ReactNative项目构建分析与思考之native_modules.gradle

上一篇文章分析完 react-native-gradle-plugin 后，我们知道了react-native-gradle-plugin 主要是对依赖环境，以及RN的依赖版本进行管理。
本篇文章来接着分析 native_modules.gradle 这个脚本，这个脚本是React Native构建中比较重要的一个角色。

native_modules.gradle

这是一个源码形式的脚本文件，虽然只有一个文件，但是实际上要比插件的逻辑还要复杂一些， 源码如下

import groovy.json.JsonSlurper
import org.gradle.initialization.DefaultSettings
import org.apache.tools.ant.taskdefs.condition.Os

def generatedFileName = "PackageList.java"
def generatedFilePackage = "com.facebook.react"
def generatedFileContentsTemplate = """
package $generatedFilePackage;

import android.app.Application;
import android.content.Context;
import android.content.res.Resources;

import com.facebook.react.ReactPackage;
import com.facebook.react.shell.MainPackageConfig;
import com.facebook.react.shell.MainReactPackage;
import java.util.Arrays;
import java.util.ArrayList;

{{ packageImports }}

public class PackageList {
  private Application application;
  private ReactNativeHost reactNativeHost;
  private MainPackageConfig mConfig;

  public PackageList(ReactNativeHost reactNativeHost) {
    this(reactNativeHost, null);
  }

  public PackageList(Application application) {
    this(application, null);
  }

  public PackageList(ReactNativeHost reactNativeHost, MainPackageConfig config) {
    this.reactNativeHost = reactNativeHost;
    mConfig = config;
  }

  public PackageList(Application application, MainPackageConfig config) {
    this.reactNativeHost = null;
    this.application = application;
    mConfig = config;
  }

  private ReactNativeHost getReactNativeHost() {
    return this.reactNativeHost;
  }

  private Resources getResources() {
    return this.getApplication().getResources();
  }

  private Application getApplication() {
    if (this.reactNativeHost == null) return this.application;
    return this.reactNativeHost.getApplication();
  }

  private Context getApplicationContext() {
    return this.getApplication().getApplicationContext();
  }

  public ArrayList<ReactPackage> getPackages() {
    return new ArrayList<>(Arrays.<ReactPackage>asList(
      new MainReactPackage(mConfig){{ packageClassInstances }}
    ));
  }
}
"""

def cmakeTemplate = """# This code was generated by [React Native CLI](https://www.npmjs.com/package/@react-native-community/cli)

cmake_minimum_required(VERSION 3.13)
set(CMAKE_VERBOSE_MAKEFILE on)

{{ libraryIncludes }}

set(AUTOLINKED_LIBRARIES
  {{ libraryModules }}
)
"""

def rncliCppTemplate = """/**
 * This code was generated by [React Native CLI](https://www.npmjs.com/package/@react-native-community/cli).
 *
 * Do not edit this file as changes may cause incorrect behavior and will be lost
 * once the code is regenerated.
 *
 */

#include "rncli.h"
{{ rncliCppIncludes }}

namespace facebook {
namespace react {

{{ rncliReactLegacyComponentNames }}

std::shared_ptr<TurboModule> rncli_ModuleProvider(const std::string moduleName, const JavaTurboModule::InitParams &params) {
{{ rncliCppModuleProviders }}
  return nullptr;
}

void rncli_registerProviders(std::shared_ptr<ComponentDescriptorProviderRegistry const> providerRegistry) {
{{ rncliCppComponentDescriptors }}
{{ rncliReactLegacyComponentDescriptors }}
  return;
}

} // namespace react
} // namespace facebook
"""

def rncliHTemplate = """/**
 * This code was generated by [React Native CLI](https://www.npmjs.com/package/@react-native-community/cli).
 *
 * Do not edit this file as changes may cause incorrect behavior and will be lost
 * once the code is regenerated.
 *
 */

#pragma once

#include <ReactCommon/JavaTurboModule.h>
#include <ReactCommon/TurboModule.h>
#include <jsi/jsi.h>
#include <react/renderer/componentregistry/ComponentDescriptorProviderRegistry.h>

namespace facebook {
namespace react {

std::shared_ptr<TurboModule> rncli_ModuleProvider(const std::string moduleName, const JavaTurboModule::InitParams &params);
void rncli_registerProviders(std::shared_ptr<ComponentDescriptorProviderRegistry const> providerRegistry);

} // namespace react
} // namespace facebook
"""

class ReactNativeModules {
  private Logger logger
  private String packageName
  private File root
  private ArrayList<HashMap<String, String>> reactNativeModules
  private ArrayList<String> unstable_reactLegacyComponentNames
  private HashMap<String, ArrayList> reactNativeModulesBuildVariants
  private String reactNativeVersion

  private static String LOG_PREFIX = ":ReactNative:"

