理解Spring的FactoryBean 和 ContextAware接口.

FactoryBean

一句话就是FactoryBean用于返回其他对象实例的,而不是自身类型的实例.

这份笔记试图打造最强的clojure小抄,keep refactoring it…

理解ES搜索中JSON DSL有助于自己写JSON查询,特别是手写复杂嵌套json.

• diffs in es 2.x and es 5.x
• query dsl
• aggr query

merge two map and sum its values

多个map合并,key相同时则value相加

val map1 = Map(1 -> 1, 2 -> 2)
val map2 = Map(1 -> 11, 3 -> 3)
val map3 = Map(1 -> 111, 3 -> 3)

val mapList = List(map1, map2, map3)

val merged = mapList.reduce((m1, m2) =>
  m1 ++ m2.map { case (k, v) => k -> (v + m1.getOrElse(k, 0)) }
)

some notes on scala future, includes:

• future
• executor context
• await future result
• callback
• recover