ARouter初始化及跳转原理

ARouter初始化及跳转原理

编译后生成文件

仓库类

``

class Warehouse {
    // Cache route and metas
    static Map<String, Class<? extends IRouteGroup>> groupsIndex = new HashMap<>();
    static Map<String, RouteMeta> routes = new HashMap<>();

    // Cache provider
    static Map<Class, IProvider> providers = new HashMap<>();
    static Map<String, RouteMeta> providersIndex = new HashMap<>();

    // Cache interceptor
    static Map<Integer, Class<? extends IInterceptor>> interceptorsIndex = new UniqueKeyTreeMap<>("More than one interceptors use same priority [%s]");
    static List<IInterceptor> interceptors = new ArrayList<>();
    //省略部分代码
}

1.初始化代码追踪

ARouter.init(this);

进入ARouter.java

进入__ARouter.java

进入LogisticsCenter.java

``

public synchronized static void init(Context context, ThreadPoolExecutor tpe) throws HandlerException {
    mContext = context;
    executor = tpe;

  //省略部分代码
            Set<String> routerMap;

            // It will rebuild router map every times when debuggable.
            //如果是debug模式，或者是新版本，则更新，否则直接从sp中获取
            if (ARouter.debuggable() || PackageUtils.isNewVersion(context)) {
             		//关键代码1：获取“com.alibaba.android.arouter.routes”包名下的所有的class类名
             		//“com.alibaba.android.arouter.routes”即编译时生成的代码
                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 {
                routerMap = new HashSet<>(context.getSharedPreferences(AROUTER_SP_CACHE_KEY, Context.MODE_PRIVATE).getStringSet(AROUTER_SP_KEY_MAP, new HashSet<String>()));
            }

						//进行实例化，只针对Root，Interceptor，provider
            for (String className : routerMap) {
                //com.alibaba.android.arouter.routes$$.ARouter$$Root
                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);
                }
            }
				}
}

1.首先通过包名获取包名下的class类名

2.反射进行实例化后，跳用loadInto,进行数据加载，将数据保存到Warehouse.groupsIndex

``

/**
 * DO NOT EDIT THIS FILE!!! IT WAS GENERATED BY AROUTER. */
public class ARouter$$Root$$app implements IRouteRoot {
  @Override
  public void loadInto(Map<String, Class<? extends IRouteGroup>> routes) {
    routes.put("demo", ARouter$$Group$$demo.class);
    routes.put("uri", ARouter$$Group$$uri.class);
  }
}

END

跳转

ARouter.getInstance().build(RouteConstant.LOGIN)
        .withString(LoginActivity.KEY_PATH, postcard.getPath())
        .navigation();

1.build

``

/**
 * Build postcard by path and default group
 */
protected Postcard build(String path) {
    if (TextUtils.isEmpty(path)) {
        throw new HandlerException(Consts.TAG + "Parameter is invalid!");
    } else {
        PathReplaceService pService = ARouter.getInstance().navigation(PathReplaceService.class);
        if (null != pService) {
            path = pService.forString(path);
        }
        return build(path, extractGroup(path));
    }
}

如果有PathReplaceService，则进行路径替换。所以我们可以在项目中继承PathReplaceService来实现路径替换

``

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);
        }
        //关键代码 ：创建Postcard对象。Postcard对象中包含了跳转所需要的class对象，参数等必须元素，此处只是设置了Postcard的path和group，其他属性的设置在navigation中完成
        return new Postcard(path, group);
    }
}

2.navigation

Postcard.java

``

public Object navigation() {
    return navigation(null);
}
public Object navigation(Context context) {
        return navigation(context, null);
    }
 public Object navigation(Context context, NavigationCallback callback) {
        return ARouter.getInstance().navigation(context, this, -1, callback);
    }

ARouter.java

``

public Object navigation(Context mContext, Postcard postcard, int requestCode, NavigationCallback callback) {
    return _ARouter.getInstance().navigation(mContext, postcard, requestCode, callback);
}

_ARouter.java

``

protected Object navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback) {
		//预处理服务
    PretreatmentService pretreatmentService = ARouter.getInstance().navigation(PretreatmentService.class);
    if (null != pretreatmentService && !pretreatmentService.onPretreatment(context, postcard)) {
        // Pretreatment failed, navigation canceled.
        return null;
    }

    try {
      //关键代码，对postcard剩余字段进行赋值
        LogisticsCenter.completion(postcard);
    } catch (NoRouteFoundException ex) {
				//省略部分代码
        if (null != callback) {
            callback.onLost(postcard);
        } else {
            // No callback for this invoke, then we use the global degrade service.
          	//全局降级，即跳转失败时通过回调做一些处理
            DegradeService degradeService = ARouter.getInstance().navigation(DegradeService.class);
            if (null != degradeService) {
                degradeService.onLost(context, postcard);
            }
        }

        return null;
    }

    if (null != callback) {
        callback.onFound(postcard);
    }
		//greenChannel = true 时拦截器不工作，eg: fragment 的greenChannel 为true
    if (!postcard.isGreenChannel()) {   // It must be run in async thread, maybe interceptor cost too mush time made ANR.
        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);
                }

                logger.info(Consts.TAG, "Navigation failed, termination by interceptor : " + exception.getMessage());
            }
        });
    } else {
        return _navigation(context, postcard, requestCode, callback);
    }

    return null;
}

LogisiticsCenter.java

``

public synchronized static void completion(Postcard postcard) {
    if (null == postcard) {
        throw new NoRouteFoundException(TAG + "No postcard!");
    }

    RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath());
    if (null == routeMeta) {    // Maybe its does't exist, or didn't load.
        Class<? extends IRouteGroup> groupMeta = Warehouse.groupsIndex.get(postcard.getGroup());  // Load route meta.拿到group的class对象
        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 {
                 //省略代码
								/********************关键代码****************/
                //通过class对象进行初始化
                IRouteGroup iGroupInstance = groupMeta.getConstructor().newInstance();
              	//将要跳转的activity roteMeta数据加载到Warehouse.routes
                iGroupInstance.loadInto(Warehouse.routes);
                Warehouse.groupsIndex.remove(postcard.getGroup());
  							//省略代码
            } 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()) {
                    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;
        }
    }
}

``

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);
            }

            // Set Actions
            String action = postcard.getAction();
            if (!TextUtils.isEmpty(action)) {
                intent.setAction(action);
            }

            // Navigation in main looper.
            runInMainThread(new Runnable() {
                @Override
                public void run() {
                    startActivity(requestCode, currentContext, intent, postcard, callback);
                }
            });

            break;

					//省略其他case
    return null;
}

End