使用 class Kotlin Android 解析 json 时出错

Question

嗨，我正在尝试用 kotlin 解析 JSON

下面是我的 json 代码

    [{
    "module":"1",
    "books":[{"name":"bookname1","authors":"author1, author 2"},
             {"name":"bookname2","authors":"author1, author 2"},
             {"name":"bookname3","authors":"author1, author 2"}]
},
{
    "module":"2",
    "books":[{"name":"bookname1","authors":"author1, author 2"},
             {"name":"bookname2","authors":"author1, author 2"},
             {"name":"bookname3","authors":"author1, author 2"}]
},
{
    "module":"3",
    "books":[{"name":"bookname1","authors":"author1, author 2"},
             {"name":"bookname2","authors":"author1, author 2"},
             {"name":"bookname3","authors":"author1, author 2"}]
},
{
    "module":"4",
    "books":[{"name":"bookname1","authors":"author1, author 2"},
             {"name":"bookname2","authors":"author1, author 2"},
             {"name":"bookname3","authors":"author1, author 2"}]
},
{
    "module":"5",
    "books":[{"name":"bookname1","authors":"author1, author 2"},
             {"name":"bookname2","authors":"author1, author 2"},
             {"name":"bookname3","authors":"author1, author 2"}]
}]

请注意，此 json 响应以数组开头

这是我的 class 来解析它

class SemdetailsPArser {

    @SerializedName("module")
    @Expose
    var module: String? = null
    @SerializedName("books")
    @Expose
    var books: List<Book>? = null




}

class Book {

    @SerializedName("name")
    @Expose
    var name: String? = null
    @SerializedName("authors")
    @Expose
    var authors: String? = null

}

这是我的代码

//interface

interface SemdetailsFetcher {
    @GET("test/json/sub1.json")
    fun getCurrentSemData(): Call<SemdetailsPArser>
}

这是我的活动代码

fun getCurrentData() {
        val retrofit = Retrofit.Builder()
            .baseUrl(BaseUrl)
            .addConverterFactory(GsonConverterFactory.create())
            .build()
        val service = retrofit.create(SemdetailsFetcher::class.java)
        val call = service.getCurrentSemData()
        call.enqueue(object : Callback, retrofit2.Callback<SemdetailsPArser> {
            override fun onResponse(
                call: retrofit2.Call<SemdetailsPArser>?,
                response: retrofit2.Response<SemdetailsPArser>?
            ) {
               // val thisthig = response?.body();
                println("here 1 ${response?.body().toString()}")
            }

            override fun onFailure(call: Call?, e: IOException?) {
                println("here 2")
            }

            override fun onFailure(call: retrofit2.Call<SemdetailsPArser>?, t: Throwable?) {
                println("here 3 $t")
            }

            override fun onResponse(call: Call, response: Response) {
                if (response.code() == 200) {

                    println("secodn success")
                    val sampleResp = response.body()!!

                    println(sampleResp)
                }
            }


        })
    }

我收到了这个错误

here 3 com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2 path $

我知道这可能与我的解析 class 有关

在这里，我得到了一组 json 信息，我用另一个 json 尝试了相同的代码

{
    "person": {
        "name": "Don",
        "age": 35
    },
    "books": [{
            "id": 800,
            "name": "book 1",
            "description": "clear sky",
            "icon": "01n"
        },
        {
            "id": 801,
            "name": "book 2",
            "description": "clear sky 1",
            "icon": "01N"
        }
    ],

    "city": "bgvnslsl",
    "id": 1851632,
    "bname": "abcd",
    "code": 200
}

当我更改解析 class 和接口时，这工作得很好

我的问题是我不知道如何编写 class 来解析以数组开头的 json 响应

Answer 1

您期待SemdetailsPArser列表，因此您应该将返回类型定义为SemdetailsPArser列表

这应该可以解决问题。

interface SemdetailsFetcher {
    @GET("test/json/sub1.json")
    fun getCurrentSemData(): Call<List<SemdetailsPArser>>
}

您还需要在代码的其他部分进行更改。

Answer 2

您收到的错误意味着您正在尝试解析 JSON 数组，认为它应该是 JSON object。 JSON 数组是这些[]之间的东西，而 JSON object 在像这样的大括号中{} 。 所以你的第一个 JSON 对应于List<Module>之类的东西，它不是 object，而是它们的列表。 每个模块都有一个书籍列表。

所以都说应该是这样的

interface SemdetailsFetcher {
    @GET("test/json/sub1.json")
    fun getCurrentSemData(): Call<List<SemdetailsPArser>>
}

顺便说一句，如果您正确定义 POJO，则不需要所有注释。

Answer 3

创建 SemdetailsPARser class

data class SemdetailsPArser( val books: List<Book>, val module: String )

接下来创建书 class

data class Book(
val authors: String,
val name: String

)

界面中的下一步（SemdetailsFetcher）

interface SemdetailsFetcher {
@GET("test/json/sub1.json")
fun getCurrentSemData(): Call<List<SemdetailsPArser>>

}