启动 flutter项目时报Could not find com.android.tools.build:gradle:3.2.1.

Error running Gradle:
ProcessException: Process "D:\Android\APP path\flutter_app2\flutter_app2\android\gradlew.bat" exited abnormally:

> Configure project :app

Project evaluation failed including an error in afterEvaluate {}. Run with --stacktrace for details of the afterEvaluate {} error.

FAILURE: Build failed with an exception.

* Where:
Build file 'D:\Android\APP path\flutter_app2\flutter_app2\android\app\build.gradle' line: 25

* What went wrong:
A problem occurred evaluating project ':app'.
> Could not resolve all artifacts for configuration 'classpath'.
   > Could not find com.android.tools.build:gradle:3.2.1.
     Searched in the following locations:
       - https://maven.aliyun.com/repository/jcenter/com/android/tools/build/gradle/3.2.1/gradle-3.2.1.pom
       - https://maven.aliyun.com/repository/jcenter/com/android/tools/build/gradle/3.2.1/gradle-3.2.1.jar
       - http://maven.aliyun.com/nexus/content/groups/public/com/android/tools/build/gradle/3.2.1/gradle-3.2.1.pom
       - http://maven.aliyun.com/nexus/content/groups/public/com/android/tools/build/gradle/3.2.1/gradle-3.2.1.jar
     Required by:
         unspecified:unspecified:unspecified

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full
insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 3s
Picked up _JAVA_OPTIONS: -Djava.NET.preferIPv4Stack=true
  Command: D:\Android\APP path\flutter_app2\flutter_app2\android\gradlew.bat app:properties

Please review your Gradle project setup in the android/ folder.

大致意思是说：运行Gradle时出错，导致构建flutter构建失败

原因是因为获取不到 com.android.tools.build:gradle:3.2.1

原因一：

获取不到的原因一般是因为在中国没办法访问谷歌资源（有外网，等的除外），此时的解决办法是 改用阿里的镜像。

分两步：

• 第一步：修改掉项目下的 android目录下的 build.gradle 文件，把 google() 和 jcenter()这两行去掉。
  并在下面添加阿里的链接 （注意：有两处修改）

  maven { url 'https://maven.aliyun.com/repository/google' }
  maven { url 'https://maven.aliyun.com/repository/jcenter' }
  maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
  

  如下：

  buildscript {
      repositories {
  //        google()
  //        jcenter()
  		// 添加
          maven { url 'https://maven.aliyun.com/repository/google' }
          maven { url 'https://maven.aliyun.com/repository/jcenter' }
          maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
      }
  
      dependencies {
          classpath 'com.android.tools.build:gradle:3.2.1'
      }
  }
  
  allprojects {
      repositories {
  //        google()
  //        jcenter()
  //        maven {
  //            url 'https://google.bintray.com/exoplayer/'
  //        }
  		// 添加
          maven { url 'https://maven.aliyun.com/repository/google' }
          maven { url 'https://maven.aliyun.com/repository/jcenter' }
          maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
      }
  }
  
  rootProject.buildDir = '../build'
  subprojects {
      project.buildDir = "${rootProject.buildDir}/${project.name}"
  }
  subprojects {
      project.evaluationDependsOn(':app')
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  
  

• 第二步：修改 Flutter SDK 包下的 flutter.gradle 文件
  路径根据你的sdk存放位置，例如我的是D:\SDK\Flutter\packages\flutter_tools\gradle\flutter.gradle
  同样将 google()和 jcenter() 修改为阿里的链接

  maven { url 'https://maven.aliyun.com/repository/jcenter' }
  maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
  

  如下：

  buildscript {
      repositories {
          //google()
          //jcenter()
          // 添加
  		maven { url 'https://maven.aliyun.com/repository/jcenter' }
  		maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.2.1'
      }
  }
  

至此，在国内没办法访问谷歌资源的问题就解决了

然而，我的问题并没解决

仔细看报错信息后，发现找不到以下资源地址

    -  https://maven.aliyun.com/repository/jcenter/com/android/tools/build/gradle/3.2.1/gradle-3.2.1.pom
    -  https://maven.aliyun.com/repository/jcenter/com/android/tools/build/gradle/3.2.1/gradle-3.2.1.jar
    -  http://maven.aliyun.com/nexus/content/groups/public/com/android/tools/build/gradle/3.2.1/gradle-3.2.1.pom
    -  http://maven.aliyun.com/nexus/content/groups/public/com/android/tools/build/gradle/3.2.1/gradle-3.2.1.jar

看到这里说明阿里链接是配置上了的，之所以找不到是因为gradle-3.2.1这个3.2.1版本太高了，应该是最新的

阿里连接中的gradle最高版本好像才3.1.2，所以获取不到

所以，解决办法是将项目下的android目录下的build.gradle文件和flutter SDK包下的flutter.gradle文件中的gradle版本改为阿里镜像中存在的版本

	dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
    }

来自于 https://blog.csdn.net/qq_33684444/article/details/86656301