Jackson Scala模块的小例子？

Question

任何人都可以指出我用他们的Scala模块2.10进行杰克逊序列化/反序列化的简单例子吗？我正在寻找基于反射的JSON,不需要逐个字段的注释或赋值,它似乎可以做到这一点,但他们的文档不包含任何示例.

如果我有一个案例类:

case class Person(name:String, age:Int)
val person = Person("Fred", 65)

所以从他们的github自述文件:

val mapper = new ObjectMapper()
mapper.registerModule(DefaultScalaModule)

好的,现在是什么......？如何将p转换为/从JSON转换？

Answer 1

试一试:

val person = Person("fred", 25)
val mapper = new ObjectMapper()
mapper.registerModule(DefaultScalaModule)    

val out = new StringWriter
mapper.writeValue(out, person)
val json = out.toString()
println(json)

val person2 = mapper.readValue(json, classOf[Person])
println(person2)

编辑

请务必将该Person类声明为顶级,否则将无效.

Answer 2

这是一个完整的例子:

package com.example.samples

import org.junit.Test
import com.fasterxml.jackson.databind.ObjectMapper
import org.springframework.context.annotation.Bean
import java.io.File
import com.fasterxml.jackson.module.scala.DefaultScalaModule
import java.io.StringWriter

class JacksonTest {

  @Test
  @throws[Exception] def jacksonTest(): Unit = {

    //case class Person(var name: String = "", var age: Int = 0)
    //case class Person(@Bean var name: String, @Bean var age: Int)
    case class Person( name: String, age: Int )

    val person = Person("fred", 25)
    val mapper = new ObjectMapper()
    mapper.registerModule(DefaultScalaModule)

    val out = new StringWriter
    mapper.writeValue(out, person)
    val json = out.toString()
    println(json)

    val person2 = mapper.readValue(json, classOf[Person])
    println(person2)
  }
}

但是,这在mapper.readValue中失败了.

这是我的配置:

<!-- Jackson libraries for JSON marshalling and unmarshalling -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.2.3</version>
</dependency>

<!-- Jackson module for scala object marshalling and unmarshalling -->
<dependency>
    <groupId>com.fasterxml.jackson.module</groupId>
    <artifactId>jackson-module-scala_2.10</artifactId>
    <version>2.2.2</version>
</dependency>

<!-- Scala Compiler -->
<dependency>
    <groupId>org.scala-lang</groupId>
    <artifactId>scala-compiler</artifactId>
    <version>2.10.2</version>
</dependency>

任何想法为什么失败？我看不出与工作实例的区别.