13 mvvm GitHubService

 mvvm GitHubService

그래들 설정 

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:27.1.1'
    implementation 'com.android.support.constraint:constraint-layout:1.1.2'
    implementation 'com.android.support:design:27.1.1'
    implementation 'com.android.support:cardview-v7:27.1.1'
    
    // http image 
    implementation 'com.github.bumptech.glide:glide:3.6.1'

    // API액세스
    implementation 'com.squareup.retrofit2:retrofit:2.0.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.0.0'
    implementation 'com.squareup.retrofit2:adapter-rxjava:2.0.0'
    implementation 'com.squareup.okhttp3:logging-interceptor:3.0.1'

    // Rx
    implementation 'io.reactivex:rxjava:1.0.17'
    implementation 'io.reactivex:rxandroid:1.1.0'

    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

매니페스트 설정 : 어플리케이션 클래스 등록 

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.neofuture.myapplication">

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

    <application
        android:name=".NewGitHubReposApplication"
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".view.RepositoryListViewActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

application class

public class NewGitHubReposApplication extends Application {
  private Retrofit retrofit;
  private GitHubService gitHubService;

  @Override
  public void onCreate() {
    super.onCreate();
    // 어느 Activity에서라도 API를 이용할 수 있게 이 클래스에서 API를 이용한다
    setupAPIClient();
  }

  private void setupAPIClient() {
    HttpLoggingInterceptor logging = new HttpLoggingInterceptor(new HttpLoggingInterceptor.Logger() {
      @Override
      public void log(String message) {
        Log.d("API LOG", message);
      }
    });

    logging.setLevel(HttpLoggingInterceptor.Level.BASIC);

    OkHttpClient client = new OkHttpClient.Builder().addInterceptor(logging).build();

    retrofit = new Retrofit.Builder()
        .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
        .baseUrl("https://api.github.com")
        .addConverterFactory(GsonConverterFactory.create())
        .client(client)
        .build();

    gitHubService = retrofit.create(GitHubService.class);
  }

  public GitHubService getGitHubService() {
    return gitHubService;
  }
}

retrofit interface

/**
 * Retrofit로 GitHub의 API를 이용하기 위한 클래스
 */
public interface GitHubService {
  /**
   * GitHub의 리포지터리 검색결과를 가져온다 
   * https://developer.github.com/v3/search/
   * @param query GitHub의 API로 검색하는 내용 
   * @return API 액세스 결과 취득 후의 콜백으로서 SearchResponse를 얻을 수 있는 RxJavaのObservable로 반환한다
   */
  @GET("search/repositories?sort=stars&order=desc")
  Observable<Repositories> listRepos(@Query("q") String query);

  /**
   * 리포지토리 상세 내역을 가져온다 
   * https://developer.github.com/v3/repos/#get
   * @return API 액세스 결과 취득 후의 콜백으로서 RepositoryItem을 얻을 수 있는 RxJavaのObservable로 반환한다 
   */
  @GET("repos/{repoOwner}/{repoName}")
  Observable<RepositoryItem> detailRepo(@Path(value = "repoOwner") String owner, @Path(value = "repoName") String repoName);


  /**
   * API 액세스 결과가 이 클래스에 들어온다 
   * GitHub의 리포지터리 목록이 들어있다 
   * @see GitHubService#listRepos(String)
   */
  public static class Repositories {

    public final List<RepositoryItem> items;

    public Repositories(List<RepositoryItem> items) {
      this.items = items;
    }

  }

  /**
   * API 액세스 결과가 이 클래스에 들어온다 
   * GitHub의 리포지터리 데이터가 들어있다 
   * @see GitHubService#detailRepo(String, String)
   */
  public static class RepositoryItem {

    public final String description;
    public final Owner owner;
    public final String language;
    public final String name;
    public final String stargazers_count;
    public final String forks_count;
    public final String full_name;
    public final String html_url;


    public RepositoryItem(String description, Owner owner, String language, String name, String stargazers_count, String forks_count, String full_name, String html_url) {
      this.description = description;
      this.owner = owner;
      this.language = language;
      this.name = name;
      this.stargazers_count = stargazers_count;
      this.forks_count = forks_count;
      this.full_name = full_name;
      this.html_url = html_url;
    }
  }