  ReactNativeModules(Logger logger, File root) {
    this.logger = logger
    this.root = root

    def (nativeModules, reactNativeModulesBuildVariants, androidProject, reactNativeVersion) = this.getReactNativeConfig()
    this.reactNativeModules = nativeModules
    this.reactNativeModulesBuildVariants = reactNativeModulesBuildVariants
    this.packageName = androidProject["packageName"]
    this.unstable_reactLegacyComponentNames = androidProject["unstable_reactLegacyComponentNames"]
    this.reactNativeVersion = reactNativeVersion
  }

  /**
   * Include the react native modules android projects and specify their project directory
   */
  void addReactNativeModuleProjects(DefaultSettings defaultSettings) {
    reactNativeModules.forEach { reactNativeModule ->
      String nameCleansed = reactNativeModule["nameCleansed"]
      String androidSourceDir = reactNativeModule["androidSourceDir"]
      defaultSettings.include(":${nameCleansed}")
      defaultSettings.project(":${nameCleansed}").projectDir = new File("${androidSourceDir}")
    }
  }

  /**
   * Adds the react native modules as dependencies to the users `app` project
   */
  void addReactNativeModuleDependencies(Project appProject) {
    reactNativeModules.forEach { reactNativeModule ->
      def nameCleansed = reactNativeModule["nameCleansed"]
      def dependencyConfiguration = reactNativeModule["dependencyConfiguration"]
      appProject.dependencies {
        if (reactNativeModulesBuildVariants.containsKey(nameCleansed)) {
          reactNativeModulesBuildVariants
            .get(nameCleansed)
            .forEach { buildVariant ->
              if(dependencyConfiguration != null) {
                "${buildVariant}${dependencyConfiguration}"
              } else {
                "${buildVariant}Implementation" project(path: ":${nameCleansed}")
              }
            }
        } else {
          if(dependencyConfiguration != null) {
            "${dependencyConfiguration}"
          } else {
             implementation project(path: ":${nameCleansed}")
          }
        }
      }
    }
  }

  /**
   * Code-gen a java file with all the detected ReactNativePackage instances automatically added
   *
   * @param outputDir
   * @param generatedFileName
   * @param generatedFileContentsTemplate
   */
  void generatePackagesFile(File outputDir, String generatedFileName, String generatedFileContentsTemplate) {
    ArrayList<HashMap<String, String>> packages = this.reactNativeModules
    String packageName = this.packageName

    String packageImports = ""
    String packageClassInstances = ""

    if (packages.size() > 0) {
      def interpolateDynamicValues = {
        it
                // Before adding the package replacement mechanism,
                // BuildConfig and R classes were imported automatically
                // into the scope of the file. We want to replace all
                // non-FQDN references to those classes with the package name
                // of the MainApplication.
                //
                // We want to match "R" or "BuildConfig":
                //  - new Package(R.string…),
                //  - Module.configure(BuildConfig);
                //    ^ hence including (BuildConfig|R)
                // but we don't want to match "R":
                //  - new Package(getResources…),
                //  - new PackageR…,
                //  - new Royal…,
                //    ^ hence excluding \w before and after matches
                // and "BuildConfig" that has FQDN reference:
                //  - Module.configure(com.acme.BuildConfig);
                //    ^ hence excluding . before the match.
                .replaceAll(~/([^.\w])(BuildConfig|R)([^\w])/, {
                  wholeString, prefix, className, suffix ->
                    "${prefix}${packageName}.${className}${suffix}"
                })
      }
      packageImports = packages.collect {
        "// ${it.name}\n${interpolateDynamicValues(it.packageImportPath)}"
      }.join('\n')
      packageClassInstances = ",\n      " + packages.collect {
        interpolateDynamicValues(it.packageInstance)
      }.join(",\n      ")
    }

    String generatedFileContents = generatedFileContentsTemplate
      .replace("{{ packageImports }}", packageImports)
      .replace("{{ packageClassInstances }}", packageClassInstances)

    outputDir.mkdirs()
    final FileTreeBuilder treeBuilder = new FileTreeBuilder(outputDir)
    treeBuilder.file(generatedFileName).newWriter().withWriter { w ->
      w << generatedFileContents
    }
  }

  void generateCmakeFile(File outputDir, String generatedFileName, String generatedFileContentsTemplate) {
    ArrayList<HashMap<String, String>> packages = this.reactNativeModules
    String packageName = this.packageName
    String codegenLibPrefix = "react_codegen_"
    String libraryIncludes = ""
    String libraryModules = ""

    if (packages.size() > 0) {
      libraryIncludes = packages.collect {
        if (it.libraryName != null && it.cmakeListsPath != null) {
          // If user provided a custom cmakeListsPath, let's honor it.
          String nativeFolderPath = it.cmakeListsPath.replace("CMakeLists.txt", "")
          "add_subdirectory($nativeFolderPath ${it.libraryName}_autolinked_build)"
        } else {
          null
        }
      }.minus(null).join('\n')
      libraryModules = packages.collect {
        it.libraryName ? "${codegenLibPrefix}${it.libraryName}" : null
      }.minus(null).join('\n  ')
    }

