首先我们都知道 ARouter是以路由的方式实现组件间（组件化项目）通讯的的框架。
路由的本质，是映射和寻址，收集所有的注册类，生成字符串和注册类的映射关系，这样就可以通过字符串找到对应的类.
解决的问题，没有依赖关系的两个模块，不能直接交互，路由提供了仓库，可以通过字符串找到注入仓库的类，解决类模块间交互的问题（组件间通讯）
如何分组和构建路由表的呢？
一.从使用说起
-
我们按照文档使用ARouter 的时候注意到， 使用@Route注解的模块，需要在modeule 的build.gradle里添加：
defaultConfig { javaCompileOptions { annotationProcessorOptions { arguments = [AROUTER_MODULE_NAME: project.getName()] } } }
没有这段代码会在build项目时爆错：
These no module name, at 'build.gradle', like : ...
-
必须在每个使用@Route 注解的模块里都引入ARouter的注解处理器，否则这个模块里注解不会被处理
annotationProcessor 'com.alibaba:arouter-compiler:1.5.2' -
@Route 注解的path 至少需要有两级
@Route(path = "/test/activity") public class YourActivity extend Activity { ... }否则toast提示：“There's no route matched! Path = [/xxx/xxx] Group = [xxxx]”
编译生成的类：
root类
Root类
24938213e1e7af99c8fa3aa0.png
group类
24938213ebe75c033fba54dc.png
* ARouter$Root$$xxx(modulename) 把所有的组(ARouter$Group$xxx) put到Map集合里（routers）
* ARouter$Group$$xxx(groupname) 把一个分组下的所有路径(RouteMeta)存入map
* ARouter$Providers$$xxx(modulename) 把注册的接口存入map
二.ARouter 注解处理器:RouteProcessor
有注解就有注解处理器，ARouter也是基于APT，构建路由表的逻辑就在RouteProcessor，也是在RouteProcessor里生成了上面的那些类
APT 和 javapoat 有同学分享过，这也是APT 和 javapoat的一次应用
-
BaseProcessor
RouteProcessor 继承了 BaseProcessor
public abstract class BaseProcessor extends AbstractProcessor { ... // 模块名 String moduleName = null; //是否需要生成router 文档 boolean generateDoc; @Override public synchronized void init(ProcessingEnvironment processingEnv) { super.init(processingEnv); //初始化工具类 mFiler = processingEnv.getFiler(); types = processingEnv.getTypeUtils(); elementUtils = processingEnv.getElementUtils(); typeUtils = new TypeUtils(types, elementUtils); logger = new Logger(processingEnv.getMessager()); // Attempt to get user configuration [moduleName] MapgetSupportedOptions() { return new HashSet () {{ this.add(KEY_MODULE_NAME); this.add(KEY_GENERATE_DOC_NAME); }}; } } 主要初始化工具类，从gradle 配置里获取 moduleName
-
getSupportedOptions()
KEY_MODULE_NAME的值：
// Options of processor public static final String KEY_MODULE_NAME = "AROUTER_MODULE_NAME"; public static final String KEY_GENERATE_DOC_NAME = "AROUTER_GENERATE_DOC";就是我们在build.gradle里配置的 AROUTER_MODULE_NAME
2493821365b453ece9e5cca9.png -
init（）
从 options 里获取 moduleName，如果moduleName为空抛出异常； 异常信息就是这段字符串：
2493821354ae74e74f7443f0.png
这就是为什么如果不在build.gradle里配置AROUTER_MODULE_NAME，会异常的原因， moduleName有什么用？
-
RouteProcessor
public class RouteProcessor extends BaseProcessor { private Map创建两个map，分别用来存放当前模块下所有的分组（rootMap），和每个分组下的路径（groupMap）
private Map
private Mapprocess（）方法调用了parseRoutes（）方法，处理注解的逻辑在这个方里
获取activity/fragment/service 的类型，用于后面的类型判断
private void parseRoutes(Set routeElements) throws IOException { if (CollectionUtils.isNotEmpty(routeElements)) { // prepare the type an so on. logger.info(">>> Found routes, size is " + routeElements.size() + " <<<"); rootMap.clear(); TypeMirror type_Activity = elementUtils.getTypeElement(ACTIVITY).asType(); TypeMirror type_Service = elementUtils.getTypeElement(SERVICE).asType(); TypeMirror fragmentTm = elementUtils.getTypeElement(FRAGMENT).asType(); TypeMirror fragmentTmV4 = elementUtils.getTypeElement(Consts.FRAGMENT_V4).asType(); // Interface of ARouter TypeElement type_IRouteGroup = elementUtils.getTypeElement(IROUTE_GROUP); TypeElement type_IProviderGroup = elementUtils.getTypeElement(IPROVIDER_GROUP); ClassName routeMetaCn = ClassName.get(RouteMeta.class); ClassName routeTypeCn = ClassName.get(RouteType.class);创建 RouteMeta 对象，RouteMeta主要存放的是路径信息，包含了Rout注解的值，activity/fragment/service枚举，className，以及跳转参数信息。
