ARouter是阿里巴巴出品，帮助 Android App 进行组件化改造的路由框架，我们项目也使用的是ARouter路由框架进行解耦；
我打算分三部分进行解析ARouter框架：
第一部分：代码生成
第二部分：路由加载
第三部分：路由跳转
第一部分：代码生成
ARouter使用annotationProcessor配合JavaPoet进行代码生成；annotationProcessor顾名思义是注解处理器的意思。它对源代码文件进行检测找出其中的Annotation，根据注解自动生成代码。 Annotation处理器在处理Annotation时可以根据源文件中的Annotation生成额外的源文件和其它的文件，之后将编译生成的源文件和原来的源文件一起生成class文件。由于annotationProcessor不属于本篇范畴请点击这里查看详细用法。
arouter-compiler.jpg
上图为ARouter annotationProcessor的代码；
AutowiredProcessor
AutowiredProcessor类的作用是根据Autowired注解的字段和这个注解字段的外围类来生成对应的类，生成的这个类命名方式为ClassName+\$$ARouter$$Autowired，并且实现接口implements ISyringe的public void inject(Object target)方法。ARouter.getInstance().inject(this);底层就调用的是这个inject方法。
如果上面这段文字很难理解请看下面源码解析一目了然：
注解类
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.CLASS)
public @interface Autowired {
// Mark param's name or service name.
//用来指定获取数据的名字，如果不设置直接用字段的名字获取数据
String name() default "";
// If required, app will be crash when value is null.
// Primitive type wont be check!
//true，如果被修饰的字段没有获取到数据会抛出异常
boolean required() default false;
// Description of the field
//对这个字段进行解释，可以生成javadoc
String desc() default "No desc.";
}
文件处理的入口方法
@Override
public boolean process(Set<? extends TypeElement> set, RoundEnvironment roundEnvironment) {
if (CollectionUtils.isNotEmpty(set)) {
try {
logger.info(">>> Found autowired field, start... <<<");
//根据注解处理源码，生成Map<TypeElement, List<Element>>形式的map，
// TypeElement为Autowired字段修饰的外围类，List<Element>为这个外围类中Autowired修饰的所有字段
categories(roundEnvironment.getElementsAnnotatedWith(Autowired.class));
//根据上个方法生成的结构来创建java类
generateHelper();
} catch (Exception e) {
logger.error(e);
}
return true;
}
return false;
}
处理注解字段和外围类的方法
private void categories(Set<? extends Element> elements) throws IllegalAccessException {
if (CollectionUtils.isNotEmpty(elements)) {
for (Element element : elements) {
//获取这个element的外围类
TypeElement enclosingElement = (TypeElement) element.getEnclosingElement();
if (element.getModifiers().contains(Modifier.PRIVATE)) {
throw new IllegalAccessException("The autowired fields CAN NOT BE 'private'!!! please check field ["
+ element.getSimpleName() + "] in class [" + enclosingElement.getQualifiedName() + "]");
}
//判断外围类是否存在
if (parentAndChild.containsKey(enclosingElement)) { // Has categries
//如果存在直接将Autowired注解修饰的字段添加到这个外围类中
parentAndChild.get(enclosingElement).add(element);
} else {
//如果外围类不存在，创建
List<Element> childs = new ArrayList<>();
childs.add(element);
parentAndChild.put(enclosingElement, childs);
}
}
logger.info("categories finished.");
}
}
根据上面方法过滤出的结构创建文件的方法
private void generateHelper() throws IOException, IllegalAccessException {
TypeElement type_ISyringe = elements.getTypeElement(ISYRINGE);
TypeElement type_JsonService = elements.getTypeElement(JSON_SERVICE);
TypeMirror iProvider = elements.getTypeElement(Consts.IPROVIDER).asType();
TypeMirror activityTm = elements.getTypeElement(Consts.ACTIVITY).asType();
TypeMirror fragmentTm = elements.getTypeElement(Consts.FRAGMENT).asType();
TypeMirror fragmentTmV4 = elements.getTypeElement(Consts.FRAGMENT_V4).asType();
// Build input param name.
