Refactored Plugin into an interface, make Javaplugin and relevant code to attempt to actually load plugins

By: Dinnerbone <dinnerbone@dinnerbone.com>

paper-api/src/org/bukkit/plugin/java/JavaPlugin.java

@@ -0,0 +1,91 @@
+
+package org.bukkit.plugin.java;
+
+import java.io.File;
+import org.bukkit.Server;
+import org.bukkit.plugin.Plugin;
+import org.bukkit.plugin.PluginDescriptionFile;
+import org.bukkit.plugin.PluginLoader;
+
+/**
+ * Represents a Java plugin
+ */
+public abstract class JavaPlugin implements Plugin {
+    private boolean isEnabled = false;
+    private final PluginLoader loader;
+    private final Server server;
+    private final File file;
+    private final PluginDescriptionFile description;
+    private final ClassLoader classLoader;
+
+    /**
+     * Constructs a new Java plugin instance
+     *
+     * @param pluginLoader PluginLoader that is responsible for this plugin
+     * @param instance Server instance that is running this plugin
+     * @param desc PluginDescriptionFile containing metadata on this plugin
+     * @param plugin File containing this plugin
+     * @param cLoader ClassLoader which holds this plugin
+     */
+    protected JavaPlugin(PluginLoader pluginLoader, Server instance, PluginDescriptionFile desc, File plugin, ClassLoader cLoader) {
+        loader = pluginLoader;
+        server = instance;
+        file = plugin;
+        description = desc;
+        classLoader = cLoader;
+    }
+
+    /**
+     * Gets the associated PluginLoader responsible for this plugin
+     *
+     * @return PluginLoader that controls this plugin
+     */
+    public final PluginLoader getPluginLoader() {
+        return loader;
+    }
+
+    /**
+     * Returns the Server instance currently running this plugin
+     *
+     * @return Server running this plugin
+     */
+    public final Server getServer() {
+        return server;
+    }
+
+    /**
+     * Returns a value indicating whether or not this plugin is currently enabled
+     *
+     * @return true if this plugin is enabled, otherwise false
+     */
+    public final boolean isEnabled() {
+        return isEnabled;
+    }
+
+    /**
+     * Returns the file which contains this plugin
+     *
+     * @return File containing this plugin
+     */
+    protected File getFile() {
+        return file;
+    }
+
+    /**
+     * Returns the plugin.yaml file containing the details for this plugin
+     *
+     * @return Contents of the plugin.yaml file
+     */
+    public PluginDescriptionFile getDescription() {
+        return description;
+    }
+
+    /**
+     * Returns the ClassLoader which holds this plugin
+     *
+     * @return ClassLoader holding this plugin
+     */
+    protected ClassLoader getClassLoader() {
+        return classLoader;
+    }
+}

paper-api/src/org/bukkit/plugin/java/JavaPluginLoader.java

@@ -2,10 +2,19 @@
 package org.bukkit.plugin.java;
 
 import java.io.File;
+import java.io.FileNotFoundException;
+import java.lang.reflect.Constructor;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 import org.bukkit.plugin.Plugin;
 import org.bukkit.plugin.PluginLoader;
 import java.util.regex.Pattern;
 import org.bukkit.Server;
+import org.bukkit.plugin.InvalidPluginException;
+import org.bukkit.plugin.PluginDescriptionFile;
 
 /**
  * Represents a Java plugin loader, allowing plugins in the form of .jars
@@ -32,8 +41,26 @@ public final class JavaPluginLoader implements PluginLoader {
         throw new UnsupportedOperationException("Not supported yet.");
     }
 
-    public Plugin loadPlugin(File file) {
-        throw new UnsupportedOperationException("Not supported yet.");
+    public Plugin loadPlugin(File file) throws InvalidPluginException {
+        JavaPlugin result = null;
+        PluginDescriptionFile description = new PluginDescriptionFile("Sample Plugin", "org.bukkit.plugin.sample.main");
+
+        if (!file.exists()) {
+            throw new InvalidPluginException(new FileNotFoundException(String.format("%s does not exist", file.getPath())));
+        }
+
+        try {
+            ClassLoader loader = URLClassLoader.newInstance(new URL[]{file.toURI().toURL()}, getClass().getClassLoader());
+            Class<?> jarClass = Class.forName(description.getMain());
+            Class<? extends JavaPlugin> plugin = jarClass.asSubclass(JavaPlugin.class);
+            Constructor<? extends JavaPlugin> constructor = plugin.getConstructor(PluginLoader.class, Server.class, PluginDescriptionFile.class, File.class, ClassLoader.class);
+
+            result = constructor.newInstance(this, server, description, file, loader);
+        } catch (Exception ex) {
+            throw new InvalidPluginException(ex);
+        }
+
+        return (Plugin)result;
     }
 
     public Pattern[] getPluginFileFilters() {