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Arouter源码分析之页面跳转

Arouter源码分析之页面跳转

作者: 风月寒 | 来源:发表于2020-10-16 10:11 被阅读0次
    ARouter.getInstance()
           .build("/main/LogoutActivity")
           .navigation();
    
    ARouter.getInstance()
    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;
            }
        }
    

    用双检测模式得到一个ARouter实例。

    ARouter # build()
    public Postcard build(String path) {
        return _ARouter.getInstance().build(path);
    }
    
    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));
            }
        }
        
        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);
            }
        }
    

    ARouter# build() 返回的是一个Postcard对象

    当前返回的Postcard对象携带 path和group两个路由地址数据

    Postcard # navigation()

    navigation()有多个构造方法,最终调的是

    public Object navigation(Context mContext, Postcard postcard, int requestCode, NavigationCallback callback) {
            return _ARouter.getInstance().navigation(mContext, postcard, requestCode, callback);
        }
        
     
    
    _ARouter # navigation()
    protected Object navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback) {
            PretreatmentService pretreatmentService = ARouter.getInstance().navigation(PretreatmentService.class);
            if (null != pretreatmentService && !pretreatmentService.onPretreatment(context, postcard)) {
                // Pretreatment failed, navigation canceled.
                return null;
            }
    
            try {
            // 分析1:
                LogisticsCenter.completion(postcard);
            } catch (NoRouteFoundException ex) {
                return null;
            }
    
            if (null != callback) {
                callback.onFound(postcard);
            }
    
            //针对Fragment或者Provider类型的 不会走拦截器的逻辑
            // 默认不是绿色通道
            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) {
                    // ---------> 分析2:
                        _navigation(context, postcard, requestCode, callback);
                    }
    
                    @Override
                    public void onInterrupt(Throwable exception) {
                        if (null != callback) {
                            callback.onInterrupt(postcard);
                        }
                    }
                });
            } else {
                //--------> 分析2:直接进行跳转了
                return _navigation(context, postcard, requestCode, callback);
            }
    
            return null;
        }
    
    LogisticsCenter.completion(postcard);
    public synchronized static void completion(Postcard postcard) {
            //校验 postcard
            if (null == postcard) {
                throw new NoRouteFoundException(TAG + "No postcard!");
            }
            
            // postcard.getPath() ----> "/main/login"
            // 从仓库的路由地址清单列表中拿到对应的RouteMeta
            RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath());
            // 如果获取到的为null,说明当前路由地址清单没有被加载
            if (null == routeMeta) {    
                // 根据一级地址,拿到对应的路由地址清单的文件类(ARouter$$Root$$工程名)
                Class<? extends IRouteGroup> groupMeta = Warehouse.groupsIndex.get(postcard.getGroup());  // Load route meta.
                // 如果获取到的当前路由地址清单文件类不存在。就抛出一个异常
                if (null == groupMeta) {
                    throw new NoRouteFoundException(TAG + "There is no route match the path [" + postcard.getPath() + "], in group [" + postcard.getGroup() + "]");
                } else {
                    try {
                        if (ARouter.debuggable()) {
                            logger.debug(TAG, String.format(Locale.getDefault(), "The group [%s] starts loading, trigger by [%s]", postcard.getGroup(), postcard.getPath()));
                        }
                        
                        // 通过反射拿到路由地址清单文件类
                        IRouteGroup iGroupInstance = groupMeta.getConstructor().newInstance();
                        // 调用loadInto(),传入Warehouse.routes,装载路由地址清单数据
                        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() + "]");
                    }
                    // 重新调用一下自己,
                    completion(postcard);   // Reload
                }
            } else {
            // 当从路由地址清单文件中找到当前路由地址对应的RouteMeta,就进行Postcard的数据填充。
                // routeMeta.getDestination() ------> 获取到的是 目标类的 Class对象
                postcard.setDestination(routeMeta.getDestination());
                // routeMeta.getType() ---> 目标类的类别 (Activity ,Fragment,Provider,Interceptor)
                postcard.setType(routeMeta.getType());
                //当前的优先级
                postcard.setPriority(routeMeta.getPriority());
                //携带的数据Bundle
                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()) {
                    // 是provider类型的目标类必须实现IProvider的接口
                    case PROVIDER:  
                        
                        //获取provider目标类的Class对象
                        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 {
                                //  通过反射拿到目标类的实例
                                provider = providerMeta.getConstructor().newInstance();
                                //执行初始化操作
                                provider.init(mContext);
                                // 存储 目标类的数据和目标类的实例的映射关系
                                Warehouse.providers.put(providerMeta, provider);
                                instance = provider;
                            } catch (Exception e) {
                                throw new HandlerException("Init provider failed! " + e.getMessage());
                            }
                        }
                        // 当是provider类型的时候,把获取到的目标类的实例设置到Postcard中,
                        postcard.setProvider(instance);
                        // 设置是绿色通道 ---> 所谓的绿色的通道就是不用去执行拦截器的逻辑
                        postcard.greenChannel();    
                        break;
                    case FRAGMENT:
                        //同样是fragment类别的 也是绿色通道的
                        postcard.greenChannel();    
                    default:
                        break;
                }
            }
        }
    
    _navigation()
    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()) {
                //如果是ACTIVITY类型
                case ACTIVITY:
                    // Build intent
                    // postcard.getDestination() ---> 获取到的是目标类
                    //进行Intent的拼装
                    final Intent intent = new Intent(currentContext, postcard.getDestination());
                    intent.putExtras(postcard.getExtras());
    
                    // 设置falg信息
                    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);
                    }
    
                    // 设置Action的信息
                    String action = postcard.getAction();
                    if (!TextUtils.isEmpty(action)) {
                        intent.setAction(action);
                    }
    
                    runInMainThread(new Runnable() {
                        @Override
                        public void run() {
                        // 因为正常的页面跳转 在跳转钱都会执行拦截器的操作,为拦截器的执行是在线程池中
                        // 对应的回调也运行在工作线程中
                        // 调用startActivity()方法,发起页面跳转的请求
                            startActivity(requestCode, currentContext, intent, postcard, callback);
                        }
                    });
    
                    break;
                case PROVIDER:
                // 是provider类型,就返回Provider实现子类的对象
                    return postcard.getProvider();
                case BOARDCAST:
                case CONTENT_PROVIDER:
                case FRAGMENT:
                    Class fragmentMeta = postcard.getDestination();
                    try {
                        Object instance = fragmentMeta.getConstructor().newInstance();
                        //如果手Fragment类型
                        // 把要传递到Fragment中的数据 设置给当前的Fragmenrt
                        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;
        }
    

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