导入android.support.v4.app.ActivityCompat;

这是我添加“ simple_permissions”软件包时看到的错误。我怎样才能解决这个问题？我最近升级了flutter，在升级之前，它曾经工作得很好。/root/flutter/.pub-cache/hosted/pub.dartlang.org/simple_permissions-0.1.9/android/src/main/java/com/ethras/simplepermissions/SimplePermissionsPlugin.java:9：错误：找不到符号导入android.support.v4.app.ActivityCompat;

/root/flutter/.pub-cache/hosted/pub.dartlang.org/simple_permissions-0.1.9/android/src/main/java/com/ethras/simplepermissions/SimplePermissionsPlugin.java:9: error: cannot find symbol
import android.support.v4.app.ActivityCompat;

  symbol:   class ActivityCompat
  location: package android.support.v4.app
/root/flutter/.pub-cache/hosted/pub.dartlang.org/simple_permissions-0.1.9/android/src/main/java/com/ethras/simplepermissions/SimplePermissionsPlugin.java:10: error: package android.support.v4.content does not exist
import android.support.v4.content.ContextCompat;
                                 ^
/root/flutter/.pub-cache/hosted/pub.dartlang.org/simple_permissions-0.1.9/android/src/main/java/com/ethras/simplepermissions/SimplePermissionsPlugin.java:156: error: cannot find symbol
        ActivityCompat.requestPermissions(activity, perm, 0);
        ^
  symbol:   variable ActivityCompat
  location: class SimplePermissionsPlugin
/root/flutter/.pub-cache/hosted/pub.dartlang.org/simple_permissions-0.1.9/android/src/main/java/com/ethras/simplepermissions/SimplePermissionsPlugin.java:163: error: cannot find symbol
        return PackageManager.PERMISSION_GRANTED == ContextCompat.checkSelfPermission(activity, permission);
  symbol:   variable ContextCompat
  location: class SimplePermissionsPlugin
/root/flutter/.pub-cache/hosted/pub.dartlang.org/simple_permissions-0.1.9/android/src/main/java/com/ethras/simplepermissions/SimplePermissionsPlugin.java:171: error: cannot find symbol
            if (ActivityCompat.shouldShowRequestPermissionRationale(registrar.activity(), permission)) {
                ^
  symbol:   variable ActivityCompat
  location: class SimplePermissionsPlugin
/root/flutter/.pub-cache/hosted/pub.dartlang.org/simple_permissions-0.1.9/android/src/main/java/com/ethras/simplepermissions/SimplePermissionsPlugin.java:175: error: cannot find symbol
                if (ActivityCompat.checkSelfPermission(registrar.context(), permission) == PackageManager.PERMISSION_GRANTED) {
                    ^
  symbol:   variable ActivityCompat
  location: class SimplePermissionsPlugin
6 errors

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':simple_permissions:compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.
* 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
The built failed likely due to AndroidX incompatibilities in a plugin. The tool is about to try using Jetfier to solve the incompatibility.
[!] Flutter tried to create the file `android/settings_aar.gradle`, but failed.
To manually update `settings.gradle`, follow these steps:
    1. Copy `settings.gradle` as `settings_aar.gradle`
    2. Remove the following code from `settings_aar.gradle`:
        def localPropertiesFile = new File(rootProject.projectDir, "local.properties")
        def properties = new Properties()
        assert localPropertiesFile.exists()
        localPropertiesFile.withReader("UTF-8") { reader -> properties.load(reader) }
        def flutterSdkPath = properties.getProperty("flutter.sdk")
        assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
        apply from: "$flutterSdkPath/packages/flutter_tools/gradle/app_plugin_loader.gradle"
Exception: Please create the file and run this command again.
Exited (sigterm)