轻松解决Android复杂数据结构序列化

问题描述

当我编写quickupload库时，因为需要在 Service中进行上传任务，向Service传递时我发现需要传递的数据很多并且结构复杂，如果处理不好就会导致以下几个问题

耗时: 需要更多时间进行开发和测试以确保正确的数据处理。
容易出错: 由于手动序列化和反序列化逻辑，出现错误的风险更高。
维护: 维护和更新代码的工作量增加，尤其是数据结构发生变化时。

解决方案：

为了解决这个问题，需要编写 PersistableData

open class PersistableData() : Parcelable {protected val data = HashMap<String, Any>()override fun equals(other: Any?): Boolean {if (other == null || other !is PersistableData) return falsereturn data == other.data}override fun hashCode() = data.hashCode()@SuppressLint("ParcelClassLoader")private constructor(parcel: Parcel) : this() {parcel.readBundle()?.let { bundle ->bundle.keySet().forEach { key ->when (val value = bundle[key]) {is Boolean, is Double, is Int, is Long, is String -> data[key] = value}}}}override fun describeContents() = 0override fun writeToParcel(dest: Parcel, flags: Int) {toBundle().writeToParcel(dest, flags)}companion object CREATOR : Parcelable.Creator<PersistableData> {private const val separator = "$"override fun createFromParcel(parcel: Parcel) = PersistableData(parcel)override fun newArray(size: Int): Array<PersistableData?> = arrayOfNulls(size)/*** 从PersistableData JSON表示创建 [PersistableData]。*/@JvmStaticfun fromJson(rawJsonString: String): PersistableData {val json = JSONObject(rawJsonString)val data = PersistableData()json.keys().forEach { key ->when (val value = json.get(key)) {is Boolean, is Double, is Int, is Long, is String -> data.data[key] = value}}return data}}private fun String.validated(checkExists: Boolean = false): String {if (contains(separator))throw IllegalArgumentException("key cannot contain $separator as it's a reserved character, used for nested data")if (checkExists && !data.containsKey(this))throw IllegalArgumentException("no data found for key \"$this\"")return this}fun putBoolean(key: String, value: Boolean) {data[key.validated()] = value}fun getBoolean(key: String) = data[key.validated(checkExists = true)] as Booleanfun putDouble(key: String, value: Double) {data[key.validated()] = value}fun getDouble(key: String) = data[key.validated(checkExists = true)] as Doublefun putInt(key: String, value: Int) {data[key.validated()] = value}fun getInt(key: String) = data[key.validated(checkExists = true)] as Intfun putLong(key: String, value: Long) {data[key.validated()] = value}fun getLong(key: String) = data[key.validated(checkExists = true)] as Longfun putString(key: String, value: String) {data[key.validated()] = value}fun getString(key: String) = data[key.validated(checkExists = true)] as Stringfun putData(key: String, data: PersistableData) {data.data.forEach { (dataKey, value) ->this.data["$key$separator$dataKey"] = value}}fun getData(key: String): PersistableData {val entries = data.entries.filter { it.key.startsWith("$key$separator") }if (entries.isEmpty()) return PersistableData()return PersistableData().also { extractedData ->entries.forEach { (entryKey, entryValue) ->extractedData.data[entryKey.removePrefix("$key$separator")] = entryValue}}}fun putArrayData(key: String, data: List<PersistableData>) {data.forEachIndexed { index, persistableData ->persistableData.data.forEach { (dataKey, value) ->this.data["$key$separator$index$separator$dataKey"] = value}}}fun getArrayData(key: String): List<PersistableData> {val entries = ArrayList(data.entries.filter { it.key.startsWith("$key$separator") })if (entries.isEmpty()) return emptyList()var index = 0var elements = entries.filter { it.key.startsWith("$key$separator$index$separator") }val outList = ArrayList<PersistableData>()while (elements.isNotEmpty()) {outList.add(PersistableData().also { extractedData ->elements.forEach { (entryKey, entryValue) ->extractedData.data[entryKey.removePrefix("$key$separator$index$separator")] =entryValue}entries.removeAll(elements)})index += 1elements = entries.filter { it.key.startsWith("$key$separator$index$separator") }}return outList}/*** 创建一个新的包，其中包含此 [PersistableData] 中存在的所有字段。*/fun toBundle() = Bundle().also { bundle ->data.keys.forEach { key ->when (val value = data[key]) {is Boolean -> bundle.putBoolean(key, value)is Double -> bundle.putDouble(key, value)is Int -> bundle.putInt(key, value)is Long -> bundle.putLong(key, value)is String -> bundle.putString(key, value)}}}/*** 创建一个包含所有字段的JSON字符串表示* 在此 [PersistableData] 中。** 这并不意味着人类可读，而是一种方便的方式来传递复杂的* 使用字符串的结构化数据。*/fun toJson() = JSONObject().also { json ->data.keys.forEach { key ->when (val value = data[key]) {is Boolean, is Double, is Int, is Long, is String -> json.put(key, value)}}}.toString()
}

简单总结一下：

存储各种类型的键值对（Boolean、Double、Int、Long、String）。
提供放入和获取数据的方法（putBoolean、getBoolean等）。
使用带有分隔符的键支持嵌套和数组数据结构。
转换数据为Bundle和JSON格式，便于存储和检索。
实现Parcelable接口，允许在Android组件之间传递数据。

为了在使用时保持统一性

编写接口 Persistable

interface Persistable {fun toPersistableData(): PersistableDatainterface Creator<T> {fun createFromPersistableData(data: PersistableData): T}
}

简单总结一下：

定义了一个可以转换为PersistableData对象的契约。
确保数据对象的序列化和反序列化方式一致。

当需要对某个数据类进行序列化时只需要实现接口 Persistable，例如 UploadFile数据类

@Parcelize
data class UploadFile @JvmOverloads constructor(val path: String,val properties: LinkedHashMap<String, String> = LinkedHashMap()
) : Parcelable, Persistable {companion object : Persistable.Creator<UploadFile> {private object CodingKeys {const val path = "path"const val properties = "props"}override fun createFromPersistableData(data: PersistableData) = UploadFile(path = data.getString(CodingKeys.path),properties = LinkedHashMap<String, String>().apply {val bundle = data.getData(CodingKeys.properties).toBundle()bundle.keySet().forEach { propKey ->put(propKey, bundle.getString(propKey)!!)}})}override fun toPersistableData() = PersistableData().apply {putString(CodingKeys.path, path)putData(CodingKeys.properties, PersistableData().apply {properties.entries.forEach { (propKey, propVal) ->putString(propKey, propVal)}})}
}