Implemented gradle plugin and cleaned up code

Release 1.0.0

Author: RaphiMC

README.md

@@ -29,6 +29,47 @@ Here is an example command to convert the jar input.jar to Java 8 and output it
 ## Usage (As a library)
 To transform a ``ClassNode`` you can use the ``JavaDowngrader`` class.  
 As a low level class modification framework in your application [ClassTransform](https://github.com/Lenni0451/ClassTransform) is recommended.
+JavaDowngrader provides the ``impl-classtransform`` submodule which contains various utility classes for ClassTransform.
+
+## Usage (In Gradle)
+To use JavaDowngrader in gradle (To downgrade a whole jar or one of your source sets) you have to add the following to the top of your build.gradle:
+```groovy
+buildscript {
+    repositories {
+        maven {
+            name = "Lenni0451 Releases"
+            url "https://maven.lenni0451.net/releases"
+        }
+    }
+
+    dependencies {
+        classpath "net.raphimc.javadowngrader:gradle-plugin:1.0.0"
+    }
+}
+```
+
+### Downgrade the main source set
+```groovy
+tasks.register("java8Main", DowngradeSourceSetTask) {
+    sourceSet = sourceSets.main
+}.get().dependsOn("classes")
+classes.finalizedBy("java8Main")
+```
+
+### Downgrade the built jar (If you use Java 8+ libraries)
+```groovy
+tasks.register("java8Jar", DowngradeJarTask) {
+    input = tasks.jar.archiveFile.get().asFile
+    outputSuffix = "+java8"
+    compileClassPath = sourceSets.main.compileClasspath
+}.get().dependsOn("build")
+build.finalizedBy("java8Jar")
+```
+
+Some of the optional properties include:
+- ``targetVersion``: The target classfile version (Default: 8)
+- ``outputSuffix``: The suffix to append to the output jar file (Default: "-downgraded")
+- ``copyRuntimeClasses``: Whether to copy the JavaDowngrader runtime classes to the output jar (Default: true). Should be set to false if your jar already contains JavaDowngrader itself
 
 ## Contact
 If you encounter any issues, please report them on the

build.gradle

@@ -14,6 +14,14 @@ allprojects {
 
     repositories {
         mavenCentral()
+        maven {
+            name = "Lenni0451 Releases"
+            url "https://maven.lenni0451.net/releases"
+        }
+        maven {
+            name = "Lenni0451 Snapshots"
+            url "https://maven.lenni0451.net/snapshots"
+        }
     }
 
     java {

gradle-plugin/build.gradle

@@ -0,0 +1,5 @@
+dependencies {
+    api project(":impl-classtransform")
+
+    implementation gradleApi()
+}

gradle-plugin/gradle.properties

@@ -0,0 +1 @@
+maven_name=gradle-plugin

gradle-plugin/src/main/java/net/raphimc/javadowngrader/gradle/task/DowngradeJarTask.java

