房间类型地图转换器 [英] Room TypeConverter for map

问题描述

您将如何编写Map的TypeConverter?我的方法是由Moshi做到

How would you write TypeConverter for Map? My approach was to do it by Moshi

class Converters() {

    val moshi = Moshi
            .Builder()
            .add(KotlinJsonAdapterFactory())
            .build()

    val mapOfStringsType = Types.newParameterizedType(Map::class.java, String::class.java, String::class.java)
    val mapOfStringsAdapter = moshi.adapter<Map<String, String>>(mapOfStringsType)


    @TypeConverter
    fun stringToMap(data: String): Map<String, String> {
        return mapOfStringsAdapter.fromJson(data).orEmpty()
    }

    @TypeConverter
    fun mapToString(map: Map<String, String>): String {
        return mapOfStringsAdapter.toJson(map)
    }
}

但是，它闻起来是因为我无法通过Converters()构造函数注入Moshi. 而且，恐怕也不是最好的表现.

However, it smells, because I can't inject Moshi by Converters() constructor. And, I'm afraid, it's not the best performance either.

推荐答案

我通常将gson用作Room TypeConverters.它提供了适用于所有对象类型的简单实现:

I usually use gson for Room TypeConverters. It allows for simple implementation that will work for all object types:

public class StringMapConverter {
    @TypeConverter
    public static Map<String, String> fromString(String value) {
        Type mapType = new TypeToken<Map<String, String>>() {
        }.getType();
        return new Gson().fromJson(value, mapType);
    }

    @TypeConverter
    public static String fromStringMap(Map<String, String> map) {
        Gson gson = new Gson();
        return gson.toJson(map);
    }
}

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