    String generatedFileContents = generatedFileContentsTemplate
      .replace("{{ libraryIncludes }}", libraryIncludes)
      .replace("{{ libraryModules }}", libraryModules)

    outputDir.mkdirs()
    final FileTreeBuilder treeBuilder = new FileTreeBuilder(outputDir)
    treeBuilder.file(generatedFileName).newWriter().withWriter { w ->
      w << generatedFileContents
    }
  }

  void generateRncliCpp(File outputDir, String generatedFileName, String generatedFileContentsTemplate) {
    ArrayList<HashMap<String, String>> packages = this.reactNativeModules
    ArrayList<String> unstable_reactLegacyComponentNames = this.unstable_reactLegacyComponentNames
    String rncliCppIncludes = ""
    String rncliCppModuleProviders = ""
    String rncliCppComponentDescriptors = ""
    String rncliReactLegacyComponentDescriptors = ""
    String rncliReactLegacyComponentNames = ""
    String codegenComponentDescriptorsHeaderFile = "ComponentDescriptors.h"
    String codegenReactComponentsDir = "react/renderer/components"

    if (packages.size() > 0) {
      rncliCppIncludes = packages.collect {
        if (!it.libraryName) {
          return null
        }
        def result = "#include <${it.libraryName}.h>"
        if (it.componentDescriptors && it.componentDescriptors.size() > 0) {
          result += "\n#include <${codegenReactComponentsDir}/${it.libraryName}/${codegenComponentDescriptorsHeaderFile}>"
        }
        result
      }.minus(null).join('\n')
      rncliCppModuleProviders = packages.collect {
        it.libraryName ? """  auto module_${it.libraryName} = ${it.libraryName}_ModuleProvider(moduleName, params);
  if (module_${it.libraryName} != nullptr) {
    return module_${it.libraryName};
  }""" : null
      }.minus(null).join("\n")
      rncliCppComponentDescriptors = packages.collect {
        def result = ""
        if (it.componentDescriptors && it.componentDescriptors.size() > 0) {
          result += it.componentDescriptors.collect {
            "  providerRegistry->add(concreteComponentDescriptorProvider<${it}>());"
          }.join('\n')
        }
        result
      }.join("\n")
    }

    rncliReactLegacyComponentDescriptors = unstable_reactLegacyComponentNames.collect {
      "  providerRegistry->add(concreteComponentDescriptorProvider<UnstableLegacyViewManagerInteropComponentDescriptor<${it}>>());"
    }.join("\n")
    rncliReactLegacyComponentNames = unstable_reactLegacyComponentNames.collect {
      "extern const char ${it}[] = \"${it}\";"
    }.join("\n")
    if (unstable_reactLegacyComponentNames && unstable_reactLegacyComponentNames.size() > 0) {
      rncliCppIncludes += "\n#include <react/renderer/components/legacyviewmanagerinterop/UnstableLegacyViewManagerInteropComponentDescriptor.h>"
    }

    String generatedFileContents = generatedFileContentsTemplate
      .replace("{{ rncliCppIncludes }}", rncliCppIncludes)
      .replace("{{ rncliCppModuleProviders }}", rncliCppModuleProviders)
      .replace("{{ rncliCppComponentDescriptors }}", rncliCppComponentDescriptors)
      .replace("{{ rncliReactLegacyComponentDescriptors }}", rncliReactLegacyComponentDescriptors)
      .replace("{{ rncliReactLegacyComponentNames }}", rncliReactLegacyComponentNames)

    outputDir.mkdirs()
    final FileTreeBuilder treeBuilder = new FileTreeBuilder(outputDir)
    treeBuilder.file(generatedFileName).newWriter().withWriter { w ->
      w << generatedFileContents
    }
  }

  void generateRncliH(File outputDir, String generatedFileName, String generatedFileContentsTemplate) {
    String generatedFileContents = generatedFileContentsTemplate

    outputDir.mkdirs()
    final FileTreeBuilder treeBuilder = new FileTreeBuilder(outputDir)
    treeBuilder.file(generatedFileName).newWriter().withWriter { w ->
      w << generatedFileContents
    }
  }

  /**
   * Runs a specified command using Runtime exec() in a specified directory.
   * Throws when the command result is empty.
   */
  String getCommandOutput(String[] command, File directory) {
    try {
      def output = ""
      def cmdProcess = Runtime.getRuntime().exec(command, null, directory)
      def bufferedReader = new BufferedReader(new InputStreamReader(cmdProcess.getInputStream()))
      def buff = ""
      def readBuffer = new StringBuffer()
      while ((buff = bufferedReader.readLine()) != null) {
        readBuffer.append(buff)
      }
      output = readBuffer.toString()
      if (!output) {
        this.logger.error("${LOG_PREFIX}Unexpected empty result of running '${command}' command.")
        def bufferedErrorReader = new BufferedReader(new InputStreamReader(cmdProcess.getErrorStream()))
        def errBuff = ""
        def readErrorBuffer = new StringBuffer()
        while ((errBuff = bufferedErrorReader.readLine()) != null) {
          readErrorBuffer.append(errBuff)
        }
        throw new Exception(readErrorBuffer.toString())
      }
      return output
    } catch (Exception exception) {
      this.logger.error("${LOG_PREFIX}Running '${command}' command failed.")
      throw exception
    }
  }

