androidgradle源码,Androidgradle打包涉及task源码解析
（五）
⽂章序号
此篇⽂章将分析如下3个task。
:app:transformClassesWithDexBuilderForDebug
:app:transformDexArchiveWithExternalLibsDexMergerForDebug
:app:transformDexArchiveWithDexMergerForDebug
transform vs task
本篇⽂章主要分析transform相关的任务，分析transform任务之前跟⼤家⼤致的聊下transform和task的关联。
在本篇之前的⽂章分析的task基本都是Task的⼦类。 transform相关的任务均是Transform的⼦类。那task和transform有什么关联呢？先看下Transform：
public abstract class Transform {
public abstract String getName();
public abstract Set getInputTypes();
public Set getOutputTypes() {
return getInputTypes();
}
public abstract Set super Scope> getScopes();
public Set super Scope> getReferencedScopes() {
return ImmutableSet.of();
}
public Collection getSecondaryFileInputs() {
return ImmutableList.of();
}
public Collection getSecondaryFiles() {
return ImmutableList.of();
}
public Collection getSecondaryFileOutputs() {
return ImmutableList.of();
}
public Collection getSecondaryDirectoryOutputs() {
return ImmutableList.of();
}
public Map getParameterInputs() {
return ImmutableMap.of();
}
public abstract boolean isIncremental();
public void transform(
@NonNull Context context,
@NonNull Collection inputs,
@NonNull Collection referencedInputs,
@Nullable TransformOutputProvider outputProvider,
boolean isIncremental) throws IOException, TransformException, InterruptedException {
}
public void transform(@NonNull TransformInvocation transformInvocation)
throws TransformException, InterruptedException, IOException {
// Just delegate to old method, for code that uses the old API.
//noinspection deprecation
Context(), Inputs(),
transformInvocation.isIncremental());
}
public boolean isCacheable() {
return false;
}
}
Transform实际就是⼀个抽象类，提供了⼀些抽象⽅法，仔细看会发现很多⽅法定义的和Task中的⽅法定义的很类似。接下来我们下TransformManager.java⾥⾯的addTransform()⽅法：
public Optional> addTransform(
@NonNull TaskFactory taskFactory,
@NonNull TransformVariantScope scope,
@NonNull T transform,
@Nullable TransformTask.ConfigActionCallback callback) {
...
transforms.add(transform);
// create
AndroidTask task =
taskFactory,
new TransformTask.ConfigAction<>(
taskName,
transform,
inputStreams,
referencedStreams,
outputStream,
recorder,
callback));
return Optional.ofNullable(task);
}
addTransform ⽅法在执⾏过程中，会将 Transform 包装成⼀个 AndroidTask 对象，所以transfrom最终会被转换成⼀个task。了解了transform，我们接下来继续分析这⼏个task。
transformClassesWithDexBuilderForDebug
输⼊命令：./gradlew transformClassesWithDexBuilderForDebug
inputs&outputs
input file:/Users/chao.zheng/.gradle/caches/transforms-1/files-1.1/appcompat-v7-
26.1.0.aar/6b443e96f1af9aa241aaa70576c67a57/jars/classes.jar
input file:/Users/chao.zheng/.gradle/caches/transforms-1/files-1.1/constraint-layout-
1.1.3.aar/f44da5c361a1f52801511229596f72e7/jars/classes.jar
input file:/Users/chao.zheng/.gradle/caches/transforms-1/files-1.1/butterknife-
8.5.1.aar/9d5de52440cb778daab09db33955642f/jars/classes.jar
...
input
file:/Users/chao.zheng/sunday/OpenSpace/TasksPro/app/build/intermediates/classes/debug/android/support/constraint/R$id.cla
input
file:/Users/chao.zheng/sunday/OpenSpace/TasksPro/app/build/intermediates/classes/debug/android/support/constraint/R$style
input
file:/Users/chao.zheng/sunday/OpenSpace/TasksPro/app/build/intermediates/classes/debug/android/support/constraint/R$attr.
input
file:/Users/chao.zheng/sunday/OpenSpace/TasksPro/app/build/intermediates/classes/debug/android/arch/lifecycle/R.class
input file:/Users/chao.zheng/sunday/OpenSpace/TasksPro/app/build/intermediates/classes/debug/butterknife/R.class
---------------------------------------------------
output file:/Users/chao.zheng/sunday/OpenSpace/TasksPro/app/build/intermediates/transforms/dexBuilder/debug 输⼊⽂件⽐较多，中间省略了⼀部分，但是还是⽐较明显的看出输⼊⽂件分为两种类型：
1、依赖库的jar⽂件；
2、intermediates/classes/debug/⽬下的class⽂件(即本项⽬产⽣的class⽂件)。
输出⽂件：
1、编号0-16的jar包；
2、本项⽬的class⽂件⽣成的dex⽂件。
源码
主要代码逻辑
DexArchiveBuilderTransform.java类中的transform()⽅法：
public void transform(@NonNull TransformInvocation transformInvocation)
throws TransformException, IOException, InterruptedException {
...
try {
// 1、遍历输⼊
for (TransformInput input : Inputs()) {
/
/ 2、输⼊的类型是Directory，调⽤convertToDexArchive()⽅法。
for (DirectoryInput dirInput : DirectoryInputs()) {
logger.verbose("Dir input %s", File().toString());
convertToDexArchive(
dirInput,
outputProvider,
transformInvocation.isIncremental());
}
// 3、输⼊类型是Jar，则调⽤processJarInput⽅法。
for (JarInput jarInput : JarInputs()) {
logger.verbose("Jar input %s", File().toString());
List dexArchives =
processJarInput(
transformInvocation.isIncremental(),
jarInput,
outputProvider);
cacheableItems.putAll(jarInput, dexArchives);
}
}
...
}
通过代码分析，知道transform是遍历所有的输⼊⽂件，分为两种类型来处理：
1、输⼊的类型是Directory，调⽤convertToDexArchive()⽅法，接着调⽤了launchProcessing()⽅法，最终调⽤DxDexArchiveBuilder的dex()⽅法，代码如下：
// 1、通过⽅法应该就能知道，这个⽅法就是将class转变成dex的。
public void dex(String relativePath, ByteArray classBytes, DexArchive output)
throws IOException {
// Copied from dx, from com.android.dxmand.dexer.Main
DirectClassFile cf = new DirectClassFile(classBytes, relativePath, true);
cf.setAttributeFactory(StdAttributeFactory.THE_ONE);
// 2、DexFile obj
// starts the actual translation and writes the content to the dex file
// specified
DexFile dexFile = new DexOptions());
// Copied from dx, from com.android.dxmand.dexer.Main
ClassDefItem classDefItem =
cf,
null,
dexFile);
dexFile.add(classDefItem);
if (outStorage != null) {
ByteArrayAnnotatedOutput byteArrayAnnotatedOutput = dexFile.writeTo(outStorage);
output.addFile(
ClassFileEntry.withDexExtension(relativePath),
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