YAML解析

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开发技巧

1. YAML文件的结构

参考 Working with YAML: Configuration Files

2. Snake Yaml

通过SnakeYaml，可以在Scala/Java代码中解析一个yaml文件。

假设一个yaml文件内容如下：

name: CCC
age: 26
city: TRUE
height: 0.015
# details 是一个map
details:
  first_name: chuchu
  last_name: chen
  home: 泰兴

下面，我们将展示如何解析这个yaml文件

2.1 将yaml转换成Bean

一个yaml实际上是一个Map结构，它可以对应到一个实现定义的Bean，现在我们定义一个名为SpeedyConfig的Bean:

import scala.beans.BeanProperty
class SpeedyConfig extends Serializable {
  @BeanProperty var name: String = "Unknown name"
  @BeanProperty var age: Int = -1
  @BeanProperty var city: String = "Unknown city"
  @BeanProperty var height: Float = 0
  @BeanProperty var details: util.HashMap[String, Object] = null
}

然后，将yaml文件的内容填充到这个Bean中：

val stream = getClass.getResourceAsStream("/sample.yaml")
val yaml = new Yaml(new Constructor(classOf[SpeedyConfig]))
val config: SpeedyConfig = yaml.load(stream).asInstanceOf[SpeedyConfig]
println(s"${config.getName}, ${config.getAge}, ${config.getCity}")
println(config.getDetails)

输出如下：

2.2 将yaml转化为HashMap结构

val stream = getClass.getResourceAsStream("/sample.yaml")
val yaml = new Yaml()
val obj = yaml.load(stream).asInstanceOf[util.HashMap[String, Object]]
val stringValue   = obj.get("name")
val intValue      = obj.get("age").asInstanceOf[Int]
val booleanValue  = obj.get("city").asInstanceOf[Boolean]
val floatValue    = obj.get("height").asInstanceOf[Double].toFloat
val mapValue = obj.get("details").asInstanceOf[util.HashMap[String, Object]]
println(s"name    -> ${stringValue}, " +
        s"age     -> ${intValue}, " +
        s"city    -> ${booleanValue}, " +
        s"height  -> ${floatValue}")
println(s"map -> ${mapValue}")

运行输出为：