ARouter源码解析04-interceptor拦截器
上篇文章我们分析了ARouter的路由跳转，这篇文章我们来分析interceptor拦截器。
首先，同样在IDE编译过程中，拦截器也会产生相应的文件。(详见ARouter源码解析01-编译生成文件)
public class ARouter$$Interceptors$$app implements IInterceptorGroup {
@Override
public void loadInto(Map> interceptors) {
interceptors.put(3, Test2Interceptor.class);
interceptors.put(5, Test3Interceptor.class);
interceptors.put(7, Test1Interceptor.class);
}
}
可以看到，这里根据priority将Intercepter按照级别进行排序，级别从高到第依次put到interceptors集合中。那么，这些intercepter是在什么地方加载到内存中的呢？
同时，我们知道，拦截器有个init()方法，会在程序初始化的时候，进行调用，那么，是在哪里执行拦截器的init()方法的呢？
再回到ARouter.init()来看
public static void init(Application application) {
//...
hasInit = _ARouter.init(application);
if (hasInit) {
_ARouter.afterInit();
}
//...
}
这里有个afterInit方法，我们跟进去看下
static void afterInit() {
// Trigger interceptor init, use byName.
interceptorService = (InterceptorService) ARouter.getInstance().build("/arouter/service/interceptor").navigation();
}
这里，通过路由跳转，调用了InterceptorServiceImpl，但是在路由app模块build文件中，并没有/arouter/service/interceptor这个路由表单，那么ARouter这里是通过怎么跳转的呢？
原来，在aroute-api中，还有个arouter的build文件，在这个文件下，有着和app模块下build包名相同的ARouter开头的几个文件(故ARouter.init的时候，也会把这几个路由表单加载进去)
package com.alibaba.android.arouter.routes;
public class ARouter$$Group$$arouter implements IRouteGroup {
@Override
public void loadInto(Map atlas) {
atlas.put("/arouter/service/autowired", RouteMeta.build(RouteType.PROVIDER, AutowiredServiceImpl.class, "/arouter/service/autowired", "arouter", null, -1, -2147483648));
atlas.put("/arouter/service/interceptor", RouteMeta.build(RouteType.PROVIDER, InterceptorServiceImpl.class, "/arouter/service/interceptor", "arouter", null, -1, -2147483648));
}
}
我们再来在InterceptorServiceImpl，首先会在navigation的时候调用 LogisticsCenter.completion从而调用provider.init()方法进行初始化。
@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;
synchronized (interceptorInitLock) {
interceptorInitLock.notifyAll();
}
}
}
});
}
可以发现，大体的，就是通过线程池.execute()，在异步线程中，获取所有的拦截器IInterceptor，调用他们的init方法，并把拦截器添加到Warehouse.interceptors集合中。
知道了
接着，继续在navigation方法中，如果没有把postcard.isGreenChannel设为true，那么调用interceptorService.doInterceptions执行拦截器，处理是否拦截。
完成了拦截器的init()，再来看navigation的时候，拦截器的拦截，
final class _ARouter {
protected Object navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback) {
LogisticsCenter.completion(postcard);
//isGreenChannel為ture，說明不需要interceptor，要跳過interceptor
if (!postcard.isGreenChannel()) {
interceptorService.doInterceptions(postcard, new InterceptorCallback() {
@Override
public void onContinue(Postcard postcard) {
_navigation(context, postcard, requestCode, callback);
}
@Override
public void onInterrupt(Throwable exception) {
if (null != callback) {
callback.onInterrupt(postcard);
}
}
});
} else {
return _navigation(context, postcard, requestCode, callback);
}
return null;
}
}
来看doInterceptions()，这里进行拦截器的拦截，会遍历拦截器列表，并调用拦截器的process()，最终，根据结果回调onContinue或onInterrupt来继续navigation或终止navigation。
@Override
public void doInterceptions(final Postcard postcard, final InterceptorCallback callback) {
// 检查拦截器列表是否为空
if (CollectionUtils.isNotEmpty(Warehouse.interceptors)) {
// 等待拦截器服务完成初始化
// ......
LogisticsCenter.executor.execute(new Runnable() {
@Override
public void run() {
// CountDown倒数计数器
CancelableCountDownLatch interceptorCounter = new CancelableCountDownLatch(Warehouse.interceptors.size());
try {
// 在另一个线程中递归依次执行拦截器操作
_excute(0, interceptorCounter, postcard);
// 等待超时
interceptorCounter.await(postcard.getTimeout(), TimeUnit.SECONDS);
// 倒数计时器不为0,表示还有拦截器未执行完成
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();
}
});
}
}
至此，即完成了interceptor的拦截，下篇文章，我们来解析ARouter的自动注入参数的功能。