ARouter源码解析04-interceptor拦截器

来源：互联网发布：网络it外包编辑：程序博客网时间：2024/05/21 09:28

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<Integer, Class<? extends IInterceptor>> 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<String, RouteMeta> 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。

@Overridepublic void init(final Context context) {    LogisticsCenter.executor.execute(new Runnable() {        @Override        public void run() {            if (MapUtils.isNotEmpty(Warehouse.interceptorsIndex)) {                for (Map.Entry<Integer, Class<? extends IInterceptor>> entry : Warehouse.interceptorsIndex.entrySet()) {                    Class<? extends IInterceptor> 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。

@Overridepublic 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。

阅读全文

0 0