在前面中我們對(duì)ARouter的頁(yè)面跳轉(zhuǎn)功能的使用有了基本的了解，由于篇幅的原因沒(méi)有對(duì)跳轉(zhuǎn)的源碼進(jìn)行分析，今天我們就來(lái)探究一下頁(yè)面的跳轉(zhuǎn)過(guò)程。在看這篇文章之前建議小伙伴們先看下面鏈接給出的文章好有個(gè)整體的了解。
ARouter解析一：基本使用及頁(yè)面注冊(cè)源碼解析
整個(gè)流程示意圖如下，接下來(lái)我們會(huì)對(duì)著這個(gè)示意圖開始開車。
1.獲取ARouter實(shí)例
我們先從簡(jiǎn)單的說(shuō)起，不帶參數(shù)的頁(yè)面跳轉(zhuǎn)，一行代碼實(shí)現(xiàn)。
ARouter.getInstance().build("/test/activity2").navigation();
用戶基本需要打交道的接口都在ARouter中，該類使用的是單例模式。使用這個(gè)框架的前提就是需要初始化Router，否則會(huì)報(bào)錯(cuò)。
調(diào)用
ARouter.init(getApplication());進(jìn)行初始化。單例模式是典型寫法，有兩個(gè)if判斷，第一個(gè)判斷沒(méi)什么可說(shuō)的，之后synchronized上鎖，再進(jìn)行判斷是否null，這個(gè)主要是為了多線程環(huán)境保護(hù)。
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;
}
}
2.構(gòu)造路由信息的容器Postcard
得到ARouter實(shí)例后調(diào)用build方法，傳入目標(biāo)頁(yè)面的path("/test/activity2")，我們來(lái)看看build的源碼。這里使用的是代理模式，其實(shí)是調(diào)用_ARouter的build方法，這里需要提的一點(diǎn)是ARouter.init也是調(diào)用的_ARouter的init方法，里面主要是做一些映射文件的加載工作。
public Postcard build(String path) {
return _ARouter.getInstance().build(path);
}
接著往下看，來(lái)到_ARouter的build方法,注意路徑不能為空，也就是目標(biāo)頁(yè)面必須要有注解@Route(path = "/test/activity2")。然后會(huì)返回一個(gè)Postcard，官方解釋A container that contains the roadmap.這是個(gè)路由信息的存儲(chǔ)器，里面包含頁(yè)面跳轉(zhuǎn)的所有信息。
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);
}
}
在new Postcard(path, group)中，第一個(gè)參數(shù)就是路徑，第二個(gè)參數(shù)是組別信息。那我們的栗子path = "/test/activity2來(lái)說(shuō)test就是group。這里就需要提下，ARouter框架是分組管理，按需加載。提起來(lái)很高深的樣子呢！其實(shí)解釋起來(lái)就是，在編譯期框架掃描了所有的注冊(cè)頁(yè)面／服務(wù)／字段／攔截器等，那么很明顯運(yùn)行期不可能一股腦全部加載進(jìn)來(lái)，這樣就太不和諧了。所以就分組來(lái)管理，ARouter在初始化的時(shí)候只會(huì)一次性地加載所有的root結(jié)點(diǎn)，而不會(huì)加載任何一個(gè)Group結(jié)點(diǎn)，這樣就會(huì)極大地降低初始化時(shí)加載結(jié)點(diǎn)的數(shù)量。比如某些Activity分成一組，組名就叫test，然后在第一次需要加載組內(nèi)的某個(gè)頁(yè)面時(shí)再將test這個(gè)組加載進(jìn)來(lái)。
3.路由信息完善與跳轉(zhuǎn)
ok，我們言歸正傳，就下來(lái)就是一行代碼的最后一個(gè)方法navigation。這里其實(shí)是postcard的navigation方法。
ARouter.getInstance().build("/test/activity2").navigation();
最后會(huì)來(lái)到_ARouter的navigation方法，方法比較長(zhǎng)，為了更好的說(shuō)清今天的主題我做了點(diǎn)手腳刪掉一些，不要打我:)我們分成幾個(gè)步驟，第二個(gè)回調(diào)的步驟沒(méi)什么可說(shuō)的，接下來(lái)詳細(xì)解釋下第一和第三步。
1.首先調(diào)用LogisticsCenter.completion完成postcard的補(bǔ)充，這個(gè)詳見后面解析。
2.然后如果有回調(diào)函數(shù)就進(jìn)行回調(diào)。
3.如果需要攔截，就進(jìn)行攔截器的處理，否則就調(diào)用_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 (null != callback) {//如果有回調(diào)就進(jìn)行回調(diào)
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()) { //如果需要攔截
……
} else {//不需要攔截
return _navigation(context, postcard, requestCode, callback);
}
return null;
}
3.1.路由信息完善
postcard我們前面說(shuō)過(guò)是所有路由信息的容器，那么到目前為止我們的postcard中只有path和group的信息，目標(biāo)頁(yè)面是什么還不知道，是不是我吹牛了？別急，LogisticsCenter.completion就是干這個(gè)活的，用來(lái)補(bǔ)充postcard信息的。我們看下源碼，也是比較長(zhǎng)。嘿嘿你猜錯(cuò)了，這個(gè)我就不再做刪減，原生的，我們一步步來(lái)看。
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.
