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Diffstat (limited to 'libraries/launcher/org/prismlauncher/utils/ReflectionUtils.java')
| -rw-r--r-- | libraries/launcher/org/prismlauncher/utils/ReflectionUtils.java | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/libraries/launcher/org/prismlauncher/utils/ReflectionUtils.java b/libraries/launcher/org/prismlauncher/utils/ReflectionUtils.java new file mode 100644 index 00000000..dd212ef9 --- /dev/null +++ b/libraries/launcher/org/prismlauncher/utils/ReflectionUtils.java @@ -0,0 +1,154 @@ +// 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)); + } + +} |