Use Moshi in SpringBoot

[KevinnZou]

I am writing a spring boot project with Kotlin. Thus, I want to use Moshi to replace Jackson as the HttpMessageConverter. However, I cannot find out a way to do that. Could you show an example?

[lemondkel]

HttpMessageConverter does not exist by default on moshi.

[unoexperto]

I used following implementation

import com.mentalcrm.misc.DurationJsonAdapter
import com.mentalcrm.misc.InstantJsonAdapter
import com.mentalcrm.misc.URLJsonAdapter
import com.squareup.moshi.Moshi
import dev.zacsweers.moshix.reflect.MetadataKotlinJsonAdapterFactory
import okio.buffer
import okio.sink
import okio.source
import org.springframework.http.MediaType
import org.springframework.http.converter.json.AbstractJsonHttpMessageConverter
import java.io.*
import java.lang.reflect.Type

class MoshiHttpMessageConverter : AbstractJsonHttpMessageConverter() {

    private val jsonParser = Moshi.Builder()
        .add(MetadataKotlinJsonAdapterFactory())
        .build()

    init {
        this.supportedMediaTypes = listOf(MediaType.APPLICATION_JSON)
    }

    @Throws(Exception::class)
    override fun readInternal(resolvedType: Type, reader: Reader): Any {
        asInputStream(reader).source().buffer().use { source ->
            val adapter = jsonParser.adapter<Any>(resolvedType)
            return adapter.fromJson(source)!!
        }
    }

    @Throws(Exception::class)
    override fun writeInternal(value: Any, type: Type?, writer: Writer) {

        try {
            val adapter = jsonParser.adapter<Any>(type ?: error("Type is null"))
            asOutputStream(writer).sink().buffer().use { bufferedSink ->
                adapter.toJson(bufferedSink, value)
                bufferedSink.flush()
            }
        } catch (ex: Throwable) {
            throw ex
        }
    }

    private fun asInputStream(reader: Reader): InputStream {
        return object : InputStream() {
            @Throws(IOException::class)
            override fun read(): Int {
                return reader.read()
            }
        }
    }

    private fun asOutputStream(writer: Writer): OutputStream {
        return object : OutputStream() {
            @Throws(IOException::class)
            override fun write(b: Int) {
                writer.write(b)
            }
        }
    }
}