  /**
   * Runs a process to call the React Native CLI Config command and parses the output
   */
  ArrayList<HashMap<String, String>> getReactNativeConfig() {
    if (this.reactNativeModules != null) return this.reactNativeModules

    ArrayList<HashMap<String, String>> reactNativeModules = new ArrayList<HashMap<String, String>>()
    HashMap<String, ArrayList> reactNativeModulesBuildVariants = new HashMap<String, ArrayList>()

    /**
     * Resolve the CLI location from Gradle file
     *
     * @todo: Sometimes Gradle can be called outside of the JavaScript hierarchy (-p flag) which
     * will fail to resolve the script and the dependencies. We should resolve this soon.
     *
     * @todo: `fastlane` has been reported to not work too.
     */
    def cliResolveScript = "try {console.log(require('@react-native-community/cli').bin);} catch (e) {console.log(require('react-native/cli').bin);}"
    String[] nodeCommand = ["node", "-e", cliResolveScript]
    def cliPath = this.getCommandOutput(nodeCommand, this.root)

    String[] reactNativeConfigCommand = ["node", cliPath, "config"]
    def reactNativeConfigOutput = this.getCommandOutput(reactNativeConfigCommand, this.root)

    def json
    try {
      json = new JsonSlurper().parseText(reactNativeConfigOutput)
    } catch (Exception exception) {
      throw new Exception("Calling `${reactNativeConfigCommand}` finished with an exception. Error message: ${exception.toString()}. Output: ${reactNativeConfigOutput}");
    }
    def dependencies = json["dependencies"]
    def project = json["project"]["android"]
    def reactNativeVersion = json["version"]

    if (project == null) {
      throw new Exception("React Native CLI failed to determine Android project configuration. This is likely due to misconfiguration. Config output:\n${json.toMapString()}")
    }

    def engine = new groovy.text.SimpleTemplateEngine()

    dependencies.each { name, value ->
      def platformsConfig = value["platforms"];
      def androidConfig = platformsConfig["android"]

      if (androidConfig != null && androidConfig["sourceDir"] != null) {
        this.logger.info("${LOG_PREFIX}Automatically adding native module '${name}'")

        HashMap reactNativeModuleConfig = new HashMap<String, String>()
        def nameCleansed = name.replaceAll('[~*!\'()]+', '_').replaceAll('^@([\\w-.]+)/', '$1_')
        reactNativeModuleConfig.put("name", name)
        reactNativeModuleConfig.put("nameCleansed", nameCleansed)
        reactNativeModuleConfig.put("androidSourceDir", androidConfig["sourceDir"])
        reactNativeModuleConfig.put("packageInstance", androidConfig["packageInstance"])
        reactNativeModuleConfig.put("packageImportPath", androidConfig["packageImportPath"])
        reactNativeModuleConfig.put("libraryName", androidConfig["libraryName"])
        reactNativeModuleConfig.put("componentDescriptors", androidConfig["componentDescriptors"])
        reactNativeModuleConfig.put("cmakeListsPath", androidConfig["cmakeListsPath"])

        if (androidConfig["buildTypes"] && !androidConfig["buildTypes"].isEmpty()) {
          reactNativeModulesBuildVariants.put(nameCleansed, androidConfig["buildTypes"])
        }
        if(androidConfig.containsKey("dependencyConfiguration")) {
          reactNativeModuleConfig.put("dependencyConfiguration", androidConfig["dependencyConfiguration"])
        } else if (project.containsKey("dependencyConfiguration")) {
          def bindings = ["dependencyName": nameCleansed]
          def template = engine.createTemplate(project["dependencyConfiguration"]).make(bindings)

          reactNativeModuleConfig.put("dependencyConfiguration", template.toString())
        }

        this.logger.trace("${LOG_PREFIX}'${name}': ${reactNativeModuleConfig.toMapString()}")

        reactNativeModules.add(reactNativeModuleConfig)
      } else {
        this.logger.info("${LOG_PREFIX}Skipping native module '${name}'")
      }
    }

    return [reactNativeModules, reactNativeModulesBuildVariants, json["project"]["android"], reactNativeVersion];
  }
}


/*
 * Sometimes Gradle can be called outside of JavaScript hierarchy. Detect the directory
 * where build files of an active project are located.
 */
def projectRoot = rootProject.projectDir

def autoModules = new ReactNativeModules(logger, projectRoot)

def reactNativeVersionRequireNewArchEnabled(autoModules) {
    def rnVersion = autoModules.reactNativeVersion
    def regexPattern = /^(\d+)\.(\d+)\.(\d+)(?:-(\w+(?:[-.]\d+)?))?$/

    if (rnVersion =~ regexPattern) {
        def result = (rnVersion =~ regexPattern).findAll().first()

        def major = result[1].toInteger()
        if (major > 0 && major < 1000) {
            return true
        }
    }
    return false
}

