public class MyEventBus {
private static MyEventBus instance = new MyEventBus();
private Map<Object, List<SubscribleMethod>> cacheMap;
private Handler mHandler;
private ExecutorService executorService;
private MyEventBus(){
cacheMap = new HashMap<>();
// 主进程Handler
mHandler = new Handler(Looper.getMainLooper());
// 执行子任务的线程池
executorService = Executors.newCachedThreadPool();
}
public static MyEventBus getDefault(){
return instance;
}
/**
* 注册接收事件的类
* @param subscriber MainActivity
*/
public void register(Object subscriber){
Class<?> subscriberClass = subscriber.getClass();
List<SubscribleMethod> subscribleMethods = cacheMap.get(subscriberClass);
// 等于空就表示这个subscriber没有注册到cacheMap中
if(subscribleMethods == null){
subscribleMethods = getMethodsFromSubscriber(subscriber);
cacheMap.put(subscriber,subscribleMethods);
}
}
// 寻找订阅者(MainActivity)中的订阅方法。即打了Subscrible注解的方法
private List<SubscribleMethod> getMethodsFromSubscriber(Object subscriber) {
List<SubscribleMethod> subscribleMethodList = new ArrayList<>();
Class<?> subscriberClass = subscriber.getClass();
// Eventbus也许是注册在BaseActivity中的，所以要父类也需要遍历。
while (subscriberClass != null){
String name = subscriberClass.getName();
// BaseActiviy的父类是Activity，Activity肯定是不需要遍历的，Activity的包名以Android.开头，所以遍历到这里，就break
if(name.startsWith("java.") || name.startsWith("javax.") || name.startsWith("android.") || name.startsWith("androidx.")){
break;
}
Method[] methods = subscriberClass.getDeclaredMethods();
// 寻找和 EventBus 相关的方法，并保存
for(int i = 0; i < methods.length; i++){
// EventBus语法，只能接收一个参数。
if(methods[i].getParameterTypes().length != 1){
continue;
}
// 必须要有 MySubscribe 注解，才是 EventBus 需要的方法
MySubscribe annotation = methods[i].getAnnotation(MySubscribe.class);
if(annotation == null){
continue;
}
MyThreadMode myThreadMode = annotation.threadMode();
Class<?> eventType = methods[i].getParameterTypes()[0]; // 只有一个参数，所以获取第0个位置上的数据
SubscribleMethod method = new SubscribleMethod(methods[i],myThreadMode,eventType);
// 将符合条件的方法保存到List集合中，并返回
subscribleMethodList.add(method);
}
subscriberClass = subscriberClass.getSuperclass();
}
return subscribleMethodList;
}
/**
* 发送事件
* @param event MessageEvent
*/
public void post(Object event){
Set<Object> keySet = cacheMap.keySet();
Iterator<Object> iterator = keySet.iterator();
// 遍历所有的注册类，在他们的注册事件中寻找类型一样的方法，利用反射执行这些方法
while(iterator.hasNext()){
// 注册类 （MainActivity）
Object next = iterator.next();
List<SubscribleMethod> subscribleMethodList = cacheMap.get(next);
for(int i = 0; i < subscribleMethodList.size(); i++){
SubscribleMethod method = subscribleMethodList.get(i);
if(method.getEventType().isAssignableFrom(event.getClass())){
try{
invoke(method,next,event);
}catch (Exception e){
e.printStackTrace();
}
}
}
}
}
// 使用反射执行
private void invoke(final SubscribleMethod method,final Object next,final Object event) throws Exception{
// 注册事件 指定的线程
try{
MyThreadMode threadMode = method.getThreadMode();
if(threadMode == MyThreadMode.MAIN){
// 发送事件如果是主线程
if(Looper.myLooper() == Looper.getMainLooper()){
// 主线程发送，主线程接收
method.getMethod().invoke(next,event);
}else{
// 发送事件是子线程，使用Handler发送消息
// 子线程发送，主线程接收
mHandler.post(new Runnable(){
@Override
public void run() {
try{
method.getMethod().invoke(next,event);
}catch (Exception e){
e.printStackTrace();
}
}
});
}
}else if(threadMode == MyThreadMode.ASYNC){
if(Looper.myLooper() == Looper.getMainLooper()){
// 使用线程池，创建任务异步执行
// 主线程发送，子线程接收
executorService.execute(new Runnable() {
@Override
public void run() {
try{
method.getMethod().invoke(next,event);
}catch (Exception e){
e.printStackTrace();
}
}
});
}else {
// 子线程发送，子线程接收
method.getMethod().invoke(next,event);
}
}else{
method.getMethod().invoke(next,event);
}
}catch (Exception e){
e.printStackTrace();
}
}
/**
* 解除订阅
*/
public void unregister(Object subscriber){
List<SubscribleMethod> subscribleMethodList = cacheMap.get(subscriber);
if(subscribleMethodList != null){
cacheMap.remove(subscriber);
}
}
}
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface MySubscribe {
MyThreadMode threadMode() default MyThreadMode.POSTING;
}
// 注册类中的注册方法信息
public class SubscribleMethod {
// 注册方法
private Method method;
// 线程类型
private MyThreadMode threadMode;
// 事件类型
private Class<?> eventType;
public SubscribleMethod(Method method, MyThreadMode threadMode, Class<?> eventType) {
this.method = method;
this.threadMode = threadMode;
this.eventType = eventType;
}
public Method getMethod() {
return method;
}
public MyThreadMode getThreadMode() {
return threadMode;
}
public Class<?> getEventType() {
return eventType;
}
}
public enum MyThreadMode {
// 谁发送的事件就在谁的线程中执行
POSTING,
// 在主线程中执行
MAIN,
// 在子线程中执行
ASYNC
}
测试代码
public class MainActivity extends AppCompatActivity {
private TextView tv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MyEventBus.getDefault().register(this);
tv = findViewById(R.id.tv);
tv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this,MainActivity2.class);
MainActivity.this.startActivity(intent);
}
});
}
@MySubscribe(threadMode = MyThreadMode.MAIN)
public void get(MessageEvent event){
Log.e("xsl", event.getStr() );
tv.setText(event.getStr());
}
@Override
protected void onDestroy() {
super.onDestroy();
MyEventBus.getDefault().unregister(this);
}
}
public class MainActivity2 extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
}
public void send(View view){
new Thread(new Runnable() {
@Override
public void run() {
MyEventBus.getDefault().post(new MessageEvent("我有一个小毛驴，我一直都不骑！"));
}
}).start();
}
}
结果
image.png
<https://github.com/xslandlr/AndroidStudy>
** MyEventBus **
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