gradle 自定义transform实践

2019-08-28 Gradle 评论

1. 工程配置

1. 添加 gradle api依赖

1 2	compile 'com.android.tools.build:gradle:3.0.1' compile group: 'org.javassist', name: 'javassist', version: '3.22.0-GA'

2. 自定义transform注入

	class MyPlugin implements Plugin<Project> {
    void apply(Project project) {
        def android = project.extensions.getByType(AppExtension)
        android.registerTransform(new CodeTrans(project))
    }
}

3. transform自定义

自定义 transform 扩展自 Transform ，实现 transform 方法即可

3.1 transform的概念

google 的android编译流程，以transform的形式提供给我们可干涉的时机
我们可以在编译成class文件并且生成dex之前拿到这些编译完成的class文件，做一些我们想要的修改。
我们自定义的transform会被包装秤一个 transform task，在 java compile task 之后执行。

3.2 transform的执行流程

transform 执行流程如下

3.3 transform api

public abstract class Transform {
    1. public abstract String getName();

    2. public abstract Set<ContentType> getInputTypes();

    3. public abstract Set<? super Scope> getScopes();

    3. public abstract boolean isIncremental(); // 是否支持增量编译
}

1. name : 此 transform的名字，也是这个transform代表的task的名字

2. getInputTypes ： 输入类型，作为输入过滤，transformManager中定义了有如下类型。

public static final Set<ContentType> CONTENT_CLASS;
   public static final Set<ContentType> CONTENT_JARS;
   public static final Set<ContentType> CONTENT_RESOURCES;
   public static final Set<ContentType> CONTENT_NATIVE_LIBS;
   public static final Set<ContentType> CONTENT_DEX;

3. getScopes ： 作用域 transformManager中定义了如下类型

public static final Set<ScopeType> PROJECT_ONLY;
   public static final Set<Scope> SCOPE_FULL_PROJECT;
   public static final Set<ScopeType> SCOPE_FULL_WITH_IR_FOR_DEXING;
   public static final Set<ScopeType> SCOPE_FULL_LIBRARY_WITH_LOCAL_JARS;

3.4 代码实例

在以下的例子中，我们继承transform方法，修改我们关心的类，在静态函数中插入一行打印语句

void transform(Context context, Collection<TransformInput> inputs, Collection<TransformInput> referencedInputs, TransformOutputProvider outputProvider, boolean isIncremental) throws IOException, TransformException, InterruptedException {

//        super.transform(context, inputs, referencedInputs, outputProvider, isIncremental)

        ExtParams params = project.extParams

        println " params.logEnable is ${ params.logEnable }"

        println "transform method is invoked  ====== --------------- "
//        System.out.println("=======================================doPathTransform{ context=${context}, inputs=${inputs}, referencedInputs=${referencedInputs}, outputProvider=${outputProvider}, isIncremental=${isIncremental}")


        inputs.each { TransformInput input ->

            input.directoryInputs.each { DirectoryInput directoryInput ->

				//修改我们关注的类
                InjectU.inject(directoryInput.file.absolutePath)

                //获取输出目录
               def dest = outputProvider.getContentLocation(
                       directoryInput.name,directoryInput.contentTypes,directoryInput.scopes,
                       Format.DIRECTORY)

//                println "directory name location is ${directoryInput.name}"


                com.android.utils.FileUtils.copyDirectory(
                        directoryInput.file,dest)
            }

            input.jarInputs.each { JarInput jarInput ->

                //jar文件一般是第三方依赖库jar文件
                // 重命名输出文件（同目录copyFile会冲突）

                def jarName = jarInput.name
                def md5 = DigestUtils.md5Hex(jarInput.file.getAbsolutePath())
                if (jarName.endsWith(".jar")) {
                    jarName = jarName.substring(0,jarName.length() - 4 )
                }

                //输出
                def dest = outputProvider.getContentLocation(jarName,
                    jarInput.contentTypes,jarInput.scopes,Format.JAR)

//                println " jar name location is ${jarInput.name}"

                FileUtils.copyFile(jarInput.file,dest)

            }
        }

    }

以下代码用javassist实现了再构造函数中插入语句的代码

class InjectU {


    static ClassPool pool = ClassPool.getDefault()

    static String injectStr = "System.out.println(\"I Love android-----\" ); "


    /**
     *
     * @param path file path
     */
    static void inject(String path) {

        pool.appendClassPath(path)


        def dir = new File(path);

        if (dir.isDirectory()) {

            dir.eachFileRecurse { File file ->

                def filePath = file.absolutePath



                //确保当前文件是class文件，并且不是系统自动生成的class文件
                if (filePath.endsWith(".class")
                        && !filePath.contains('R$')
                        && !filePath.contains('R.class')
                        && !filePath.contains("BuildConfig.class")) {

                    println "file path is ${filePath}"

                    int index = filePath.indexOf("com/example/pluginproject");

                    if (index != -1) {


                        int end = filePath.length() - 6 // .class = 6

                        String className = filePath.substring(index, end)
                                .replace('\\', '.').replace('/', '.')

                        println "not -1 class name is ${className}"

                        def c = pool.getCtClass(className)

                        if (c.isFrozen()) {
                            c.defrost()
                        }


                        CtConstructor[] declaredConstructors = c.getDeclaredConstructors();
                        if (declaredConstructors == null || declaredConstructors.length == 0) {
                            CtConstructor constructor = new CtConstructor(new CtClass[0], c);
                            c.addConstructor(constructor);
                            constructor.insertBeforeBody(injectStr);
                        } else {
                            declaredConstructors[0].insertBeforeBody(injectStr);
                        }

                        c.writeFile(path)
                        c.detach()
                    }
                }

            }
        }
    }


}