调用原生模块

1.自定义模块继承ReactContextBaseJavaModule

public class XXX extends ReactContextBaseJavaModule {
    //构造方法
    public XXX(ReactApplicationContext reactContext) {
        super(reactContext);
    }

    //重写getName，返回值为Js中调用的控件名称
    @Override
    public String getName() {
    return "ToastAndroid";
    }

    //返回一些常量
     @Override
    public Map getConstants() {
        final Map constants = new HashMap<>();
        constants.put(String, Onjrct);
        return constants;
    }

    //需加注解关键字ReactMethod
    @ReactMethod
    public void show(String message, int duration) {
        //TODO

  }
}

2.注册模块继承ReactPackage

public class XXX implements ReactPackage {

 @Override
 public List> createJSModules() {
    return Collections.emptyList();
  }

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

  @Override
  public List createNativeModules(
                              ReactApplicationContext reactContext) {
    List modules = new ArrayList<>();
    modules.add(new XXX(reactContext));
    return modules;
  }

在Application中的getPackage()方法中实例化注册模块
代码如下

   @Override
    protected List getPackages() {
        return Arrays.asList(
                new MainReactPackage(),
                new XXX()
        );
    }

3.在RN中使用

import { NativeModules } from 'react-native';

var xxx = NativeModules.XXX;