/** -----------------------
 *    Exported Extensions
 * ------------------------ */

ext.applyNativeModulesSettingsGradle = { DefaultSettings defaultSettings ->
  autoModules.addReactNativeModuleProjects(defaultSettings)
}

ext.applyNativeModulesAppBuildGradle = { Project project ->
  autoModules.addReactNativeModuleDependencies(project)

  def generatedSrcDir = new File(buildDir, "generated/rncli/src/main/java")
  def generatedCodeDir = new File(generatedSrcDir, generatedFilePackage.replace('.', '/'))
  def generatedJniDir = new File(buildDir, "generated/rncli/src/main/jni")

  task generatePackageList {
    doLast {
      autoModules.generatePackagesFile(generatedCodeDir, generatedFileName, generatedFileContentsTemplate)
    }
  }

  task generateNewArchitectureFiles {
    doLast {
      autoModules.generateCmakeFile(generatedJniDir, "Android-rncli.cmake", cmakeTemplate)
      autoModules.generateRncliCpp(generatedJniDir, "rncli.cpp", rncliCppTemplate)
      autoModules.generateRncliH(generatedJniDir, "rncli.h", rncliHTemplate)
    }
  }

  preBuild.dependsOn generatePackageList
  def isNewArchEnabled = (project.hasProperty("newArchEnabled") && project.newArchEnabled == "true") ||
    reactNativeVersionRequireNewArchEnabled(autoModules)
  if (isNewArchEnabled) {
    preBuild.dependsOn generateNewArchitectureFiles
  }

  android {
    sourceSets {
      main {
        java {
          srcDirs += generatedSrcDir
        }
      }
    }
  }
}

还记得在settings.gradle中有如下代码吗？

apply from: file("../node_modules/@react-native-community/cli-platform-android/native_modules.gradle");
applyNativeModulesSettingsGradle(settings)

也就是在settings.gradle中引入了native_modules.gradle，并且随后调用了 applyNativeModulesSettingsGradle 方法。

那就以 applyNativeModulesSettingsGradle 方法为入口，来逐步的进行分析。

def autoModules = new ReactNativeModules(logger, projectRoot)

//该方法会在settings.gradle中被调用，作用是把RN需要的三方库include到settings.gradle中
ext.applyNativeModulesSettingsGradle = { DefaultSettings defaultSettings ->
    autoModules.addReactNativeModuleProjects(defaultSettings)
}

可以看到，实际上这个方法就是调用了ReactNativeModules实例中的addReactNativeModuleProjects方法，我们重点来看下ReactNativeModules类

//部分源码
class ReactNativeModules {
    //日志
    private Logger logger
    //Android包名
    private String packageName
    //根目录
    private File root
    //react-native模块
    private ArrayList<HashMap<String, String>> reactNativeModules
    //不稳定的遗留组件名称
    private ArrayList<String> unstable_reactLegacyComponentNames
    //react-native模块构建变体
    private HashMap<String, ArrayList> reactNativeModulesBuildVariants
    //react-native版本
    private String reactNativeVersion

    private static String LOG_PREFIX = ":ReactNative:"

    ReactNativeModules(Logger logger, File root) {
        this.logger = logger
        this.root = root

        //获取react-native配置
        def (nativeModules, reactNativeModulesBuildVariants, androidProject, reactNativeVersion) = this.getReactNativeConfig()
        this.reactNativeModules = nativeModules
        this.reactNativeModulesBuildVariants = reactNativeModulesBuildVariants
        this.packageName = androidProject["packageName"]
        this.unstable_reactLegacyComponentNames = androidProject["unstable_reactLegacyComponentNames"]
        this.reactNativeVersion = reactNativeVersion
    }
}

首先在创建ReactNativeModules实例的时候，会调用getReactNativeConfig 方法获取react-native的配置信息，随后把这些配置信息保存到ReactNativeModules实例中。

我们接着看一下 getReactNativeConfig 方法
下面的代码我增加了些注释，方便大家理解

    /**
     * 执行react-native config命令，获取react-native配置
     * @return
     */
    ArrayList<HashMap<String, String>> getReactNativeConfig() {
        //如果已经获取过配置，直接返回
        if (this.reactNativeModules != null) return this.reactNativeModules

        //存储react-native模块
        ArrayList<HashMap<String, String>> reactNativeModules = new ArrayList<HashMap<String, String>>()
        //存储react-native模块构建变体
        HashMap<String, ArrayList> reactNativeModulesBuildVariants = new HashMap<String, ArrayList>()

        /**
         * 执行一段脚本，获取react-native-cli的路径
         * 最终获取的结果：xxx/node_modules/@react-native-community/cli/build/bin.js
         */
        def cliResolveScript = "try {console.log(require('@react-native-community/cli').bin);} catch (e) {console.log(require('react-native/cli').bin);}"
        String[] nodeCommand = ["node", "-e", cliResolveScript]
        def cliPath = this.getCommandOutput(nodeCommand, this.root)
        /**
         * 执行 node xxx/node_modules/@react-native-community/cli/build/bin.js config  获取rn配置的结果
         * 这个node命令执行的逻辑比较复杂，内部的流程很多，大致上就是调用了react-native-cli的config命令，从而获取到了RN的版本，配置，依赖库等关键信息
         *
         */
        String[] reactNativeConfigCommand = ["node", cliPath, "config"]
        def reactNativeConfigOutput = this.getCommandOutput(reactNativeConfigCommand, this.root)

        def json
        try {
            //将json字符串转换成json对象
            json = new JsonSlurper().parseText(reactNativeConfigOutput)
        } catch (Exception exception) {
            throw new Exception("Calling `${reactNativeConfigCommand}` finished with an exception. Error message: ${exception.toString()}. Output: ${reactNativeConfigOutput}");
        }

