ReactNative分包實踐

1. 實現思路

1. RN從本地中讀取bundle檔案進行顯示
2. 將JS檔案進行分包打包
3. Native實現頁面跳轉，每個包跳轉都為一個新的Activity
4. 進行bundle檔案基礎包與功能包的拆分，使用Google的diff_match_patch演算法生成差異檔案
5. 網路下載差異檔案進行合併
6. 展示新頁面

2. 操作步驟

Android 
1. 修改MainApplication
2. 修改MainActivity
3. 建立LocalReactActivityDelegate
4. 打第一bundle
react-native bundle --platform android --dev false --entry-file index.js --bundle-output bundle/index.android.bundle --assets-dest bundle/assets/

5. 打第二個bundle
react-native bundle --platform android --dev false --entry-file src/indexNet.js --bundle-output bundle/index1.android.bundle --assets-dest bundle/assets/
其中indexNet.js是新頁面的入口檔案
6. 使用google-diff-match-patch進行差異比對

3. 本地載入實現

1). 修改MainApplication

public class MainApplication extends Application {
  
  private static MainApplication sInstance;
  
  /**
   * 獲取當前物件
   */
  public static MainApplication getInstance() {
    return sInstance;
  }
  
  @Override
  public void onCreate() {
    super.onCreate();
    sInstance = this;
    SoLoader.init(this, /* native exopackage */ false);
  }
}

這裡主要是將Application中實現的介面取消，轉由MainActivity中提供.

2). 修改MainActivity

public class MainActivity extends ReactActivity {

    /**
     * Returns the name of the main component registered from JavaScript.
     * This is used to schedule rendering of the component.
     */
    @Override
    protected String getMainComponentName() {
        return "Unpacking";
    }
    
    @Override
    protected ReactActivityDelegate createReactActivityDelegate() {
        return new LocalReactActivityDelegate(this, getMainComponentName());
    }
}

這裡實現ReactActivity中的createReactActivityDelegate方法，自定義代理設定

3). LocalReactActivityDelegate代理程式碼

/**
 * 本地ReactActivity代理
 */
class LocalReactActivityDelegate(activity: Activity, @Nullable mainComponentName: String) :
        ReactActivityDelegate(activity, mainComponentName) {
  
  private val mReactNativeHost: ReactNativeHost = object : ReactNativeHost(MainApplication.getInstance()) {
    /**
     * 返回ReactPackage物件
     */
    override fun getPackages(): MutableList<ReactPackage> = Arrays.asList(
            MainReactPackage(),
            CustomPackage()
    )
  
    /**
     * 是否為開發
     */
    override fun getUseDeveloperSupport(): Boolean = BuildConfig.DEBUG
  
    /**
     * 返回JSBundle檔案路徑
     */
    override fun getJSBundleFile(): String? = "${Environment.getExternalStorageDirectory()}/bundle/index.android.bundle"
  }
  
  /**
   * 返回ReactNativeHost物件
   */
  override fun getReactNativeHost(): ReactNativeHost = mReactNativeHost
}

4). Native實現頁面跳轉

I. 建立CustomPackage

/**
 * 自定義ReactPackage
 */
class CustomPackage : ReactPackage {
  /**
   * 建立本地模組
   */
  override fun createNativeModules(reactContext: ReactApplicationContext?): MutableList<NativeModule>
    = Arrays.asList(PageModule(reactContext))
  
  /**
   * 建立檢視管理者
   */
  override fun createViewManagers(reactContext: ReactApplicationContext?): MutableList<ViewManager<View, ReactShadowNode<*>>>
    = Collections.emptyList()
  
}

5). 建立PageMoudle

/**
 * 頁面管理模組
 */
@ReactModule(name = "PageModule")
class PageModule(reactContext: ReactApplicationContext?) : ReactContextBaseJavaModule(reactContext) {
  override fun getName(): String = "PageModule"
  
