Android Transform
2023-06-17, by alamide
Android Gradle 提供了 Transform API 工具，它可以在将 .class 文件转换为 dex 文件之前对其进行操作。可以通过自定义 Gradle 插件来注册自定义的 Transform，通过注册的 Transform 可以对 .class 文件来做一些操作。
Transform 的作用位置在在如图位置
1.定义插件
插件可以在 buildSrc 中直接定义，定义完后可以在工程模块中直接使用，注意 buildSrc 目录名不能错
public class MyPlugin implements Plugin<Project> {
@Override
public void apply(Project project) {
System.out.println("-=--=-=-=Plugin-=-=-=-=-=-=");
project.getPlugins().forEach(System.out::println);
}
}
要使定义的插件被发现，还需要在 resources/META-INF/gradle-plugins/ 目录中定义 xxx.properties 配置文件，xxx 为插件 id 。配置文件中配置具体的插件类：
implementation-class=com.alamide.gradle.MyPlugin
引用插件，在 app 模块的 build.gradle 中引用
plugins {
id 'com.android.application'
id 'xxx'
}
重新构建项目，可以看到输出要打印的内容
2.注册 Transform
public class MyPlugin implements Plugin<Project> {
@Override
public void apply(Project project) {
boolean isApp = project.getPlugins().hasPlugin(AppPlugin.class);
if(isApp) {
AppExtension android = project.getExtensions().getByType(AppExtension.class);
android.registerTransform(new MyTransform());
}
}
}
public class MyTransform extends Transform {
@Override
public String getName() {
return "com.alamide.xxx";
}
@Override
public Set<QualifiedContent.ContentType> getInputTypes() {
return TransformManager.CONTENT_CLASS;
}
@Override
public Set<? super QualifiedContent.Scope> getScopes() {
return TransformManager.SCOPE_FULL_PROJECT;
}
@Override
public boolean isIncremental() {
return false;
}
private void printDivider(){
System.out.println("---=-=----=-=-=-=-=----=-=-=-=-=-=-==-=-=-=");
}
@Override
public void transform(TransformInvocation transformInvocation) throws TransformException, InterruptedException, IOException {
super.transform(transformInvocation);
}
}
其中方法 transform(TransformInvocation transformInvocation) 为我们要操作 .class 文件的地方
3.TransformInvocation 的一些 API
3.1 transformInvocation.getInputs()->getDirectoryInputs()
为具体输入的内容，当输入类型为 CONTENT_CLASS 时，输入的内容为 jar 和 引用插件工程的 build/intermediates/javac/debug/classes 目录。Jar 文件为其它模块的 jar 文件，及引用的第三方工程。有点绕，具体看代码，
引用插件的工程有如下的 Class 文件
@Override
public void transform(TransformInvocation transformInvocation) {
transformInvocation.getInputs().forEach( transformInput -> {
transformInput.getDirectoryInputs().forEach(directoryInput -> {
printDivider();
Collection<File> files = FileUtils.listFiles(directoryInput.getFile(), null, true);
files.forEach(f -> {
System.out.println(f.getName());
});
printDivider();
});
});
}
输出：
---=-=----=-=-=-=-=----=-=-=-=-=-=-==-=-=-=
MainActivity.class
MainAnno.class
BuildConfig.class
APIInterface.class
MainAnno_RouteRegister.class
MainActivity_RouteRegister.class
---=-=----=-=-=-=-=----=-=-=-=-=-=-==-=-=-=
DirectoryInputs 输出本工程的所有编译后的 Class 文件
3.2 transformInvocation.getInputs()->getJarInputs()
public void transform(TransformInvocation transformInvocation) {
transformInvocation.getInputs().forEach(transformInput -> {
printDivider();
transformInput.getJarInputs().forEach(jarInput -> {
System.out.println(jarInput.getFile().getAbsolutePath().substring(18));
});
printDivider();
});
}
输出：
---=-=----=-=-=-=-=----=-=-=-=-=-=-==-=-=-=
......
