1.在原有 Android 项目中嵌入 ReactNative 模块

ReactNative的发展已经进入了很多开发者视野，作为一名原生开发者更是对 RN 充满了无限的好奇和期待,
本节将详细讲述如何将一个原生的 Android App 项目嵌入最新的 RN 模块

1. 准备开始

1.  一个已有的 Android 原生项目
2. 已经配置好的原生 Android 开发环境和 node.js已经 RN 环境
3. 改造之后的流程图

图片

2.开始改造

在原生 Android 项目的在app/build.gradle文件中，添加React Native依赖：

compile"com.facebook.react:react-native:+

加入.so 库

ndk {
    abiFilters "armeabi-v7a", "x86"
}

在工程目录下找到工程的 build.gradle文件中，添加 maven依赖

allprojects {
    repositories {
        jcenter()
        maven {
            // All of React Native (JS, Android binaries) is installed from npm
            url "$rootDir/node_modules/react-native/android"
        }
    }
}

3. 在 app 目录里添加需要的权限

 
 /**设置调试 的权限**/

4.添加 FaceBook 的 ReactNative 调试的 activity

2. 编写原生的 ReactNative 模块，废话不多说，直接上代码

package com.allen.reactapp;

import android.app.Activity;
import android.os.Bundle;

import com.facebook.react.LifecycleState;
import com.facebook.react.ReactInstanceManager;
import com.facebook.react.ReactRootView;
import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
import com.facebook.react.shell.MainReactPackage;

/**
 * 作者: allen on 16/7/31.
 */
public  class MyReactActivity extends Activity implements DefaultHardwareBackBtnHandler {
    private ReactRootView mReactRootView;
    private ReactInstanceManager mReactInstanceManager;

    @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())
                /**
                 * http://stackoverflow.com/questions/37951246/react-native-cannot-find-development-server-integrating-existing-android-app
                 * 调试模式下,建议直接写成 true 吧,我就因为这个错误,调了两天原因
                 */
//                .setUseDeveloperSupport(BuildConfig.DEBUG)
                .setUseDeveloperSupport(true)
                .setInitialLifecycleState(LifecycleState.RESUMED)
                .build();
        mReactRootView.startReactApplication(mReactInstanceManager, "myreactactivity", null);

        setContentView(mReactRootView);
    }

    @Override
    public void invokeDefaultOnBackPressed() {
        super.onBackPressed();
    }
    @Override
    protected void onPause() {
        super.onPause();

        if (mReactInstanceManager != null) {
            mReactInstanceManager.onHostPause();
        }
    }

    @Override
    protected void onResume() {
        super.onResume();

        if (mReactInstanceManager != null) {
            mReactInstanceManager.onHostResume(this, this);
        }
    }

    @Override
    public void onBackPressed() {
        if (mReactInstanceManager != null) {
            mReactInstanceManager.onBackPressed();
        } else {
            super.onBackPressed();
        }
    }


}

到此为止我们的Android项目Activity和配置文件以及完成了最基本的配置方法了。

========================================================================

3. 下面配置工程项目的 RN开发环境

1. 先后顺序依次执行一下命令

 $ npm init

该命令会创建一个package.json文件，并且提示我们输入一些信息，默认不输入即可，不过name必须要为全英文小写哦，

然后再依次去执行以下命令

 $ npm install --save react
 $ npm install --save react-native
 $ curl -o .flowconfig https://raw.githubusercontent.com/facebook/react-native/master/.flowconfig

创建完成后，去工程目录下修改 package.json
在scripts标签那边添加如下代码:

"start":"node_modules/react-native/packager/packager.sh"

package_json

3. 工程目录下创建 index.android.js 由于是测试代码直接 Copy FaceBook 的源码



/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */

import React, { Component } from 'react';
import {
  AppRegistry,
  StyleSheet,
  Text,
  View
} from 'react-native';

class AwesomeProject extends Component {
  render() {
    return (
      
        
          Welcome to React Native!
        
        
          我是 原生项目嵌入的 ReactNative
        
        
          Press Cmd+R to reload,{'\n'}
          Cmd+D or shake for dev menu
        
      
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
});

AppRegistry.registerComponent('myreactactivity', () => AwesomeProject);

注意：此处需要修改注册的入口保持一致，我的是 my_react_activity

4.检查以上所有步骤，有无遗漏，如果正常，接下来就可以顺利的运行你的混合 APP 了，如果还不行，你需要检查你的姿势是否正确？

运行你的 APP

1. 在项目的工程路径运行以下命令来启动你的开发服务器

react-native start

或者执行

npm start

2. android studio 调试你的 APP
3. 演示效果图

===================

错误解决：

  Process: com.allen.reactapp, PID: 20469
java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: Could not connect to development server.
Try the following to fix the issue:
Ensure that the packager server is running
Ensure that your device/emulator is connected to your machine and has USB debugging enabled - run 'adb devices' to see a list of connected devices
If you're on a physical device connected to the same machine, run 'adb reverse tcp:8081 tcp:8081' to forward requests from your device
If your device is on the same Wi-Fi network, set 'Debug server host & port for device' in 'Dev settings' to y
at com.facebook.react.ReactInstanceManagerImpl.createReactContext(ReactInstanceManagerImpl.java:911)
at com.facebook.react.ReactInstanceManagerImpl.access$700(ReactInstanceManagerImpl.java:100)
at com.facebook.react.ReactInstanceManagerImpl$ReactContextInitAsyncTask.doInBackground(ReactInstanceManagerImpl.java:197)
at com.facebook.react.ReactInstanceManagerImpl$ReactContextInitAsyncTask.doInBackground(ReactInstanceManagerImpl.java:180)
at android.os.AsyncTask$2.call(AsyncTask.java:295)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: Could not connect to development server.
Try the following to fix the issue:
Ensure that the packager server is running
Ensure that your device/emulator is connected to your machine and has USB debugging enabled - run 'adb devices' to see a list of connected devices
If you're on a physical device connected to the same machine, run 'adb reverse tcp:8081 tcp:8081' to forward requests from your device
If your device is on the same Wi-Fi network, set 'Debug server host & port for device' in 'Dev settings' to y
at com.facebook.react.common.futures.SimpleSettableFuture.get(SimpleSettableFuture.java:68)
at com.facebook.react.ReactInstanceManagerImpl.createReactContext(ReactInstanceManagerImpl.java:882)
    ... 9 more
Caused by: java.lang.RuntimeException: Could not connect to development server.
Try the following to fix the issue:
Ensure that the packager server is running
Ensure that your device/emulator is connected to your machine and has USB debugging enabled - run 'adb devices' to see a list of connected devices

解决办法：
.setUseDeveloperSupport(true) 调试模式下,建议直接写成 true 吧,

签名打包混合 APP
1. 将 js 文件存入 bundle 一起打包
执行命令：

curl -k "http://localhost:8081/index.android.bundle"> reactapp/src/main/assets/index.android.bundle

执行完命令成功，在 assets目录应该看到 index.android.bundle文件

Android studio 执行打包过程，作为一名 Android 老司机我就不再具体描述了

原 Android 移植 React Native 项目地址

Android 项目中嵌入 ReactNative 模块