[Android React Native] javascript에서 native 함수 호출

1. Manager 생성

package com.rncli;

import com.facebook.react.ReactPackage;
import com.facebook.react.bridge.JavaScriptModule;
import com.facebook.react.bridge.NativeModule;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.uimanager.ViewManager;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Manager implements ReactPackage {

    @Override
    public List<ViewManager> createViewManagers(ReactApplicationContext reactContext) {
        return Collections.emptyList();
    }

    @Override
    public List<NativeModule> createNativeModules(
            ReactApplicationContext reactContext) {
        List<NativeModule> modules = new ArrayList<>();

        modules.add(new Module(reactContext));

        return modules;
    }


    // Backward compatibility
    public List<Class<? extends JavaScriptModule>> createJSModules() {
        return new ArrayList<>();
    }
}

2. Module 생성

package com.rncli;

import android.widget.Toast;

import com.facebook.react.bridge.NativeModule;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContext;
import com.facebook.react.bridge.ReactContextBaseJavaModule;
import com.facebook.react.bridge.ReactMethod;

import java.util.Map;
import java.util.HashMap;

import android.util.Log;

public class Module extends ReactContextBaseJavaModule {
    private static ReactApplicationContext reactContext;

    private static final String DURATION_SHORT_KEY = "SHORT";
    private static final String DURATION_LONG_KEY = "LONG";

    Module(ReactApplicationContext context) {
        super(context);
        reactContext = context;
    }


    @Override
    public String getName() {
        return "module";
    }

    @ReactMethod
    public void hello() {
       // your code
    }
    
    @ReactMethod(isBlockingSynchronousMethod = true)
    public String hi() {
       // your code
    }

}

3. MainApplication 수정

        @Override
        protected List<ReactPackage> getPackages() {
          @SuppressWarnings("UnnecessaryLocalVariable")
          List<ReactPackage> packages = new PackageList(this).getPackages();
          packages.add(new Manager()); // 추가

          return packages;
        }

4. App.js에서 호출

import { NativeModules } from 'react-native';

NativeModules.module.hello();
var r = NativeModules.module.hi();