  /**
   * GitHub의 리포지터리에 대한 소유자 데이터가 들어 있다 
   * @see GitHubService#detailRepo(String, String)
   */
  public static class Owner {
    public final String received_events_url;
    public final String organizations_url;
    public final String avatar_url;
    public final String gravatar_id;
    public final String gists_url;
    public final String starred_url;
    public final String site_admin;
    public final String type;
    public final String url;
    public final String id;
    public final String html_url;
    public final String following_url;
    public final String events_url;
    public final String login;
    public final String subscriptions_url;
    public final String repos_url;
    public final String followers_url;

    public Owner(String received_events_url, String organizations_url, String avatar_url, String gravatar_id, String gists_url, String starred_url, String site_admin, String type, String url, String id, String html_url, String following_url, String events_url, String login, String subscriptions_url, String repos_url, String followers_url) {
      this.received_events_url = received_events_url;
      this.organizations_url = organizations_url;
      this.avatar_url = avatar_url;
      this.gravatar_id = gravatar_id;
      this.gists_url = gists_url;
      this.starred_url = starred_url;
      this.site_admin = site_admin;
      this.type = type;
      this.url = url;
      this.id = id;
      this.html_url = html_url;
      this.following_url = following_url;
      this.events_url = events_url;
      this.login = login;
      this.subscriptions_url = subscriptions_url;
      this.repos_url = repos_url;
      this.followers_url = followers_url;
    }

  }


}

xml 생성 

activity_repository.xml

<?xml version="1.0" encoding="utf-8"?>
<layout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>
        <!-- RepositoryListViewModel에 바인딩한다 -->
        <variable
            name="viewModel"
            type="com.github.advanced_android.newgithubrepo.viewmodel.RepositoryListViewModel"/>
    </data>

    <android.support.design.widget.CoordinatorLayout
        android:id="@+id/coordinator_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        tools:context=".view.RepositoryListActivity">

        <android.support.design.widget.AppBarLayout
            android:id="@+id/app_bar"
            android:layout_width="match_parent"
            android:layout_height="@dimen/app_bar_height"
            android:fitsSystemWindows="true"
            android:theme="@style/AppTheme.AppBarOverlay">

            <android.support.design.widget.CollapsingToolbarLayout
                android:id="@+id/toolbar_layout"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:fitsSystemWindows="true"
                app:contentScrim="?attr/colorPrimary"
                app:layout_scrollFlags="scroll|exitUntilCollapsed">

                <android.support.v7.widget.Toolbar
                    android:id="@+id/toolbar"
                    android:layout_width="match_parent"
                    android:layout_height="?attr/actionBarSize"
                    app:layout_collapseMode="pin"
                    app:popupTheme="@style/AppTheme.PopupOverlay"/>

            </android.support.design.widget.CollapsingToolbarLayout>

            <!-- ViewModelのonLanguageSpinnerItemSelected()를 onItemSelectedListener로 이용한다 -->
            <Spinner
                android:id="@+id/language_spinner"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="16dp"
                android:fitsSystemWindows="true"
                android:onItemSelected="@{viewModel::onLanguageSpinnerItemSelected}"
                />

        </android.support.design.widget.AppBarLayout>

        <include layout="@layout/content_repository_list"/>

        <!-- ViewModelのprogressBarVisibility를 View의 visibility(View 표시 여부)로 이용한다 -->
        <ProgressBar
            android:id="@+id/progress_bar"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:visibility="@{viewModel.progressBarVisibility}"
            />
    </android.support.design.widget.CoordinatorLayout>
</layout>