.gradle/caches/modules-2/files-2.1/androidx.lifecycle/lifecycle-common/2.4.0/1fdb7349701e9cf2f0a69fc10642b6fef6bb3e12/lifecycle-common-2.4.0.jar
.gradle/caches/transforms-3/014f9ec8829ee24d4e7888e04bc3a29f/transformed/jetified-okhttp-3.14.9.jar
.gradle/caches/transforms-3/193a6746e66b6c261483446bc75f8b6e/transformed/jetified-okio-1.17.2.jar
---=-=----=-=-=-=-=----=-=-=-=-=-=-==-=-=-=
---=-=----=-=-=-=-=----=-=-=-=-=-=-==-=-=-=
AndroidStudioProjects/RRRAndroid/m_first/build/intermediates/runtime_library_classes_jar/debug/classes.jar
AndroidStudioProjects/RRRAndroid/m_second/build/intermediates/runtime_library_classes_jar/debug/classes.jar
AndroidStudioProjects/RRRAndroid/m_third/build/intermediates/runtime_library_classes_jar/debug/classes.jar
AndroidStudioProjects/RRRAndroid/m_login/build/intermediates/runtime_library_classes_jar/debug/classes.jar
AndroidStudioProjects/RRRAndroid/router_api/build/intermediates/runtime_library_classes_jar/debug/classes.jar
AndroidStudioProjects/RRRAndroid/router_annotation/build/.transforms/e7e597def674fada74d3d517fe8267c6/transformed/jetified-router_annotation.jar
---=-=----=-=-=-=-=----=-=-=-=-=-=-==-=-=-=
可以看到输出的都是其他模块的 Jar 包和引入的第三方 Jar 包
3.3 transformInvocation.isIncremental()
是否是增量更新，不是增量更新时，需要清除所有内容
@Override
public void transform(TransformInvocation transformInvocation) throws IOException {
boolean incremental = transformInvocation.isIncremental();
if (!incremental){
transformInvocation.getOutputProvider().deleteAll();
}
}
3.4 transformInvocation.getOutputProvider().getContentLocation()
获取处理后的文件存放位置，这是一定要实现的，否则处理的文件将会丢失，无法生成可运行的 APK 。知道这一点，我们就可以自己处理 Jar 包或 Directory 中的 Class 文件了。
@Override
public void transform(TransformInvocation transformInvocation) throws IOException {
boolean incremental = transformInvocation.isIncremental();
if (!incremental){
transformInvocation.getOutputProvider().deleteAll();
}
transformInvocation.getInputs().forEach( transformInput -> {
transformInput.getDirectoryInputs().forEach(directoryInput -> {
try {
File contentLocation = transformInvocation.getOutputProvider().getContentLocation(directoryInput.getName(), directoryInput.getContentTypes(), directoryInput.getScopes(), Format.DIRECTORY);
FileUtils.copyDirectory(directoryInput.getFile(), contentLocation);
} catch (IOException e) {
throw new RuntimeException(e);
}
});
transformInput.getJarInputs().forEach(jarInput -> {
try {
File contentLocation = transformInvocation.getOutputProvider().getContentLocation(jarInput.getName(), jarInput.getContentTypes(), jarInput.getScopes(), Format.JAR);
FileUtils.copyFile(jarInput.getFile(), contentLocation);
} catch (IOException e) {
throw new RuntimeException(e);
}
});
});
}
4.小实验
Transform 的作用是什么，可以简单理解为一个对接器或一个滤网，我们可以在过滤的时候处理 Class 文件。
实验目标：统计本项目中每个 Activity 类 onCreate 方法的执行时间，例如如下的 Activity
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn1 = findViewById(R.id.btn1);
btn1.setOnClickListener(v -> {
RouterCenter.navigateTo(MainActivity.this, "/app/first");
});
}
}
修改后代码为
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
long startMillis = System.currentTimeMillis();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn1 = findViewById(R.id.btn1);
btn1.setOnClickListener(v -> {
RouterCenter.navigateTo(MainActivity.this, "/app/first");
});
long duration = System.currentTimeMillis() - startMillis;
Toast.makeText(this, "time cost is " + duration + "ms", Toast.LENGTH_LONG).show();
}
}
先编写 ASM 代码，由于修改增加了局部变量，会造成本地变量栈的变动，所以使用 GeneratorAdapter 来辅助添加局部变量
private byte[] insertCode(InputStream is) {
try {
ClassReader cr = new ClassReader(is);
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
ClassVisitor cv = new ClassVisitor(Opcodes.ASM5, cw) {
private boolean isActivity;
@Override
public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
super.visit(version, access, name, signature, superName, interfaces);
if (name.startsWith("com/alamide") && superName.endsWith("Activity")) {
isActivity = true;
}
}
@Override
public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
