Scala中具有类型类的DAO

Order

Product

Customer

DAO

DAO

OrderDAO

ProductDAO

trait DAO[T] {
  def create(t:T)
  ... // other CRUD operations
}
...
// DAO implementations for specific business objects
implicit object OrderDAO extends DAO[Order] {
   def create(o:Order) {...}
   ... // other CRUD operations
}
...
// create a business object in the database
def create[T](t:T)(implicit dao:DAO[T]) {dao.create(t)}

DAOs

DataSource

DAOs

objects

DataSource

DAOs

DataSource

def dataSource():DataSource = {...}

trait KeyValuable[T] {
  def toMap(t: T): Map[String, String]
}

trait DataSource

class MyDataSource extends DataSource

object DataSources {
  @volatile var dataSource: () => DataSource = () => new MyDataSource
}