我正在尝试使用gson从反序列化中排除Kotlin属性。我尝试了不同的方法，从用@Transient注释属性到创建自定义注释策略(当然是在gson生成器中指定策略(，但似乎都不起作用，因为属性一直为null，而不是我初始化属性时使用的值。
我没有尝试使用@Expose注释，但我不想用@Expose注释其他字段
请问，我如何使用gson+Kotlin来实现这一点？
@瞬变为我工作。
@Transient lateinit var bar: SomeCustomType
根据@瞬态定义：
将注释属性的JVM后台字段标记为CCD_ 4，这意味着它不是对象的默认序列化形式的一部分。
data class Foo (
@Expose(deserialize = false) val bar: Bar
)
我还没有找到一个更优雅的解决方案，但目前，我已经为该属性指定了一个不同的名称，并将其从类的默认构造函数中删除。
{
"fName": "Bilbo"
"lName": "Baggins"
}
data class Person(val fName: String) {
lateinit var lNameObj: String
}
然后我可以在我的自定义反序列化程序中分配lNameObj。
您可以使用注释来实现这一点。示例
package com.xently.utils
import com.google.gson.*
import com.xently.utils.Exclude.During.*
import org.intellij.lang.annotations.Language
import java.text.DateFormat
@Retention(value = AnnotationRetention.RUNTIME)
@Target(AnnotationTarget.FIELD)
/**
* Excludes field(s) from json serialization and/or deserialization depending on [during]
* @param during When to exclude field from serialization and/or deserialization
*/
annotation class Exclude(val during: During = BOTH) {
/**
* @see SERIALIZATION Exclude field ONLY from json serialization
* @see DESERIALIZATION Exclude field ONLY from json deserialization
* @see BOTH Exclude field from json serialization and deserialization
*/
enum class During {
/**
* Exclude field ONLY from json serialization
*/
SERIALIZATION,
/**
* Exclude field ONLY from json deserialization
*/
DESERIALIZATION,
/**
* Exclude field from json serialization and deserialization
*/
BOTH
}
}
interface IData<T> {
fun fromJson(@Language("JSON") json: String?): T?
fun fromMap(map: Map<String, Any?>): T? = fromJson(JSON_CONVERTER.toJson(map))
}
inline fun <reified T> fromJson(json: String?): T? = if (json.isNullOrBlank()) null else try {
JSON_CONVERTER.fromJson(json, T::class.java)
} catch (ex: Exception) {
null
}
private fun getExclusionStrategy(during: Exclude.During = Exclude.During.BOTH): ExclusionStrategy {
return object : ExclusionStrategy {
override fun shouldSkipClass(clazz: Class<*>?): Boolean {
return false
}
override fun shouldSkipField(f: FieldAttributes?): Boolean {
return if (f == null) true else {
val annotation = f.getAnnotation(Exclude::class.java)
if (annotation == null) {
false
} else {
annotation.during == during
}
}
}
}
}
val JSON_CONVERTER: Gson = GsonBuilder()
.enableComplexMapKeySerialization()
.addSerializationExclusionStrategy(getExclusionStrategy(SERIALIZATION))
.addDeserializationExclusionStrategy(getExclusionStrategy(DESERIALIZATION))
.setExclusionStrategies(getExclusionStrategy())
.serializeNulls()
.setDateFormat(DateFormat.LONG)
.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
.create()
data class GsonSerializable(
val name: String?,
val age: Int = 0,
val sex: Sex = Sex.MALE,
@Exclude
val ignore: String? = "ISD",
@Exclude(DESERIALIZATION)
val ignoreDes: String? = "ID",
@Exclude(SERIALIZATION)
val ignoreSer: String? = "IS"
) {
enum class Sex {
MALE,
FEMALE
}
@Exclude(SERIALIZATION)
/**
* Without annotation it'd be serialized!
*/
val increaseAgeBy: (increment: Int) -> Int = {
age + it
}
override fun toString(): String = JSON_CONVERTER.toJson(this)
companion object : IData<GsonSerializable> {
override fun fromJson(json: String?): GsonSerializable? = com.xently.utils.fromJson(json)
}
}
单元测试
package com.xently.utils
import org.hamcrest.MatcherAssert.assertThat
import org.hamcrest.Matchers.equalTo
import org.hamcrest.Matchers.isEmptyOrNullString
import org.junit.Test
class GsonSerializableTest {
@Test
fun excludeAnnotationWorksCorrectly() {
val test1 = GsonSerializable("My name", 23, GsonSerializable.Sex.FEMALE)
val json1 = test1.toString()
val testDesJson1 =
GsonSerializable.fromJson("""{"name":"My name","age":23,"sex":"FEMALE","ignore_des":"ID","ignore_ser":"IS"}""")
assertThat(test1.increaseAgeBy.invoke(2), equalTo(25))
assertThat(
json1,
equalTo("""{"name":"My name","age":23,"sex":"FEMALE","ignore_des":"ID"}""")
)
if (testDesJson1 != null) {
assertThat(testDesJson1.ignoreDes, isEmptyOrNullString())
assertThat(testDesJson1.ignoreSer, equalTo("IS"))
}
}
}
我从baeldung 那里学到了注释的东西
我试图排除displayedName和我曾在这里尝试过解决方案，但对我有效的是
data class Social(
val id: Int? = null,
var social_media_url: String? = null,
val gym_id: Int? = null,
val social_media: String? = null,
val displayedName:String? = null)
在上传请求之前，我将displayedName设置为null，这样它就不会序列化