原理
ARouter在编译期的时候，利用自定义注解完成了自动注册。
ARouter的编译
通过RouteProcessor。
process()
process()方法相当于处理器的主函数main()，可以在这个方法中扫描、评估和处理注解的代码，以及生成Java文件。
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// 判断被注解了的元素集合是否为空
if (CollectionUtils.isNotEmpty(annotations)) {
// 获取所有被@Route注解的元素集合，元素可以是类、方法、变量等
Set<? extends Element> routeElements = roundEnv.getElementsAnnotatedWith(Route.class);
try {
logger.info(">>> Found routes, start... <<<");
this.parseRoutes(routeElements);
} catch (Exception e) {
logger.error(e);
}
return true;
}
return false;
}然后进入parseRoutes()。
parseRoutes()
if (CollectionUtils.isNotEmpty(routeElements)) {
// Perpare the type an so on.
logger.info(">>> Found routes, size is " + routeElements.size() + " <<<");
rootMap.clear();
// TypeElement表示一个类或接口元素
TypeMirror type_Activity = elements.getTypeElement(ACTIVITY).asType();
TypeMirror type_Service = elements.getTypeElement(SERVICE).asType();
TypeMirror fragmentTm = elements.getTypeElement(FRAGMENT).asType();
TypeMirror fragmentTmV4 = elements.getTypeElement(Consts.FRAGMENT_V4).asType();
// Interface of ARouter
TypeElement type_IRouteGroup = elements.getTypeElement(IROUTE_GROUP);
TypeElement type_IProviderGroup = elements.getTypeElement(IPROVIDER_GROUP);
// 获取RouteMeta和RouteType的类信息
ClassName routeMetaCn = ClassName.get(RouteMeta.class);
ClassName routeTypeCn = ClassName.get(RouteType.class);
/*
Build input type, format as :
```Map<String, Class<? extends IRouteGroup>>```
*/
// 得到对应的参数类型, 如Map<String, Class<? extends IRouteGroup>>
ParameterizedTypeName inputMapTypeOfRoot = ParameterizedTypeName.get(
ClassName.get(Map.class),
ClassName.get(String.class),
ParameterizedTypeName.get(
ClassName.get(Class.class),
WildcardTypeName.subtypeOf(ClassName.get(type_IRouteGroup))
)
);
/*
```Map<String, RouteMeta>```
*/
// 得到对应的参数类型, 如Map<String, RouteMeta>
ParameterizedTypeName inputMapTypeOfGroup = ParameterizedTypeName.get(
ClassName.get(Map.class),
ClassName.get(String.class),
ClassName.get(RouteMeta.class)
);
/*
Build input param name.
*/
// 创建输入参数名
ParameterSpec rootParamSpec = ParameterSpec.builder(inputMapTypeOfRoot, "routes").build();
ParameterSpec groupParamSpec = ParameterSpec.builder(inputMapTypeOfGroup, "atlas").build();
ParameterSpec providerParamSpec = ParameterSpec.builder(inputMapTypeOfGroup, "providers").build(); // Ps. its param type same as groupParamSpec!
/*
Build method : 'loadInto'
*/
// 创建ARouter$$Root$$xxx类中的loadInto()方法
MethodSpec.Builder loadIntoMethodOfRootBuilder = MethodSpec.methodBuilder(METHOD_LOAD_INTO)
.addAnnotation(Override.class)
.addModifiers(PUBLIC)
.addParameter(rootParamSpec);
// Follow a sequence, find out metas of group first, generate java file, then statistics them as root.
// 按顺序，先找到group的信息，生成Java文件
for (Element element : routeElements) {
TypeMirror tm = element.asType();
Route route = element.getAnnotation(Route.class);
RouteMeta routeMeta = null;
if (types.isSubtype(tm, type_Activity)) { // Activity
// 如果是Activity
logger.info(">>> Found activity route: " + tm.toString() + " <<<");
// Get all fields annotation by @Autowired
// 找到所有注解为@Autowired的成员变量
Map<String, Integer> paramsType = new HashMap<>();
for (Element field : element.getEnclosedElements()) {
if (field.getKind().isField() && field.getAnnotation(Autowired.class) != null && !types.isSubtype(field.asType(), iProvider)) {
// It must be field, then it has annotation, but it not be provider.
