Added JSON (flatfile) database type

src/main/java/world/bentobox/bentobox/database/DatabaseSetup.java

@@ -2,6 +2,7 @@ package world.bentobox.bentobox.database;
 
 import world.bentobox.bentobox.BentoBox;
 import world.bentobox.bentobox.database.flatfile.FlatFileDatabase;
+import world.bentobox.bentobox.database.json.JSONDatabase;
 import world.bentobox.bentobox.database.mongodb.MongoDBDatabase;
 import world.bentobox.bentobox.database.mysql.MySQLDatabase;
 
@@ -9,7 +10,7 @@ public interface DatabaseSetup {
 
     /**
      * Gets the type of database being used.
-     * Currently supported options are FLATFILE, MYSQL and MONGODB.
+     * Currently supported options are FLATFILE, JSON, MYSQL and MONGODB.
      * Default is FLATFILE.
      * @return Database type
      */
@@ -24,6 +25,7 @@ public interface DatabaseSetup {
 
     enum DatabaseType {
         FLATFILE(new FlatFileDatabase()),
+        JSON(new JSONDatabase()),
         MYSQL(new MySQLDatabase()),
         MONGODB(new MongoDBDatabase());
 

src/main/java/world/bentobox/bentobox/database/json/JSONDatabase.java

@@ -0,0 +1,13 @@
+package world.bentobox.bentobox.database.json;
+
+import world.bentobox.bentobox.BentoBox;
+import world.bentobox.bentobox.database.AbstractDatabaseHandler;
+import world.bentobox.bentobox.database.DatabaseSetup;
+
+public class JSONDatabase implements DatabaseSetup {
+
+    @Override
+    public <T> AbstractDatabaseHandler<T> getHandler(Class<T> dataObjectClass) {
+        return new JSONDatabaseHandler<>(BentoBox.getInstance(), dataObjectClass, new JSONDatabaseConnector(BentoBox.getInstance()));
+    }
+}

src/main/java/world/bentobox/bentobox/database/json/JSONDatabaseConnector.java

@@ -0,0 +1,53 @@
+package world.bentobox.bentobox.database.json;
+
+import world.bentobox.bentobox.BentoBox;
+import world.bentobox.bentobox.database.DatabaseConnector;
+
+import java.io.File;
+import java.util.UUID;
+
+public class JSONDatabaseConnector implements DatabaseConnector {
+
+    private static final int MAX_LOOPS = 100;
+    private static final String DATABASE_FOLDER_NAME = "database";
+    private final BentoBox plugin;
+    private final File dataFolder;
+
+    public JSONDatabaseConnector(BentoBox plugin) {
+        this.plugin = plugin;
+        dataFolder = new File(plugin.getDataFolder(), DATABASE_FOLDER_NAME);
+    }
+
+    @Override
+    public String getUniqueId(String tableName) {
+        UUID uuid = UUID.randomUUID();
+        File file = new File(dataFolder, tableName + File.separator + uuid.toString() + ".json");
+        int limit = 0;
+        while (file.exists() && limit++ < MAX_LOOPS) {
+            uuid = UUID.randomUUID();
+            file = new File(dataFolder, tableName + File.separator + uuid.toString() + ".json");
+        }
+        return uuid.toString();
+    }
+
+    @Override
+    public boolean uniqueIdExists(String tableName, String key) {
+        File file = new File(dataFolder, tableName + File.separator + key + ".json");
+        return file.exists();
+    }
+
+    @Override
+    public Object createConnection() {
+        return null; // Not used
+    }
+
+    @Override
+    public String getConnectionUrl() {
+        return null; // Not used
+    }
+
+    @Override
+    public void closeConnection() {
+        // Not used
+    }
+}