//方法参数为 （Object target）
ParameterSpec objectParamSpec = ParameterSpec.builder(TypeName.OBJECT, "target").build();
if (MapUtils.isNotEmpty(parentAndChild)) {
for (Map.Entry<TypeElement, List<Element>> entry : parentAndChild.entrySet()) {
// Build method : 'inject'
/**
* 创建的方法为
* Override
* public void inject(Object target);
*/
MethodSpec.Builder injectMethodBuilder = MethodSpec.methodBuilder(METHOD_INJECT)
.addAnnotation(Override.class)
.addModifiers(PUBLIC)
.addParameter(objectParamSpec);
//外围类
TypeElement parent = entry.getKey();
//所有注解的字段
List<Element> childs = entry.getValue();
//获取外围类包名加类的名字，例如：com.arouter.demo.Test1Activity
String qualifiedName = parent.getQualifiedName().toString();
//获取包名例如：com.arouter.demo
String packageName = qualifiedName.substring(0, qualifiedName.lastIndexOf("."));
//拼接生成类的名字Test1Activity$$ARouter$$Autowired
String fileName = parent.getSimpleName() + NAME_OF_AUTOWIRED;
logger.info(">>> Start process " + childs.size() + " field in " + parent.getSimpleName() + " ... <<<");
//类的信息 javadoc public class Test1Activity$$ARouter$$Autowired implements ISyringe
TypeSpec.Builder helper = TypeSpec.classBuilder(fileName)
.addJavadoc(WARNING_TIPS)
.addSuperinterface(ClassName.get(type_ISyringe))
.addModifiers(PUBLIC);
//创建字段 private SerializationService serializationService;
FieldSpec jsonServiceField = FieldSpec.builder(TypeName.get(type_JsonService.asType()), "serializationService", Modifier.PRIVATE).build();
helper.addField(jsonServiceField);
/**
* 在方法体内创建赋值代码
* serializationService = ARouter.getInstance().navigation(ARouter.class);
* Test1Activity substitute = (Test1Activity)target;
*/
injectMethodBuilder.addStatement("serializationService = $T.getInstance().navigation($T.class);", ARouterClass, ClassName.get(type_JsonService));
injectMethodBuilder.addStatement("$T substitute = ($T)target", ClassName.get(parent), ClassName.get(parent));
// Generate method body, start inject.
for (Element element : childs) {
Autowired fieldConfig = element.getAnnotation(Autowired.class);
String fieldName = element.getSimpleName().toString();
if (types.isSubtype(element.asType(), iProvider)) { // It's provider
//如果继承IProvider
//判断Autowired是否写了name，如果写了就取name值获取数据，如果没写就用field字段本身的名字获取数据
if ("".equals(fieldConfig.name())) { // User has not set service path, then use byType.
// Getter
//substitute.fieldName = ARouter.getInstance().navigation(ARouter.class);
injectMethodBuilder.addStatement(
"substitute." + fieldName + " = $T.getInstance().navigation($T.class)",
ARouterClass,
ClassName.get(element.asType())
);
} else { // use byName
// Getter
//substitute.fieldName = ARouter.getInstance().navigation(ARouter.class);
injectMethodBuilder.addStatement(
"substitute." + fieldName + " = ($T)$T.getInstance().build($S).navigation();",
ClassName.get(element.asType()),
ARouterClass,
fieldConfig.name()
);
}
// Validater
//如果Autowired中的required返回true，那么fieldName
if (fieldConfig.required()) {
injectMethodBuilder.beginControlFlow("if (substitute." + fieldName + " == null)");
injectMethodBuilder.addStatement(
"throw new RuntimeException(\"The field '" + fieldName + "' is null, in class '\" + $T.class.getName() + \"!\")", ClassName.get(parent));
injectMethodBuilder.endControlFlow();
}
} else { // It's normal intent value
String statment = "substitute." + fieldName + " = substitute.";
boolean isActivity = false;
if (types.isSubtype(parent.asType(), activityTm)) { // Activity, then use getIntent()
isActivity = true;
statment += "getIntent().";
} else if (types.isSubtype(parent.asType(), fragmentTm) || types.isSubtype(parent.asType(), fragmentTmV4)) { // Fragment, then use getArguments()
statment += "getArguments().";
} else {
throw new IllegalAccessException("The field [" + fieldName + "] need autowired from intent, its parent must be activity or fragment!");
}
/**
* 如上代码判断如果是activity就用getIntent()形式
* 如果是fragment就用getArguments()形式
* substitute.fieldName = substitute.getIntent().getStringExtra(); //如下1可以由多种形式，下面展示了两种形式
* serializationService.json2Object(substitute.getIntent().getStringExtra($S), $T.class)";
* if (null != serializationService){ //如2
* substitute.fieldName = serializationService.json2Object(substitute.getIntent().getStringExtra($S), $T.class)";
* }else{
* ARouter.e("ARouter::",You want automatic inject the field 'fieldName' in class 'Test1Activity' , then you should implement 'SerializationService' to support object auto inject!\")"
* }
*/
statment = buildStatement(statment, typeUtils.typeExchange(element), isActivity); //1
if (statment.startsWith("serializationService.")) { // Not mortals
injectMethodBuilder.beginControlFlow("if (null != serializationService)"); //2
injectMethodBuilder.addStatement(
"substitute." + fieldName + " = " + statment,
(StringUtils.isEmpty(fieldConfig.name()) ? fieldName : fieldConfig.name()),
ClassName.get(element.asType())
);
injectMethodBuilder.nextControlFlow("else");
injectMethodBuilder.addStatement(
"$T.e(\"" + Consts.TAG + "\", \"You want automatic inject the field '" + fieldName + "' in class '$T' , then you should implement 'SerializationService' to support object auto inject!\")", AndroidLog, ClassName.get(parent));
injectMethodBuilder.endControlFlow();
} else {
//substitute.fieldName = substitute.getIntent().getStringExtra();
injectMethodBuilder.addStatement(statment, StringUtils.isEmpty(fieldConfig.name()) ? fieldName : fieldConfig.name());
}
// Validator
//如果Autowired.required返回true，那么对这个字段进行强制校验，判断为null抛出异常
if (fieldConfig.required() && !element.asType().getKind().isPrimitive()) { // Primitive wont be check.
