ARouter探究（一）
前言
- ARouter 是 Alibaba 开源的一款 Android 页面路由框架，特别适用于模块化开发过程中，页面跳转所带来的耦合问题。由于自己才疏学浅，有理解不当之处还请指教。
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简介
别人有详细的介绍，这就不写了
技术准备
几个问题
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怎么支持多模块的？
- 首先在编译期怎么知道多个模块怎么加载，我们看下ARouter怎么做到的？
- 既然是编译期我们猜想肯定用到APT,在Apt技术中可以通过在buidGradle文件中拿到参数，然后交给Process进行处理。看下ARouter是不是这样做的？
- build.gradle文件中配置
javaCompileOptions { annotationProcessorOptions { arguments = [ moduleName : project.getName() ] } } - 我们可以在AbstractProcessor类中的init(ProcessingEnvironment processingEnv)方法里面获取配置
Map<String, String> options = processingEnv.getOptions(); if (MapUtils.isNotEmpty(options)) { moduleName = options.get(KEY_MODULE_NAME); }
- build.gradle文件中配置
- 既然是编译期我们猜想肯定用到APT,在Apt技术中可以通过在buidGradle文件中拿到参数，然后交给Process进行处理。看下ARouter是不是这样做的？
- 首先在编译期怎么知道多个模块怎么加载，我们看下ARouter怎么做到的？
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怎么加载模块的数据的呢？
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针对路由存在路由表，那么必然存在初始化的过程？
- ARouter.init(getApplication()); ARouter的初始化此过程是初始化路由表信息。我们看下做了啥？
我们发现他调用了
此处ARouter用了代理模式，实际使用了_Arouter的init方法。我们再进去看发现__ARouter.init(application)
初始化交给了LogisticsCenter这个类，它是处理路由跳转的核心类。init方法里如下LogisticsCenter.init(mContext, executor);
final String ROUTE_ROOT_PAKCAGE = "com.alibaba.android.arouter.routes";
List<String> classFileNames = ClassUtils.getFileNameByPackageName(mContext, ROUTE_ROOT_PAKCAGE);
这是什么鬼？看到这里我们可能要蒙了，这是干什么的。因为我们前面说了init肯定要把路由信息加载到我们要存储的地方。 ClassUtils.getFileNameByPackageName()方法，我们根据方法名可以判断是遍历包名下的文件拿到我们Clas名，这个包名就是我们apt生成文件所在的包下，我们先看几个类APT生产的类目录结构如下？for (String className : classFileNames) { if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_ROOT)) { // This one of root elements, load root. ((IRouteRoot) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.groupsIndex); } else if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_INTERCEPTORS)) { // Load interceptorMeta ((IInterceptorGroup) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.interceptorsIndex); } else if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_PROVIDERS)) { // Load providerIndex ((IProviderGroup) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.providersIndex); } }
image
- 打开ARouter$$Root$$app
对于刚才LogisticsCenter.init方法里的public class ARouter$$Root$$app implements IRouteRoot { @Override public void loadInto(Map<String, Class<? extends IRouteGroup>> routes) { routes.put("service", ARouter$$Group$$service.class); routes.put("test", ARouter$$Group$$test.class); } }
这个地方就是利用反射生成ARouter$$Root$$app对象，调用loadinto方法最后把内容传给了Warehouse.groupsIndex。WareHouse是干啥的呢？看代码if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_ROOT)) { // This one of root elements, load root. ((IRouteRoot) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.groupsIndex); }class Warehouse { // Cache route and metas static Map<String, Class<? extends IRouteGroup>> groupsIndex = new HashMap<>(); static Map<String, RouteMeta> routes = new HashMap<>(); // Cache provider static Map<Class, IProvider> providers = new HashMap<>(); static Map<String, RouteMeta> providersIndex = new HashMap<>(); // Cache interceptor static Map<Integer, Class<? extends IInterceptor>> interceptorsIndex = new UniqueKeyTreeMap<>("More than one interceptors use same priority [%s]"); static List<IInterceptor> interceptors = new ArrayList<>(); static void clear() { routes.clear(); groupsIndex.clear(); providers.clear(); providersIndex.clear(); interceptors.clear(); interceptorsIndex.clear(); } }
- ARouter.init(getApplication()); ARouter的初始化此过程是初始化路由表信息。我们看下做了啥？
我们看到这里就是我们路由表缓存信息，交给对应的集合存储，这里groupsIndex就存了我们的分组信息。我们看到这里初始化的时候只是把分组存进去了，但具体的路由信息并没有加载进来，==这符合作者说的按组分类，按需加载提高查找效率，但是什么时候加载呢，我们先留个问号？后边会讲述==
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路由怎么完成查找的的？首先看用例
ARouter.getInstance().build("/test/activity2").navigation();- .build("/test/activity2")源码如下