        //获取react-native的依赖模块
        def dependencies = json["dependencies"]
        //获取react-native的android配置
        def project = json["project"]["android"]
        //获取react-native的版本
        def reactNativeVersion = json["version"]

        if (project == null) {
            throw new Exception("React Native CLI failed to determine Android project configuration. This is likely due to misconfiguration. Config output:\n${json.toMapString()}")
        }

        def engine = new groovy.text.SimpleTemplateEngine()
        //处理react-native的依赖模块
        dependencies.each { name, value ->
            //获取react-native模块的android配置
            def platformsConfig = value["platforms"];
            //获取android配置
            def androidConfig = platformsConfig["android"]

            if (androidConfig != null && androidConfig["sourceDir"] != null) {
                this.logger.info("${LOG_PREFIX}Automatically adding native module '${name}'")

                HashMap reactNativeModuleConfig = new HashMap<String, String>()
                def nameCleansed = name.replaceAll('[~*!\'()]+', '_').replaceAll('^@([\\w-.]+)/', '$1_')
                reactNativeModuleConfig.put("name", name)
                reactNativeModuleConfig.put("nameCleansed", nameCleansed)
                reactNativeModuleConfig.put("androidSourceDir", androidConfig["sourceDir"])
                reactNativeModuleConfig.put("packageInstance", androidConfig["packageInstance"])
                reactNativeModuleConfig.put("packageImportPath", androidConfig["packageImportPath"])
                reactNativeModuleConfig.put("libraryName", androidConfig["libraryName"])
                reactNativeModuleConfig.put("componentDescriptors", androidConfig["componentDescriptors"])
                reactNativeModuleConfig.put("cmakeListsPath", androidConfig["cmakeListsPath"])

                if (androidConfig["buildTypes"] && !androidConfig["buildTypes"].isEmpty()) {
                    reactNativeModulesBuildVariants.put(nameCleansed, androidConfig["buildTypes"])
                }
                if (androidConfig.containsKey("dependencyConfiguration")) {
                    reactNativeModuleConfig.put("dependencyConfiguration", androidConfig["dependencyConfiguration"])
                } else if (project.containsKey("dependencyConfiguration")) {
                    def bindings = ["dependencyName": nameCleansed]
                    def template = engine.createTemplate(project["dependencyConfiguration"]).make(bindings)

                    reactNativeModuleConfig.put("dependencyConfiguration", template.toString())
                }

                this.logger.trace("${LOG_PREFIX}'${name}': ${reactNativeModuleConfig.toMapString()}")

                reactNativeModules.add(reactNativeModuleConfig)
            } else {
                this.logger.info("${LOG_PREFIX}Skipping native module '${name}'")
            }
        }

        //返回数据
        return [reactNativeModules, reactNativeModulesBuildVariants, json["project"]["android"], reactNativeVersion];
    }
}

可以看到，getReactNativeConfig 主要做了以下几件事情

• 通过node命令获取react-native-cli的路径

  node -e "try {console.log(require('@react-native-community/cli').bin);} catch (e) {console.log(require('react-native/cli').bin);}"
  

  • 这里实际上就是通过node -e 执行一段js代码，上面的js代码会从当前目录的node_modules中获取cli的路径.
  • 返回值是一个路径，示例：xxx/node_modules/@react-native-community/cli/build/bin.js
• 接着执行node xxx/node_modules/@react-native-community/cli/build/bin.js config命令，获取react-native的配置信息
  • 这个node命令执行的逻辑比较复杂，内部的流程很多，后面再详细分析
  • 返回值是一个json字符串，包含了react-native的版本，配置，依赖库等关键信息
• 最后把这些配置信息处理以下保存到ReactNativeModules实例中

下面接着看一下调用 autoModules.addReactNativeModuleProjects(defaultSettings) 的 addReactNativeModuleProjects 方法的源码

/**
 * Include the react native modules android projects and specify their project directory
 */
void addReactNativeModuleProjects(DefaultSettings defaultSettings) {
    reactNativeModules.forEach { reactNativeModule ->
        String nameCleansed = reactNativeModule["nameCleansed"]
        String androidSourceDir = reactNativeModule["androidSourceDir"]

        System.out.println("nameCleansed: ${nameCleansed}, androidSourceDir: ${androidSourceDir}")
        defaultSettings.include(":${nameCleansed}")
        defaultSettings.project(":${nameCleansed}").projectDir = new File("${androidSourceDir}")
    }
}