injectMethodBuilder.beginControlFlow("if (null == substitute." + fieldName + ")");
injectMethodBuilder.addStatement(
"$T.e(\"" + Consts.TAG + "\", \"The field '" + fieldName + "' is null, in class '\" + $T.class.getName() + \"!\")", AndroidLog, ClassName.get(parent));
injectMethodBuilder.endControlFlow();
}
}
}
helper.addMethod(injectMethodBuilder.build());
// Generate autowire helper
JavaFile.builder(packageName, helper.build()).build().writeTo(mFiler);
logger.info(">>> " + parent.getSimpleName() + " has been processed, " + fileName + " has been generated. <<<");
}
logger.info(">>> Autowired processor stop. <<<");
}
}
通过如下两段代码来看源文件和生成之后的文件
源文件
@Route(path = "/test/fragment")
public class BlankFragment extends Fragment {
@Autowired
String name;
@Autowired(required = true)
TestObj obj;
public BlankFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
TextView textView = new TextView(getActivity());
return textView;
}
}
生成之后的文件
**
* DO NOT EDIT THIS FILE!!! IT WAS GENERATED BY AROUTER. */
public class BlankFragment$$ARouter$$Autowired implements ISyringe {
private SerializationService serializationService;
@Override
public void inject(Object target) {
serializationService = ARouter.getInstance().navigation(SerializationService.class);;
BlankFragment substitute = (BlankFragment)target;
substitute.name = substitute.getArguments().getString("name");
if (null != serializationService) {
substitute.obj = serializationService.json2Object(substitute.getArguments().getString("obj"), TestObj.class);
} else {
Log.e("ARouter::", "You want automatic inject the field 'obj' in class 'BlankFragment' , then you should implement 'SerializationService' to support object auto inject!");
}
if (null == substitute.obj) {
Log.e("ARouter::", "The field 'obj' is null, in class '" + BlankFragment.class.getName() + "!");
}
}
}
InterceptorProcessor
InterceptorProcessor类的作用是根据Interceptor注解的类来生成对应的类，生成的这个类命名方式为ARouter$$Interceptors$$moduleName其中moduleName为build.gradle中配置的，并且实现接口implements IInterceptorGroup的public void loadInto(Map<Integer, Class<? extends IInterceptor>> interceptors)方法。在ARouter初始化的时候通过这个类的这个方法来获取所有的拦截器。
文件处理的入口方法
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
if (CollectionUtils.isNotEmpty(annotations)) {
//获取所有被Interceptor注解的element
Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(Interceptor.class);
try {
//生成代码
parseInterceptors(elements);
} catch (Exception e) {
logger.error(e);
}
return true;
}
return false;
}
根据Interceptor注解生成代码
private void parseInterceptors(Set<? extends Element> elements) throws IOException {
if (CollectionUtils.isNotEmpty(elements)) {
logger.info(">>> Found interceptors, size is " + elements.size() + " <<<");
// Verify and cache, sort incidentally.
for (Element element : elements) {
//检查拦截器，必须实现IInterceptor接口并且使用Interceptor注解
if (verify(element)) { // Check the interceptor meta
logger.info("A interceptor verify over, its " + element.asType());
Interceptor interceptor = element.getAnnotation(Interceptor.class);
Element lastInterceptor = interceptors.get(interceptor.priority());
//不允许多个拦截器使用同一个优先级
if (null != lastInterceptor) { // Added, throw exceptions
throw new IllegalArgumentException(
String.format(Locale.getDefault(), "More than one interceptors use same priority [%d], They are [%s] and [%s].",
interceptor.priority(),
lastInterceptor.getSimpleName(),
element.getSimpleName())
);
}
//根据优先级缓存
interceptors.put(interceptor.priority(), element);
} else {
logger.error("A interceptor verify failed, its " + element.asType());
}
}
// Interface of ARouter.
TypeElement type_ITollgate = elementUtil.getTypeElement(IINTERCEPTOR);
TypeElement type_ITollgateGroup = elementUtil.getTypeElement(IINTERCEPTOR_GROUP);
/**
* Build input type, format as :
*
* ```Map<Integer, Class<? extends ITollgate>>```
*/
ParameterizedTypeName inputMapTypeOfTollgate = ParameterizedTypeName.get(
ClassName.get(Map.class),
ClassName.get(Integer.class),
ParameterizedTypeName.get(
ClassName.get(Class.class),
WildcardTypeName.subtypeOf(ClassName.get(type_ITollgate))
)
);
// Build input param name.
