ARouter 拦截器与路由的实现(源码分析)
哈哈哈，之前说的ARouter后续分析来了，我是个老湿人。
由于我们的ARouter是通过注解的方式实现的，所以一上来又是APT那套东西，这次呢就不重点讲这个东西，大概说一下，主要笔者对于那些API也不是很熟，只是知道大概在干什么事。接下来就是正文了。
我们都知道，拦截器需要注解@Interceptor，这个注解的接口如下
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.CLASS)
public @interface Interceptor {
/**
* The priority of interceptor, ARouter will be excute them follow the priority.
*/
int priority();
/**
* The name of interceptor, may be used to generate javadoc.
*/
String name() default "Default";
}priority: 优先级，越小，优先级越高
接下来是拦截器的代码生成，这一步的处理是在InterceptorProcessor中，这个代码就不展开说了，这里面主要做的就是代码生成，之前ARouter依赖注入的代码讲了一下，可以去看看 ，最终生成的代码是如下的：
/**
* DO NOT EDIT THIS FILE!!! IT WAS GENERATED BY AROUTER. */
public class ARouter$$Interceptors$$app implements IInterceptorGroup {
@Override
public void loadInto(Map> interceptors) {
interceptors.put(7, Test1Interceptor.class);
}
} 接下来就是本文的重点咯。
初始化：
ARouter.init(this);跟进去看
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.");
}
}然后我们进入
_ARouter.init(application);然后看到的代码是
protected static synchronized boolean init(Application application) {
mContext = application;
LogisticsCenter.init(mContext, executor);
logger.info(Consts.TAG, "ARouter init success!");
hasInit = true;
// It's not a good idea.
// if (Build.VERSION.SDK_INT > Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
// application.registerActivityLifecycleCallbacks(new AutowiredLifecycleCallback());
// }
return true;
}然后在进入
LogisticsCenter.init(mContext, executor);重点来了
public synchronized static void init(Context context, ThreadPoolExecutor tpe) throws HandlerException {
mContext = context;
executor = tpe;
try {
// These class was generate by arouter-compiler.
// 由compiler生成的类，获取报名下面的所有类
List classFileNames = ClassUtils.getFileNameByPackageName(mContext, ROUTE_ROOT_PAKCAGE);
//
for (String className : classFileNames) {
if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_ROOT)) {
// This one of root elements, load root.
//加载root节点
((IRouteRoot) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.groupsIndex);
} else if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_INTERCEPTORS)) {
// Load interceptorMeta
//加载拦截器
((IInterceptorGroup) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.interceptorsIndex);
} else if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_PROVIDERS)) {
// Load providerIndex
//加载providers
((IProviderGroup) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.providersIndex);
}
}
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() + "]");
}
} 这里的流程为：扫描包名下面所有的类—>然后根据前缀来区分类的作用，然后放入到不同的容器中，
这里的容器为Warehouse类里面的一些容器，我们先看看Warehouse这个类
class Warehouse {
// Cache route and metas
static Map> groupsIndex = new HashMap<>();
static Map routes = new HashMap<>();
// Cache provider
static Map providers = new HashMap<>();
static Map providersIndex = new HashMap<>();
// Cache interceptor
static Map> interceptorsIndex = new UniqueKeyTreeMap<>("More than one interceptors use same priority [%s]");
static List interceptors = new ArrayList<>();
static void clear() {
routes.clear();
groupsIndex.clear();
providers.clear();
providersIndex.clear();
interceptors.clear();
interceptorsIndex.clear();
}
} 看到这里就明白了，刚刚那一步的作用就是要把所有的group节点加入到Warehouse.groupsIndex，把所有的拦截器加入到Warehouse.interceptorsIndex，把所有的provider加入到Warehouse.providersIndex
现在回到初始化这里 我们在进入
if (hasInit) {
_ARouter.afterInit();
}看这个代码
static void afterInit() {
// Trigger interceptor init, use byName.