  /**
   * 開啟網路上的模組頁面
   */
  @ReactMethod
  fun startNetActivity() {
    val intent = Intent(currentActivity, NetActivity::class.java)
    currentActivity?.startActivity(intent)
  }
  
}

6). NetActivity頁面

/**
 * 新頁面
 */
class NetActivity : ReactActivity() {
  override fun getMainComponentName(): String? {
    return "NetActivity"
  }
  
  override fun createReactActivityDelegate(): ReactActivityDelegate =
          object: ReactActivityDelegate(this, mainComponentName) {
            override fun getReactNativeHost(): ReactNativeHost = object : ReactNativeHost(MainApplication.getInstance()) {
              override fun getPackages(): MutableList<ReactPackage> = Arrays.asList(MainReactPackage())
  
              override fun getUseDeveloperSupport(): Boolean = BuildConfig.DEBUG
  
              override fun getJSBundleFile(): String? = "${Environment.getExternalStorageDirectory()}/bundle/index1.android.bundle"
            }
          }
}

7). RN中使用

修改App.js檔案

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

import React, {Component} from `react`;
import {Platform, StyleSheet, Text, View, NativeModules, TouchableOpacity} from `react-native`;

const PageModule = NativeModules.PageModule;

const instructions = Platform.select({
  ios: `Press Cmd+R to reload,
` + `Cmd+D or shake for dev menu`,
  android:
    `Double tap R on your keyboard to reload,
` +
    `Shake or press menu button for dev menu`,
});

type Props = {};
export default class App extends Component<Props> {
    startPage() {
        PageModule.startNetActivity()
    }
  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>Welcome to React Native!</Text>
        <Text style={styles.instructions}>To get started, edit App.js</Text>
        <Text style={styles.instructions}>{instructions}</Text>
                <TouchableOpacity
                    onPress={() => this.startPage()}
                >
                    <Text style={styles.instructions}>開啟新頁面</Text>
                </TouchableOpacity>
      </View>
    );
  }
}

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,
  },
});

8). 執行打包

react-native bundle --platform android --dev false --entry-file index.js --bundle-output bundle/index.android.bundle --assets-dest bundle/assets/

–platform: 平臺
–dev: 是否為開發模式
–entry-file: 入口檔案
–bundle-output: bundle輸出路徑，這裡注意bundle資料夾必須存在
–assets-dest: 資原始檔存放路徑

9). 測試

I. 生成之後將bundle資料夾拷貝至sdcard下
II. 如果想要在除錯時可用，務必修改android/app/build.gradle檔案,將bundleInDebug設定為false, 設定為false之後即不將bundle檔案打包進app

project.ext.react = [
        entryFile    : "index.js",
        bundleInDebug: false
]

III. 執行
注：此時無法開啟新的頁面，因為新頁面的js檔案不存在

4. 開啟新頁面

1). RN中建立入口檔案indexNet.js

/** @format */

import {AppRegistry} from `react-native`;
import NetJs from `./NetJs`;
import {name as appName} from `./NetActivity`;

AppRegistry.registerComponent(appName, () => NetJs);

2). RN中建立NetActivity.json檔案

{
  "name": "NetActivity",
  "displayName": "NetActivity"
}

注：此處的name和displayName應當與NetActivity.kt中的getMainComponentName方法返回的一致。

3). NetJs.js檔案內容

import React, {PureComponent} from `react`;
import {
    StyleSheet, Text,
    View
} from `react-native`;

/**
 * @FileName: NetJs
 * @Author: mazaiting
 * @Date: 2018/10/9
 * @Description:
 */
class NetJs extends PureComponent {
    render() {
        return (
            <View style={styles.container}>
                <Text>Welcome mazaiting!</Text>
            </View>
        )
    }
}

/**
 * 樣式屬性
 */
const styles = StyleSheet.create({
    container: {
        backgroundColor: `#DDD`
    }
});

/**
 * 匯出當前Module
 */
module.exports = NetJs;

4). 打包

react-native bundle --platform android --dev false --entry-file src/indexNet.js --bundle-output bundle/index1.android.bundle --assets-dest bundle/assets/