@@ -0,0 +1,187 @@
+/*
+ * This file is part of JavaDowngrader - https://github.com/RaphiMC/JavaDowngrader
+ * Copyright (C) 2023 RK_01/RaphiMC and contributors
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package net.raphimc.javadowngrader.gradle.task;
+
+import net.lenni0451.classtransform.TransformerManager;
+import net.lenni0451.classtransform.utils.tree.BasicClassProvider;
+import net.raphimc.javadowngrader.impl.classtransform.JavaDowngraderTransformer;
+import net.raphimc.javadowngrader.impl.classtransform.classprovider.LazyFileClassProvider;
+import net.raphimc.javadowngrader.impl.classtransform.classprovider.PathClassProvider;
+import net.raphimc.javadowngrader.impl.classtransform.util.ClassNameUtil;
+import net.raphimc.javadowngrader.impl.classtransform.util.FileSystemUtil;
+import net.raphimc.javadowngrader.runtime.RuntimeRoot;
+import net.raphimc.javadowngrader.util.Constants;
+import org.gradle.api.DefaultTask;
+import org.gradle.api.file.FileCollection;
+import org.gradle.api.tasks.Internal;
+import org.gradle.api.tasks.TaskAction;
+import org.objectweb.asm.Opcodes;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Collections;
+import java.util.Objects;
+import java.util.stream.Stream;
+
+public class DowngradeJarTask extends DefaultTask {
+
+    @Internal
+    private File input;
+
+    @Internal
+    private String outputSuffix = "-downgraded";
+
+    @Internal
+    private FileCollection compileClassPath;
+
+    @Internal
+    private int targetVersion = Opcodes.V1_8;
+
+    @Internal
+    private boolean copyRuntimeClasses = true;
+
+    @TaskAction
+    public void run() throws IOException, URISyntaxException {
+        Objects.requireNonNull(this.input, "input must be set");
+        Objects.requireNonNull(this.outputSuffix, "outputSuffix must be set");
+        Objects.requireNonNull(this.compileClassPath, "compileClassPath must be set");
+        if (!this.input.exists()) throw new IllegalArgumentException("input does not exist");
+        if (!this.input.isFile() || !this.input.getName().endsWith(".jar")) throw new IllegalArgumentException("input is not a jar file");
+
+        System.out.println("Downgrading jar: " + this.input.getName());
+        try (FileSystem inFs = FileSystems.newFileSystem(this.input.toPath(), null)) {
+            final Path inRoot = inFs.getRootDirectories().iterator().next();
+
+            final TransformerManager transformerManager = new TransformerManager(
+                    new PathClassProvider(inRoot, new LazyFileClassProvider(this.compileClassPath.getFiles(), new BasicClassProvider()))
+            );
+            transformerManager.addBytecodeTransformer(new JavaDowngraderTransformer(
+                    transformerManager, this.targetVersion, c -> Files.isRegularFile(inRoot.resolve(ClassNameUtil.toClassFilename(c)))
+            ));
+
+            final String outputName = this.input.getName().substring(0, this.input.getName().length() - 4) + this.outputSuffix;
+            final File outputFile = new File(this.input.getParentFile(), outputName + ".jar");
+
+            try (FileSystem outFs = FileSystems.newFileSystem(new URI("jar:" + outputFile.toURI()), Collections.singletonMap("create", "true"))) {
+                final Path outRoot = outFs.getRootDirectories().iterator().next();
+
+                // Downgrade classes
+                try (Stream<Path> stream = Files.walk(inRoot)) {
+                    stream.forEach(path -> {
+                        try {
+                            final String relative = ClassNameUtil.slashName(inRoot.relativize(path));
+                            final Path dest = outRoot.resolve(relative);
+                            if (Files.isDirectory(path)) {
+                                Files.createDirectories(dest);
+                                return;
+                            }
+                            final Path parent = dest.getParent();
+                            if (parent != null) {
+                                Files.createDirectories(parent);
+                            }
+                            if (!relative.endsWith(".class") || relative.contains("META-INF/versions/")) {
+                                Files.copy(path, dest);
+                                return;
+                            }
+                            final String className = ClassNameUtil.toClassName(relative);
+                            final byte[] bytecode = Files.readAllBytes(path);
+                            final byte[] result;
+                            try {
+                                result = transformerManager.transform(className, bytecode);
+                            } catch (Throwable e) {
+                                throw new RuntimeException("Failed to transform " + className, e);
+                            }
+                            Files.write(dest, result != null ? result : bytecode);
+                        } catch (IOException e) {
+                            throw new UncheckedIOException(e);
+                        }
+                    });
+                }
+
+                // Copy runtime classes
+                if (this.copyRuntimeClasses) {
+                    try (FileSystem runtimeRootFs = FileSystemUtil.getOrCreateFileSystem(RuntimeRoot.class.getResource("").toURI())) {
+                        final Path runtimeRoot = runtimeRootFs.getPath(Constants.JAVADOWNGRADER_RUNTIME_PACKAGE);
+                        try (Stream<Path> stream = Files.walk(runtimeRoot)) {
+                            stream.filter(Files::isRegularFile)
+                                    .filter(p -> !p.getFileName().toString().equals(Constants.JAVADOWNGRADER_RUNTIME_ROOT))
+                                    .forEach(path -> {
+                                        final String relative = ClassNameUtil.slashName(runtimeRoot.relativize(path));
+                                        final Path dest = outRoot.resolve(Constants.JAVADOWNGRADER_RUNTIME_PACKAGE + relative);
+                                        try {
+                                            Files.createDirectories(dest.getParent());
+                                            Files.copy(path, dest);
+                                        } catch (IOException e) {
+                                            throw new UncheckedIOException(e);
+                                        }
+                                    });
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    public File getInput() {
+        return this.input;
+    }
+
+    public String getOutputSuffix() {
+        return this.outputSuffix;
+    }
+
+    public FileCollection getCompileClassPath() {
+        return this.compileClassPath;
+    }
+
+    public int getTargetVersion() {
+        return this.targetVersion;
+    }
+
+    public boolean getCopyRuntimeClasses() {
+        return this.copyRuntimeClasses;
+    }
+
+    public void setInput(final File input) {
+        this.input = input;
+    }
+
+    public void setOutputSuffix(final String outputSuffix) {
+        this.outputSuffix = outputSuffix;
+    }
+
+    public void setCompileClassPath(final FileCollection compileClassPath) {
+        this.compileClassPath = compileClassPath;
+    }
+
+    public void setTargetVersion(final int targetVersion) {
+        this.targetVersion = targetVersion;
+    }
+
+    public void setCopyRuntimeClasses(final boolean copyRuntimeClasses) {
+        this.copyRuntimeClasses = copyRuntimeClasses;
+    }
+
+}