android - React-Native:未启用 Hermes

Question

我正在尝试启用 Hermes在一个新项目中，但尽管我在 android/app/build.gradle 中启用了它，但它没有启用。如文档中所述，我无法在应用程序中看到 Engine: Hermes 文本。我正在使用 WebStorm 2019.2 项目模板。

App.js:

// imports
const App = () => {
  return (
    <Fragment>
      <StatusBar barStyle="dark-content"/>
      <SafeAreaView>
        <ScrollView
          contentInsetAdjustmentBehavior="automatic"
          style={styles.scrollView}>
          <Header/>
          {global.HermesInternal == null ? null : (
            <View style={styles.engine}>
              <Text style={styles.footer}>Engine: Hermes</Text>
            </View>
          )}
          // rest of the default ui omitted
        </ScrollView>
      </SafeAreaView>
    </Fragment>
  );
};

export default App;

babel.cofig.js:

module.exports = {
  presets: ['module:metro-react-native-babel-preset'],
};

metro.config.js:

module.exports = {
  transformer: {
    getTransformOptions: async () => ({
      transform: {
        experimentalImportSupport: false,
        inlineRequires: false
      }
    })
  }
};

package.js:

{
  "name": "hermes",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "react-native start",
    "test": "jest",
    "lint": "eslint ."
  },
  "dependencies": {
    "react": "16.8.6",
    "react-native": "0.60.4"
  },
  "devDependencies": {
    "@babel/core": "^7.5.5",
    "@babel/runtime": "^7.5.5",
    "@react-native-community/eslint-config": "^0.0.5",
    "babel-jest": "^24.8.0",
    "eslint": "^6.1.0",
    "jest": "^24.8.0",
    "metro-react-native-babel-preset": "^0.55.0",
    "react-test-renderer": "16.8.6"
  },
  "jest": {
    "preset": "react-native"
  }
}

您可以从 here checkout 并测试项目.

更新:

升级到 RN v0.62.2 后，我设法启用了 Hermes 和自动链接。这是我当前的设置和依赖项:

• Package.json
• 项目级别 build.gradle
• 模块级别 build.gradle

Answer 1

根据您开始项目的方式，您可能需要转到 android/gradle.properties 并更改expo.jsEngine=jsc到expo.jsEngine=hermes

确保清理 gradle:cd android && ./gradlew clean && cd ..

这就是启用 Hermes 所需的全部内容。要检查是否正确，您可以在应用程序安装后使用 HermesInternal 全局变量

const isHermes = () => !!global.HermesInternal;
console.log("isHermesEnabled:", isHermes());