本系列 Tinker 源码解析基于 Tinker v1.9.12

自动生成TinkerApplication

接入 Tinker 第一步就是改造 Application 。官方推荐是利用 @DefaultLifeCycle 动态生成 Application

    @DefaultLifeCycle(application = "tinker.sample.android.app.SampleApplication",                      flags = ShareConstants.TINKER_ENABLE_ALL,                      loadVerifyFlag = false)    public class SampleApplicationLike extends DefaultApplicationLike {    }

那我们来解析一下 Tinker 是如何生成 Application 以及在 Application 中做了什么事？

看到 @DefaultLifeCycle 注解，我们可想而知应该是经过 processor 解决后动态生成了 Application 。

查看 Tinker 工程可以发现在 tinker-android-anno 下面有一个 AnnotationProcessor

    @Override    public Set<String> getSupportedAnnotationTypes() {        final Set<String> supportedAnnotationTypes = new LinkedHashSet<>();            supportedAnnotationTypes.add(DefaultLifeCycle.class.getName());            return supportedAnnotationTypes;    }        @Override    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {        processDefaultLifeCycle(roundEnv.getElementsAnnotatedWith(DefaultLifeCycle.class));        return true;    }

发现它正是解决 @DefaultLifeCycle 的。

下面重要看 processDefaultLifeCycle 方法。

private void processDefaultLifeCycle(Set<? extends Element> elements) {    // DefaultLifeCycle    for (Element e : elements) {        DefaultLifeCycle ca = e.getAnnotation(DefaultLifeCycle.class);        String lifeCycleClassName = ((TypeElement) e).getQualifiedName().toString();        String lifeCyclePackageName = lifeCycleClassName.substring(0, lifeCycleClassName.lastIndexOf('.'));        lifeCycleClassName = lifeCycleClassName.substring(lifeCycleClassName.lastIndexOf('.') + 1);        String applicationClassName = ca.application();        if (applicationClassName.startsWith(".")) {            applicationClassName = lifeCyclePackageName + applicationClassName;        }        String applicationPackageName = applicationClassName.substring(0, applicationClassName.lastIndexOf('.'));        applicationClassName = applicationClassName.substring(applicationClassName.lastIndexOf('.') + 1);        String loaderClassName = ca.loaderClass();        if (loaderClassName.startsWith(".")) {            loaderClassName = lifeCyclePackageName + loaderClassName;        }        System.out.println("*");        final InputStream is = AnnotationProcessor.class.getResourceAsStream(APPLICATION_TEMPLATE_PATH);        final Scanner scanner = new Scanner(is);        final String template = scanner.useDelimiter("\\A").next();        final String fileContent = template            .replaceAll("%PACKAGE%", applicationPackageName)            .replaceAll("%APPLICATION%", applicationClassName)            .replaceAll("%APPLICATION_LIFE_CYCLE%", lifeCyclePackageName + "." + lifeCycleClassName)            .replaceAll("%TINKER_FLAGS%", "" + ca.flags())            .replaceAll("%TINKER_LOADER_CLASS%", "" + loaderClassName)            .replaceAll("%TINKER_LOAD_VERIFY_FLAG%", "" + ca.loadVerifyFlag());        try {            JavaFileObject fileObject = processingEnv.getFiler().createSourceFile(applicationPackageName + "." + applicationClassName);            processingEnv.getMessager().printMessage(Diagnostic.Kind.NOTE, "Creating " + fileObject.toUri());            Writer writer = fileObject.openWriter();            try {                PrintWriter pw = new PrintWriter(writer);                pw.print(fileContent);                pw.flush();            } finally {                writer.close();            }        } catch (IOException x) {            processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, x.toString());        }    }}

整个 processDefaultLifeCycle 方法看下来，其实主要在做的就是去读取一份模版，而后用注解中设置的值替换里面的少量占位符。这个模版就是 resouces/TinkerAnnoApplication.tmpl

package %PACKAGE%;import com.tencent.tinker.loader.app.TinkerApplication;/** * * Generated application for tinker life cycle * */public class %APPLICATION% extends TinkerApplication {    public %APPLICATION%() {        super(%TINKER_FLAGS%, "%APPLICATION_LIFE_CYCLE%", "%TINKER_LOADER_CLASS%", %TINKER_LOAD_VERIFY_FLAG%);    }}

