Android

Android - Retrofit and RxJava

Android, Retrofit, RxJava

개인 공부 후 자료를 남기기 위한 목적임으로 내용 상에 큰 문제가 있을 수도 있습니다.
잘못된 내용이 있다면 언제든지 편하게 댓글 남겨주시면 감사하겠습니다.

프로젝트에 사용할 준비물

먼저 라이브러리를 Gradle에 다음과 같이 추가하고 적용한다.

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//Retrofit2
implementation 'com.squareup.retrofit2:converter-gson:2.3.0'
implementation 'com.squareup.retrofit2:adapter-rxjava2:2.3.0'

//RxJava
implementation "io.reactivex.rxjava2:rxjava:2.1.7"
implementation "io.reactivex.rxjava2:rxandroid:2.0.1"

//Support
implementation 'com.android.support:cardview-v7:27.1.1'
implementation 'com.android.support:recyclerview-v7:27.1.1'

AndroidMenifest.xml에 Internt을 추가한다.

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<uses-permission android:name="android.permission.INTERNET"/>

Fake Online REST API를 준비

Pojo Model

Json을 Pojo 모델로 변환 하자

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public class Comment {
    private String name;
    private String email;
    private String body;

    public Comment() {
    }

    public Comment(String name, String email, String body) {
        this.name = name;
        this.email = email;
        this.body = body;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getBody() {
        return body;
    }

    public void setBody(String body) {
        this.body = body;
    }
}

Retrofit2 with RxJava

  • Retrofit은 interface를 정의하여 HTTP 통신을 할 준비를 한다.
  • @Get Annotation을 추가한다.
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//Retrofit Api Method
public interface CommentAPI {
    @GET("comments")
    Observable<List<Comment>> getComments();
}
  • 통신을 하기 위해서 Instance를 생성한다.
  • Rxjava의 Observable을 통해서 어떤 클래스를 통해서 Response 받을 것인지 지정해준다.
  • GsonConverter를 통해 Json으로 파싱 후 위에 지정한 Pojo 클래스의 멤버 변수에 대입한다.
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    //Retrofit 설정
    public class RetrofitClient {
        private static Retrofit retrofitInstance;

        private RetrofitClient() {
        }

        public static Retrofit getInstance() {
            if (retrofitInstance == null)
                retrofitInstance = new Retrofit.Builder()
                        .baseUrl("http://jsonplaceholder.typicode.com/")
                        .addConverterFactory(GsonConverterFactory.create())
                        .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                        .build();

            return retrofitInstance;
        }
    }

Layout resource file

자 이제 Layout을 아래와 같이 적용해 보자.

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** activity_main.xml **
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</RelativeLayout>

** row_item.xml **
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <android.support.v7.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        android:background="@android:color/white"
        app:cardCornerRadius="4dp"
        app:cardElevation="8dp">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="8dp"
            android:orientation="vertical">

            <TextView
                android:id="@+id/txt_name"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text=""
                android:textSize="12sp"
                android:textStyle="bold"/>

            <TextView
                android:id="@+id/txt_email"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text=""
                android:textSize="12sp"
                android:textStyle="normal"/>

            <TextView
                android:id="@+id/txt_body"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text=""
                android:textSize="12sp"
                android:textStyle="normal"/>

        </LinearLayout>

    </android.support.v7.widget.CardView>

</RelativeLayout>

RecyclerView Adapter 만들기

자! 이제 RecyclerView를 사용하여 Adapter 구현하자.

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** ViewHolder **
public class CommentViewHolder extends RecyclerView.ViewHolder {
    TextView txtName, txtEmail, txtBody;

    public CommentViewHolder(View itemView) {
        super(itemView);

        txtName = (TextView) itemView.findViewById(R.id.txt_name);
        txtEmail = (TextView) itemView.findViewById(R.id.txt_email);
        txtBody = (TextView) itemView.findViewById(R.id.txt_body);
    }
}

** Adapter **
public class CommentAdapter extends RecyclerView.Adapter<CommentViewHolder> {
    private Context context;
    private List<Comment> commentList;

    public CommentAdapter(Context context, List<Comment> commentList) {
        this.context = context;
        this.commentList = commentList;
    }

    @NonNull
    @Override
    public CommentViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.row_item, parent, false);

        return new CommentViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull CommentViewHolder holder, int position) {
        holder.txtName.setText(String.valueOf(commentList.get(position).getName()));
        holder.txtEmail.setText(String.valueOf(commentList.get(position).getEmail()));
        holder.txtBody.setText(String.format("%s...", commentList.get(position).getBody()).substring(0, 25));
    }

    @Override
    public int getItemCount() {
        return commentList.size();
    }
}

데이터를 응답 받아서 처리하기

  • Scheduler 설정
    • subscribeOn: Observable의 subscribe()가 실행되는 스레드를 바꿔줍니다.
    • observeOn: subscribe 직전에 observeOn(AndroidSchedulers.mainThread())를 사용하여 onNext() 메서드가 UI Thread에서 실행되도록 구성되어 있다.
    • 공식 문서
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    private CommentAPI commentAPI;
    private RecyclerView recyclerView;
    private CompositeDisposable compositeDisposable = new CompositeDisposable();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Retrofit retrofit = RetrofitClient.getInstance();
        commentAPI = retrofit.create(CommentAPI.class);

        recyclerView = (RecyclerView) findViewById(R.id.recycler);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        importingData();

    }

    private void importingData() {
        compositeDisposable.add(commentAPI.getComments()
                .subscribeOn(Schedulers.io())               
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(new Consumer<List<Comment>>() {
                    @Override
                    public void accept(List<Comment> comments) throws Exception {
                        showData(comments);
                    }
                }));

    }

    private void showData(List<Comment> comments) {
        CommentAdapter adapter = new CommentAdapter(this, comments);
        recyclerView.setAdapter(adapter);

    }

    // 메모리 누출 방지
    @Override
    protected void onStop() {
        compositeDisposable.clear();
        super.onStop();
    }
}

구현 화면

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