public Postcard build(String path) { return _ARouter.getInstance().build(path); }==1==我们看到他还是交给了_ARouter进行处理，他的build方法如下：
protected Postcard build(String path) { if (TextUtils.isEmpty(path)) { throw new HandlerException(Consts.TAG + "Parameter is invalid!"); } else { PathReplaceService pService = ARouter.getInstance().navigation(PathReplaceService.class); if (null != pService) { path = pService.forString(path); } return build(path, extractGroup(path)); } }ARouter.getInstance().navigation(PathReplaceService.class);我们先看PathReplaceService是干啥的
public interface PathReplaceService extends IProvider { /** * For normal path. * * @param path raw path */ String forString(String path); /** * For uri type. * * @param uri raw uri */ Uri forUri(Uri uri); }==2==其实就是预处理我们的path这是重定向用的。上面的navigation（）方法肯定也是交给_ARouter进行处理的我们看下他的方法
protected <T> T navigation(Class<? extends T> service) { try { Postcard postcard = LogisticsCenter.buildProvider(service.getName()); // Compatible 1.0.5 compiler sdk. if (null == postcard) { // No service, or this service in old version. postcard = LogisticsCenter.buildProvider(service.getSimpleName()); } LogisticsCenter.completion(postcard); return (T) postcard.getProvider(); } catch (NoRouteFoundException ex) { logger.warning(Consts.TAG, ex.getMessage()); return null; } }看到这里我们看到最后还是交给了我们的核心逻辑处理类LogisticsCenter处理Postcard postcard = LogisticsCenter.buildProvider(service.getName()); 此处是创建个Postcard，它是个一个container里面有我们整个跳转所用到的所有信息包括跳转动画，看看buildProvider做了什么
public static Postcard buildProvider(String serviceName) { RouteMeta meta = Warehouse.providersIndex.get(serviceName); if (null == meta) { return null; } else { return new Postcard(meta.getPath(), meta.getGroup()); } }首先他先从warehose里面取出我们重定向的path和group重新生成Postcard，如果没有的话直接返回null，这里我们没有，所以就返回了null然后是 LogisticsCenter.completion(postcard);看代码
if (null == postcard) { throw new NoRouteFoundException(TAG + "No postcard!"); }如果为null直接抛出了异常，在哪里处理的呢，在黄字==2==的下面，然后catch异常返回了null,再回到黄字==1==处，我们走到了
build(path, extractGroup(path))然后创建了PostCard.这就build完了
- ARouter.getInstance().build("/test/activity2").navigation();==3==然后就是navigation方法,他也是有_ARouter进行处理
protected Object navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback) { try { LogisticsCenter.completion(postcard); } catch (NoRouteFoundException ex) { logger.warning(Consts.TAG, ex.getMessage()); if (debuggable()) { // Show friendly tips for user. Toast.makeText(mContext, "There's no route matched!\n" + " Path = [" + postcard.getPath() + "]\n" + " Group = [" + postcard.getGroup() + "]", Toast.LENGTH_LONG).show(); } if (null != callback) { callback.onLost(postcard); } else { // No callback for this invoke, then we use the global degrade service. DegradeService degradeService = ARouter.getInstance().navigation(DegradeService.class); if (null != degradeService) { degradeService.onLost(context, postcard); } } return null; } if (null != callback) { callback.onFound(postcard); } if (!postcard.isGreenChannel()) { // It must be run in async thread, maybe interceptor cost too mush time made ANR. interceptorService.doInterceptions(postcard, new InterceptorCallback() { /** * Continue process * * @param postcard route meta */ @Override public void onContinue(Postcard postcard) { _navigation(context, postcard, requestCode, callback); } /** * Interrupt process, pipeline will be destory when this method called. * * @param exception Reson of interrupt. */ @Override public void onInterrupt(Throwable exception) { if (null != callback) { callback.onInterrupt(postcard); } logger.info(Consts.TAG, "Navigation failed, termination by interceptor : " + exception.getMessage()); } }); } else { return _navigation(context, postcard, requestCode, callback); } return null; }还是这个类
