Android 使用Retrofit实现XML转JSON 解析报错问题及解决方案

• 业务需求：需要将如下格式的XML数据映射为JSON对象

<settings>
<client ip="......" lat="...." lon="...." isp="...." country="...."/>
<translation lang="xml"> </translation>
</settings>

• 初始配置：使用Retrofit发起请求，转换器工厂采用Moshi，配置代码如下：

Retrofit.Builder()
    .addConverterFactory(MoshiConverterFactory.create(moshi).asLenient())
    .baseUrl(BASE_URL)
    .client(okHttpClient)
    .build()

• 问题表现：尝试引入com.squareup.retrofit2:converter-simplexml:2.9.0依赖，通过SimpleXml创建响应模型实现解析时持续失败，报错信息如下：

com.squareup.moshi.JsonDataException: Expected BEGIN_OBJECT but was STRING at path $

• 原有错误响应模型代码：

@Root(name = "settings", strict = false)
data class ConfigurationEntity(

    @field:Attribute(name = "client", required = false)
    @param:Attribute(name = "client", required = false)
    val client: ClientEntity?
)

@Root(name = "client")
data class ClientEntity(

    @field:Attribute(name = "ip", required = false)
    @param:Attribute(name = "ip", required = false)
    val ip: String?,

    @field:Attribute(name = "lat", required = false)
    @param:Attribute(name = "lat", required = false)
    val lat: String?,

    @field:Attribute(name = "lon", required = false)
    @param:Attribute(name = "lon", required = false)
    val lon: String?,

    @field:Attribute(name = "isp", required = false)
    @param:Attribute(name = "isp", required = false)
    val isp: String?,

    @field:Attribute(name = "country", required = false)
    @param:Attribute(name = "country", required = false)
    val country: String?
)

1. 调整Retrofit转换器配置 #

将原有的Moshi转换器替换为SimpleXml转换器，配置如下：

Retrofit.Builder()
    .addConverterFactory(SimpleXmlConverterFactory.create())
    .baseUrl(BASE_URL)
    .client(okHttpClient)
    .build()

2. 调整实体模型定义 #

@Root(name = "settings", strict = false)
class ConfigurationEntity {

    @field:Element(required = false)
    lateinit var client: ClientEntity
}

@Root(name = "client", strict = false)
class ClientEntity {

    @field:Attribute
    lateinit var ip: String

    @field:Attribute
    lateinit var lat: String

    @field:Attribute
    lateinit var lon: String

    @field:Attribute
    lateinit var isp: String

    @field:Attribute
    lateinit var country: String
}

内容的提问来源于stack exchange，提问作者Astrit Veliu