//方法参数 (Map<Integer, Class<? extends IInterceptor>> interceptors)
ParameterSpec tollgateParamSpec = ParameterSpec.builder(inputMapTypeOfTollgate, "interceptors").build();
// Build method : 'loadInto'
/**
* 创建方法
* Override
* public void loadInto(Map<Integer, Class<? extends IInterceptor>> interceptors){}
*/
MethodSpec.Builder loadIntoMethodOfTollgateBuilder = MethodSpec.methodBuilder(METHOD_LOAD_INTO)
.addAnnotation(Override.class)
.addModifiers(PUBLIC)
.addParameter(tollgateParamSpec);
// Generate
/**
* 根据缓存生成代码
* interceptors.put(priority,Test1Interceptor.class);
*/
if (null != interceptors && interceptors.size() > 0) {
// Build method body
for (Map.Entry<Integer, Element> entry : interceptors.entrySet()) {
loadIntoMethodOfTollgateBuilder.addStatement("interceptors.put(" + entry.getKey() + ", $T.class)",
ClassName.get((TypeElement) entry.getValue()));
}
}
// Write to disk(Write file even interceptors is empty.)
/**
* 生成类
* moduleName为每个module的build.gradle里配置的
* public class ARouter$$Interceptors$$moduleName implements IInterceptorGroup{
* public void loadInto(Map<Integer, Class<? extends IInterceptor>> interceprors){
* interceptors.put(priority,Test1Interceptor.class);
* }
* }
*/
JavaFile.builder(PACKAGE_OF_GENERATE_FILE,
TypeSpec.classBuilder(NAME_OF_INTERCEPTOR + SEPARATOR + moduleName)
.addModifiers(PUBLIC)
.addJavadoc(WARNING_TIPS)
.addMethod(loadIntoMethodOfTollgateBuilder.build())
.addSuperinterface(ClassName.get(type_ITollgateGroup))
.build()
).build().writeTo(mFiler);
logger.info(">>> Interceptor group write over. <<<");
}
}
源文件
@Interceptor(priority = 7)
public class Test1Interceptor implements IInterceptor {
Context mContext;
@Override
public void process(final Postcard postcard, final InterceptorCallback callback) {
}
@Override
public void init(Context context) {
}
}
生成文件
public class ARouter$$Interceptors$$app implements IInterceptorGroup {
@Override
public void loadInto(Map<Integer, Class<? extends IInterceptor>> interceptors) {
interceptors.put(7, Test1Interceptor.class);
}
}
RouteProcessor
RouteProcessor类的作用是根据Route注解的类来生成对应的类，这个类是对应的路由表，也就是Group对应的path，path对应的类的Class。
文件处理的入口方法
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
if (CollectionUtils.isNotEmpty(annotations)) {
//所有被Route注解的Element
Set<? extends Element> routeElements = roundEnv.getElementsAnnotatedWith(Route.class);
try {
logger.info(">>> Found routes, start... <<<");
//根据Element生成代码
this.parseRoutes(routeElements);
} catch (Exception e) {
logger.error(e);
}
return true;
}
return false;
}
根据Route生成代码方法
private void parseRoutes(Set<? extends Element> routeElements) throws IOException {
if (CollectionUtils.isNotEmpty(routeElements)) {
// Perpare the type an so on.
logger.info(">>> Found routes, size is " + routeElements.size() + " <<<");
rootMap.clear();
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);
ClassName routeMetaCn = ClassName.get(RouteMeta.class);
ClassName routeTypeCn = ClassName.get(RouteType.class);
/*
Build input type, format as :
```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>```
*/
ParameterizedTypeName inputMapTypeOfGroup = ParameterizedTypeName.get(
ClassName.get(Map.class),
ClassName.get(String.class),
ClassName.get(RouteMeta.class)
);
/*
Build input param name.
(Map<String, Class<? extends IRouteGroup>> routes)
*/
ParameterSpec rootParamSpec = ParameterSpec.builder(inputMapTypeOfRoot, "routes").build();
//(Map<String, RouteMeta> atlas)
ParameterSpec groupParamSpec = ParameterSpec.builder(inputMapTypeOfGroup, "atlas").build();
//(Map<String, RouteMeta> providers)
ParameterSpec providerParamSpec = ParameterSpec.builder(inputMapTypeOfGroup, "providers").build(); // Ps. its param type same as groupParamSpec!
/*
Build method : 'loadInto'
Override
public void loadInto(Map<String, Class<? extends IRouteGroup>> routes);
*/
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.
for (Element element : routeElements) {
TypeMirror tm = element.asType();
Route route = element.getAnnotation(Route.class);
RouteMeta routeMete = null;
//如下代码组装RouterMete路由元数据
if (types.isSubtype(tm, type_Activity)) { // 1 // Activity
logger.info(">>> Found activity route: " + tm.toString() + " <<<");
// Get all fields annotation by @Autowired
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.
