編譯時註解（三）Arouter原始碼講解
阿新 • • 發佈：2018-12-02
專案中我們有時需要跨模組startActivity，但是這樣需要配置menifest，不方便。這時就需要阿里的一個路由框架Arouter
Arouter的使用就不再多說了。這篇文章主要講解他的原始碼
1.初始化
ARouter.init( this );
public static void init(Application application) { if (!hasInit) { logger = _ARouter.logger; _ARouter.logger.info(Consts.TAG, "ARouter init start."); hasInit = _ARouter.init(application);//********* if (hasInit) { _ARouter.afterInit(); //********* } _ARouter.logger.info(Consts.TAG, "ARouter init over."); } }
_ARouter.afterInit();裡面就下面一句，初始化攔截器服務
interceptorService = (InterceptorService) ARouter.getInstance().build("/arouter/service/interceptor").navigation();
下面看_ARouter.init。呼叫LogisticsCenter.init(mContext, executor);
public synchronized static void init(Context context, ThreadPoolExecutor tpe) throws HandlerException { ...... Set<String> routerMap; // It will rebuild router map every times when debuggable. if (ARouter.debuggable() || PackageUtils.isNewVersion(context)) { // debuggable預設是false。openDebug以後為true // 如果是debug模式或者是新版本 // These class was generated by arouter-compiler. routerMap = ClassUtils.getFileNameByPackageName(mContext, ROUTE_ROOT_PAKCAGE); if (!routerMap.isEmpty()) { context.getSharedPreferences(AROUTER_SP_CACHE_KEY, Context.MODE_PRIVATE).edit().putStringSet(AROUTER_SP_KEY_MAP, routerMap).apply(); } PackageUtils.updateVersion(context); // Save new version name when router map update finishes. } else { logger.info(TAG, "Load router map from cache."); routerMap = new HashSet<>(context.getSharedPreferences(AROUTER_SP_CACHE_KEY, Context.MODE_PRIVATE).getStringSet(AROUTER_SP_KEY_MAP, new HashSet<String>())); } ...... for (String className : routerMap) { 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); } } ...... }
總結來說，init過程就是把所有註解的資訊載入記憶體中，並且完成所有攔截器的初始化。（只是不明白為什麼loadInto要如此分配）
2.路由
ARouter.getInstance().build(Route.LibRoute).navigation();
看一下build幹了些什麼
if (TextUtils.isEmpty(path) || TextUtils.isEmpty(group)) { throw new HandlerException(Consts.TAG + "Parameter is invalid!"); } else { PathReplaceService pService = ARouter.getInstance().navigation(PathReplaceService.class); if (null != pService) { path = pService.forString(path); } return new Postcard(path, group); }
PathReplaceService可以自己修改path的規則實現路徑動態變化。（這裡沒實現）然後返回Postcard
再看navigation函式
protected Object navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback) {
try {
LogisticsCenter.completion(postcard);
} catch (NoRouteFoundException ex) {
......
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);//******************降級策略
if (null != degradeService) {
degradeService.onLost(context, postcard);
}
}
return null;
}
//***************************不是GreenChannel，就需要攔截器
//先不管攔截器，_navigation方法裡面就可以看到我們熟悉的startActivity
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;
}
接下來看LogisticsCenter.completion(postcard);
public synchronized static void completion(Postcard postcard) {
if (null == postcard) {
throw new NoRouteFoundException(TAG + "No postcard!");
}
RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath());
// routeMeta為空，remove然後reload
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()) {//*****************************************我們熟悉的bundle
setValue(postcard,
params.getValue(),
params.getKey(),
resultMap.get(params.getKey()));
}
// Save params name which need auto inject.
postcard.getExtras().putStringArray(ARouter.AUTO_INJECT, paramsType.keySet().toArray(new String[]{}));
}
// Save raw uri
postcard.withString(ARouter.RAW_URI, rawUri.toString());
}
switch (routeMeta.getType()) {
case PROVIDER: // if the route is provider, should find its instance
// Its provider, so it must implement IProvider
Class<? extends IProvider> providerMeta = (Class<? extends IProvider>) routeMeta.getDestination();
IProvider instance = Warehouse.providers.get(providerMeta);
if (null == instance) { // There's no instance of this provider
IProvider provider;
try {
provider = providerMeta.getConstructor().newInstance();
provider.init(mContext);
Warehouse.providers.put(providerMeta, provider);
instance = provider;
} catch (Exception e) {
throw new HandlerException("Init provider failed! " + e.getMessage());
}
}
postcard.setProvider(instance);
postcard.greenChannel(); // Provider should skip all of interceptors
break;
case FRAGMENT:
postcard.greenChannel(); // Fragment needn't interceptors
default:
break;
}
}
可以看到LogisticsCenter.completion的主要功能是找到匹配的目標類，並將目標類的一些資訊拷貝到postcard物件中。
至此整個路由跳轉的過程大致完成，整個過程可以分為：封裝Postcard -> 查詢資訊集合，例項化目標類 -> 跳轉
參考連結
https://yq.aliyun.com/articles/71687
https://www.jianshu.com/p/bc4c34c6a06c