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// SPDX-License-Identifier: GPL-3.0-only
/*
* Prism Launcher - Minecraft Launcher
* Copyright (C) 2022 icelimetea <fr3shtea@outlook.com>
* Copyright (C) 2022 solonovamax <solonovamax@12oclockpoint.com>
* Copyright (C) 2022 TheKodeToad <TheKodeToad@proton.me>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 3.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* Linking this library statically or dynamically with other modules is
* making a combined work based on this library. Thus, the terms and
* conditions of the GNU General Public License cover the whole
* combination.
*
* As a special exception, the copyright holders of this library give
* you permission to link this library with independent modules to
* produce an executable, regardless of the license terms of these
* independent modules, and to copy and distribute the resulting
* executable under terms of your choice, provided that you also meet,
* for each linked independent module, the terms and conditions of the
* license of that module. An independent module is a module which is
* not derived from or based on this library. If you modify this
* library, you may extend this exception to your version of the
* library, but you are not obliged to do so. If you do not wish to do
* so, delete this exception statement from your version.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
* This file incorporates work covered by the following copyright and
* permission notice:
*
* Copyright 2013-2021 MultiMC Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.prismlauncher.utils;
import java.applet.Applet;
import java.io.File;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import org.prismlauncher.utils.logging.Log;
public final class ReflectionUtils {
private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();
private static final ClassLoader LOADER = ClassLoader.getSystemClassLoader();
/**
* Construct a Java applet by its class name.
*
* @param clazz The class name
* @return The applet instance
* @throws Throwable
*/
public static Applet createAppletClass(String clazz) throws Throwable {
Class<?> appletClass = LOADER.loadClass(clazz);
MethodHandle appletConstructor = LOOKUP.findConstructor(appletClass, MethodType.methodType(void.class));
return (Applet) appletConstructor.invoke();
}
/**
* Best guess of the game directory field within net.minecraft.client.Minecraft.
* Designed for legacy versions - newer versions do not use a static field.
*
* @param clazz The class
* @return The first field matching criteria
*/
public static Field findMinecraftGameDirField(Class<?> clazz) {
Log.debug("Resolving minecraft game directory field");
// search for private static File
for (Field field : clazz.getDeclaredFields()) {
if (field.getType() != File.class) {
continue;
}
int fieldModifiers = field.getModifiers();
if (!Modifier.isStatic(fieldModifiers)) {
Log.debug("Rejecting field " + field.getName() + " because it is not static");
continue;
}
if (!Modifier.isPrivate(fieldModifiers)) {
Log.debug("Rejecting field " + field.getName() + " because it is not private");
continue;
}
if (Modifier.isFinal(fieldModifiers)) {
Log.debug("Rejecting field " + field.getName() + " because it is final");
continue;
}
Log.debug("Identified field " + field.getName() + " to match conditions for game directory field");
return field;
}
return null;
}
/**
* Gets the main method within a class.
*
* @param clazz The class
* @return A method matching the descriptor of a main method
* @throws ClassNotFoundException
* @throws NoSuchMethodException
* @throws IllegalAccessException
*/
public static MethodHandle findMainMethod(Class<?> clazz) throws NoSuchMethodException, IllegalAccessException {
return LOOKUP.findStatic(clazz, "main", MethodType.methodType(void.class, String[].class));
}
/**
* Gets the main method within a class by its name.
*
* @param clazz The class name
* @return A method matching the descriptor of a main method
* @throws ClassNotFoundException
* @throws NoSuchMethodException
* @throws IllegalAccessException
*/
public static MethodHandle findMainMethod(String clazz)
throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException {
return findMainMethod(LOADER.loadClass(clazz));
}
}
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