这个scala代码中发生了什么

时间：2018-06-02 01:56:01

标签： java scala jackson deserialization

我正在尝试在此链接中运行代码，但是我收到以下错误。不确定我做错了什么。

Using Jackson to (De)-serialize a Scala Case Class 

/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/bin/java
"-javaagent:/Users/Jaisantosh/Library/Application
Support/JetBrains/Toolbox/apps/IDEA-C/ch-0/181.4668.68/IntelliJ IDEA
CE.app/Contents/lib/idea_rt.jar=49300:/Users/Jaisantosh/Library/Application
Support/JetBrains/Toolbox/apps/IDEA-C/ch-0/181.4668.68/IntelliJ IDEA
CE.app/Contents/bin" -Dfile.encoding=UTF-8 -classpath
/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/lib/tools.jar:/Users/Jaisantosh/Desktop/springapps/prsr/target/scala-2.12/classes:/Users/Jaisantosh/.sbt/boot/scala-2.12.6/lib/scala-library.jar:/Users/Jaisantosh/.sbt/boot/scala-2.12.6/lib/scala-reflect.jar:/Users/Jaisantosh/.ivy2/cache/com.thoughtworks.paranamer/paranamer/bundles/paranamer-2.8.jar:/Users/Jaisantosh/.ivy2/cache/com.fasterxml.jackson.module/jackson-module-scala_2.12/bundles/jackson-module-scala_2.12-2.9.5.jar:/Users/Jaisantosh/.ivy2/cache/com.fasterxml.jackson.module/jackson-module-paranamer/bundles/jackson-module-paranamer-2.9.5.jar:/Users/Jaisantosh/.ivy2/cache/com.fasterxml.jackson.core/jackson-databind/bundles/jackson-databind-2.9.5.jar:/Users/Jaisantosh/.ivy2/cache/com.fasterxml.jackson.core/jackson-core/bundles/jackson-core-2.9.5.jar:/Users/Jaisantosh/.ivy2/cache/com.fasterxml.jackson.core/jackson-annotations/bundles/jackson-annotations-2.9.5.jar
pars objc[5094]: Class JavaLaunchHelper is implemented in both
/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/bin/java
(0x1019674c0) and
/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home/jre/lib/libinstrument.dylib
(0x1019eb4e0). One of the two will be used. Which one is undefined.
Exception in thread "main"
com.fasterxml.jackson.databind.JsonMappingException: Cannot
deserialize Class pars$Person$3 (of type local/anonymous) as a Bean 
at [Source: (String)"{"FName":"Mad", "LName": "Max"}"; line: 1,
column: 1]  at
com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:305)
    at
com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DerializerCache.java:268)
    at
com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCacheValueDeserializer(DeserializerCache.java:244)
    at
com.fasterxml.jackson.databind.deser.DeserializerCache.findValueDeserializer(DeserializerCache.java:142)
    at
com.fasterxml.jackson.databind.DeserializationContext.findRootValueDeserializer(DeserializationContext.java:477)
    at
com.fasterxml.jackson.databind.ObjectMapper._findRootDeserializer(ObjectMapper.java:4178)
    at
com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3997)
    at
com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3030)
    at
com.fasterxml.jackson.module.scala.experimental.ScalaObjectMapper.readValue(ScalaObjectMapper.scala:190)
    at
com.fasterxml.jackson.module.scala.experimental.ScalaObjectMapper.readValue$(ScalaObjectMapper.scala:189)
    at pars$$anon$1.readValue(pars.scala:9)     at
pars$.jsonToType(pars.scala:11)     at pars$.main(pars.scala:17)    at
pars.main(pars.scala) Caused by: java.lang.IllegalArgumentException:
Cannot deserialize Class pars$Person$3 (of type local/anonymous) as a
Bean    at
com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.isPotentialBeanType(BeanDeserializerFactory.java:875)
    at
com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.createBeanDeserializer(BeanDeserializerFactory.java:131)
    at
com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer2(DeserializerCache.java:411)
    at
com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer(DeserializerCache.java:349)
    at
com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DeserializerCache.java:264)
    ... 12 more

使用退出代码1完成处理

如何解决问题？

import com.fasterxml.jackson.annotation.JsonProperty
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.module.scala.DefaultScalaModule
import com.fasterxml.jackson.module.scala.experimental.ScalaObjectMapper

def jsonToType[T](json:String)(implicit m: Manifest[T]) :T = {
   val objectMapper = new ObjectMapper() with ScalaObjectMapper
   objectMapper.registerModule(DefaultScalaModule)
   objectMapper.readValue[T](json)
}

  case class Person(@JsonProperty("name") Name:String, @JsonProperty("age") Age:Int)

val personName = jsonToType[Person](jsonString).name

SBT 

name := "prsr"

version := "0.1"

scalaVersion := "2.12.6"

libraryDependencies ++= Seq(
  "com.fasterxml.jackson.core" % "jackson-databind" % "2.9.5",
  "com.fasterxml.jackson.module" %% "jackson-module-scala" % "2.9.5"
)

1 个答案:

答案 0 :(得分：0)

看起来您的地图无效。 JSON对象具有FName和LName，而您的类具有名称和年龄作为相应的映射。您能否验证映射是否正确？

[Source: (String)"{"FName":"Mad", "LName": "Max"}"; line: 1,
column: 1]
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