interceptorService = (InterceptorService) ARouter.getInstance().build("/arouter/service/interceptor").navigation();
}我们先看看这个build方法，一步一步点进去，最后看到的代码是
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);
}
}他返回了一个 Postcard对象，这个对象很重要，这个对象继承自RouteMeta，他拥有很多属性，比如路由地址，bundle参数等等。
private RouteType type; // Type of route
private Element rawType; // Raw type of route
private Class destination; // Destination
private String path; // Path of route
private String group; // Group of route
private int priority = -1; // The smaller the number, the higher the priority
private int extra; // Extra data
private Map paramsType; // Param type
private Uri uri;
private Object tag; // A tag prepare for some thing wrong.
private Bundle mBundle; // Data to transform
private int flags = -1; // Flags of route
private int timeout = 300; // Navigation timeout, TimeUnit.Second
private IProvider provider; // It will be set value, if this postcard was provider.
private boolean greenChannel;
private SerializationService serializationService;
// Animation
private Bundle optionsCompat; // The transition animation of activity
private int enterAnim;
private int exitAnim; 好， 回到刚才的代码
interceptorService = (InterceptorService) ARouter.getInstance().build("/arouter/service/interceptor").navigation();我们进入navigation()方法
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;
}第一步我们进入
LogisticsCenter.completion(postcard);这段代码很简单，看注释就好了
public synchronized static void completion(Postcard postcard) {
if (null == postcard) {
throw new NoRouteFoundException(TAG + "No postcard!");
}
// 如果路由的路径没找到，那么可能是这个group下的路径还没有加载
// 首先获取到group，然后将当前group下的所有path加入到仓库的routes 这个map中 (Warehouse.routes)
// 然后从仓库的groupsIndex这个map中删掉这个group
// 然后重新加载 在执行一次本方法
// 如果已经加载了则执行else
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);
// TODO: 2017/10/26 不懂为什么需要删掉这个group
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 {
//往postcard里面填充信息
//设置跳转的class对象
postcard.setDestination(routeMeta.getDestination());
//设置类型
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.
//解析路径上的参数
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 autoinject.
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 be implememt 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();
//初始化所有的拦截器
provider.init(mContext);
Warehouse.providers.put(providerMeta, provider);
instance = provider;
} catch (Exception e) {
throw new HandlerException("Init provider failed! " + e.getMessage());
}
}
postcard.setProvider(instance);
//provider也不需要拦截器
postcard.greenChannel(); // Provider should skip all of interceptors
break;
case FRAGMENT:
//设置绿色通道为true，fragment不需要拦截器
postcard.greenChannel(); // Fragment needn't interceptors
default:
break;
}
}
} 看到初始化拦截器这里
@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();
//初始化
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();
}
}
}
});
} 接着LogisticsCenter.completion(postcard);继续执行下去
然后由于provider是绿色通道，所以直接执行_navigation(context, postcard, requestCode, callback);
然后返回，这样初始化流程中拦截器就初始完成了。
接下来就是路由和拦截器拦截了
现在就不从最开始讲了，读者可以一步一步跳进去，然后跟着走。
请读者先跳到
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;
}我们直接看到这段代码的
if (!postcard.isGreenChannel())
一般来说我们的activity没有设置成绿色通道，所以会进入这个条件语句，我们进入 interceptorService.doInterceptions方法
我们看到这段代码
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);
}
}
});在这里面最关键的就是一个CancelableCountDownLatch类，这个类是继承于CountDownLatch,在异步线程中，每执行一次_excute()方法，就countDown一次，这样就能保证在这个线程中，将所有的拦截器都执行一次。当所有的拦截器都通过之后，会调用 onContinue回调，在回调中会执行
@Override
public void onContinue(Postcard postcard) {
_navigation(context, postcard, requestCode, callback);
}进入这个方法
private 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 ((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);
}
}
});
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;
}这里就是我们的跳转处理了。