Autowired paramConfig = field.getAnnotation(Autowired.class);
paramsType.put(StringUtils.isEmpty(paramConfig.name()) ? field.getSimpleName().toString() : paramConfig.name(), typeUtils.typeExchange(field));
}
}
// 生成一个对应的RouteMeta，以下也是类似的
routeMeta = new RouteMeta(route, element, RouteType.ACTIVITY, paramsType);
} else if (types.isSubtype(tm, iProvider)) { // IProvider
// 如果是Provider
logger.info(">>> Found provider route: " + tm.toString() + " <<<");
routeMeta = new RouteMeta(route, element, RouteType.PROVIDER, null);
} else if (types.isSubtype(tm, type_Service)) { // Service
// 如果是Service
logger.info(">>> Found service route: " + tm.toString() + " <<<");
routeMeta = new RouteMeta(route, element, RouteType.parse(SERVICE), null);
} else if (types.isSubtype(tm, fragmentTm) || types.isSubtype(tm, fragmentTmV4)) {
// 如果是Fragment
logger.info(">>> Found fragment route: " + tm.toString() + " <<<");
routeMeta = new RouteMeta(route, element, RouteType.parse(FRAGMENT), null);
} else {
// 如果都不是，抛出异常
throw new RuntimeException("ARouter::Compiler >>> Found unsupported class type, type = [" + types.toString() + "].");
}
// 对RouteMeta进行分类，categories()可以跳到后文去查看
categories(routeMeta);
// if (StringUtils.isEmpty(moduleName)) { // Hasn't generate the module name.
// moduleName = ModuleUtils.generateModuleName(element, logger);
// }
}
// 创建ARouter$$Providers$$xxx类中的loadInto()方法
MethodSpec.Builder loadIntoMethodOfProviderBuilder = MethodSpec.methodBuilder(METHOD_LOAD_INTO)
.addAnnotation(Override.class)
.addModifiers(PUBLIC)
.addParameter(providerParamSpec);
// Start generate java source, structure is divided into upper and lower levels, used for demand initialization.
// 开始生成Java源文件
for (Map.Entry<String, Set<RouteMeta>> entry : groupMap.entrySet()) {
String groupName = entry.getKey();
// 创建ARouter$$Group$$xxx类中的loadInto()方法
MethodSpec.Builder loadIntoMethodOfGroupBuilder = MethodSpec.methodBuilder(METHOD_LOAD_INTO)
.addAnnotation(Override.class)
.addModifiers(PUBLIC)
.addParameter(groupParamSpec);
// Build group method body
// 创建方法体
Set<RouteMeta> groupData = entry.getValue();
for (RouteMeta routeMeta : groupData) {
switch (routeMeta.getType()) {
// 如果节点类型是Provider，
case PROVIDER: // Need cache provider's super class
List<? extends TypeMirror> interfaces = ((TypeElement) routeMeta.getRawType()).getInterfaces();
for (TypeMirror tm : interfaces) {
if (types.isSameType(tm, iProvider)) { // Its implements iProvider interface himself.
// This interface extend the IProvider, so it can be used for mark provider
// 如果就是iProvider
loadIntoMethodOfProviderBuilder.addStatement(
"providers.put($S, $T.build($T." + routeMeta.getType() + ", $T.class, $S, $S, null, " + routeMeta.getPriority() + ", " + routeMeta.getExtra() + "))",
(routeMeta.getRawType()).toString(),
routeMetaCn,
routeTypeCn,
ClassName.get((TypeElement) routeMeta.getRawType()),
routeMeta.getPath(),
routeMeta.getGroup());
} else if (types.isSubtype(tm, iProvider)) {
// This interface extend the IProvider, so it can be used for mark provider
// 如果是iProvider的实现类
loadIntoMethodOfProviderBuilder.addStatement(
"providers.put($S, $T.build($T." + routeMeta.getType() + ", $T.class, $S, $S, null, " + routeMeta.getPriority() + ", " + routeMeta.getExtra() + "))",
tm.toString(), // So stupid, will duplicate only save class name.
