Question

我有一个可以随时间变化的JSON和使用case Class可能不方便，因为每次JSON更改时我都需要更改它的结构。

例如，如果我有这样的JSON：

val json= """{
  "accounts": [
  { "emailAccount": {
    "accountName": "YMail",
    "username": "USERNAME",
    "password": "PASSWORD",
    "url": "imap.yahoo.com",
    "minutesBetweenChecks": 1,
    "usersOfInterest": ["barney", "betty", "wilma"]
  }},
  { "emailAccount": {
    "accountName": "Gmail",
    "username": "USER",
    "password": "PASS",
    "url": "imap.gmail.com",
    "minutesBetweenChecks": 1,
    "usersOfInterest": ["pebbles", "bam-bam"]
  }}
  ]
}"""

我可以通过以下方式访问它：

val parsedJSON = parse(json)
parsedJSON.accounts(0).emailAccount.accountName

Answer 1

circe的光学模块几乎完全支持您要求的语法：

import io.circe.optics.JsonPath.root

val accountName = root.accounts.at(0).emailAccount.accountName.as[String]

然后，如果您已获得此JSON值（我使用了circe的JSON文字支持，但您也可以使用io.circe.jawn.parse解析字符串（parse函数）获取您正在使用的Json值：

import io.circe.Json, io.circe.literal._

val json: Json = json"""{
  "accounts": [
  { "emailAccount": {
    "accountName": "YMail",
    "username": "USERNAME",
    "password": "PASSWORD",
    "url": "imap.yahoo.com",
    "minutesBetweenChecks": 1,
    "usersOfInterest": ["barney", "betty", "wilma"]
  }},
  { "emailAccount": {
    "accountName": "Gmail",
    "username": "USER",
    "password": "PASS",
    "url": "imap.gmail.com",
    "minutesBetweenChecks": 1,
    "usersOfInterest": ["pebbles", "bam-bam"]
  }}
  ]
}"""

您可以尝试访问帐户名称，如下所示：

scala> accountName.getOption(json)
res0: Option[String] = Some(YMail)

因为circe-optics建立在Monocle上，你会得到一些其他不错的功能，比如不可变更新：

scala> accountName.modify(_.toLowerCase)(json)
res2: io.circe.Json =
{
  "accounts" : [
    {
      "emailAccount" : {
        "accountName" : "ymail",
        ...

等等。

更新：circe旨在实现模块化，因此您只需支付＆＃34;你需要的东西。上面的示例需要类似于以下SBT设置：

scalaVersion := "2.11.8"

val circeVersion = "0.4.1"

libraryDependencies ++= Seq(
  "io.circe" %% "circe-core" % circeVersion,
  "io.circe" %% "circe-jawn" % circeVersion,
  "io.circe" %% "circe-literal" % circeVersion,
  "io.circe" %% "circe-optics" % circeVersion
)

...或Maven：

<dependency>
  <groupId>io.circe</groupId>
  <artifactId>circe-core_2.11</artifactId>
  <version>0.4.1</version>
</dependency>
<dependency>
  <groupId>io.circe</groupId>
  <artifactId>circe-jawn_2.11</artifactId>
  <version>0.4.1</version>
</dependency>
<dependency>
  <groupId>io.circe</groupId>
  <artifactId>circe-literal_2.11</artifactId>
  <version>0.4.1</version>
</dependency>
<dependency>
  <groupId>io.circe</groupId>
  <artifactId>circe-optics_2.11</artifactId>
  <version>0.4.1</version>
</dependency>

如何解析没有案例类的JSON Scala

1 个答案: