DatabaseLib v3

How-to

Installation

1. Put the .jar in the plugin folder
2. Start the server
3. Stop the server
4. Configure the config.yml and sql_pool.yml
5. Start the server again

Usage

1. Create a new class (or use a preexisting one) and extend PluginSqlTaskSubmitter.
2. Create a new instance of your class by either passing a JavaPlugin (Bukkit) or a Plugin instance (BungeeCord).

Take a look at the examples below for a complete example of a Bukkit plugin.

General information

Callbacks

When you create or submit tasks, you have to pass a non-null callback. The type of the callback depends on whether the asynchronously executed method returns something or not. If the method doesn't return anything (i.e. there is no return statement), the type of the callback is Consumer<Throwable>. Otherwise, it is BiConsumer<ReturnType, Throwable>.

Some examples:

• if there is no return statement, pass a Consumer<Throwable>
• if you return an Integer, pass a BiConsumer<Integer, Throwable>
• if you return a String, pass a BiConsumer<String, Throwable>
• in general: if you return something of type R, pass a BiConsumer<? super R, Throwable>

<details> <summary>Usage example</summary>

public static final class UserRepo extends PluginSqlTaskSubmitter {
    public UserRepo(JavaPlugin plugin) { super(plugin); }

    public void deleteUser(UUID uuid, Consumer<Throwable> callback) {
        String query = "DELETE FROM `users` WHERE `uuid` = ?";
        submitSqlPreparedStatementTask(query, preparedStatement -> {
            preparedStatement.setString(1, uuid.toString());
            preparedStatement.execute();
        }, callback);
    }

    public void getUser(UUID uuid, BiConsumer<User, Throwable> callback) {
        String query = "SELECT * FROM `users` WHERE `uuid` = ?";
        submitSqlPreparedStatementTask(query, preparedStatement -> {
            preparedStatement.setString(1, uuid.toString());
            ResultSet rs = preparedStatement.executeQuery();
            return rs.next()
                    ? new User(uuid.toString(), rs.getString("email"))
                    : null;
        }, callback);
    }
}

</details>

Task submission without callbacks (new in 3.1.0)

You can submit tasks which don't require a callback method and which instead return a CompletionStage. The result of the CompletionStage is the result of the function that is given when the task is submitted.

<details> <summary>Usage example</summary>

public static final class UserRepo extends PluginSqlTaskSubmitter {
    public UserRepo(JavaPlugin plugin) { super(plugin); }

    public CompletionStage<List<User>> getUsers() {
        String sql = "SELECT * FROM `users`";
        return submitSqlPreparedStatementTask(sql, preparedStatement -> {
            List<User> users = new ArrayList<>();
            ResultSet resultSet = preparedStatement.executeQuery();
            while (resultSet.next()) {
                String uuid = resultSet.getString("uuid");
                String name = resultSet.getString("name");
                users.add(new User(uuid, name));
            }
            return users;
        });
    }
}

</details>

Asynchronous execution of tasks

All tasks that are submitted through one of the different submit... methods are executed asynchronously in whichever thread the library chooses. After a task completes (either normally or by throwing an exception), its callback method is executed in the server thread (Bukkit plugins) or in one of the plugin threads (Bungee plugins). If the task completes exceptionally, the Throwable passed to the callback is non-null.

Closing Connections and Statements

All library supplied Connections and Statements are closed automatically, so you don't have to call close() on them. However, you still need to close all Statements you created yourself (e.g. when using an SqlConnectionTask). The only exception to this rule is when you use getConnection() (see next section).

Synchronous execution of queries

Sometimes you don't want to execute queries asynchronously. In these cases you can get a Connection directly from the pool by calling getConnection().

You are responsible for closing the connection after usage. If you forget to do so, the pool will run out of Connections, so it's best to use a try-with-resources block wherever possible when acquiring them this way.

Be aware that a call to getConnection() is blocking. If no Connection is available (e.g. because of the pool being empty), the thread in which this method is called will be blocked.

(new in 3.4.0) Instead of using a call to getConnection() you can also use any of apply... methods. These methods call getConnection() for you but try to reduce boilerplate by catching any occurring SQLExceptions and rethrowing them wrapped in RuntimeExceptions.