//如果外围类是Activity，里面有被Autowired注解的字段且不是IProvider类型的，添加到Map中key为名字，value为字段类型的枚举值，具体查看typeUtils.typeExchange(field)方法
Autowired paramConfig = field.getAnnotation(Autowired.class);
paramsType.put(StringUtils.isEmpty(paramConfig.name()) ?
field.getSimpleName().toString() : paramConfig.name(), typeUtils.typeExchange(field));
}
}
routeMete = new RouteMeta(route, element, RouteType.ACTIVITY, paramsType);
} else if (types.isSubtype(tm, iProvider)) { // IProvider
logger.info(">>> Found provider route: " + tm.toString() + " <<<");
routeMete = new RouteMeta(route, element, RouteType.PROVIDER, null);
} else if (types.isSubtype(tm, type_Service)) { // Service
logger.info(">>> Found service route: " + tm.toString() + " <<<");
routeMete = new RouteMeta(route, element, RouteType.parse(SERVICE), null);
} else if (types.isSubtype(tm, fragmentTm) || types.isSubtype(tm, fragmentTmV4)) {
logger.info(">>> Found fragment route: " + tm.toString() + " <<<");
routeMete = new RouteMeta(route, element, RouteType.parse(FRAGMENT), null);
}
categories(routeMete);
// if (StringUtils.isEmpty(moduleName)) { // Hasn't generate the module name.
// moduleName = ModuleUtils.generateModuleName(element, logger);
// }
}
/**
* Override
* public void loadInto(Map<String, RouteMeta> providers);
*/
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.
for (Map.Entry<String, Set<RouteMeta>> entry : groupMap.entrySet()) {
String groupName = entry.getKey();
/**
* Override
* public void loadInto(Map<String, RouteMeta> atlas);
*/
MethodSpec.Builder loadIntoMethodOfGroupBuilder = MethodSpec.methodBuilder(METHOD_LOAD_INTO)
.addAnnotation(Override.class)
.addModifiers(PUBLIC)
.addParameter(groupParamSpec);
// Build group method body
Set<RouteMeta> groupData = entry.getValue();
for (RouteMeta routeMeta : groupData) {
switch (routeMeta.getType()) {
case PROVIDER: // Need cache provider's super class
List<? extends TypeMirror> interfaces = ((TypeElement) routeMeta.getRawType()).getInterfaces();
/**
* 如下代码在方法public void loadInto(Map<String, RouteMeta> providers);中生成
* prvoiders.put("com.xxx.demo.HelloService",RouteMeta.build(RouteType.PROVIDER,HelloService.class,"/service/hello","service",null,priority,extra));
*/
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
//tm 和 iProvider 相同
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
// tm 是 iProvider 的子类
loadIntoMethodOfProviderBuilder.addStatement(
"providers.put($S, $T.build($T." + routeMeta.getType() + ", $T.class, $S, $S, null, " + routeMeta.getPriority() + ", " + routeMeta.getExtra() + "))",
// tm.toString().substring(tm.toString().lastIndexOf(".") + 1), // Spite unuseless name
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
/**
* 如下代码只有Activity的时候才运行，查看上面 1
* 生成代码
* typeExchange,如上代码，为Autowired注解字段的类型
* put("Autowired.name",typeExchange);
*/
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();
/**
* 如下代码在方法public void loadInto(Map<String, RouteMeta> atlas);中生成如下
* atlas.put("/service/hello",RouteMeta.build(RouteType.PROVIDER,HelloService.class,"/service/hello","service",null,priority,extra));
* 如果routeMeta.getType()为RouteType.ACTIVITY为下面这种形式
* atlas.put("/service/hello",RouteMeta.build(RouteType.PROVIDER,HelloService.class,"/service/hello","service",new java.util.HashMap<String, Integer>(){{put("Autowired.name",typeExchange);},priority,extra));
*/
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
/**
* 如下代码生成类
* package com.alibaba.android.arouter.routes;
* public class ARouter$$Group$$groupName implements IRouteGroup{
* public void loadInto(Map<String, RouteMeta> atlas){
* atlas.put("/service/hello",RouteMeta.build(RouteType.PROVIDER,HelloService.class,"/service/hello","service",null,priority,extra));
* atlas.put("/service/hello",RouteMeta.build(RouteType.PROVIDER,HelloService.class,"/service/hello","service",new java.util.HashMap<String, Integer>(){{put("Autowired.name",typeExchange);},priority,extra));
* }
* }
*/
String groupFileName = NAME_OF_GROUP + groupName;
JavaFile.builder(PACKAGE_OF_GENERATE_FILE,
TypeSpec.classBuilder(groupFileName)
.addJavadoc(WARNING_TIPS)
.addSuperinterface(ClassName.get(type_IRouteGroup))
.addModifiers(PUBLIC)
.addMethod(loadIntoMethodOfGroupBuilder.build())
.build()
).build().writeTo(mFiler);
logger.info(">>> Generated group: " + groupName + "<<<");
rootMap.put(groupName, groupFileName);
}
/**
* 如下方法是在
* Override public void loadInto(Map<String, Class<? extends IRouteGroup>> routes);
* 方法中创建如下代码
* routes.put(groupName, ARouter$$Group$$groupName.class)
*/
if (MapUtils.isNotEmpty(rootMap)) {
// Generate root meta by group name, it must be generated before root, then I can findout the class of group.
