Network Requests with Retrofit in Android
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Preparing the Service
To start, open MovieDiaryApiService.kt and replace the code inside with the following:
@POST("user/register")
fun registerUser(@Body body: RequestBody): Call<ResponseBody>
@POST("user/login")
fun loginUser(@Body body: RequestBody): Call<ResponseBody>
@GET("user")
fun getProfile(): Call<ResponseBody>
@GET("sampleMovies")
fun getMovies(): Call<ResponseBody>
@POST("movies")
fun postReview(@Body body: RequestBody): Call<ResponseBody>
Replacing HttpUrlConnection with Retrofit
With the service methods ready, navigate to MovieDiaryApi.kt and delete the old registerUser method. You’ll implement it again to work with Retrofit. To start, add the following code:
fun registerUser(
username: String,
email: String,
password: String,
onResponse: (String?, Throwable?) -> Unit,
) {}
val jsonBody = JSONObject().apply {
put("username", username)
put("email", email)
put("password", password)
}.toString()
val body = RequestBody.create(MediaType.parse("application/json"), jsonBody)
apiService.registerUser(body).enqueue(object : Callback<ResponseBody> {
override fun onResponse(call: Call<ResponseBody>, response: Response<ResponseBody>) {
}
override fun onFailure(call: Call<ResponseBody>, error: Throwable) {
}
})
onResponse(null, error)
val message = response.body()?.string()
if (message == null) {
val error = response.errorBody()?.string()
onResponse(null, Throwable(error))
return
} else {
onResponse(message, null)
}
Implementing User Login
Implement loginUser in the same way as registerUser. Remove the suspend modifier from the method and update loginUser with the following:
fun loginUser(username: String, password: String, onResponse: (String?, Throwable?) -> Unit) {
val jsonBody = JSONObject().apply {
put("username", username)
put("password", password)
}.toString()
val body = RequestBody.create(MediaType.parse("application/json"), jsonBody)
apiService.loginUser(body).enqueue(object : Callback<ResponseBody> {
override fun onResponse(call: Call<ResponseBody>, response: Response<ResponseBody>) {
val message = response.body()?.string()
if (message == null) {
val error = response.errorBody()?.string()
onResponse(null, Throwable(error))
return
} else {
}
}
override fun onFailure(call: Call<ResponseBody>, error: Throwable) {
onResponse(null, error)
}
})
}
JSONObject(message).run {
val token = getString("token")
onResponse(token, null)
}
Fetching the Movies
Navigate back to MovieDiaryApi.kt and scroll down to getMovies. Replace the comment with the following code:
apiService.getMovies().enqueue(object : Callback<ResponseBody> {
override fun onResponse(call: Call<ResponseBody>, response: Response<ResponseBody>) {
}
override fun onFailure(call: Call<ResponseBody>, error: Throwable) {
onResponse(null, error)
}
})
if (response.isSuccessful) {
val movieReviews = mutableListOf<MovieReview>()
JSONArray(response.body()?.string()).also { array ->
for (i in 0 until array.length()) {
array.getJSONObject(i).run {
MovieReview(
title = getString("title"),
description = getString("description"),
comment = getString("comment")
).also { movieReviews.add(it) }
}
}
}
onResponse(movieReviews, null)
}
else {
onResponse(null, Throwable(response.errorBody()?.string()))
}