DatabaseManager Class

DatabaseManager Class

This class allows the access and creation of databases.

Class Information

Class declaration:

public final class DatabaseManager

Known subclasses: N/A(Since the class is final).

Superclass: java.lang.Object

Implemented Interfaces: none

Constructors

• public DatabaseManager()

This constructor instantiates a DatabaseManager instance.

Instance Methods

• public Database access(String path, String user, String password) throws Throwable

This method allows access for a Specific Database given the credentials(Username and Password)

Throws:

• Throwable - When something went wrong

Returns: A io.github.demnetwork.sjdb.Database instance that represents the Database.

• public void createDatabase(String user, String password, String path) throws IOException

This method creates a Database and saves it into a file.

Throws:

• IOException - If the file already exists

Returns: N\A

Inner Types

No Public Inner Types.

Example Usage

Example: Accessing a Database

Maven/Classpath installation:

import io.github.demnetwork.sjdb.*

public class Main {
    public static void main(String[] args) {
        DatabaseManager mgr = new DatabaseManager();
        Database db = null;
        try {
            db = mgr.access();
        } catch (Throwable t) {
            // Handle Exception here
        }
        if (db != null) {
            // Do something with the Database
        }
    }
}

Reflection installation

import java.lang.reflect.*
import java.net.*
import java.util.*
import java.io.*;

public class Main {
    private static int bn;

    public static void main(String[] args) throws Exception {
        File f = new File("./SJDB/sjdb.jar"); // Get File Object
        if (!f.exists())
            throw new Error("Cannot find SJDB jar file"); // Throw error if file is not found
        URLClassLoader cl = new URLClassLoader(new URL[] { f.toURI().toURL() }); // Create a class loader
        Class<?> runtimeClass = cl.loadClass("io.github.demnetwork.sjdb.internal.SJDBRuntime"); // Get the SJDBRuntime class
        bn = ((Integer) runtimeClass.getMethod("getBuildNumber").invoke(null)).intValue(); // Get the Build Number from SJDBRuntime
        if (bn != 1) {
            cl.close(); // Close URLClassLoader
            throw new Error("Incompatible SJDB Version."); // Throw error due to incompatible version
        }
        //Load Classes
        Class<?> databaseManagerClass = cl.loadClass("io.github.demnetwork.sjdb.DatabaseManager");
        Class<?> dbClass = cl.loadClass("io.github.demnetwork.sjdb.Database");
        //Create Objects
        Object mgr = databaseManagerClass.getConstructor().newInstance();
        Method mgrAccessMethod = databaseManager.getMethod("access", String.class, String.class, String.class);
        Object db = mgrAccessMethod.invoke(mgr, "path/to/database.sdb", "username", "password");
        //Do something with the db Object
    }
}

(Note: make sure to close the URLClassLoader after you no longer need to load classes)