Android Studio offline为Gradle添加Android插件`

我使用 Android Studio 3.1.2 具有 Gradle 4.4 而且必须强制 Gradle 待办事项 离线工作 ,因为当我正常(在线)使用它时,同步需要很长时间,而且会失败。起初,我遇到了以下错误:

No cached version of com.android.tools.build:gradle:3.1.2 available for offline mode.
Disable Gradle 'offline mode' and sync project

所以我下载了 gradle-3.1.2.jar ,放入 <project root>/libs/ 和更改 build.gradle 将我的项目复制到此状态:

buildscript {

    repositories {
        google()
        jcenter()
        flatDir {
            dirs 'libs'
        }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
    }
}

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

现在似乎解决了之前的错误,但又出现了另一个错误:

Unable to load class 'com.android.tools.lint.gradle.api.ToolingRegistryProvider'.
Possible causes for this unexpected error include:<ul><li>Gradle's dependency cache may be corrupt (this sometimes occurs after a network connection timeout.)
Re-download dependencies and sync project (requires network)</li><li>The state of a Gradle build process (daemon) may be corrupt. Stopping all Gradle daemons may solve this problem.
Stop Gradle build processes (requires restart)</li><li>Your project may be using a third-party plugin which is not compatible with the other plugins in the project or the version of Gradle requested by the project.</li></ul>In the case of corrupt Gradle processes, you can also try closing the IDE and then killing all Java processes.

我怎样才能解决这个问题?

编辑

我知道正常的方式是在线工作,至少在第一次构建时是这样。但必须有一种方法可以离线添加它。难道没有这样的方法吗?