routeMetaCn,
routeTypeCn,
ClassName.get((TypeElement) routeMeta.getRawType()),
routeMeta.getPath(),
routeMeta.getGroup());
}
}
break;
default:
break;
}
// Make map body for paramsType
// 获取RouteMeta中被@Autowired注解的属性集合，用字符串拼接
StringBuilder mapBodyBuilder = new StringBuilder();
Map<String, Integer> paramsType = routeMeta.getParamsType();
if (MapUtils.isNotEmpty(paramsType)) {
for (Map.Entry<String, Integer> types : paramsType.entrySet()) {
mapBodyBuilder.append("put(\"").append(types.getKey()).append("\", ").append(types.getValue()).append("); ");
}
}
String mapBody = mapBodyBuilder.toString();
// 向ARouter$$Group$$xxx类中的loadInto()添加方法体
loadIntoMethodOfGroupBuilder.addStatement(
"atlas.put($S, $T.build($T." + routeMeta.getType() + ", $T.class, $S, $S, " + (StringUtils.isEmpty(mapBody) ? null : ("new java.util.HashMap<String, Integer>(){{" + mapBodyBuilder.toString() + "}}")) + ", " + routeMeta.getPriority() + ", " + routeMeta.getExtra() + "))",
routeMeta.getPath(),
routeMetaCn,
routeTypeCn,
ClassName.get((TypeElement) routeMeta.getRawType()),
routeMeta.getPath().toLowerCase(),
routeMeta.getGroup().toLowerCase());
}
// Generate groups
// 最终生成ARouter$$Group$$XXX的Java文件
String groupFileName = NAME_OF_GROUP + groupName;
JavaFile.builder(PACKAGE_OF_GENERATE_FILE,
TypeSpec.classBuilder(groupFileName)
.addJavadoc(WARNING_TIPS)
.addSuperinterface(ClassName.get(type_IRouteGroup))
.addModifiers(PUBLIC)
.addMethod(loadIntoMethodOfGroupBuilder.build())
.build()
).build().writeTo(mFiler);
logger.info(">>> Generated group: " + groupName + "<<<");
// 将生成的组文件放在rootmap集合中去，为下面生成ARouter$$Root$$xxx文件做准备
rootMap.put(groupName, groupFileName);
}
if (MapUtils.isNotEmpty(rootMap)) {
// Generate root meta by group name, it must be generated before root, then I can find out the class of group.
// 遍历rootMap集合，向ARouter$$Root$$xxx的`loadInto()`添加方法体
for (Map.Entry<String, String> entry : rootMap.entrySet()) {
loadIntoMethodOfRootBuilder.addStatement("routes.put($S, $T.class)", entry.getKey(), ClassName.get(PACKAGE_OF_GENERATE_FILE, entry.getValue()));
}
}
// Wirte provider into disk
// 生成ARouter$$Providers$$xxx文件
String providerMapFileName = NAME_OF_PROVIDER + SEPARATOR + moduleName;
JavaFile.builder(PACKAGE_OF_GENERATE_FILE,
TypeSpec.classBuilder(providerMapFileName)
.addJavadoc(WARNING_TIPS)
.addSuperinterface(ClassName.get(type_IProviderGroup))
.addModifiers(PUBLIC)
.addMethod(loadIntoMethodOfProviderBuilder.build())
.build()
).build().writeTo(mFiler);
logger.info(">>> Generated provider map, name is " + providerMapFileName + " <<<");
// Write root meta into disk.
// 生成ARouter$$Root$$xxx文件
String rootFileName = NAME_OF_ROOT + SEPARATOR + moduleName;
JavaFile.builder(PACKAGE_OF_GENERATE_FILE,
TypeSpec.classBuilder(rootFileName)
.addJavadoc(WARNING_TIPS)
.addSuperinterface(ClassName.get(elements.getTypeElement(ITROUTE_ROOT)))
.addModifiers(PUBLIC)
.addMethod(loadIntoMethodOfRootBuilder.build())
.build()
).build().writeTo(mFiler);
logger.info(">>> Generated root, name is " + rootFileName + " <<<");
}
}
编译过后，我们发现会根据以上过程生成的文件：
再看一下生成文件中的内容：
public class ARouter$$Group$$service implements IRouteGroup {
@Override
public void loadInto(Map<String, RouteMeta> atlas) {
atlas.put("/service/json", RouteMeta.build(RouteType.PROVIDER, JsonServiceImpl.class, "/service/json", "service", null, -1, -2147483648));
}
}
public class ARouter$$Group$$tsnt implements IRouteGroup {
@Override
public void loadInto(Map<String, RouteMeta> atlas) {
atlas.put("/tsnt/aroutertest2", RouteMeta.build(RouteType.ACTIVITY, ARouterTest2Activity.class, "/tsnt/aroutertest2", "tsnt", new java.util.HashMap<String, Integer>(){{put("hometown", 8); put("person", 10); put("name", 8); put("age", 3); }}, -1, -2147483648));
atlas.put("/tsnt/aroutertest3", RouteMeta.build(RouteType.ACTIVITY, ARouterTest3Activity.class, "/tsnt/aroutertest3", "tsnt", null, -1, -2147483648));
}
}
public class ARouter$$Providers$$app implements IProviderGroup {
@Override
public void loadInto(Map<String, RouteMeta> providers) {
providers.put("com.alibaba.android.arouter.facade.service.SerializationService", RouteMeta.build(RouteType.PROVIDER, JsonServiceImpl.class, "/service/json", "service", null, -1, -2147483648));
}
}
public class ARouter$$Root$$app implements IRouteRoot {
@Override
public void loadInto(Map<String, Class<? extends IRouteGroup>> routes) {
routes.put("service", ARouter$$Group$$service.class);
routes.put("tsnt", ARouter$$Group$$tsnt.class);
}
}确实就是根据parseRoutes()生成的。
categories()
/**
* Sort metas in group.