for (Map.Entry<String, String> entry : rootMap.entrySet()) {
loadIntoMethodOfRootBuilder.addStatement("routes.put($S, $T.class)", entry.getKey(), ClassName.get(PACKAGE_OF_GENERATE_FILE, entry.getValue()));
}
}
// Wirte provider into disk
/**
* package com.alibaba.android.arouter.routes;
* public class ARouter$$Providers$$moudleName implements IProviderGroup{
* public void loadInto(Map<String, RouteMeta> providers){
* prvoiders.put("com.xxx.demo.HelloService",RouteMeta.build(RouteType.PROVIDER,HelloService.class,"/service/hello","service",null,priority,extra));
* }
* }
*/
String providerMapFileName = NAME_OF_PROVIDER + SEPARATOR + moduleName;
JavaFile.builder(PACKAGE_OF_GENERATE_FILE,
TypeSpec.classBuilder(providerMapFileName)
.addJavadoc(WARNING_TIPS)
.addSuperinterface(ClassName.get(type_IProviderGroup))
.addModifiers(PUBLIC)
.addMethod(loadIntoMethodOfProviderBuilder.build())
.build()
).build().writeTo(mFiler);
logger.info(">>> Generated provider map, name is " + providerMapFileName + " <<<");
// Write root meta into disk.
/**
* package com.alibaba.android.arouter.routes;
* public class ARouter&&Root$$moduleName implements IRouteRoot{
* Override
* public void loadInto(Map<String, Class<? extends IRouteGroup>> routes){
* routes.put(groupName, ARouter$$Group$$groupName.class)
* }
* }
*/
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 + " <<<");
}
}
生成文件
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("test", ARouter$$Group$$test.class);
}
}
public class ARouter$$Group$$service implements IRouteGroup {
@Override
public void loadInto(Map<String, RouteMeta> atlas) {
atlas.put("/service/hello", RouteMeta.build(RouteType.PROVIDER, HelloServiceImpl.class, "/service/hello", "service", null, -1, -2147483648));
atlas.put("/service/json", RouteMeta.build(RouteType.PROVIDER, JsonServiceImpl.class, "/service/json", "service", null, -1, -2147483648));
atlas.put("/service/single", RouteMeta.build(RouteType.PROVIDER, SingleService.class, "/service/single", "service", null, -1, -2147483648));
}
}
总结：
上面对代码生成部分做了详细的代码注释，主要用到的技术就是annotationProcessor配合JavaPoet进行代码生成。
第二部分：路由加载
本地生成文件也进行编译打包，那么程序是如何找到这些路由加载到内存中呢，我们直接找到'LogisticsCenter.public synchronized static void init(Context context, ThreadPoolExecutor tpe)'方法
public synchronized static void init(Context context, ThreadPoolExecutor tpe) throws HandlerException {
mContext = context;
executor = tpe;
try {
// These class was generate by arouter-compiler.
//在所有的dex中根据package包名获取arouter-compiler生成的class文件
List<String> classFileNames = ClassUtils.getFileNameByPackageName(mContext, ROUTE_ROOT_PAKCAGE);
//根据上面代码过滤出的class路径来讲Route加载到内存中
for (String className : classFileNames) {
if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_ROOT)) {
// This one of root elements, load root.
/**
* 获取arouter-compiler生成的ARouter$$Root$$moduleName类中的映射表
* 例如
* 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("test", ARouter$$Group$$test.class);
* }
* }
*/
((IRouteRoot) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.groupsIndex);
} else if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_INTERCEPTORS)) {
// Load interceptorMeta
/**
* 获取arouter-compiler生成的ARouter$$Interceptors$$moduleName类的映射表
* 例如
* public class ARouter$$Interceptors$$app implements IInterceptorGroup {
* @Override
* public void loadInto(Map<Integer, Class<? extends IInterceptor>> interceptors) {
* interceptors.put(7, Test1Interceptor.class);
* }
* }
*/
((IInterceptorGroup) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.interceptorsIndex);
} else if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_PROVIDERS)) {
// Load providerIndex
/**
* 获取arouter-compiler生成的ARouter$$Providers$$moduleName类的映射表
* public class ARouter$$Providers$$app implements IProviderGroup {
* @Override
* public void loadInto(Map<String, RouteMeta> providers) {
* providers.put("com.alibaba.android.arouter.demo.testservice.SingleService", RouteMeta.build(RouteType.PROVIDER, SingleService.class, "/service/single", "service", null, -1, -2147483648));
* }
* }
*/
((IProviderGroup) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.providersIndex);
}
}
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() + "]");
}
}
在这个方法中难理解的地方是ClassUtils.getFileNameByPackageName(mContext, ROUTE_ROOT_PAKCAGE);方法，这个方法又调用List<String> getSourcePaths(Context context)方法，如下两个方法的代码注释：
/**
* 通过指定包名，扫描包下面包含的所有的ClassName
*
* @param context U know
* @param packageName 包名
* @return 所有class的集合