for (Element element : routeElements) { TypeMirror tm = element.asType(); Route route = element.getAnnotation(Route.class); RouteMeta routeMeta; //6。注解的是 Activity or Fragment if (types.isSubtype(tm, type_Activity) || types.isSubtype(tm, fragmentTm) || types.isSubtype(tm, fragmentTmV4)) { // Get all fields annotation by @Autowired Map1.先判断路径path是否合法；然后把RouteMeta按groupName分组存入 groupMap
private void categories(RouteMeta routeMete) { //验证routeMete if (routeVerify(routeMete)) { logger.info(">>> Start categories, group = " + routeMete.getGroup() + ", path = " + routeMete.getPath() + " <<<"); SetrouteMetas = groupMap.get(routeMete.getGroup()); if (CollectionUtils.isEmpty(routeMetas)) { Set routeMetaSet = new TreeSet<>(new Comparator () { @Override public int compare(RouteMeta r1, RouteMeta r2) { try { return r1.getPath().compareTo(r2.getPath()); } catch (NullPointerException npe) { logger.error(npe.getMessage()); return 0; } } }); routeMetaSet.add(routeMete); groupMap.put(routeMete.getGroup(), routeMetaSet); } else { routeMetas.add(routeMete); } } else { logger.warning(">>> Route meta verify error, group is " + routeMete.getGroup() + " <<<"); } }
判断路径方法 ，从下面这段代码知道了
path 必须“/”开头，并且第一段作为默认 group 名；
private boolean routeVerify(RouteMeta meta) {
String path = meta.getPath();
if (StringUtils.isEmpty(path) || !path.startsWith("/")) { // The path must be start with '/' and not empty!
return false;
}
if (StringUtils.isEmpty(meta.getGroup())) { // Use default group(the first word in path)
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;
}
开始生成代码
for (Map.Entry> entry : groupMap.entrySet()) {
//组名
String groupName = entry.getKey();
// 构建方法
/**
* @Override
* public void loadInto(Map providers);
*/
MethodSpec.Builder loadIntoMethodOfGroupBuilder = MethodSpec.methodBuilder(METHOD_LOAD_INTO)
.addAnnotation(Override.class)
.addModifiers(PUBLIC)
.addParameter(groupParamSpec);
List routeDocList = new ArrayList<>();
Set groupData = entry.getValue();
for (RouteMeta routeMeta : groupData) {
// Build group method body
RouteDoc routeDoc = extractDocInfo(routeMeta);
ClassName className = ClassName.get((TypeElement) routeMeta.getRawType());
// 构建跳转参数的map
StringBuilder mapBodyBuilder = new StringBuilder();
Map paramsType = routeMeta.getParamsType();
Map injectConfigs = routeMeta.getInjectConfig();
if (MapUtils.isNotEmpty(paramsType)) {
List paramList = new ArrayList<>();
for (Map.Entry types : paramsType.entrySet()) {
mapBodyBuilder.append("put(\"").append(types.getKey()).append("\", ").append(types.getValue()).append("); ");
RouteDoc.Param param = new RouteDoc.Param();
Autowired injectConfig = injectConfigs.get(types.getKey());
param.setKey(types.getKey());
param.setType(TypeKind.values()[types.getValue()].name().toLowerCase());
param.setDescription(injectConfig.desc());
param.setRequired(injectConfig.required());
paramList.add(param);
}
routeDoc.setParams(paramList);
}
String mapBody = mapBodyBuilder.toString();
//生成 map的 put 代码
loadIntoMethodOfGroupBuilder.addStatement(
"atlas.put($S, $T.build($T." + routeMeta.getType() + ", $T.class, $S, $S, " + (StringUtils.isEmpty(mapBody) ? null : ("new java.util.HashMap(){{" + mapBodyBuilder.toString() + "}}")) + ", " + routeMeta.getPriority() + ", " + routeMeta.getExtra() + "))",
routeMeta.getPath(),
routeMetaCn,
routeTypeCn,
className,
routeMeta.getPath().toLowerCase(),
routeMeta.getGroup().toLowerCase());
routeDoc.setClassName(className.toString());