src/main/java/world/bentobox/bentobox/database/json/JSONDatabaseHandler.java

@@ -0,0 +1,153 @@
+package world.bentobox.bentobox.database.json;
+
+import world.bentobox.bentobox.BentoBox;
+import world.bentobox.bentobox.database.DatabaseConnector;
+
+import java.beans.IntrospectionException;
+import java.beans.PropertyDescriptor;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.nio.file.Files;
+import java.nio.file.StandardCopyOption;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+import java.util.Objects;
+
+public class JSONDatabaseHandler<T> extends AbstractJSONDatabaseHandler<T> {
+
+    /**
+     * Constructor
+     *
+     * @param plugin
+     * @param type              The type of the objects that should be created and filled with
+     *                          values from the database or inserted into the database
+     * @param databaseConnector Contains the settings to create a connection to the database
+     */
+    JSONDatabaseHandler(BentoBox plugin, Class<T> type, DatabaseConnector databaseConnector) {
+        super(plugin, type, databaseConnector);
+    }
+
+    @Override
+    public List<T> loadObjects() {
+        // In this case, all the objects of a specific type are being loaded.
+        List<T> list = new ArrayList<>();
+
+        // The path is the simple name of the class
+        String path = dataObject.getSimpleName();
+
+        // The database folder name is in the plugin's data folder
+        File dataFolder = new File(plugin.getDataFolder(), DATABASE_FOLDER_NAME);
+        // The folder for the objects (tables in database terminology) is here
+        File tableFolder = new File(dataFolder, path);
+        if (!tableFolder.exists()) {
+            // Nothing there...
+            tableFolder.mkdirs();
+        }
+        // Load each object from the file system, filtered, non-null
+        for (File file: Objects.requireNonNull(tableFolder.listFiles((dir, name) ->  name.toLowerCase(Locale.ENGLISH).endsWith(".json")))) {
+            try {
+                list.add(getGson().fromJson(new FileReader(file), dataObject));
+            } catch (FileNotFoundException e) {
+                plugin.logError("Could not load file '" + file.getName() + "': File not found.");
+            }
+        }
+        return list;
+    }
+
+    @Override
+    public T loadObject(String uniqueId) {
+        // Objects are loaded from a folder named after the simple name of the class being stored
+        String path = DATABASE_FOLDER_NAME + File.separator + dataObject.getSimpleName();
+
+        String fileName = path + File.separator + uniqueId;
+        if (!fileName.endsWith(".json")) {
+            fileName = fileName + ".json";
+        }
+
+        T result = null;
+        try {
+            result = getGson().fromJson(new FileReader(new File(plugin.getDataFolder(), fileName)), dataObject);
+        } catch (FileNotFoundException e) {
+            plugin.logError("Could not load file '" + fileName + "': File not found.");
+        }
+
+        return result;
+    }
+
+    @Override
+    public void saveObject(T instance) throws IllegalAccessException, InvocationTargetException, IntrospectionException {
+        String path = DATABASE_FOLDER_NAME + File.separator + dataObject.getSimpleName();
+
+        // Obtain the value of uniqueId within the instance (which must be a DataObject)
+        PropertyDescriptor propertyDescriptor = new PropertyDescriptor("uniqueId", dataObject);
+        Method method = propertyDescriptor.getReadMethod();
+        String fileName = (String) method.invoke(instance);
+
+        File tableFolder = new File(plugin.getDataFolder(), path);
+        File file = new File(tableFolder, fileName);
+        if (!tableFolder.exists()) {
+            tableFolder.mkdirs();
+        }
+
+        String toStore = getGson().toJson(instance);
+
+        try {
+            File tmpFile = new File(tableFolder, fileName + ".bak");
+            if (file.exists()) {
+                // Make a backup of file
+                Files.copy(file.toPath(), tmpFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
+            }
+            FileWriter fileWriter = new FileWriter(file);
+            fileWriter.write(toStore);
+            fileWriter.close();
+            Files.deleteIfExists(tmpFile.toPath());
+        } catch (IOException e) {
+            plugin.logError("Could not save json file: " + path + " " + fileName + " " + e.getMessage());
+        }
+    }
+
+    @Override
+    public void deleteObject(T instance) throws IllegalAccessException, InvocationTargetException, IntrospectionException {
+        // Obtain the value of uniqueId within the instance (which must be a DataObject)
+        PropertyDescriptor propertyDescriptor = new PropertyDescriptor("uniqueId", dataObject);
+        Method method = propertyDescriptor.getReadMethod();
+        String fileName = (String) method.invoke(instance);
+
+        // The filename of the JSON file is the value of uniqueId field plus .json. Sometimes the .json is already appended.
+        if (!fileName.endsWith(".json")) {
+            fileName = fileName + ".json";
+        }
+
+        // Get the database and table folders
+        File dataFolder = new File(plugin.getDataFolder(), DATABASE_FOLDER_NAME);
+        File tableFolder = new File(dataFolder, dataObject.getSimpleName());
+        if (tableFolder.exists()) {
+            // Obtain the file and delete it
+            File file = new File(tableFolder, fileName);
+            try {
+                Files.delete(file.toPath());
+            } catch (IOException e) {
+                plugin.logError("Could not delete json database object! " + file.getName() + " - " + e.getMessage());
+            }
+        }
+    }
+
+    @Override
+    public boolean objectExists(String uniqueId) {
+        // Check if the uniqueId (key) exists in the file system
+        return databaseConnector.uniqueIdExists(dataObject.getSimpleName(), uniqueId);
+    }
+
+    @Override
+    public void close() {
+        // Not used
+    }
+}