Various tweaks to the Java component of the launcher

Signed-off-by: TheKodeToad <TheKodeToad@proton.me>

libraries/launcher/org/prismlauncher/impl/AbstractLauncher.java

@@ -0,0 +1,95 @@
+/* Copyright 2012-2021 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.impl;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import org.prismlauncher.Launcher;
+import org.prismlauncher.exception.ParseException;
+import org.prismlauncher.utils.Parameters;
+
+public abstract class AbstractLauncher implements Launcher {
+
+    private static final int DEFAULT_WINDOW_WIDTH = 854;
+    private static final int DEFAULT_WINDOW_HEIGHT = 480;
+
+    // parameters, separated from ParamBucket
+    protected final List<String> mcParams;
+    private final String mainClass;
+
+    // secondary parameters
+    protected final int width;
+    protected final int height;
+    protected final boolean maximize;
+
+    protected final String serverAddress, serverPort;
+
+    protected final ClassLoader classLoader;
+
+    public AbstractLauncher(Parameters params) {
+        classLoader = ClassLoader.getSystemClassLoader();
+
+        mcParams = params.allSafe("param", new ArrayList<String>());
+        mainClass = params.firstSafe("mainClass", "net.minecraft.client.Minecraft");
+
+        serverAddress = params.firstSafe("serverAddress", null);
+        serverPort = params.firstSafe("serverPort", null);
+
+        String windowParams = params.firstSafe("windowParams", null);
+
+        if ("max".equals(windowParams) || windowParams == null) {
+            maximize = windowParams != null;
+
+            width = DEFAULT_WINDOW_WIDTH;
+            height = DEFAULT_WINDOW_HEIGHT;
+        } else {
+            maximize = false;
+
+            int byIndex = windowParams.indexOf('x');
+
+            if (byIndex != -1) {
+                try {
+                    width = Integer.parseInt(windowParams.substring(0, byIndex));
+                    height = Integer.parseInt(windowParams.substring(byIndex + 1));
+                    return;
+                } catch(NumberFormatException pass) {
+                }
+            }
+
+            throw new ParseException("Invalid window size parameter value: " + windowParams);
+        }
+    }
+
+    protected Class<?> loadMain() throws ClassNotFoundException {
+        return classLoader.loadClass(mainClass);
+    }
+
+    protected void loadAndInvokeMain() throws Throwable, ClassNotFoundException {
+        invokeMain(loadMain());
+    }
+
+    protected void invokeMain(Class<?> mainClass) throws Throwable {
+        MethodHandle method = MethodHandles.lookup().findStatic(mainClass, "main", MethodType.methodType(void.class, String[].class));
+
+        method.invokeExact(mcParams.toArray(new String[0]));
+    }
+
+}