routeDocList.add(routeDoc);
}
// 生成ARouter$Group$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 + "<<<");
rootMap.put(groupName, groupFileName);
docSource.put(groupName, routeDocList);
}
上面这段代码生成类 ARouter$$Group$login，groupname = login；
public class ARouter$$Group$xxx（groupname） implements IRouteGroup {
@Override
public void loadInto(Map atlas) {
atlas.put("/login/loginX", RouteMeta.build(RouteType.ACTIVITY, LoginActivity.class, "/login/loginx", "login", null, -1, -2147483648));
atlas.put("/login/register", RouteMeta.build(RouteType.ACTIVITY, RegisterActivity.class, "/login/register", "login", null, -1, -2147483648))；
}
}
有多少group就有多少这样的类，然后把这些类名存入rootMap
if (MapUtils.isNotEmpty(rootMap)) {
// Generate root meta by group name, it must be generated before root, then I can find out the class of group.
for (Map.Entry entry : rootMap.entrySet()) {
loadIntoMethodOfRootBuilder.addStatement("routes.put($S, $T.class)", entry.getKey(), ClassName.get(PACKAGE_OF_GENERATE_FILE, entry.getValue()));
}
}
// Write provider into disk
String providerMapFileName = NAME_OF_PROVIDER + SEPARATOR + moduleName;
JavaFile.builder(PACKAGE_OF_GENERATE_FILE,
TypeSpec.classBuilder(providerMapFileName)
.addJavadoc(WARNING_TIPS)
.addSuperinterface(ClassName.get(type_IProviderGroup))
.addModifiers(PUBLIC)
.addMethod(loadIntoMethodOfProviderBuilder.build())
.build()
).build().writeTo(mFiler);
上面这段代码，我们看到了moduleName,也就是gradle里的project.getName()，这段代码生成下面这个类， moduleName =“LoginSDK”
public class ARouter$$Providers$$LoginSDK implements IProviderGroup {
@Override
public void loadInto(Map providers) {
providers.put("com.example.loginsdk.IUserInfo", RouteMeta.build(RouteType.PROVIDER, UserInfoManager.class, "/interface/user", "interface", null, -1, -2147483648));
}
}
可以看到这个类命名：ARouter+Providers+moduleName，Module里只有一个这样的类，把这个模块里注册的接口（接口都继承IProvider）put到map集合里
接着生成root
String rootFileName = NAME_OF_ROOT + SEPARATOR + moduleName;
JavaFile.builder(PACKAGE_OF_GENERATE_FILE,
TypeSpec.classBuilder(rootFileName)
.addJavadoc(WARNING_TIPS)
.addSuperinterface(ClassName.get(elementUtils.getTypeElement(ITROUTE_ROOT)))
.addModifiers(PUBLIC)
.addMethod(loadIntoMethodOfRootBuilder.build())
.build()
).build().writeTo(mFiler);
rootFileName =“ARouter$$Root$LoginSDK”，其中moduleName = LoginSDK
最终生成的类是：
public class ARouter$$Root$$LoginSDK implements IRouteRoot {
@Override
public void loadInto(Map> routes) {
routes.put("interface", ARouter$$Group$$interface.class);
routes.put("login", ARouter$$Group$$login.class);
}
}
这个类也只有一个，把前面生成的所有 ARouter$Group 都类存入map，到此就完所有注解的分组和映射。
模块间以modleName分离，每个模块有多个组，分组能够更好的管理和查找路由信息。
映射关系构建好了，类文件创建出来， 什么时候加载调用的呢？
三、ARouter 初始化
一般在application里初始化
public class MainApplication extends Application {
@Override
public void onCreate() {
super.onCreate();
ARouter.openDebug();
ARouter.init(this);
}
开发过程中如果没有 开启 ARouter.openDebug();会发现新增的path 跳转不了，但是release可以跳转
来看看init （）方法
public static void init(Application application) {
if (!hasInit) {
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.");
}
调用里 _ARouter.init(application)
protected static synchronized boolean init(Application application) {
mContext = application;
LogisticsCenter.init(mContext, executor);
logger.info(Consts.TAG, "ARouter init success!");
hasInit = true;
mHandler = new Handler(Looper.getMainLooper());
return true;
}
_ARouter 又调用了 LogisticsCenter.init(mContext, executor)，并传入了一个线程池
public synchronized static void init(Context context, ThreadPoolExecutor tpe) throws HandlerException {