/**
 * 리포지토리 목록을 표시하는 액티비티
 * MVVM의 뷰 역할을 한다
 */
public class RepositoryListActivity extends AppCompatActivity implements RepositoryListViewContract {

  private Spinner languageSpinner;
  private CoordinatorLayout coordinatorLayout;

  private RepositoryAdapter repositoryAdapter;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ActivityRepositoryListBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_repository_list);
    final GitHubService gitHubService = ((NewGitHubReposApplication) getApplication()).getGitHubService();
    binding.setViewModel(new RepositoryListViewModel((RepositoryListViewContract) this, gitHubService));

    // 뷰를 셋업
    setupViews();
  }

  /**
   * 목록 등 화면 요소를 만든다
   */
  private void setupViews() {
    // 툴바 설정
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    // Recycler View
    RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_repos);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    repositoryAdapter = new RepositoryAdapter((Context) this, (RepositoryListViewContract) this);
    recyclerView.setAdapter(repositoryAdapter);

    // SnackBar 표시에서 이용한다
    coordinatorLayout = (CoordinatorLayout) findViewById(R.id.coordinator_layout);

    // Spinner
    languageSpinner = (Spinner) findViewById(R.id.language_spinner);
    ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_item);
    adapter.addAll("java", "objective-c", "swift", "groovy", "python", "ruby", "c");
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    languageSpinner.setAdapter(adapter);
  }

  // =====RepositoryListViewContract 구현=====
  // 여기서 Presenter로부터 지시를 받아 뷰의 변경 등을 한다

  @Override
  public void startDetailActivity(String full_name) {
    DetailActivity.start(this, full_name);
  }

  @Override
  public void showRepositories(GitHubService.Repositories repositories) {
    repositoryAdapter.setItemsAndRefresh(repositories.items);
  }

  @Override
  public void showError() {
    Snackbar.make(coordinatorLayout, "읽을 수 없습니다", Snackbar.LENGTH_LONG)
            .setAction("Action", null).show();
  }

}

/**
 * MVVM의 ViewModel 역할을 하는 클래스
 */
public class RepositoryListViewModel {

  public final ObservableInt progressBarVisibility = new ObservableInt(View.VISIBLE);
  private final RepositoryListViewContract repositoryListView;
  private final GitHubService gitHubService;

  public RepositoryListViewModel(RepositoryListViewContract repositoryListView, GitHubService gitHubService) {
    this.repositoryListView = repositoryListView;
    this.gitHubService = gitHubService;
  }

  public void onLanguageSpinnerItemSelected(AdapterView<?> parent, View view, int position, long id) {
    //  스피너의 선택 내용이 바뀌면 호출된다
    loadRepositories((String) parent.getItemAtPosition(position));
  }

  /**
   * 지난 일주일간 만들어진 라이브러리를 인기순으로 가져온다
   */
  private void loadRepositories(String langugae) {
    // 로딩 중이므로 진행바를 표시한다
    progressBarVisibility.set(View.VISIBLE);

    // 일주일 전 날짜 문자열 지금이 2016-10-27이라면 2016-10-20이라는 문자열을 얻는다
    final Calendar calendar = Calendar.getInstance();
    calendar.add(Calendar.DAY_OF_MONTH, -7);
    String text = DateFormat.format("yyyy-MM-dd", calendar).toString();

    // Retrofit을 이용해 서버에 액세스한다

    // 지난 일주일간 만들어졌고 언어가 language인 것을 쿼리로 전달한다
    Observable<GitHubService.Repositories> observable = gitHubService.listRepos("language:" + langugae + " " + "created:>" + text);
    // 입출력(IO)용 스레드로 통신하고, 메인스레드로 결과를 받도록 한다
    observable.subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe(new Subscriber<GitHubService.Repositories>() {
      @Override
      public void onNext(GitHubService.Repositories repositories) {
        // 로딩이 끝났으므로 진행바를 표시하지 않는다
        progressBarVisibility.set(View.GONE);
        // 가져온 아이템을 표시하고자, RecyclerView에 아이템을 설정해 갱신한다
        repositoryListView.showRepositories(repositories);
      }

