我正在关注 Google Android Developer Codelab，并且参与了一个名为“Bookshelf”的项目。主要思想是使用 Google API 来处理图书，以便：
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"Ted Gioia"
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应用程序应显示使用 Coil 从 API 异步获取的每本书的
thumbnailimageLinks我定义了以下Serialized数据类：
@Serializable
data class BookshelfBook(
val items: List<Map<String, String>>
)
@Serializable
data class BookshelfVolume(
val imageLinks: Map<String, String>
)
我正在尝试使用以下 API 接口获取数据
interface BookshelfApiService {
@GET("?q=jazz+history")
suspend fun getBooks(): List<BookshelfBook>
@GET("{volume_id}")
suspend fun getVolume(bookId: String): List<BookshelfVolume>
}
将它们全部放在以下存储库中：
interface BookshelfRepository {
suspend fun getBookshelfBooks(): List<BookshelfBook>
suspend fun getBookshelfVolumes(books: List<BookshelfBook>): List<BookshelfVolume>
}
class NetworkBookshelfRepository(
private val bookshelfApiService: BookshelfApiService
) : BookshelfRepository {
override suspend fun getBookshelfBooks(): List<BookshelfBook> =
bookshelfApiService.getBooks()
override suspend fun getBookshelfVolumes(books: List<BookshelfBook>): List<BookshelfVolume> =
ERROR ---> listOf(books.forEach { bookshelfApiService.getVolume(it["id"]) })
}
尝试在
BookshelfVolumeoverride suspend fun getBookShelfVolumesType mismatch: inferred type is List<Unit> but List<BookshelfVolume> was expected
这些在 ViewModel 中使用：
package com.example.bookshelf.ui.model
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.setValue
import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
import androidx.lifecycle.ViewModelProvider.AndroidViewModelFactory.Companion.APPLICATION_KEY
import androidx.lifecycle.viewModelScope
import androidx.lifecycle.viewmodel.initializer
import androidx.lifecycle.viewmodel.viewModelFactory
import com.example.bookshelf.BookshelfApplication
import com.example.bookshelf.data.BookshelfRepository
import com.example.bookshelf.network.BookshelfVolume
import kotlinx.coroutines.launch
import java.io.IOException
sealed interface BookshelfUiState {
data class Success(val volumes: List<BookshelfVolume>): BookshelfUiState
object Loading: BookshelfUiState
object Error: BookshelfUiState
}
class BookshelfViewModel(
private val bookshelfRepository: BookshelfRepository
) : ViewModel() {
var bookshelfUiState: BookshelfUiState by mutableStateOf(BookshelfUiState.Loading)
private set
init {
getBookshelfVolumes()
}
fun getBookshelfVolumes() {
viewModelScope.launch {
bookshelfUiState = try {
val books = bookshelfRepository.getBookshelfBooks()
BookshelfUiState.Success(bookshelfRepository.getBookshelfVolumes(books))
} catch (e: IOException) {
BookshelfUiState.Error
}
}
}
companion object {
val Factory: ViewModelProvider.Factory = viewModelFactory {
initializer {
val application = (this[APPLICATION_KEY] as BookshelfApplication)
val bookshelfRepository = application.container.bookshelfRepository
BookshelfViewModel(bookshelfRepository = bookshelfRepository)
}
}
}
}
因此，原则上：
我不确定如何修复存储库，以便我可以为获取的每本书构建
BookshelfVolumehttps://www.googleapis.com/books/v1/volumes?q=jazz+history有关如何操作的任何提示
@GET("{volume_id}")调用相同
BookshelfApiService获取的书籍的每个 id 调用
getVolume(bookId: String)时，
满足
@GET("?q=jazz+history")界面中的
BookshelfApiService
通过解析每本书获取的详细信息（卷）的“imageLinks”地图来构建“缩略图”链接列表
？
通过以下方法解决了这个问题
package com.example.bookshelf.network
import retrofit2.http.GET
import retrofit2.http.Path
interface BookshelfApiService {
@GET("?q=jazz+history")
suspend fun getBooks(): List<BookshelfBook>
@GET("{volume_id}")
suspend fun getVolume(@Path("id") id: String): BookshelfVolume
}
package com.example.bookshelf.network
import kotlinx.serialization.Serializable
@Serializable
data class BookshelfBook(
val id: String
)
package com.example.bookshelf.network
import kotlinx.serialization.Serializable
@Serializable
data class BookshelfVolume(
val imageLinks: Map<String, String>
)
package com.example.bookshelf.data
import com.example.bookshelf.network.BookshelfApiService
import com.example.bookshelf.network.BookshelfBook
import com.example.bookshelf.network.BookshelfVolume
interface BookshelfRepository {
suspend fun getBookshelfBooks(): List<BookshelfBook>
suspend fun getBookshelfVolume(id: String): BookshelfVolume
}
class NetworkBookshelfRepository(
private val bookshelfApiService: BookshelfApiService
) : BookshelfRepository {
override suspend fun getBookshelfBooks(): List<BookshelfBook> =
bookshelfApiService.getBooks()
override suspend fun getBookshelfVolume(id: String): BookshelfVolume =
bookshelfApiService.getVolume(id)
}
package com.example.bookshelf.ui.model
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.setValue
import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
import androidx.lifecycle.ViewModelProvider.AndroidViewModelFactory.Companion.APPLICATION_KEY
import androidx.lifecycle.viewModelScope
import androidx.lifecycle.viewmodel.initializer
import androidx.lifecycle.viewmodel.viewModelFactory
import com.example.bookshelf.BookshelfApplication
import com.example.bookshelf.data.BookshelfRepository
import com.example.bookshelf.network.BookshelfVolume
import kotlinx.coroutines.launch
import java.io.IOException
sealed interface BookshelfUiState {
data class Success(val volumes: List<BookshelfVolume>): BookshelfUiState
object Loading: BookshelfUiState
object Error: BookshelfUiState
}
class BookshelfViewModel(
private val bookshelfRepository: BookshelfRepository
) : ViewModel() {
var bookshelfUiState: BookshelfUiState by mutableStateOf(BookshelfUiState.Loading)
private set
init {
getBookshelfVolumes()
}
fun getBookshelfVolumes() {
viewModelScope.launch {
bookshelfUiState = try {
val books = bookshelfRepository.getBookshelfBooks().map { it.id }
val volumes = books.map { id ->
bookshelfRepository.getBookshelfVolume(id)
}
BookshelfUiState.Success(volumes)
} catch (e: IOException) {
BookshelfUiState.Error
}
}
}
companion object {
val Factory: ViewModelProvider.Factory = viewModelFactory {
initializer {
val application = (this[APPLICATION_KEY] as BookshelfApplication)
val bookshelfRepository = application.container.bookshelfRepository
BookshelfViewModel(bookshelfRepository = bookshelfRepository)
}
}
}
}