mContext = context;
executor = tpe;
try {
long startInit = System.currentTimeMillis();
//load by plugin first
loadRouterMap();
//使用gradle插件自动处理了
if (registerByPlugin) {
logger.info(TAG, "Load router map by arouter-auto-register plugin.");
} else {
//手动处理
Set routerMap;
// It will rebuild router map every times when debuggable.
if (ARouter.debuggable() || PackageUtils.isNewVersion(context)) {
// These class was generated by arouter-compiler.
//通过指定包名，扫描包下面包含的所有的ClassName
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 {
logger.info(TAG, "Load router map from cache.");
routerMap = new HashSet<>(context.getSharedPreferences(AROUTER_SP_CACHE_KEY, Context.MODE_PRIVATE).getStringSet(AROUTER_SP_KEY_MAP, new HashSet()));
}
。。。
for (String className : routerMap) {
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);
}
}
}
。。。
} catch (Exception e) {
throw new HandlerException(TAG + "ARouter init logistics center exception! [" + e.getMessage() + "]");
}
}
有个getFileNameByPackageName（）方法
public static Set getFileNameByPackageName(Context context, final String packageName) throws PackageManager.NameNotFoundException, IOException, InterruptedException {
final Set classNames = new HashSet<>();
List paths = getSourcePaths(context);
final CountDownLatch parserCtl = new CountDownLatch(paths.size());
for (final String path : paths) {
DefaultPoolExecutor.getInstance().execute(new Runnable() {
@Override
public void run() {
DexFile dexfile = null;
try {
if (path.endsWith(EXTRACTED_SUFFIX)) {
//NOT use new DexFile(path), because it will throw "permission error in /data/dalvik-cache"
dexfile = DexFile.loadDex(path, path + ".tmp", 0);
} else {
dexfile = new DexFile(path);
}
Enumeration dexEntries = dexfile.entries();
while (dexEntries.hasMoreElements()) {
String className = dexEntries.nextElement();
if (className.startsWith(packageName)) {
classNames.add(className);
}
}
。。。
}
});
}
parserCtl.await();
return classNames;
}
通过指定包名，扫描包下面所有的文件ClassName；在编译阶段注解处理器在“com.alibaba.android.arouter.routes”这个包下面生成了文件，通过这个方法就可以扫描这个包下所有的类名；扫描的操作是运行在线程池里的，与_ARouter里的线程池是同一个
在这之前有个判断条件：
if (ARouter.debuggable() || PackageUtils.isNewVersion(context))，如果开启了ARouter.openDebug()或者 项目的版本有变化，则重新生成routerMap并且存入sp，否则直接用sp里的缓存，新增的path不会被加载，这解释了上面出现不能跳转的问题。
继续
for (String className : routerMap) {
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);
}
}
可以看到init（）里加载了 ARouter$Providers$、ARouter$Root、ARouter$Interceptors，但是没有加载任何一个ARouter$Group;那group是什么时候加载的呢
四、navigation()
如何根据path找到跳转目标（寻址）？
ARouter.getInstance().build("login/loginX").navigation();
build（）会进入 _ARouter.build(String 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), true);
}
}
这里有个方法，可以看到path 必须以“/”开头且至少两段，否则会抛异常
private String extractGroup(String path) {
if (TextUtils.isEmpty(path) || !path.startsWith("/")) {
throw new HandlerException(Consts.TAG + "Extract the default group failed, the path must be start with '/' and contain more than 2 '/'!");
}
try {
String defaultGroup = path.substring(1, path.indexOf("/", 1));
if (TextUtils.isEmpty(defaultGroup)) {
throw new HandlerException(Consts.TAG + "Extract the default group failed! There's nothing between 2 '/'!");
} else {
return defaultGroup;
}
} catch (Exception e) {
logger.warning(Consts.TAG, "Failed to extract default group! " + e.getMessage());
return null;
}
}
build()方法创建了Postcard对象，然后看Postcard.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;
}
// Set context to postcard.