*
* @param routeMete metas.
*/
private void categories(RouteMeta routeMete) {
// 验证RouteMeta的正确性
if (routeVerify(routeMete)) {
logger.info(">>> Start categories, group = " + routeMete.getGroup() + ", path = " + routeMete.getPath() + " <<<");
// 从groupMap中获取对应的RouteMeta集合
Set<RouteMeta> routeMetas = groupMap.get(routeMete.getGroup());
if (CollectionUtils.isEmpty(routeMetas)) {
// 如果没有对应的RouteMeta集合，创建一个新的集合
Set<RouteMeta> routeMetaSet = new TreeSet<>(new Comparator<RouteMeta>() {
@Override
public int compare(RouteMeta r1, RouteMeta r2) {
try {
return r1.getPath().compareTo(r2.getPath());
} catch (NullPointerException npe) {
logger.error(npe.getMessage());
return 0;
}
}
});
// 将RouteMeta加入RouteMeta集合
routeMetaSet.add(routeMete);
// 将RouteMeta集合加入groupMap
groupMap.put(routeMete.getGroup(), routeMetaSet);
} else {
routeMetas.add(routeMete);
}
} else {
logger.warning(">>> Route meta verify error, group is " + routeMete.getGroup() + " <<<");
}
}
/**
* Verify the route meta
*
* @param meta raw meta
*/
private boolean routeVerify(RouteMeta meta) {
// 获取对应的path参数
String path = meta.getPath();
if (StringUtils.isEmpty(path) || !path.startsWith("/")) { // The path must be start with '/' and not empty!
// 如果为空或者不以"/"开头，返回false
return false;
}
if (StringUtils.isEmpty(meta.getGroup())) { // Use default group(the first word in path)
// 如果没有设置对应的group, 从path中获取第一段路径作为group
// 例如：path是"/x/y/z"，group就是"z"
try {
String defaultGroup = path.substring(1, path.indexOf("/", 1));
if (StringUtils.isEmpty(defaultGroup)) {
return false;
}
meta.setGroup(defaultGroup);
return true;
} catch (Exception e) {
logger.error("Failed to extract default group! " + e.getMessage());
return false;
}
}
return true;
}ARouter的初始化
经过编译后，生成了相应的映射文件，ARouter的初始化会将这些文件加载到内存中去，形成一个路由表，以供后面路由查找跳转之用。
init()
/**
* Init, it must be call before used router.
*/
public static void init(Application application) {
if (!hasInit) {
// 没被初始化，就去初始化
logger = _ARouter.logger;
_ARouter.logger.info(Consts.TAG, "ARouter init start.");
hasInit = _ARouter.init(application);
if (hasInit) {
_ARouter.afterInit();
}
_ARouter.logger.info(Consts.TAG, "ARouter init over.");
}
}实际调用_ARouter的init()：
protected static synchronized boolean init(Application application) {
mContext = application;
LogisticsCenter.init(mContext, executor);
logger.info(Consts.TAG, "ARouter init success!");
hasInit = true;
// It's not a good idea.
// if (Build.VERSION.SDK_INT > Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
// application.registerActivityLifecycleCallbacks(new AutowiredLifecycleCallback());
// }
return true;
}其中关键的一句是LogisticsCenter.init(mContext, executor);：
public synchronized static void init(Context context, ThreadPoolExecutor tpe) throws HandlerException {
mContext = context;
executor = tpe;
try {
long startInit = System.currentTimeMillis();
Set<String> routerMap;
// It will rebuild router map every times when debuggable.
if (ARouter.debuggable() || PackageUtils.isNewVersion(context)) {
// 如果是可测试的，或者是App的新版本，才会去生成新的路由表
logger.info(TAG, "Run with debug mode or new install, rebuild router map.");
// These class was generate by arouter-compiler.
