android – 如何理解React Native中“向Javascript发送事件”中的“ReactContext”

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我想使用方法sendEvent(),但是如何获取ReactContext reactContext?
  1. private void sendEvent(ReactContext reactContext,String eventName,@Nullable WritableMap params) {reactContext
  2. .getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class)
  3. .emit(eventName,params);}

解决方法

我通过在MainActivity类上保存对ReactInstanceManager的静态引用,并添加了一个public static getContext()方法来暂时解决了这个问题.它感觉不对,但似乎有效.
  1. public final class MainActivity extends ReactActivity {
  2.  
  3. private static ReactInstanceManager sReactInstanceManager = null;
  4.  
  5. /* [...] */
  6.  
  7. @Override
  8. protected ReactInstanceManager createReactInstanceManager() {
  9. ReactInstanceManager manager = super.createReactInstanceManager();
  10. sReactInstanceManager = manager;
  11. return manager;
  12. }
  13.  
  14. public static ReactContext getContext() {
  15. if (sReactInstanceManager == null){
  16. // This doesn't seem to happen ...
  17. throw new IllegalStateException("Instance manager not available");
  18. }
  19. final ReactContext context = sReactInstanceManager.getCurrentReactContext();
  20. if (context == null){
  21. // This really shouldn't happen ...
  22. throw new IllegalStateException("React context not available");
  23. }
  24. return context;
  25. }
  26.  
  27. /* [...] */
  28. }

createReactInstanceManager()由ReactActivity的onCreate()方法调用,所以我认为可以安全地假设sReactInstanceManager将指向正确的实例,但不要相信我的话.

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