如何创建一个android的react-native组件(一)

刚刚接触react-native不到一月,从一开始照着React Native上文档的例子熟悉每一个控件的使用,到页面跳转,跳转到android原生Activity,再到自己实现一些简单的原生的android react-native组件,这是我上传到npm的两个组件(react-native-gotoactivity-android 和react-native-segmented-android),可以使用下面的命令下载

$ npm install react-native-segmented-android --save
$ npm install react-native-gotoactivity-android --save

先说一下实现原理,如果是实现类似与Android的Toast与Dialog等一般继承ReactContextBaseJavaModule来实现,如果是ViewGroup类型(有子View)的,例如ScrollView等则继承ViewGroupManager,如果是View类型(无子View)例如Text,Image等则继承BaseViewManager 或者SimpleViewManager等。

我们以ToastAndroid为例子,来讲解如何创建原生android react-native组件,其实facebook官方团队已经实现了,这个比较简单,容易理解。其实我主要就是说明实现的步骤;如有错误,请大家多多反馈。希望与大家共同学习进步。

开始

Step 1 - 新建react-native工程 ReactNativeToastAndroid

$ react-native init ReactNativeToastAndroid

Step 2 - 将新建的工程导入android studio然后新建空library(以react-native-toast-android为library的名称)之所以要新建一个library而不在ReactNativeToastAndroid工程中写呢,主要是为了方便上传到npm及github上方便其他开发者使用,一般以react-native-xxx-android命名方便识别这是react-native组件。

Step 3 - 新建空library(以react-native-toast-android为library的名称)
在library目录下的build.gradle中添加react-native的依赖

// file: android/react-native-toast-android/build.gradle
...

dependencies {
    ...
    compile 'com.facebook.react:react-native:0.16.+' 
}

Step 4 - 继承ReactContextBaseJavaModule ,大家可以很明显的发现show()方法上多了一个‘@ReactMethod’,加上了‘@ReactMethod'的方法可以被js调用。

public class AndroidToastModule extends ReactContextBaseJavaModule {

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

    public AndroidToastModule(ReactApplicationContext reactContext) {
        super(reactContext);
    }

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

    @Override
    public Map getConstants() {
        final Map constants = MapBuilder.newHashMap();
        constants.put(DURATION_SHORT_KEY, Toast.LENGTH_SHORT);
        constants.put(DURATION_LONG_KEY, Toast.LENGTH_LONG);
        return constants;
    }

    @ReactMethod
    public void show(String message, int duration) {
        Toast.makeText(getReactApplicationContext(), message, duration).show();
    }
}

Step 5 - 继承ReactPackage,注意createNativeModules()返回的是加入了 AndroidToastModule 的集合,createJSModules()与createViewManagers()返回的都是空集合,如果Step 4 步继承的是BaseViewManager或其子类,那么createViewManagers()中返回的就是加入了BaseViewManager的集合,其他的就是空集合,一般情况createJSModules()的返回值都是空集合。

public class AndroidToastPackage implements ReactPackage {

    @Override
    public List createNativeModules(ReactApplicationContext reactContext) {
        return Arrays.asList(new AndroidToastModule(reactContext));
    }

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

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

Step 6 - 新建ToastForAndroid.js,文件位置
‘ android/react-native-toast-android/ToastForAndroid.js ’代码如下,然后在 ‘android/react-native-toast-android/’下运行如下命令生成package.json文件

$ npm init      //生成package.json文件
'use strict';

var RCTToastAndroid = require('NativeModules').ToastForAndroid;


var ToastForAndroid = {

  SHORT: RCTToastAndroid.SHORT,
  LONG: RCTToastAndroid.LONG,

  show: function (
    message: string,
    duration: number
  ): void {
    RCTToastAndroid.show(message, duration);
  },

};

module.exports = ToastForAndroid;

Step 7 - 复制ToastForAndroid.js 文件到‘/ReactNativeToastAndroid/ ’ 目录下,如下是index.android.js代码,然后运行测试

'use strict';
 
var React = require('react-native');
var {
  AppRegistry,
  StyleSheet,
  Text,
  Dimensions,
  TouchableHighlight,
  View,
} = React;
 
// var ToastForAndroid = require('react-native-toast-android');
var ToastForAndroid = require('./ToastForAndroid');
var deviceWidth = Dimensions.get('window').width;
var deviceHeight = Dimensions.get('window').height;
 
var ReactNativeSegmentedExample = React.createClass({
   _onPressButton:function(){
          ToastForAndroid.show('点击了!', ToastAndroid.SHORT)
      }); 
   },
  render: function() {
    return (
      renderButton: function() {
        return (
          
            click goto activity
          
        );
      },
    );
  }
});
...

Step 9 - 测试成功,在目录‘ /android/react-native-toast-android/ ’下运行命令:

$ npm adduser   //增加npm用户
$ npm publish   //上传react-naive-toast-android到npm上

Step 10 - 其他开发者使用你上传到npm上的组件方法(github上的模板)

Example

'use strict';
 
var React = require('react-native');
var {
  AppRegistry,
  StyleSheet,
  Text,
  Dimensions,
  TouchableHighlight,
  View,
} = React;
 
var ToastForAndroid = require('react-native-toast-android');
// var ToastForAndroid = require('./ToastForAndroid');
var deviceWidth = Dimensions.get('window').width;
var deviceHeight = Dimensions.get('window').height;
 
var ReactNativeSegmentedExample = React.createClass({
   _onPressButton:function(){
          ToastForAndroid.show('点击了!', ToastAndroid.SHORT)
      }); 
   },
  render: function() {
    return (
      renderButton: function() {
        return (
          
            click goto activity
          
        );
      },
    );
  }
});
...

Install

Step 1 - Install the npm package

$ npm install react-native-toast-android --save

Step 2 - Update Gradle Settings

// file: android/settings.gradle
...

include ':react-native-toast-android', ':app'
project(':react-native-toast-android').projectDir = new File(rootProject.projectDir,'../node_modules/react-native-toast-android')

Step 3 - Update app Gradle Build

// file: android/app/build.gradle
...

dependencies {
    ...
    compile project(':react-native-toast-android')
}

Step 4 - Register React Package

...
import com.higo.zhangyp.toast.AndroidForToastPackage; // <-- import

public class MainActivity extends FragmentActivity implements DefaultHardwareBackBtnHandler {

    private ReactInstanceManager mReactInstanceManager;
    private ReactRootView mReactRootView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mReactRootView = new ReactRootView(this);
        mReactInstanceManager = ReactInstanceManager.builder()
                .setApplication(getApplication())
                .setBundleAssetName("index.android.bundle")
                .setJSMainModuleName("index.android")
                .addPackage(new MainReactPackage())
                .addPackage(new AndroidForToastPackage()) // <-- Register package here
                .setUseDeveloperSupport(BuildConfig.DEBUG)
                .setInitialLifecycleState(LifecycleState.RESUMED)
                .build();
        mReactRootView.startReactApplication(mReactInstanceManager, "AwesomeProject", null);
        setContentView(mReactRootView);
    }
...

2.如何自定义react-native的android组件(二)
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