      @Override
      public void onError(Throwable e) {
        // 통신에 실패하면 호출된다
        // 여기서는 스낵바를 표시한다(아래에 표시되는 바)
        repositoryListView.showError();
      }

      @Override
      public void onCompleted() {
        // 아무것도 하지 않는다
      }
    });
  }
}

/**
 * 리포지터리 목록 화면이 가진 Contract(계약)를 정의해두는 인터페이스
 * <p>
 * ViewModel이 직접 Activity를 참조하지 않도록 인터페이스로 명확히 나눈다.
 */
public interface RepositoryListViewContract {
  void showRepositories(GitHubService.Repositories repositories);

  void showError();

  void startDetailActivity(String fullRepositoryName);
}

content_repository_list.xml

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
       xmlns:tools="http://schemas.android.com/tools"
       tools:showIn="@layout/activity_repository_list">


    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler_repos"
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        tools:context=".view.RepositoryListActivity"
        tools:listitem="@layout/repo_item"
        tools:showIn="@layout/activity_repository_list">

    </android.support.v7.widget.RecyclerView>
</merge>

/**
 * RecyclerView에서 리포지토리 목록을 표시하기 위한 Adapter 클래스
 * 이 클래스에 의해 RecyclerView 아이템의 뷰를 생성하고 뷰에 데이터를 넣는다
 */
public class RepositoryAdapter extends RecyclerView.Adapter<RepositoryAdapter.RepoViewHolder> {
  private final RepositoryListViewContract view;
  private final Context context;
  private List<GitHubService.RepositoryItem> items;

  public RepositoryAdapter(Context context, RepositoryListViewContract view) {
    this.context = context;
    this.view = view;
  }

  /**
   * 리포지토리의 데이터를 설정해서 갱신한다
   * @param items
   */
  public void setItemsAndRefresh(List<GitHubService.RepositoryItem> items) {
    this.items = items;
    notifyDataSetChanged();
  }

  public GitHubService.RepositoryItem getItemAt(int position) {
    return items.get(position);
  }

  /**
   * RecyclerView의 아이템의 뷰 작성과 뷰를 보존할 ViewHolder를 생성
   */
  @Override
  public RepoViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    RepoItemBinding binding = DataBindingUtil.inflate(LayoutInflater.from(context), R.layout.repo_item, parent, false);
    binding.setViewModel(new RepositoryItemViewModel(view));
    return new RepoViewHolder(binding.getRoot(), binding.getViewModel());
  }

  /**
   * onCreateViewHolder에서 만든 ViewHolder의 뷰에
   * setItemsAndRefresh(items)에서 설정된 데이터를 넣는다
   */
  @Override
  public void onBindViewHolder(final RepoViewHolder holder, final int position) {
    final GitHubService.RepositoryItem item = getItemAt(position);
    holder.loadItem(item);

  }

  @Override
  public int getItemCount() {
    if (items == null) {
      return 0;
    }
    return items.size();
  }

  /**
   * 뷰를 보존해 둘 클래스
   * 여기서는 ViewModel을 가진다
   */
  static class RepoViewHolder extends RecyclerView.ViewHolder {
    private final RepositoryItemViewModel viewModel;

    public RepoViewHolder(View itemView, RepositoryItemViewModel viewModel) {
      super(itemView);
      this.viewModel = viewModel;
    }

    public void loadItem(GitHubService.RepositoryItem item) {
      viewModel.loadItem(item);
    }
  }


}

 repo_item.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:bind="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <variable
            name="viewModel"
            type="com.github.advanced_android.newgithubrepo.viewmodel.RepositoryItemViewModel" />
    </data>

