jcenter访问超时下载不了时，用国内镜像下载解决

用flutter create flutterdemo1无法运行android项目，下载超时

修改build.gradle,以下是原本的配置信息

buildscript {
    ext.kotlin_version = '1.2.71'
    repositories {
        google()
        jcenter()

    }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

rootProject.buildDir = '../build'
subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
    project.evaluationDependsOn(':app')
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

修改成以下的配置信息

buildscript {
    ext.kotlin_version = '1.2.71'
    repositories {
        maven{ url'http://maven.aliyun.com/nexus/content/groups/public/' }
        maven{ url'http://maven.aliyun.com/nexus/content/repositories/jcenter'}
        google()
        jcenter()

    }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

allprojects {
    repositories {
        maven{ url'http://maven.aliyun.com/nexus/content/groups/public/' }
        maven{ url'http://maven.aliyun.com/nexus/content/repositories/jcenter'}
        google()
        jcenter()
    }
}

rootProject.buildDir = '../build'
subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
    project.evaluationDependsOn(':app')
}

task clean(type: Delete) {
    delete rootProject.buildDir
}