无法构建Flutter应用-棉绒渐变错误

Question

我刚刚开始使用Flutter，但是在运行默认项目时遇到了问题。我已经运行了 flutter医生，一切都很好，但是当我运行 flutter run 时，出现了gradle错误，提示“失败：构建失败，并出现异常。”

* What went wrong:
A problem occurred evaluating project ':app'.
> Could not resolve all artifacts for configuration 'classpath'.
   > Could not find lint-gradle-api.jar (com.android.tools.lint:lint-gradle-api:26.1.2).
     Searched in the following locations:
         https://jcenter.bintray.com/com/android/tools/lint/lint-gradle-api/26.1.2/lint-gradle-api-26.1.2.jar

这是我的build.gradle：

buildscript {
    repositories {
        google()
        jcenter()
    }

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

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
}

我不确定发生了什么，因为一切几乎都是开箱即用的，但是任何帮助都将不胜感激。我还尝试了flutter升级，并且一切都是最新的。