postcard.setContext(null == context ? mContext : context);
try {
LogisticsCenter.completion(postcard);
这里调用了 LogisticsCenter.completion(postcard) ，找到跳转目标，给postcart赋值
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.
if (!Warehouse.groupsIndex.containsKey(postcard.getGroup())) {
throw new NoRouteFoundException(TAG + "There is no route match the path [" + postcard.getPath() + "], in group [" + postcard.getGroup() + "]");
} else {
try {
。。。
addRouteGroupDynamic(postcard.getGroup(), null);
。。。
} catch (Exception e) {
。。。
}
completion(postcard); // Reload
}
} else {
postcard.setDestination(routeMeta.getDestination());
postcard.setType(routeMeta.getType());
postcard.setPriority(routeMeta.getPriority());
postcard.setExtra(routeMeta.getExtra());
。。。
}
}
Warehouse.routes如果已经加载了path，直接赋值给postcard，如果没找到但是在Warehouse.groupsIndex里有这个group（Warehouse.groupsIndex是在init（）里添加元素的，ARouter$$Root$xxx这个类的loadInto(）方法里） 就会执行
addRouteGroupDynamic(postcard.getGroup(), null)方法
public synchronized static void addRouteGroupDynamic(String groupName, IRouteGroup group) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
if (Warehouse.groupsIndex.containsKey(groupName)){
// If this group is included, but it has not been loaded
// load this group first, because dynamic route has high priority.
Warehouse.groupsIndex.get(groupName).getConstructor().newInstance().loadInto(Warehouse.routes);
Warehouse.groupsIndex.remove(groupName);
}
// cover old group.
if (null != group) {
group.loadInto(Warehouse.routes);
}
}
Warehouse.groupsIndex.get(groupName).getConstructor().newInstance().loadInto(Warehouse.routes);
加载一个ARouter$$Group$xxx 类，调用其loadInto（）方法给Warehouse.routes添加元素 ，寻址完成。
看到这里我们就知道了ARouter$Group$xxx是在调用ARouter.getInstance().build（“/group/path”).navigation()时候加载，使用时才加载。
跳转：
_ARouter._navigation().startActivity()
private Object _navigation(final Postcard postcard, final int requestCode, final NavigationCallback callback) {
final Context currentContext = postcard.getContext();
switch (postcard.getType()) {
case ACTIVITY:
// Build intent
final Intent intent = new Intent(currentContext, postcard.getDestination());
intent.putExtras(postcard.getExtras());
// Set flags.
int flags = postcard.getFlags();
if (0 != flags) {
intent.setFlags(flags);
}
// Non activity, need FLAG_ACTIVITY_NEW_TASK
if (!(currentContext instanceof Activity)) {
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
}
// Set Actions
String action = postcard.getAction();
if (!TextUtils.isEmpty(action)) {
intent.setAction(action);
}
// Navigation in main looper.
runInMainThread(new Runnable() {
@Override
public void run() {
startActivity(requestCode, currentContext, intent, postcard, callback);
}
});
总结
- ARouter 编译期间构建路由表和映射关系，分模块分组；
- 有自己的线程池，编译完成后扫描dex文件，扫出apt生成的文件的类名
- 初始化只加载了 ARouter$Providers$、ARouter$Root$、ARouter$Interceptors，;ARouter$Group 在第一次使用时加载。