*/
public static List<String> getFileNameByPackageName(Context context, String packageName) throws PackageManager.NameNotFoundException, IOException {
List<String> classNames = new ArrayList<>();
for (String path : getSourcePaths(context)) {
DexFile dexfile = null;
try {
if (path.endsWith(EXTRACTED_SUFFIX)) {
//NOT use new DexFile(path), because it will throw "permission error in /data/dalvik-cache"
//提示权限错误 /data/dalvik-cache 这个目录
dexfile = DexFile.loadDex(path, path + ".tmp", 0);
} else {
//虚拟机将在目录/data/dalvik-cache下生成对应的文件名字并打开它
dexfile = new DexFile(path);
}
Enumeration<String> dexEntries = dexfile.entries();
while (dexEntries.hasMoreElements()) {
String className = dexEntries.nextElement();
if (className.contains(packageName)) {
classNames.add(className);
}
}
} catch (Throwable ignore) {
Log.e("ARouter", "Scan map file in dex files made error.", ignore);
} finally {
if (null != dexfile) {
try {
dexfile.close();
} catch (Throwable ignore) {
}
}
}
}
Log.d("ARouter", "Filter " + classNames.size() + " classes by packageName <" + packageName + ">");
return classNames;
}
List<String> getSourcePaths(Context context)方法
public static List<String> getSourcePaths(Context context) throws PackageManager.NameNotFoundException, IOException {
ApplicationInfo applicationInfo = context.getPackageManager().getApplicationInfo(context.getPackageName(), 0);
File sourceApk = new File(applicationInfo.sourceDir);
// Log.e(TAG,sourceApk.getAbsolutePath());
// Log.e(TAG,"12121212 : " + applicationInfo.sourceDir);
logger.info(TAG,"12121212 : " + applicationInfo.sourceDir);
List<String> sourcePaths = new ArrayList<>();
sourcePaths.add(applicationInfo.sourceDir); //add the default apk path
//the prefix of extracted file, ie: test.classes
String extractedFilePrefix = sourceApk.getName() + EXTRACTED_NAME_EXT;
Log.e(TAG,extractedFilePrefix);
// 如果VM已经支持了MultiDex，就不要去Secondary Folder加载 Classesx.zip了，那里已经么有了
// 通过是否存在sp中的multidex.version是不准确的，因为从低版本升级上来的用户，是包含这个sp配置的
/**
* 如下这个方法判断虚拟机是否支持multidex，java.vm.version大于2.1的就是art虚拟机默认支持multidex
* 如果虚拟机为art默认支持multidex那么dex的路径只有一个那就是applicationInfo.sourceDir例如： /data/app/com.alibaba.android.arouter.demo-wqT7WUHrcYy8UDBDFIXTmg==/base.apk
* 如果虚拟机为dalvik默认不支持multidex，且对dex进行分包处理那么加载/data/data/com.alibaba.android.arouter.demo/code_cache/secondray-dexes/
* 如果虚拟机为dalvik默认不支持multidex，且由于代码量太少没有进行分包处理那么加载applicationInfo.sourceDir路径
*/
if (!isVMMultidexCapable()) {
//the total dex numbers
int totalDexNumber = getMultiDexPreferences(context).getInt(KEY_DEX_NUMBER, 1);
File dexDir = new File(applicationInfo.dataDir, SECONDARY_FOLDER_NAME);
//扫描/data/data/com.alibaba.android.arouter.demo/code_cache/secondray-dexes/ 路径下所有的 xxx.apk.classes2.zip
for (int secondaryNumber = 2; secondaryNumber <= totalDexNumber; secondaryNumber++) {
//扫描/data/data/com.alibaba.android.arouter.demo/code_cache/secondray-dexes/ for each dex file, ie: test.classes2.zip, test.classes3.zip...
String fileName = extractedFilePrefix + secondaryNumber + EXTRACTED_SUFFIX;
File extractedFile = new File(dexDir, fileName);
if (extractedFile.isFile()) {
sourcePaths.add(extractedFile.getAbsolutePath());
//we ignore the verify zip part
} else {
throw new IOException("Missing extracted secondary dex file '" + extractedFile.getPath() + "'");
}
}
}
if (ARouter.debuggable()) { // Search instant run support only debuggable
sourcePaths.addAll(tryLoadInstantRunDexFile(applicationInfo));
}
return sourcePaths;
}
经过'public synchronized static void init(Context context, ThreadPoolExecutor tpe) throws HandlerException'方法之后将arouter-compiler生成的代码加载到内存中提供程序使用,如下类：
class Warehouse {
// Cache route and metas
//加载ARouter$$Root$$moduleName类的映射表
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<>();
//加载ARouter$$Providers$$moduleName类的映射表
static Map<String, RouteMeta> providersIndex = new HashMap<>();
// Cache interceptor
//加载ARouter$$Interceptors$$moduleName类的映射表
static Map<Integer, Class<? extends IInterceptor>> interceptorsIndex = new UniqueKeyTreeMap<>("More than one interceptors use same priority [%s]");
static List<IInterceptor> interceptors = new ArrayList<>();
}
如下两张图片图一为art虚拟机编译后获取dex文件的目录，图二为dalvik虚拟机编译后获取dex文件的目录
art.jpg
dalvik_multidex.jpg
总结：
根据虚拟机是否默认支持multidex，分别在不同的文件夹中扫描生成的zip或apk文件路径；将路径通过DexFile获取所有的className，通过指定的package来过滤出有用的className；在将过滤出来的className填充到Warehouse类中的缓存中，给程序提供使用。
第一部分：路由跳转
路由跳转方法调用栈
//ARouter类
ARouter.getInstance().build(BaseConstantDef.ROUTER_PATH_AC1).navigation();
