ARouter源代码解析
上一篇文章介绍了ARouter在编译期间做的事情，会生成一些文件，Root表，Group表，AutoWired和Intercept的代表类，理解为工厂吧，链接：https://blog.csdn.net/wangchao1412/article/details/99412922
所以我们在使用之前需要初始化，把Root表，Intercept拦截器和Provider加在到内存中，AutoWired需要inject注入。
下面来看一一下最简单的使用。
在Application中初始化
ARouter.init(getApplication());
/**
* Init, it must be call before used router.
*/
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.");
}
}
有一个hasInit变量，判断是否初始化，然后调用 _ARouter.init 和 _ARouter.afterInit()方法。
来看一下_ARouter.init方法
/**
* LogisticsCenter init, load all metas in memory. Demand initialization
*/
public synchronized static void init(Context context, ThreadPoolExecutor tpe) throws HandlerException {
mContext = context;
executor = tpe;
try {
long startInit = System.currentTimeMillis();
//billy.qi modified at 2017-12-06
//load by plugin first
loadRouterMap();
if (registerByPlugin) {
logger.info(TAG, "Load router map by arouter-auto-register plugin.");
} else {
Set routerMap;
// It will rebuild router map every times when debuggable.
if (ARouter.debuggable() || PackageUtils.isNewVersion(context)) {
logger.info(TAG, "Run with debug mode or new install, rebuild router map.");
// 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()));
}
logger.info(TAG, "Find router map finished, map size = " + routerMap.size() + ", cost " + (System.currentTimeMillis() - startInit) + " ms.");
startInit = System.currentTimeMillis();
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);
}
}
}
logger.info(TAG, "Load root element finished, cost " + (System.currentTimeMillis() - startInit) + " ms.");
if (Warehouse.groupsIndex.size() == 0) {
logger.error(TAG, "No mapping files were found, check your configuration please!");
}
if (ARouter.debuggable()) {
logger.debug(TAG, String.format(Locale.getDefault(), "LogisticsCenter has already been loaded, GroupIndex[%d], InterceptorIndex[%d], ProviderIndex[%d]", Warehouse.groupsIndex.size(), Warehouse.interceptorsIndex.size(), Warehouse.providersIndex.size()));
}
} catch (Exception e) {
throw new HandlerException(TAG + "ARouter init logistics center exception! [" + e.getMessage() + "]");
}
}
routerMap = ClassUtils.getFileNameByPackageName(mContext, ROUTE_ROOT_PAKCAGE);会返回一个set集合，里面装着com.alibaba.android.arouter.routes包下的所有的类全路径，project中所有的library和module中可能都会有com.alibaba.android.arouter.routes路径，内部是用PMS和Dex把所有的文件都加在的这个set中。然后在循环遍历set集合，根据文件路径区分Root，Provider还是Intecepter，这样很方便的用APT生成的文件把这些信息加载到对应的Map集合内存中。
然后在Init成功后，调用afterInit方法。
static void afterInit() {
// Trigger interceptor init, use byName.
interceptorService = (InterceptorService) ARouter.getInstance().build("/arouter/service/interceptor").navigation();
}这里的interceptorService就是一个拦截器真正的执行类，所有的拦截器都会调用interceptorService的
doInterceptions(final Postcard postcard, final InterceptorCallback callback)来执行，PostCard是一些信息包装，InterceptorCallback是拦截了还是没拦截的回掉。这个类后面用到在具体分析。
这样Init初始化中，就会把Root表，Provider表和Intecepte表中的信息加载到内存中，并且创建了拦截器的管理类，interceptorService。
下来分析一下下面的代码内部做了什么。
ARouter.getInstance()
.build("/test/activity2")
.withString("key1", "value1")
.navigation();
getInstance
/**
* Get instance of router. A
* All feature U use, will be starts here.
*/
public static ARouter getInstance() {
if (!hasInit) {
throw new InitException("ARouter::Init::Invoke init(context) first!");
} else {
if (instance == null) {
synchronized (ARouter.class) {
if (instance == null) {
instance = new ARouter();
}
}
}
return instance;
}
}初始化成功了，就会创建一个ARouter对象
build
/**
* Build the roadmap, draw a postcard.
*
* @param path Where you go.
*/
public Postcard build(String path) {
return _ARouter.getInstance().build(path);
}调用内部的build方法
/**
* Build postcard by path and group
*/
protected Postcard build(String path, String group) {
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);
}
}
build在内部判断path的正确性等操作后会返回一个PostCard对象。
withString
public Postcard withString(@Nullable String key, @Nullable String value) {
mBundle.putString(key, value);
return this;
}其实就是执行PostCard内部的Bundle对象putString。
navigation/**
* Use router navigation.
*
* @param context Activity or null.