最终生成的 SampleApplication 效果：

/** * * Generated application for tinker life cycle * */public class SampleApplication extends TinkerApplication {    public SampleApplication() {        super(7, "tinker.sample.android.app.SampleApplicationLike", "com.tencent.tinker.loader.TinkerLoader", false);    }}

解析 TinkerApplication

想要知道 TinkerApplication 里面干了什么？

一起看看 TinkerApplication.onCreate

@Overridepublic void onCreate() {    super.onCreate();    try {        ensureDelegate();        try {            ComponentHotplug.ensureComponentHotplugInstalled(this);        } catch (UnsupportedEnvironmentException e) {            throw new TinkerRuntimeException("failed to make sure that ComponentHotplug logic is fine.", e);        }        invokeAppLikeOnCreate(applicationLike);    } catch (TinkerRuntimeException e) {        throw e;    } catch (Throwable thr) {        throw new TinkerRuntimeException(thr.getMessage(), thr);    }}

第一步，调用 ensureDelegate 创立 application 代理商，即 applicationLike

private synchronized void ensureDelegate() {    if (applicationLike == null) {        applicationLike = createDelegate();    }}private Object createDelegate() {    try {        // Use reflection to create the delegate so it doesn't need to go into the primary dex.        // And we can also patch it        Class<?> delegateClass = Class.forName(delegateClassName, false, getClassLoader());        Constructor<?> constructor = delegateClass.getConstructor(Application.class, int.class, boolean.class,            long.class, long.class, Intent.class);        return constructor.newInstance(this, tinkerFlags, tinkerLoadVerifyFlag,            applicationStartElapsedTime, applicationStartMillisTime, tinkerResultIntent);    } catch (Throwable e) {        throw new TinkerRuntimeException("createDelegate failed", e);    }}

而后调用 invokeAppLikeOnCreate(applicationLike) 去回调 applicationLike 的 onCreate 方法。这样，applicationLike 和 application 的生命周期方法就做到同步了。另外，其他的生命周期方法也是如此来实现同步的，这里就不详细讲解了。

那么 Tinker 是什么时候加载的呢？

答案就在 attachBaseContext 中

@Overrideprotected void attachBaseContext(Context base) {    super.attachBaseContext(base);    Thread.setDefaultUncaughtExceptionHandler(new TinkerUncaughtHandler(this));    onBaseContextAttached(base);}private void onBaseContextAttached(Context base) {    try {        applicationStartElapsedTime = SystemClock.elapsedRealtime();        applicationStartMillisTime = System.currentTimeMillis();        loadTinker();        ensureDelegate();        invokeAppLikeOnBaseContextAttached(applicationLike, base);        //reset save mode        if (useSafeMode) {            ShareTinkerInternals.setSafeModeCount(this, 0);        }    } catch (TinkerRuntimeException e) {        throw e;    } catch (Throwable thr) {        throw new TinkerRuntimeException(thr.getMessage(), thr);    }}

可以看到调用了 loadTinker 方法。

private void loadTinker() {    try {        //reflect tinker loader, because loaderClass may be define by user!        Class<?> tinkerLoadClass = Class.forName(loaderClassName, false, getClassLoader());        Method loadMethod = tinkerLoadClass.getMethod(TINKER_LOADER_METHOD, TinkerApplication.class);        Constructor<?> constructor = tinkerLoadClass.getConstructor();        tinkerResultIntent = (Intent) loadMethod.invoke(constructor.newInstance(), this);    } catch (Throwable e) {        //has exception, put exception error code        tinkerResultIntent = new Intent();        ShareIntentUtil.setIntentReturnCode(tinkerResultIntent, ShareConstants.ERROR_LOAD_PATCH_UNKNOWN_EXCEPTION);        tinkerResultIntent.putExtra(INTENT_PATCH_EXCEPTION, e);    }}

这里的 loaderClassName 就是上面 @DefaultLifeCycle 中定义的 loaderClass 。默认的是 com.tencent.tinker.loader.TinkerLoader ，也支持客户自己设置 TinkerLoader 。

所以 loadTinker 中干的事就是利用反射执行了 TinkerLoader.tryLoad 方法。

至于在 tryLoad 方法中究竟做了什么事，我们等到下一篇再讲吧。