// 查找"com.alibaba.android.arouter.routes"包下的类，就是编译之后ARouter生成的文件
routerMap = ClassUtils.getFileNameByPackageName(mContext, ROUTE_ROOT_PAKCAGE);
if (!routerMap.isEmpty()) {
// 如果不为空，存入sp
context.getSharedPreferences(AROUTER_SP_CACHE_KEY, Context.MODE_PRIVATE).edit().putStringSet(AROUTER_SP_KEY_MAP, routerMap).apply();
}
} else {
logger.info(TAG, "Load router map from cache.");
// 从sp中取
routerMap = new HashSet<>(context.getSharedPreferences(AROUTER_SP_CACHE_KEY, Context.MODE_PRIVATE).getStringSet(AROUTER_SP_KEY_MAP, new HashSet<String>()));
}
logger.info(TAG, "Find router map finished, map size = " + routerMap.size() + ", cost " + (System.currentTimeMillis() - startInit) + " ms.");
startInit = System.currentTimeMillis();
for (String className : routerMap) {
if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_ROOT)) {
// This one of root elements, load root.
// 类名以“com.alibaba.android.arouter.routes.ARouter$$Root”开头，通过反射实例化，并且调用loadInto()，目的将编译生成的ARouter$$Group$$xxx文件加载到内存中，保存在Warehouse.groupsIndex；
((IRouteRoot) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.groupsIndex);
} else if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_INTERCEPTORS)) {
// Load interceptorMeta
// 类名以“com.alibaba.android.arouter.routes.ARouter$$Interceptors”开头，执行编译生成的ARouter$$Interceptors$$xxx的loadInto()，将自定义拦截器类存放在Warehouse.interceptorsIndex中
((IInterceptorGroup) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.interceptorsIndex);
} else if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_PROVIDERS)) {
// Load providerIndex
// 类名以“com.alibaba.android.arouter.routes.ARouter$$Providers”开头，执行编译生成的ARouter$$Providers$$xxx的loadInto()，将自定义iProvider存放在Warehouse.providersIndex中
((IProviderGroup) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.providersIndex);
}
}
logger.info(TAG, "Load root element finished, cost " + (System.currentTimeMillis() - startInit) + " ms.");
if (Warehouse.groupsIndex.size() == 0) {
logger.error(TAG, "No mapping files were found, check your configuration please!");
}
if (ARouter.debuggable()) {
logger.debug(TAG, String.format(Locale.getDefault(), "LogisticsCenter has already been loaded, GroupIndex[%d], InterceptorIndex[%d], ProviderIndex[%d]", Warehouse.groupsIndex.size(), Warehouse.interceptorsIndex.size(), Warehouse.providersIndex.size()));
}
} catch (Exception e) {
throw new HandlerException(TAG + "ARouter init logistics center exception! [" + e.getMessage() + "]");
}
}总结下来，其实ARouter 的初始化只做了一件事，找到自己编译期产生的清单文件，把 Group 、Interceptor 、Provider 三种清单加载到 Warehouse 内存仓库中。
ARouter的使用
给出官网的示例：
// 1. Simple jump within application (Jump via URL in 'Advanced usage')
ARouter.getInstance().build("/test/activity").navigation();
// 2. Jump with parameters
ARouter.getInstance().build("/test/1")
.withLong("key1", 666L)
.withString("key3", "888")
.withObject("key4", new Test("Jack", "Rose"))
.navigation();ARouter路由跳转采用链式调用，ARouter.getInstance()其中采用的单例模式，获取ARouter的实例。
build()
public Postcard build(String path) {
return _ARouter.getInstance().build(path);
}最终调用一个重载的方法：
/**
* Build postcard by path and group
*/
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);
}
}最后返回一个Postcard实例对象，继承自之前提到过的的RouteMeta，封装了路径，分组等节点信息：
public final class Postcard extends RouteMeta {
// Base
private Uri uri;
private Object tag; // A tag prepare for some thing wrong.
private Bundle mBundle; // Data to transform
private int flags = -1; // Flags of route
private int timeout = 300; // Navigation timeout, TimeUnit.Second
private IProvider provider; // It will be set value, if this postcard was provider.
private boolean greenChannel;
private SerializationService serializationService;
// Animation
private Bundle optionsCompat; // The transition animation of activity
private int enterAnim;
private int exitAnim;
……
}其实build()方法的目的只有一个就是根据路由，封装成Postcard对象，这个对象贯穿之后整个路由过程。
navigation()
以下是Postcard的navigation()：
/**
* Navigation to the route with path in postcard.