可以看到，实际上就是把通过 getReactNativeConfig 获取到的 reactNativeModules 信息，添加到settings.gradle中
看下打印出来的值：

nameCleansed: react-native-device-info, androidSourceDir: /Users/yuzhiqiang/workspace/RN/personal/RNProjectAnalysis/node_modules/react-native-device-info/android

就相当于我们在setting.gradle中手动添加了一个模块

include ':react-native-device-info'
project(':react-native-device-info').projectDir = new File('/Users/yuzhiqiang/workspace/RN/personal/RNProjectAnalysis/node_modules/react-native-device-info/android')

同理，在app模块的build.gradle中，有如下代码

//应用了一个脚本文件
apply from: file("../../node_modules/@react-native-community/cli-platform-android/native_modules.gradle");
applyNativeModulesAppBuildGradle(project)

同样看下 applyNativeModulesAppBuildGradle 方法的源码

ext.applyNativeModulesAppBuildGradle = { Project project ->
    autoModules.addReactNativeModuleDependencies(project)

    def generatedSrcDir = new File(buildDir, "generated/rncli/src/main/java")
    def generatedCodeDir = new File(generatedSrcDir, generatedFilePackage.replace('.', '/'))
    def generatedJniDir = new File(buildDir, "generated/rncli/src/main/jni")

    task generatePackageList {
        doLast {
            autoModules.generatePackagesFile(generatedCodeDir, generatedFileName, generatedFileContentsTemplate)
        }
    }

    task generateNewArchitectureFiles {
        doLast {
            autoModules.generateCmakeFile(generatedJniDir, "Android-rncli.cmake", cmakeTemplate)
            autoModules.generateRncliCpp(generatedJniDir, "rncli.cpp", rncliCppTemplate)
            autoModules.generateRncliH(generatedJniDir, "rncli.h", rncliHTemplate)
        }
    }

    preBuild.dependsOn generatePackageList
    def isNewArchEnabled = (project.hasProperty("newArchEnabled") && project.newArchEnabled == "true") ||
            reactNativeVersionRequireNewArchEnabled(autoModules)
    if (isNewArchEnabled) {
        preBuild.dependsOn generateNewArchitectureFiles
    }

    android {
        sourceSets {
            main {
                java {
                    srcDirs += generatedSrcDir
                }
            }
        }
    }
}

首先第一步就看到了 autoModules.addReactNativeModuleDependencies(project) 方法，很明显，这个方法跟在settings.gradle中调用的方法类似，是用来添加依赖的。 源码如下：

    /**
     * 添加react-native模块依赖到app项目
     * @param appProject
     */
    void addReactNativeModuleDependencies(Project appProject) {
        reactNativeModules.forEach { reactNativeModule ->
            def nameCleansed = reactNativeModule["nameCleansed"]
            def dependencyConfiguration = reactNativeModule["dependencyConfiguration"]
            appProject.dependencies {
                if (reactNativeModulesBuildVariants.containsKey(nameCleansed)) {
                    reactNativeModulesBuildVariants
                            .get(nameCleansed)
                            .forEach { buildVariant ->
                                if (dependencyConfiguration != null) {
                                    "${buildVariant}${dependencyConfiguration}"
                                } else {
                                    System.out.println("" + nameCleansed + "${buildVariant}Implementation project(path: \":${nameCleansed}\")")
                                    "${buildVariant}Implementation" project(path: ":${nameCleansed}")
                                }
                            }
                } else {
                    if (dependencyConfiguration != null) {
                        "${dependencyConfiguration}"
                    } else {
                        // 把依赖添加到app模块里，相当于 implementation project(path: ":xxx")
                        implementation project(path: ":${nameCleansed}")
                    }
                }
            }
        }
    }

接着，再来看下 applyNativeModulesAppBuildGradle 后续的逻辑。

在完成了app模块的依赖添加之后，紧接着会声明一个generatePackageList 的task，这个task主要就是做了一件事情，就是生成一个java文件，这个java文件里面包含了所有的react-native模块的信息。

    task generatePackageList {
        doLast {
            autoModules.generatePackagesFile(generatedCodeDir, generatedFileName, generatedFileContentsTemplate)
        }
    }

来看看 generatePackagesFile 方法里的逻辑。

    /**
     * 通过上面定义的模版生成一个PackageList.java文件，替换导包和实例
     * @param outputDir
     * @param generatedFileName
     * @param generatedFileContentsTemplate
     */
    void generatePackagesFile(File outputDir, String generatedFileName, String generatedFileContentsTemplate) {
        ArrayList<HashMap<String, String>> packages = this.reactNativeModules
        String packageName = this.packageName

        String packageImports = ""
        String packageClassInstances = ""