5). 拷貝檔案

將bundle資料夾直接拷貝到sdcard目錄下，此時再重新執行APP, 即可成功顯示頁面。

6). 帶來的問題

初始包太大，每個包都講RN基礎內容打包，此時應該比較差異，進行差異化分解。

5. 差異化

1). diff-match-patch主頁

2). 測試頁面

3). 依賴

  implementation `google-diff-match-patch:google-diff-match-patch:0.1`

4). 程式碼使用

const val FILE1 = "index.android"
const val FILE2 = "index1.android"
const val FILE3 = "$FILE2-$FILE1.patch"

const val FILE_DIR = "E:\android\React-Native-Study\Unpacking\bundle\"
const val SUFFIX = ".bundle"

object Patch {
  @JvmStatic
  fun main(args: Array<String>) {
    val file1 = "$FILE_DIR$FILE1$SUFFIX"
    val file2 = "$FILE_DIR$FILE2$SUFFIX"
    val file3 = "$FILE_DIR$FILE3"
    val patch = productPatch(file1, file2)
    
    productFile(file1, file3, patch)
  }
  
  /**
   * 生成檔案
   * @param fileOri 原始檔
   * @param fileDest 目標檔案
   * @param patchString 差異字串
   */
  private fun productFile(fileOri: String, fileDest: String, patchString: String?) {
    // 建立物件
    val patch = diff_match_patch()
    // 讀取檔案
    val file1 = readFile(fileOri)
    // 獲取補丁內容
    val patchText = patch.patch_fromText(patchString)
    // 應用補丁
    val patchApply = patch.patch_apply(LinkedList(patchText), file1)
    
    println("===============================================")
    println("結果：" + patchApply[0])
    // 寫入檔案內容
    writeResult(fileDest, patchApply[0].toString())
    println("===============================================")
    // 獲取執行結果陣列，true為成功，false為失敗
    val patchResult: BooleanArray = patchApply[1] as BooleanArray
    val result = StringBuilder()
    patchResult.forEach { result.append("$it  ") }
    
    println("result: $result")
  }
  
  /**
   * 寫入檔案
   * @param fileDest 目標檔案
   * @param string 檔案內容
   */
  private fun writeResult(fileDest: String, string: String) {
    // Read a file from disk and return the text contents.
    val output = FileWriter(fileDest)
    val writer = BufferedWriter(output)
    try {
      writer.write(string)
    } finally {
      writer.close()
      output.close()
    }
  }
  
  /**
   * 生成差異patch
   * @param fileOri 原始檔
   * @param fileDest 目標檔案
   * @return 差異字串
   */
  private fun productPatch(fileOri: String, fileDest: String): String? {
    // 建立物件
    val diff = diff_match_patch()
    // 讀取基礎檔案內容
    val file1 = readFile(fileOri)
    // 讀取目標檔案內容
    val file2 = readFile(fileDest)
    // 進行差異化
    val diffString = diff.diff_main(file1, file2, true)
    // 陣列長度大於2執行
    if (diffString.size > 2) {
      diff.diff_cleanupSemantic(diffString)
    }
    
    println(diffString)
    
    println("===============================================")
    // 生成patch內容
    val patchString = diff.patch_make(file1, diffString)
    println(patchString)
    
    println("===============================================")
    // 將patch內容轉為字串
    val patchText = diff.patch_toText(patchString)
    println(patchText)
    
    return patchText
  }
  
  /**
   * 讀取檔案
   * @param filename 檔名
   * @return 檔案內容
   */
  @Throws(IOException::class)
  private fun readFile(filename: String): String {
    // Read a file from disk and return the text contents.
    val sb = StringBuilder()
    val input = FileReader(filename)
    val bufRead = BufferedReader(input)
    try {
      var line = bufRead.readLine()
      while (line != null) {
        sb.append(line).append(`
`)
        line = bufRead.readLine()
      }
    } finally {
      bufRead.close()
      input.close()
    }
    return sb.toString()
  }
}