<details> <summary>Usage example</summary>

String query = "CREATE TABLE IF NOT EXISTS users(" +
               "    uuid  VARCHAR(36) NOT NULL PRIMARY KEY," +
               "    email VARCHAR(36)" +
               ")";
boolean result = applyStatement(statement -> statement.execute(query));

</details>

Creating your own connection pools

If your application submits many long-running tasks, or you have some reason that makes it necessary for you to manage your own set of Connections, you can instantiate a connection pool by using the static factory methods of the SqlConnectionPool class. To use these methods you have to pass a SqlPoolConfig instance which can be created by using a SqlPoolConfig.Builder. If you want your users to be able to manually configure your pool from a file, you can use a SqlPoolConfiguration to store its options.

ScriptRunner

A ScriptRunner is a utility class that lets you execute SQL scripts. An SQL script is a file that contains SQL queries delimited by ';' (semicolon). You can create a ScriptRunner by passing an instance of a Reader and a Connection to its constructor. A ScriptRunner has the ability to replace any part of a query prior to executing it.

<details> <summary>Usage example</summary>

try (Reader reader = new FileReader("my_script.sql");
     Connection connection = getConnection()) {

    ScriptRunner runner = new ScriptRunner(reader, connection);
    runner.setReplacements(Map.of("%USER%", "user1"));
    runner.runScript();

} catch (IOException | SQLException e) {
    e.printStackTrace();
}

</details>

Examples

Complete Bukkit plugin example

import de.exlll.databaselib.sql.submit.PluginSqlTaskSubmitter;
import org.bukkit.plugin.java.JavaPlugin;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.UUID;
import java.util.concurrent.CompletionStage;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import java.util.logging.Level;
import java.util.logging.Logger;

public final class ExamplePlugin extends JavaPlugin {
    private final Logger log = Logger.getLogger(ExamplePlugin.class.getName());
    private final Consumer<Throwable> exceptionLogger = throwable -> {
        if (throwable != null) {
            log.log(Level.SEVERE, throwable.getMessage(), throwable);
        }
    };
    private UserRepository userRepository;

    public void deleteUser(UUID uuid) {
        userRepository.deleteUser(uuid, exceptionLogger);
    }

    public void updateUser(UUID uuid, String email) {
        userRepository.updateUserMail(uuid, email, exceptionLogger);
    }

    public void getUser(UUID uuid) {
        userRepository.getUser(uuid, (user, throwable) -> {
            if (throwable != null) {
                exceptionLogger.accept(throwable);
            } else {
                log.info("User: " + user);
            }
        });
    }

    public void getUserWithCompletionStage(UUID uuid) {
        userRepository.getUserWithCompletionStage(uuid)
                .whenComplete((user, throwable) -> {
                    if (throwable != null) {
                        exceptionLogger.accept(throwable);
                    } else {
                        log.info("User: " + user);
                    }
                });
    }

    @Override
    public void onEnable() {
        userRepository = new UserRepository(this);
        userRepository.createTable();
    }
}

final class UserRepository extends PluginSqlTaskSubmitter {
    public UserRepository(JavaPlugin plugin) {
        super(plugin);
    }

    public void deleteUser(UUID uuid, Consumer<Throwable> callback) {
        String query = "DELETE FROM `users` WHERE `uuid` = ?";
        submitSqlPreparedStatementTask(query, preparedStatement -> {
            preparedStatement.setString(1, uuid.toString());
            preparedStatement.execute();
        }, callback);
    }

    public void updateUserMail(UUID uuid, String email, Consumer<Throwable> callback) {
        String query = "UPDATE `users` SET `email` = ? WHERE `uuid` = ?";
        submitSqlPreparedStatementTask(query, preparedStatement -> {
            preparedStatement.setString(1, email);
            preparedStatement.setString(2, uuid.toString());
            preparedStatement.execute();
        }, callback);
    }

    public void getUser(UUID uuid, BiConsumer<User, Throwable> callback) {
        String query = "SELECT * FROM `users` WHERE `uuid` = ?";
        submitSqlPreparedStatementTask(query, preparedStatement -> {
            preparedStatement.setString(1, uuid.toString());
            ResultSet rs = preparedStatement.executeQuery();
            return rs.next()
                    ? new User(uuid, rs.getString("email"))
                    : null;
        }, callback);
    }

    public CompletionStage<User> getUserWithCompletionStage(UUID uuid) {
        String query = "SELECT * FROM `users` WHERE `uuid` = ?";
        return submi