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);
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 {
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 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<? 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;
}
}
}
倉(cāng)庫(kù)查找頁(yè)面結(jié)點(diǎn)
首先根據(jù)路徑信息到Warehouse倉(cāng)庫(kù)中查找路由節(jié)點(diǎn)信息，其實(shí)就是幾個(gè)Map，包含有根節(jié)點(diǎn)／攔截器和組別等。
RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath());
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<>();
}
一開始肯定是沒(méi)有這個(gè)節(jié)點(diǎn)信息的，所以需要到Warehouse.groupsIndex中找到組別的信息，這里就是test.
Class<? extends IRouteGroup> groupMeta = Warehouse.groupsIndex.get(postcard.getGroup()); // Load route meta.
然后通過(guò)反射加載這一組類別的映射關(guān)系，就是前面提到的按需加載。然后從倉(cāng)庫(kù)中刪除這個(gè)組別信息節(jié)點(diǎn)，防止重復(fù)加載?？梢钥匆娋幾g期間已經(jīng)組成了RouteMeta這個(gè)結(jié)點(diǎn)信息，包含有目標(biāo)頁(yè)面，類型，路徑，組別，參數(shù)，優(yōu)先級(jí)等信息。
IRouteGroup iGroupInstance = groupMeta.getConstructor().newInstance();
iGroupInstance.loadInto(Warehouse.routes);
Warehouse.groupsIndex.remove(postcard.getGroup());
我們?cè)倏聪律傻挠成潢P(guān)系文件ARouter$$Group$$test長(zhǎng)什么樣.
接下來(lái)會(huì)遞歸調(diào)用completion(postcard)，現(xiàn)在routeMeta就不為空了，會(huì)走到else中，首先給postcard補(bǔ)充信息，有了這些信息postcard就可以愉快的工作了。我們這個(gè)栗子中type很明顯是activity，所以就走到default中break出來(lái)了。
3.2. _navigation跳轉(zhuǎn)
繞了一大圈終于要進(jìn)行跳轉(zhuǎn)了aaa！我們來(lái)看下怎么跳轉(zhuǎn)的，可以先猜下，無(wú)法也是startActivity，orz。來(lái)到ACTIVITY分支，從postcard中拿到目標(biāo)頁(yè)面Test2Activity.class然后組成intent，然后putExtras，如果是startActivityForResult,這里面就有參數(shù)。如果context不是activity，那么就需要另起一個(gè)棧Intent.FLAG_ACTIVITY_NEW_TASK進(jìn)行activity的展示。接下來(lái)通過(guò)handler發(fā)送啟動(dòng)activity的任務(wù)。終于找到了熟悉的ActivityCompat.startActivity和ActivityCompat.startActivityForResult，真是淚流滿面。后面就順理成章了。
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;
}
4.總結(jié)
頁(yè)面跳轉(zhuǎn)的源碼基本就是這些內(nèi)容了，分享內(nèi)容只是以頁(yè)面跳轉(zhuǎn)不帶參數(shù)為栗子，其實(shí)帶參數(shù)和頁(yè)面跳轉(zhuǎn)動(dòng)畫設(shè)置都是一樣的，信息都在postcard中，在LogisticsCenter.completion進(jìn)行構(gòu)造，依此類推?？梢钥闯稣麄€(gè)框架分層仔細(xì)，各個(gè)層之間分工明確。與編譯期間映射關(guān)系打交道的工作都下層到LogisticsCenter，與用戶打交道的API都在ARouter中。學(xué)習(xí)一個(gè)框架最好也可以學(xué)習(xí)下設(shè)計(jì)方法，提升內(nèi)功。
后面當(dāng)然還有解析三，會(huì)分享下url跳轉(zhuǎn)的使用和源碼分析等內(nèi)容，歡迎關(guān)注哦。
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