot {
             File tokenFile = Paths.get("token.txt").toFile();
             if (!tokenFile.exists()) {
                 System.out.println("[ERROR] Could not find token.txt file");
-                System.out.println("[ERROR] Please create a file called \"token.txt\" in the same folder as the jar " + "file and paste in your bot token.");
+                System.out.println("[ERROR] Please create a file called \"token.txt\" in the same folder as the jar "
+                                           + "file and paste in your bot token.");
                 return;
             }
             token = new String(Files.readAllBytes(tokenFile.toPath()));
@@ -30,6 +34,17 @@ public class Bot {
             ex.printStackTrace();
         }
         if (token == null) return;
+        // database = new Database(Database.DBType.SQLite);
+        if (database != null) {
+            if (!database.isConnected()) {
+                database = null;
+                System.out.println("[ERROR] Database connection failed. Continuing without database.");
+            } else {
+                database.update(
+                        "CREATE TABLE IF NOT EXISTS guildprefix (guildId VARCHAR(18) NOT NULL, prefix VARCHAR(8) NOT "
+                                + "NULL);");
+            }
+        }
         DefaultShardManagerBuilder builder = new DefaultShardManagerBuilder(token);
         builder.setStatus(OnlineStatus.ONLINE);
         builder.setActivity(Activity.playing("@Sokobot for info!"));
@@ -54,6 +69,10 @@ public class Bot {
         if (cmd.equalsIgnoreCase("stop")) {
             System.out.println("Shutting down...");
             shardManager.shutdown();
+            if (database != null) {
+                System.out.println("Disconnecting database...");
+                database.disconnect();
+            }
             System.out.println("Bye!");
             System.exit(0);
             return;
@@ -65,11 +84,37 @@ public class Bot {
         return shardManager;
     }
 
+    static void removePrefix(long guildId) {
+        prefixes.remove(guildId);
+        if (database != null) {
+            database.update("DELETE FROM guildprefix WHERE guildId=?;", String.valueOf(guildId));
+        }
+    }
+
     static void setPrefix(Guild guild, String prefix) {
         prefixes.put(guild.getIdLong(), prefix);
+        if (database != null) {
+            database.update("DELETE FROM guildprefix WHERE guildId=?;", guild.getId());
+            database.update("INSERT INTO guildprefix VALUES (?, ?);", guild.getId(), prefix);
+        }
     }
 
     static String getPrefix(Guild guild) {
-        return prefixes.getOrDefault(guild.getIdLong(), "!");
+        if (prefixes.containsKey(guild.getIdLong())) return prefixes.get(guild.getIdLong());
+        if (database != null) {
+            try (ResultSet rs = database.query("SELECT prefix FROM guildprefix WHERE guildId=?;", guild.getId())) {
+                if (rs.next()) {
+                    String prefix = rs.getString("prefix");
+                    prefixes.put(guild.getIdLong(), prefix);
+                    return prefix;
+                }
+                prefixes.put(guild.getIdLong(), "!");
+                return "!";
+            } catch (SQLException ex) {
+                System.out.println("[ERROR] Error at retrieving guild prefix of guild id " + guild.getId() + ": " + ex
+                        .getMessage());
+            }
+        }
+        return "!";
     }
 }

src/main/java/Commands.java

@@ -18,7 +18,7 @@ public class Commands extends ListenerAdapter {
     @Override
     public void onGuildLeave(GuildLeaveEvent event) {
         Guild guild = event.getGuild();
-        Bot.prefixes.remove(guild.getIdLong());
+        Bot.removePrefix(guild.getIdLong());
     }
 
     @Override

src/main/java/Database.java

@@ -0,0 +1,107 @@
+import java.sql.*;
+
+public class Database {
+
+    enum DBType {MySQL, SQLite}
+
+    /**
+     * SQLite Data
+     * Set this data if you use DBType#SQLite
+     *
+     * @param filePath This can either be a relative or absolute path.
+     *                 ex: sokobot.db
+     *                 or: C:/sqlite/db/sokobot.db
+     */
+    private final String filePath = "sokobot.db";
+
+    /**
+     * MySQL Data
+     * Set this data if you use DBType#MySQL
+     */
+    private final String mysql_hostname = "127.0.0.1";
+    private final int mysql_port = 3306;
+    private final String mysql_database = "sokobot";
+    private final String mysql_username = "sokobot";
+    private final String mysql_password = "$€cUR€_P4sSw0R!)";
+
+    private Connection con = null;
+
+    public Database(DBType dbType) {
+        try {
+            if (dbType == DBType.MySQL) {
+                con = DriverManager.getConnection(
+                        "jdbc:mysql://" + mysql_hostname + ":" + mysql_port + "/" + mysql_database
+                                + "?autoReconnect=true", mysql_username, mysql_password);
+            } else if(dbType == DBType.SQLite){
+                con = DriverManager.getConnection("jdbc:sqlite:" + filePath);
+            }
+        } catch (Exception ex) {
+            System.out.println("[ERROR] Error at creating database connection: " + ex.getMessage());
+        }
+    }
+
+    public void disconnect() {
+        try {
+            con.clearWarnings();
+            con.close();
+            con = null;
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+    }
+
+    public Connection getCon() {
+        return con;
+    }
+
+    public ResultSet query(String sql, Object... preparedParameters) {
+        try {
+            PreparedStatement ps = con.prepareStatement(sql);
+            int id = 1;
+            for (Object preparedParameter : preparedParameters) {
+                ps.setObject(id, preparedParameter);
+                id++;
+            }
+            return ps.executeQuery();
+        } catch (SQLException e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
+
+    public ResultSet query(String sql) {
+        try {
+            ResultSet rs = con.prepareStatement(sql).executeQuery();
+            return rs;
+        } catch (SQLException e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
+
+
+    public void update(String sql, Object... preparedParameters) {
+        try (PreparedStatement ps = con.prepareStatement(sql)) {
+            int id = 1;
+            for (Object preparedParameter : preparedParameters) {
+                ps.setObject(id, preparedParameter);
+                id++;
+            }
+            ps.executeUpdate();
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+    }
+
+    public void update(String sql) {
+        try (PreparedStatement ps = con.prepareStatement(sql)) {
+            ps.executeUpdate();
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+    }
+
+    public boolean isConnected() {
+        return con != null;
+    }
+}