public synchronized static void completion(Postcard postcard) { if (null == postcard) { throw new NoRouteFoundException(TAG + "No postcard!"); } RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath()); if (null == routeMeta) { // Maybe its does't exist, or didn't load. Class<? extends IRouteGroup> groupMeta = Warehouse.groupsIndex.get(postcard.getGroup()); // Load route meta. if (null == groupMeta) { throw new NoRouteFoundException(TAG + "There is no route match the path [" + postcard.getPath() + "], in group [" + postcard.getGroup() + "]"); } else { // Load route and cache it into memory, then delete from metas. try { if (ARouter.debuggable()) { logger.debug(TAG, String.format(Locale.getDefault(), "The group [%s] starts loading, trigger by [%s]", postcard.getGroup(), postcard.getPath())); } IRouteGroup iGroupInstance = groupMeta.getConstructor().newInstance(); iGroupInstance.loadInto(Warehouse.routes); Warehouse.groupsIndex.remove(postcard.getGroup()); if (ARouter.debuggable()) { logger.debug(TAG, String.format(Locale.getDefault(), "The group [%s] has already been loaded, trigger by [%s]", postcard.getGroup(), postcard.getPath())); } } catch (Exception e) { throw new HandlerException(TAG + "Fatal exception when loading group meta. [" + e.getMessage() + "]"); } completion(postcard); // Reload } } else { postcard.setDestination(routeMeta.getDestination()); postcard.setType(routeMeta.getType()); postcard.setPriority(routeMeta.getPriority()); postcard.setExtra(routeMeta.getExtra()); Uri rawUri = postcard.getUri(); if (null != rawUri) { // Try to set params into bundle. Map<String, String> resultMap = TextUtils.splitQueryParameters(rawUri); Map<String, Integer> paramsType = routeMeta.getParamsType(); if (MapUtils.isNotEmpty(paramsType)) { // Set value by its type, just for params which annotation by @Param for (Map.Entry<String, Integer> params : paramsType.entrySet()) { setValue(postcard, params.getValue(), params.getKey(), resultMap.get(params.getKey())); } // Save params name which need autoinject. postcard.getExtras().putStringArray(ARouter.AUTO_INJECT, paramsType.keySet().toArray(new String[]{})); } // Save raw uri postcard.withString(ARouter.RAW_URI, rawUri.toString()); } }这就是我们的重点所在，通过上面可知我们的postcard走到这里不会为null了但是RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath());这个返回的是null的因为我们是第一次加载这个分组里的routeMeta，所以进入if语句 ==Class<? extends IRouteGroup> groupMeta = Warehouse.groupsIndex.get(postcard.getGroup());查找我们PostCard里面带的分组，然后是IRouteGroup iGroupInstance = groupMeta.getConstructor().newInstance();
iGroupInstance.loadInto(Warehouse.routes);
这里就加载了我们的组内元素，也就是实现了上面所说的按需加载==，然后就completion(postcard);这时候重走方法，RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath());routeMeta就有值了我们就找到了我们要的路由信息，也就是通过path找到了routeMeta.就有了我们要给PostCard附上我们的目的地信息，参数信息等。
然后这就走完了- 有人要问跳转呢？我们回到黄字3处，return _navigation(context, postcard, requestCode, callback)最后走到这里，我们看下源码
switch (postcard.getType()) { case ACTIVITY: // Build intent final Intent intent = new Intent(currentContext, postcard.getDestination()); intent.putExtras(postcard.getExtras()); // Set flags. int flags = postcard.getFlags(); if (-1 != flags) { intent.setFlags(flags); } else if (!(currentContext instanceof Activity)) { // Non activity, need less one flag. intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); } // Navigation in main looper. new Handler(Looper.getMainLooper()).post(new Runnable() { @Override public void run() { if (requestCode > 0) { // Need start for result ActivityCompat.startActivityForResult((Activity) currentContext, intent, requestCode, postcard.getOptionsBundle()); } else { ActivityCompat.startActivity(currentContext, intent, postcard.getOptionsBundle()); } if ((0 != postcard.getEnterAnim() || 0 != postcard.getExitAnim()) && currentContext instanceof Activity) { // Old version. ((Activity) currentContext).overridePendingTransition(postcard.getEnterAnim(), postcard.getExitAnim()); } if (null != callback) { // Navigation over. callback.onArrival(postcard); } } }); }在主线程中startActivity,终于找到我们的调整目的地。写一篇会介绍依赖注入和拦截器。
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