* @param postcard Route metas
* @param requestCode RequestCode
* @param callback cb
*/
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;
}
首先调用了LogisticsCenter.completion(postcard);我们来看一下。
completion/**
* Completion the postcard by route metas
*
* @param postcard Incomplete postcard, should complete by this method.
*/
public synchronized static void completion(Postcard postcard) {
if (null == postcard) {
throw new NoRouteFoundException(TAG + "No postcard!");
}
//TODO 从Group表中拿数据
RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath());
if (null == routeMeta) { // Maybe its does't exist, or didn't load.
Class 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 resultMap = TextUtils.splitQueryParameters(rawUri);
Map paramsType = routeMeta.getParamsType();
if (MapUtils.isNotEmpty(paramsType)) {
// Set value by its type, just for params which annotation by @Param
for (Map.Entry params : paramsType.entrySet()) {
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 providerMeta = (Class) 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;
}
}
}
首先会在group表中去根据path拿RouteMeta，第一次进来肯定是null的，就去root表里根据group拿到groupClass，（这里root表在init的时候已经赋值了），拿到之后反射实例化对象，调用loadInto，把数据加载到 Warehouse.routes 内存中，然后移除root表中的此项，（优化内存），然后在调用一次completion(postcard)，这时候RouteMeta是可以获取到的，然后把RouteMeta的值给了postcard，如果是PROVIDER类型，从providers中拿到对应的Provider实例化后调用了他的init方法，然后postcard.setProvider(instance);赋值，拿的时候直接getProvider就可以了。这里PROVIDER和FRAGMENT两种类型是设置greenChannel，可以绕过拦截器。
然后回到navigation方法中，
if (!postcard.isGreenChannel())成立的话，代表需要走拦截器,interceptorService就是我们在ARouter初始化的时候创建的拦截器管理者，是通过interceptorService = (InterceptorService) ARouter.getInstance().build("/arouter/service/interceptor").navigation();方式获取的，最后也会调用navigation方法，而这个interceptorService属于Provider，所以会先调用init，所以在走道interceptorService.doInterceptions之前init一定是执行过了。那我们来先看一下它的init方法。 @Override
public void init(final Context context) {
LogisticsCenter.executor.execute(new Runnable() {
@Override
public void run() {
if (MapUtils.isNotEmpty(Warehouse.interceptorsIndex)) {
for (Map.Entry> entry : Warehouse.interceptorsIndex.entrySet()) {
Class interceptorClass = entry.getValue();
try {
IInterceptor iInterceptor = interceptorClass.getConstructor().newInstance();
iInterceptor.init(context);
Warehouse.interceptors.add(iInterceptor);
} catch (Exception ex) {
throw new HandlerException(TAG + "ARouter init interceptor error! name = [" + interceptorClass.getName() + "], reason = [" + ex.getMessage() + "]");
}
}
interceptorHasInit = true;
logger.info(TAG, "ARouter interceptors init over.");
synchronized (interceptorInitLock) {
interceptorInitLock.notifyAll();
}
}
}
});
} 首先会遍历 Warehouse.interceptorsIndex，是在init时候赋值的。如果我们自己有实现@Interceptor并使用IInterceptor接口，怎不为null，调用iInterceptor.init，也就是我们些的拦截器的init方法初始化，初始化之后添加到Warehouse.interceptors中，Warehouse.interceptors中就是存放初始化完成的拦截器。
接着看一下
doInterceptions
@Override
public void doInterceptions(final Postcard postcard, final InterceptorCallback callback) {
if (null != Warehouse.interceptors && Warehouse.interceptors.size() > 0) {
checkInterceptorsInitStatus();
if (!interceptorHasInit) {
callback.onInterrupt(new HandlerException("Interceptors initialization takes too much time."));
return;
}
LogisticsCenter.executor.execute(new Runnable() {
@Override
public void run() {
CancelableCountDownLatch interceptorCounter = new CancelableCountDownLatch(Warehouse.interceptors.size());
try {
_excute(0, interceptorCounter, postcard);
interceptorCounter.await(postcard.getTimeout(), TimeUnit.SECONDS);
if (interceptorCounter.getCount() > 0) { // Cancel the navigation this time, if it hasn't return anythings.
callback.onInterrupt(new HandlerException("The interceptor processing timed out."));
} else if (null != postcard.getTag()) { // Maybe some exception in the tag.
callback.onInterrupt(new HandlerException(postcard.getTag().toString()));
} else {
callback.onContinue(postcard);
}
} catch (Exception e) {
callback.onInterrupt(e);
}
}
});
} else {
callback.onContinue(postcard);
}
}
/**
* Excute interceptor
*
* @param index current interceptor index
* @param counter interceptor counter
* @param postcard routeMeta
*/
private static void _excute(final int index, final CancelableCountDownLatch counter, final Postcard postcard) {
if (index < Warehouse.interceptors.size()) {
IInterceptor iInterceptor = Warehouse.interceptors.get(index);
iInterceptor.process(postcard, new InterceptorCallback() {
@Override
public void onContinue(Postcard postcard) {
// Last interceptor excute over with no exception.
counter.countDown();
_excute(index + 1, counter, postcard); // When counter is down, it will be execute continue ,but index bigger than interceptors size, then U know.