MethodVisitor methodVisitor = super.visitMethod(access, name, descriptor, signature, exceptions);
if (isActivity && name.equals("onCreate")) {
methodVisitor = new CostTimeMethodAdapter(Opcodes.ASM5, methodVisitor, access, name, descriptor);
}
return methodVisitor;
}
};
cr.accept(cv, ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);
return cw.toByteArray();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
private byte[] insertCode(File file) {
try (InputStream is = new BufferedInputStream(Files.newInputStream(file.toPath()))) {
return insertCode(is);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
private static class CostTimeMethodAdapter extends GeneratorAdapter {
private int start;
protected CostTimeMethodAdapter(int api, MethodVisitor methodVisitor, int access, String name, String descriptor) {
super(api, methodVisitor, access, name, descriptor);
}
@Override
public void visitCode() {
super.visitCode();
super.visitMethodInsn(INVOKESTATIC, "java/lang/System", "currentTimeMillis", "()J", false);
start = newLocal(Type.LONG_TYPE);
storeLocal(start);
}
@Override
public void visitInsn(int opcode) {
if (opcode == Opcodes.RETURN) {
super.visitMethodInsn(INVOKESTATIC, "java/lang/System", "currentTimeMillis", "()J", false);
loadLocal(start);
super.visitInsn(LSUB);
int duration = newLocal(Type.LONG_TYPE);
storeLocal(duration);
super.visitVarInsn(ALOAD, 0);
super.visitTypeInsn(NEW, "java/lang/StringBuilder");
super.visitInsn(DUP);
super.visitMethodInsn(INVOKESPECIAL, "java/lang/StringBuilder", "<init>", "()V", false);
super.visitLdcInsn("time cost is ");
super.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false);
loadLocal(duration);
super.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(J)Ljava/lang/StringBuilder;", false);
super.visitLdcInsn("ms");
super.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false);
super.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "toString", "()Ljava/lang/String;", false);
super.visitInsn(ICONST_1);
super.visitMethodInsn(INVOKESTATIC, "android/widget/Toast", "makeText", "(Landroid/content/Context;Ljava/lang/CharSequence;I)Landroid/widget/Toast;", false);
super.visitMethodInsn(INVOKEVIRTUAL, "android/widget/Toast", "show", "()V", false);
}
super.visitInsn(opcode);
}
}
有了这个类就可以修改目标类了
先来修改目录中的 Class 文件，目录文件的修改简单点，直接修改替换，再输出就可以了
transformInvocation.getInputs().forEach(transformInput -> {
transformInput.getDirectoryInputs().forEach(directoryInput -> {
try {
File contentLocation = transformInvocation.getOutputProvider().getContentLocation(directoryInput.getName(), directoryInput.getContentTypes(), directoryInput.getScopes(), Format.DIRECTORY);
Collection<File> files = FileUtils.listFiles(directoryInput.getFile(), null, true);
for (File file : files) {
FileUtils.writeByteArrayToFile(file, insertCode(file), false);
}
FileUtils.copyDirectory(directoryInput.getFile(), contentLocation);
} catch (IOException e) {
throw new RuntimeException(e);
}
});
});
再来修改 Jar 包中的目标类
transformInvocation.getInputs().forEach(transformInput -> {
transformInput.getJarInputs().forEach(jarInput -> {
File file = jarInput.getFile();
File contentLocation = transformInvocation.getOutputProvider().getContentLocation(jarInput.getName(), jarInput.getContentTypes(), jarInput.getScopes(), Format.JAR);
try (JarFile jarFile = new JarFile(file); JarOutputStream jarOutputStream = new JarOutputStream(Files.newOutputStream(contentLocation.toPath()))) {
Enumeration<JarEntry> entries = jarFile.entries();
while (entries.hasMoreElements()) {
JarEntry jarEntry = entries.nextElement();
String entryName = jarEntry.getName();
jarOutputStream.putNextEntry(new ZipEntry(entryName));
if (entryName.contains("com/alamide") && entryName.endsWith("Activity.class")) {
byte[] bytes = insertCode(jarFile.getInputStream(jarEntry));
jarOutputStream.write(bytes);
} else {
IOUtils.copy(jarFile.getInputStream(jarEntry), jarOutputStream);
}
}
} catch (IOException e) {
throw new RuntimeException(e);
}
});
});
反编译 APK 包中的 Dex 文件，查看是否修改成功
主模块
模块一
修改成功
Tags: android - plugin
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