[英]How to write POJOs to get specific array inside an object from JSON using Retrofit2?
好吧,我需要做一个任务:新闻分页列表。 为此,我从googlesample / architecthurecomponents / PagingWithNetworkSample中获取了一个样本,并遇到了这个问题。 问题是有关Google示例中解析JSON文件的代码。
JSON网址: https : //www.reddit.com/r/androiddev/hot.json
POJO文件:
@Entity(tableName = "posts",
indices = [Index(value = ["subreddit"], unique = false)])
data class RedditPost(
@PrimaryKey
@SerializedName("name")
val name: String,
@SerializedName("title")
val title: String,
@SerializedName("score")
val score: Int,
@SerializedName("author")
val author: String,
@SerializedName("subreddit") // this seems mutable but fine for a demo
@ColumnInfo(collate = ColumnInfo.NOCASE)
val subreddit: String,
@SerializedName("num_comments")
val num_comments: Int,
@SerializedName("created_utc")
val created: Long,
val thumbnail: String?,
val url: String?) {
// to be consistent w/ changing backend order, we need to keep a data like this
var indexInResponse: Int = -1
}
这是一个api接口:
interface RedditApi {
@GET("/r/{subreddit}/hot.json")
fun getTop(
@Path("subreddit") subreddit: String,
@Query("limit") limit: Int): Call<ListingResponse>
@GET("/r/{subreddit}/hot.json")
fun getTopAfter(
@Path("subreddit") subreddit: String,
@Query("after") after: String,
@Query("limit") limit: Int): Call<ListingResponse>
@GET("/r/{subreddit}/hot.json")
fun getTopBefore(
@Path("subreddit") subreddit: String,
@Query("before") before: String,
@Query("limit") limit: Int): Call<ListingResponse>
class ListingResponse(val data: ListingData)
class ListingData(
val children: List<RedditChildrenResponse>,
val after: String?,
val before: String?
)
data class RedditChildrenResponse(val data: RedditPost)
companion object {
private const val BASE_URL = "https://www.reddit.com/"
fun create(): RedditApi = create(HttpUrl.parse(BASE_URL)!!)
fun create(httpUrl: HttpUrl): RedditApi {
val logger = HttpLoggingInterceptor(HttpLoggingInterceptor.Logger {
Log.d("API", it)
})
logger.level = HttpLoggingInterceptor.Level.BASIC
val client = OkHttpClient.Builder()
.addInterceptor(logger)
.build()
return Retrofit.Builder()
.baseUrl(httpUrl)
.client(client)
.addConverterFactory(GsonConverterFactory.create())
.build()
.create(RedditApi::class.java)
}
}
}
问题是:api请求如何准确找到我们所需要的东西,一个孩子:[...]代表一个帖子列表? 因为有一个子对象[...]驻留在对象内部,所以在代码中我们没有带@Serialized(“ children”)字段的POJO。 只能在儿童里面放些物品:[...]。 我尝试实现特定于json的此方法,但它返回空值。
谢谢大家的帮助。
如果POJO中的字段名称与JSON中的字段名称相同,则不必添加@SerializedName
批注。 这就是为什么可以将class ListingResponse(val data: ListingData)
映射到
{
"kind": "Listing",
"data": ...
}
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