}
@Override
public void onInterrupt(Throwable exception) {
// Last interceptor excute over with fatal exception.
postcard.setTag(null == exception ? new HandlerException("No message.") : exception.getMessage()); // save the exception message for backup.
counter.cancel();
// Be attention, maybe the thread in callback has been changed,
// then the catch block(L207) will be invalid.
// The worst is the thread changed to main thread, then the app will be crash, if you throw this exception!
// if (!Looper.getMainLooper().equals(Looper.myLooper())) { // You shouldn't throw the exception if the thread is main thread.
// throw new HandlerException(exception.getMessage());
// }
}
});
}
}
首先是判断是否初始化成功，成功放到线程池中之行_excute，CancelableCountDownLatch就是引用计数管理。在_excute方法中，回去递归执行我们实现的拦截器的process方法，如果通过了调用onContinue继续下一个拦截器，知道所有拦截器都通过，或则拦截就取消递归，如果没有拦截到就调用callback.onContinue,拦截到走callback.onInterrupt回掉到navigation中，如果拦截了并且有navigation有设置callback的话，发送通知就结束了，下面我们看一下没有拦截到或者isGreenChannel时走的方法。
_navigationprivate Object _navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback) {
final Context currentContext = null == context ? mContext : context;
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 ((-1 != postcard.getEnterAnim() && -1 != postcard.getExitAnim()) && currentContext instanceof Activity) { // Old version.
((Activity) currentContext).overridePendingTransition(postcard.getEnterAnim(), postcard.getExitAnim());
}
if (null != callback) { // Navigation over.
callback.onArrival(postcard);
}
}
});
break;
case PROVIDER:
return postcard.getProvider();
case BOARDCAST:
case CONTENT_PROVIDER:
case FRAGMENT:
Class fragmentMeta = postcard.getDestination();
try {
Object instance = fragmentMeta.getConstructor().newInstance();
if (instance instanceof Fragment) {
((Fragment) instance).setArguments(postcard.getExtras());
} else if (instance instanceof android.support.v4.app.Fragment) {
((android.support.v4.app.Fragment) instance).setArguments(postcard.getExtras());
}
return instance;
} catch (Exception ex) {
logger.error(Consts.TAG, "Fetch fragment instance error, " + TextUtils.formatStackTrace(ex.getStackTrace()));
}
case METHOD:
case SERVICE:
default:
return null;
}
return null;
}
如果是Activity的话，设置intent bundle，如果requestCode大于0执行startActivityForResult，否则startActivity，也可以设置动画效果，如果是PROVIDER直接把拿到的对象通过getProvider获取直接返回，如果是FRAGMENT，拿到fragment实例设置bundle把fragment返回。这就是ARouter的流程基本分析完了。下面还有@AutoWired是怎么用的呢。
注入的使用代码：
ARouter.getInstance().inject(this);
看一下inject方法：
static void inject(Object thiz) {
AutowiredService autowiredService = ((AutowiredService) ARouter.getInstance().build("/arouter/service/autowired").navigation());
if (null != autowiredService) {
autowiredService.autowire(thiz);
}
}
这里看到拿到了路由 /arouter/service/autowired的实例调用autowire，找到 /arouter/service/autowired地址对应的AutowiredServiceImpl类。同样是通过navigation获取的，并且是继承自IProvider，所以会先走init方法。看一下
AutowiredServiceImpl类@Route(path = "/arouter/service/autowired")
public class AutowiredServiceImpl implements AutowiredService {
private LruCache classCache;
private List blackList;
@Override
public void init(Context context) {
classCache = new LruCache<>(66);
blackList = new ArrayList<>();
}
@Override
public void autowire(Object instance) {
String className = instance.getClass().getName();
try {
if (!blackList.contains(className)) {
ISyringe autowiredHelper = classCache.get(className);
if (null == autowiredHelper) { // No cache.
autowiredHelper = (ISyringe) Class.forName(instance.getClass().getName() + SUFFIX_AUTOWIRED).getConstructor().newInstance();
}
autowiredHelper.inject(instance);
classCache.put(className, autowiredHelper);
}
} catch (Exception ex) {
blackList.add(className); // This instance need not autowired.
}
}
} 在autowire中根据传入的上下文拼接后缀通过反射拿到apt生成的autowired类，调用inject方法，实现了注入。
ARouter流程就讲解完了。