//_ARouter类
protected Object navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback);
//如上方法中调用
LogisticsCenter.completion(postcard);//拼装Postcard类
//符合要求执行拦截器
interceptorService.doInterceptions();
//最后调用真正的跳转方法
private Object _navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback)
上面是路由跳转的方法调用栈，下面是代码解析：
LogisticsCenter.completion(postcard)方法
public synchronized static void completion(Postcard postcard) {
if (null == postcard) {
throw new NoRouteFoundException(TAG + "No postcard!");
}
/**
* 这部分代码
* 1. path在Warehouse.routes缓存中没有，进入这个分支
* 2. 根据group在Warehouse.groupsIndex中取出对应的IRouterGroup这个接口中存放的就是这个group中所有的path
* 3. 取出之后将这个group下的所有path缓存到Warehouse.routes中，key为path，value为RouteMeta
* 4. 缓存成功删除Warehouse.groupsIndex中对应的group数据
* 5. 重复调用completion方法，根据path命中缓存取出RouteMeta
* 6. 根据RouteMeta来组装Postcard
* 7. 解析Uri中的参数，拼装成Android的bundle传输
* 8. routeMeta.getType()如果等于provider，那么从Warehouse.providers中根据routeMeta.getDestination()取出Provider
* 9. 如果取出为空那么创建，并且缓存到Warehouse.providers中，key为provider的class，value为provider的实例对象
* 10. 如果是provider 设置postcard.greenChannel() 跳过拦截器
* 11. 从第8点开始 routeMeta.getType()如果等于fragment，则直接设置postcard.greenChannel() 跳过拦截器
*/
RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath()); // 1
if (null == routeMeta) { // Maybe its does't exist, or didn't load.
Class<? extends IRouteGroup> groupMeta = Warehouse.groupsIndex.get(postcard.getGroup()); // 2 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(); // 3
iGroupInstance.loadInto(Warehouse.routes);
Warehouse.groupsIndex.remove(postcard.getGroup()); // 4
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); // 5 Reload
}
} else {
// 6
postcard.setDestination(routeMeta.getDestination());
postcard.setType(routeMeta.getType());
postcard.setPriority(routeMeta.getPriority());
postcard.setExtra(routeMeta.getExtra());
// 7
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: // 8 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 {
// 9
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(); // 10 Provider should skip all of interceptors
break;
case FRAGMENT:
postcard.greenChannel(); // Fragment needn't interceptors
default:
break;
}
}
}
interceptorService.doInterceptions()拦截器查看InterceptorServiceImpl源码：
@Override
public void doInterceptions(final Postcard postcard, final InterceptorCallback callback) {
if (null != Warehouse.interceptors && Warehouse.interceptors.size() > 0) {
checkInterceptorsInitStatus();
if (!interceptorHasInit) {
callback.onInterrupt(new HandlerException("Interceptors initialization takes too much time."));
return;
}
LogisticsCenter.executor.execute(new Runnable() {
@Override
public void run() {
//这个同步工具类是为了防止在拦截器中不回掉callback方法，或者拦截器中有线程延迟回调callback方法
CancelableCountDownLatch interceptorCounter = new CancelableCountDownLatch(Warehouse.interceptors.size());
try {
//递归执行所有拦截器
_excute(0, interceptorCounter, postcard);
//这段代码是等待拦截器中线程执行完成回调callback来清除CountDownLatch标志，但是他有个超时时间
interceptorCounter.await(postcard.getTimeout(), TimeUnit.SECONDS);
if (interceptorCounter.getCount() > 0) { // Cancel the navigation this time, if it hasn't return anythings.
callback.onInterrupt(new HandlerException("The interceptor processing timed out."));
} else if (null != postcard.getTag()) { // Maybe some exception in the tag.
callback.onInterrupt(new HandlerException(postcard.getTag().toString()));
} else {
callback.onContinue(postcard);
}
} catch (Exception e) {
callback.onInterrupt(e);
}
}
});
} else {
callback.onContinue(postcard);
}
}
protected Object navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback)
protected Object navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback) {
try {
//拼装Postcard类
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) {
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()) { // It must be run in async thread, maybe interceptor cost too mush time made ANR.
/**
*除了provider和fragment都需要走拦截器，然后在发送navigation
* 请查看InterceptorServiceImpl源码异步执行所有拦截器，并且通过CountDownLatch来进行同步
*/
interceptorService.doInterceptions(postcard, new InterceptorCallback() {
/**
* Continue process
*
* @param postcard route meta
*/
@Override
public void onContinue(Postcard postcard) {
//拦截器都正确返回
_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 {
return _navigation(context, postcard, requestCode, callback);
}
return null;
}
参考文献：
http://www.importnew.com/15731.html
https://it.baiked.com/jdkapi1.8/javax/lang/model/element/TypeElement.html
