scala中用implicit实现依赖注入

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import scala.collection.mutable/** * Created by xiaojun on 2015/2/17. */object ScalaDemo extends App {  case class User(userId: Int, userName: String)  class UserDao {    var users = mutable.HashMap((1, User(1, "aaa")), (2, User(2, "bbb")), (3, User(3, "ccc")))    def findById(userId: Int) = users.get(userId)    def findAll() = users    def updateById(u: User) = users.update(u.userId, u)  }  implicit val userDao = new UserDao  class UserService(implicit dao: UserDao) {    def getAllUsers() = dao.findAll()    def updateUser(u: User) = dao.updateById(u)  }  //这里构造函数不需要传入UserDao的实例,会自动将上面定义的userDao注入到UserService实例中  val service = new UserService  println(service.getAllUsers())  //更新users中userid=1的元组  service.updateUser(User(1, "AAA"))  println(service.getAllUsers())  //新建一个UserService实例service2,打印它可以看到和service打印的users集合石一致的,说明他们用的是同一个userDao实例  val service2 = new UserService  println(service2.getAllUsers())}

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