如果没有keystore可以通过在命令行输入：
keytool -genkey -alias release.keystore -keyalg RSA -validity 36500 -keystore release.keystore
release.keystore 代表名字
36500代表天数
signingConfigs {
release {
keyAlias 'enjoy'
keyPassword '123456'
// 因为是放到父级的根目录，使用rootProject
// 如果放在这个build.gradle的同级，直接使用file
storeFile rootProject.file('release.keystore')
storePassword '123456'
}
}
buildTypes {
release {
// TODO: Add your own signing config for the release build.
// Signing with the debug keys for now, so `flutter run --release` works.
signingConfig signingConfigs.release
}
}
通过命令行输入flutter build apk 进行打包
