如何使用回调编写一个简单的 react-native 本机模块

问题描述：

如何以最简单的方式完成这项工作，我无法将回调发送到 react-native，可能我遗漏了一些东西.

How to get this work, in the simplest way, I have trouble getting the callback send to react-native, probably I'm missing something.

@ReactMethod
public void testCallback(Callback cb) {

String sampleText = "Java is fun";
int textLength = sampleText.length();
    try{
        cb.invoke(textLength);
    }catch (Exception e){
        cb.invoke("err");
    }
}

在本机方面

var getNativeCallback = require('react-native-native-callback');


getNativeCallback.testCallback(function (result){
    console.log(result)
})

答

我不得不面对同样的问题，最后我不得不采取不同的方法，显然，@ReactProp 没有接受回调类型.

I have to face the same problem, and finally I have to take a different approach, as apparently, there is no Callback type accepted for @ReactProp.

相反，我使用了事件"方式，以便从 Android 原生到 React Native 进行响应通信.

Instead I used the 'Events' way, in order to have response communication from Android native to React Native.

在 Android 端，我设置了一个 SendEvent 函数，可以根据需要方便地触发:

In the Android side I set up a SendEvent function conveniently fired as it needs:

private void sendEventToReactFromAndroid(ReactContext reactContext,String eventName, @Nullable WritableMap params) {
    reactContext.getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class).emit(eventName, params);
}

@Override
public void customAndroidListenerFunction() {
    sendEvent(mcontext, "EventName", null);

}

然后在 React 端，如果你愿意，你会期待这个事件和参数:

Then in the React side, you will expect this event, and parameters if you may like:

var {DeviceEventEmitter} = require('react-native');
...
componentWillMount: function() {
    DeviceEventEmitter.addListener('EventName', function(e: Event) {
        console.log("Received event loud and clear in the React Native side!");
    });
},
...

希望有所帮助.

如何使用回调编写一个简单的 react-native 本机模块

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