        System.out.println("outputDir: ${outputDir}, generatedFileName: ${generatedFileName}, generatedFileContentsTemplate: ${generatedFileContentsTemplate}")
        System.out.println("packages: ${packages}")

        if (packages.size() > 0) {

            /**
             * 针对BuildConfig和R的引用，进行替换，确保使用的是正确的项目路径和包名
             */
            def interpolateDynamicValues = {
                it
                // Before adding the package replacement mechanism,
                // BuildConfig and R classes were imported automatically
                // into the scope of the file. We want to replace all
                // non-FQDN references to those classes with the package name
                // of the MainApplication.
                //
                // We want to match "R" or "BuildConfig":
                //  - new Package(R.string…),
                //  - Module.configure(BuildConfig);
                //    ^ hence including (BuildConfig|R)
                // but we don't want to match "R":
                //  - new Package(getResources…),
                //  - new PackageR…,
                //  - new Royal…,
                //    ^ hence excluding \w before and after matches
                // and "BuildConfig" that has FQDN reference:
                //  - Module.configure(com.acme.BuildConfig);
                //    ^ hence excluding . before the match.
                        .replaceAll(~/([^.\w])(BuildConfig|R)([^\w])/, { wholeString, prefix, className, suffix -> "${prefix}${packageName}.${className}${suffix}"
                        })
            }

            //拼接导包
            packageImports = packages.collect {
                "// ${it.name}\n${interpolateDynamicValues(it.packageImportPath)}"
            }.join('\n')

            System.out.println("""packageImports: ${packageImports}""")

            //拼接实例
            packageClassInstances = ",\n      " + packages.collect {
                interpolateDynamicValues(it.packageInstance)
            }.join(",\n      ")

            System.out.println("""packageClassInstances: ${packageClassInstances}""")
        }

        String generatedFileContents = generatedFileContentsTemplate
                .replace("{{ packageImports }}", packageImports)
                .replace("{{ packageClassInstances }}", packageClassInstances)

        System.out.println("generatedFileContents: ${generatedFileContents}")

        //输出文件
        outputDir.mkdirs()
        final FileTreeBuilder treeBuilder = new FileTreeBuilder(outputDir)
        treeBuilder.file(generatedFileName).newWriter().withWriter { w -> w << generatedFileContents
        }
    }

加了些注释，可以看到，实际上就是用源码中的 generatedFileContentsTemplate 模版字符串，替换了一些变量，生成了 PackageList.java 文件。 后续在执行 preBuild 任务之前，会先执行generatePackageList任务，prebuild 是 gradle 执行阶段生命周期中的一个基础任务，只要执行gradle build命令，就会执行prebuild任务，在执行 preBuild 任务之前，会先执行 generatePackageList 任务。

    //在执行 preBuild 任务之前，先执行generatePackageList任务
    preBuild.dependsOn generatePackageList

至于后面的 generateNewArchitectureFiles 任务，是用来生成一些新架构所需文件，跟上面逻辑类似。

    task generateNewArchitectureFiles {
        doLast {
            autoModules.generateCmakeFile(generatedJniDir, "Android-rncli.cmake", cmakeTemplate)
            autoModules.generateRncliCpp(generatedJniDir, "rncli.cpp", rncliCppTemplate)
            autoModules.generateRncliH(generatedJniDir, "rncli.h", rncliHTemplate)
        }
    }

    preBuild.dependsOn generatePackageList
    def isNewArchEnabled = (project.hasProperty("newArchEnabled") && project.newArchEnabled == "true") ||
            reactNativeVersionRequireNewArchEnabled(autoModules)
    if (isNewArchEnabled) {
        preBuild.dependsOn generateNewArchitectureFiles
    }

下面是生成后的代码位置

生成好的PackageList代码会在 MainApplication 中被用到。

到这里，整个流程大致上就清楚了，下面我们就可以回答下上一篇文章中提出的问题。

为什么在使用RN插件时，只需要执行一下 yarn add react-native-device-info 后就可以直接在前端代码中使用了，而不需要关心native方面的代码。

实际上在Android部分是由gradle插件以及 native_modules.gradle 脚本还有结合前端的cli工具，帮我们做了很多事情。

到这里我们基本把 native_modules.gradle 中的逻辑分析完毕了，总结一下,也能够初步的回答上面的问题了：

• 通过执行cli命令获取react-native的配置信息，其中包含了react-native的版本，配置，依赖库等关键信息
• 把react-native的依赖库信息进行处理，把模块添加到settings.gradle中，以便于后续在模块中依赖使用
• 把react-native的模块通过源码依赖的方式添加到app模块中
• 生成一个PackageList.java文件，里面包含了所有的react-native模块的信息
• 如果是新架构，还会生成一些新架构所需的文件，主要是jin相关的文件
• 最后在app模块的build.gradle中，会把生成好的PackageList.java文件引入到MainApplication中使用

这样，我们就可以在前端代码中直接使用react-native-device-info这个模块了。

到这里，算是初步对Android端RN项目构建的基本流程分析的差不多了。

本篇文章我们遗留了一个步骤中流程的分析是：执行node xxx/node_modules/@react-native-community/cli/build/bin.js config命令，获取react-native的配置信息

实际上，获取react-native的配置信息是非常重要的一个环节，是由前端cli来完成的，这个我们后续再来分析。

感谢阅读，觉有有帮助点赞支持，如果有任何疑问或建议，欢迎在评论区留言。如需转载，请注明出处：喻志强的博客 ，谢谢！文章来源地址https://www.toymoban.com/news/detail-841733.html

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