* No param, will be use application context.
*/
public Object navigation() {
return navigation(null);
}最终调用了_ARouter的navigation()：
protected Object navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback) {
try {
// 补充postcard具体信息，后文会具体分析
LogisticsCenter.completion(postcard);
} catch (NoRouteFoundException ex) {
logger.warning(Consts.TAG, ex.getMessage());
if (debuggable()) { // Show friendly tips for user.
Toast.makeText(mContext, "There's no route matched!\n" +
" Path = [" + postcard.getPath() + "]\n" +
" Group = [" + postcard.getGroup() + "]", Toast.LENGTH_LONG).show();
}
if (null != callback) {
// 如果处理postcard失败，通过callback回调失败结果
callback.onLost(postcard);
} else { // No callback for this invoke, then we use the global degrade service.
// callback为空的情况下，如果有定义全局的降级处理（DegradeService），则使用全局处理
// 降级处理也需要我们自己实现DegradeService接口
DegradeService degradeService = ARouter.getInstance().navigation(DegradeService.class);
if (null != degradeService) {
degradeService.onLost(context, postcard);
}
}
return null;
}
// 路由处理成功，回调callback.onFound()
if (null != callback) {
callback.onFound(postcard);
}
if (!postcard.isGreenChannel()) { // It must be run in async thread, maybe interceptor cost too mush time made ANR.
// 如果不走绿色通道，需要经过拦截器拦截
interceptorService.doInterceptions(postcard, new InterceptorCallback() {
/**
* Continue process
*
* @param postcard route meta
*/
@Override
public void onContinue(Postcard postcard) {
_navigation(context, postcard, requestCode, callback);
}
/**
* Interrupt process, pipeline will be destory when this method called.
*
* @param exception Reson of interrupt.
*/
@Override
public void onInterrupt(Throwable exception) {
if (null != callback) {
callback.onInterrupt(postcard);
}
logger.info(Consts.TAG, "Navigation failed, termination by interceptor : " + exception.getMessage());
}
});
} else {
// 最终调用_navigation()完成路由跳转
return _navigation(context, postcard, requestCode, callback);
}
return null;
}进入_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()) {
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;
}以上很好理解，根据各种不同的type，获取对应的实例或者完成页面跳转。
completion()
然而我们根据Postcard中的信息，如何跳转到对应的页面或者获取对应的实例的呢？
_ARouter的navigation()中有LogisticsCenter.completion(postcard);这样一段代码，它的作用是将信息不完整的Postcard填充完整：
/**
* Completion the postcard by route metas
*
* @param postcard Incomplete postcard, should completion by this method.
*/
public synchronized static void completion(Postcard postcard) {
if (null == postcard) {
throw new NoRouteFoundException(TAG + "No postcard!");
}
// 查找Warehouse仓库的RouteMeta是否已在缓存中
RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath());
if (null == routeMeta) { // Maybe its does't exist, or didn't load.
// 如果不存在，查找仓库的组别清单中是否存在该RouteMeta对应的组别，组别清单已经在初始化的时候加载到仓库中去了
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()));
}
// 实例化该组别的类，调用loadInto()，将组别中所有的路由节点加载进仓库Warehouse.routes，缓存
IRouteGroup iGroupInstance = groupMeta.getConstructor().newInstance();
iGroupInstance.loadInto(Warehouse.routes);
// 从组别清单中删除已加载的组别，防止重复加载
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() + "]");
}
// 当路由节点加载到缓存中去后，重新查找执行else代码，对postcard进行处理
completion(postcard); // Reload
}
} else {
// 给postcard设置destination，type，priority等值，供上面讲解到的_navigation()进行使用
// 其中routeMeta是在ARouter$$Group$$xxx的loadInto中创建的
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.
// 如果通过build(Uri url)进行跳转的话通过解析url，将传参保存进bundle中
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 be implememt IProvider
// 如果是PROVIDER节点类型，从服务节点列表中获取，如果没有，则实例化，并保存在服务节点列表Warehouse.providers中
// 并将实例化的对象设置给postcard的provider属性
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;
}
}
}