    <android.support.v7.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        android:clickable="true"
        android:foreground="?selectableItemBackground"
        android:onClick="@{viewModel::onItemClick}"
        android:orientation="vertical"
        app:cardUseCompatPadding="true"
        tools:showIn="@layout/activity_repository_list">

        <RelativeLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="8dp">

            <ImageView
                android:id="@+id/repo_image"
                android:layout_width="64dp"
                android:layout_height="64dp"
                android:layout_margin="8dp"
                bind:imageUrl="@{viewModel.repoImageUrl}" />

            <TextView
                android:id="@+id/repo_name"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginBottom="4dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:layout_marginTop="8dp"
                android:layout_toLeftOf="@+id/repo_star_image"
                android:layout_toRightOf="@id/repo_image"
                android:text="@{viewModel.repoName}"
                android:textAppearance="@android:style/TextAppearance.Large"
                tools:text="title" />

            <TextView
                android:id="@+id/repo_detail"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@id/repo_name"
                android:layout_marginBottom="4dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:layout_marginTop="4dp"
                android:layout_toRightOf="@id/repo_image"
                android:maxLines="20"
                android:text="@{viewModel.repoDetail}"
                android:textAppearance="@android:style/TextAppearance"
                tools:text="contents" />

            <TextView
                android:id="@+id/repo_star"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentRight="true"
                android:layout_margin="8dp"
                android:text="@{viewModel.repoStar}"
                android:textAppearance="@android:style/TextAppearance"
                tools:text="contents" />

            <ImageView
                android:id="@id/repo_star_image"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginBottom="4dp"
                android:layout_marginLeft="4dp"
                android:layout_marginTop="8dp"
                android:layout_toLeftOf="@id/repo_star"
                android:src="@drawable/ic_star_black_18dp" />


        </RelativeLayout>


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

상세 화면

/**
 * 상세 화면을 표시하는 액티비티
 */
public class DetailActivity extends AppCompatActivity implements DetailViewContract {
  private static final String EXTRA_FULL_REPOSITORY_NAME = "EXTRA_FULL_REPOSITORY_NAME";
  private String fullRepoName;

  /**
   * DetailActivity를 시작하는 메소드
   * @param fullRepositoryName 표시하고 싶은 리포지토리 이름(google/iosched 등)
   */
  public static void start(Context context, String fullRepositoryName) {
    final Intent intent = new Intent(context, DetailActivity.class);
    intent.putExtra(EXTRA_FULL_REPOSITORY_NAME, fullRepositoryName);
    context.startActivity(intent);
  }

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    final ActivityDetailBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_detail);
    final GitHubService gitHubService = ((NewGitHubReposApplication) getApplication()).getGitHubService();
    final DetailViewModel detailViewModel = new DetailViewModel((DetailViewContract) this, gitHubService);
    binding.setViewModel(detailViewModel);

    final Intent intent = getIntent();
    fullRepoName = intent.getStringExtra(EXTRA_FULL_REPOSITORY_NAME);
    detailViewModel.loadRepositories();
  }

  @Override
  public String getFullRepositoryName() {
    return fullRepoName;
  }


  /**
   * @throws Exception
   */
  @Override
  public void startBrowser(String url) {
    startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
  }

  @Override
  public void showError(String message) {
    Snackbar.make(findViewById(android.R.id.content), message, Snackbar.LENGTH_LONG)
            .show();
  }

}

<?xml version="1.0" encoding="utf-8"?>
<layout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <variable
            name="viewModel"
            type="com.github.advanced_android.newgithubrepo.viewmodel.DetailViewModel"/>
    </data>

    <android.support.v7.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        tools:context=".view.DetailActivity">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_margin="8dp">

            <ImageView
                android:id="@+id/owner_image"
                android:layout_width="72dp"
                android:layout_height="72dp"
                android:layout_centerHorizontal="true"
                android:layout_margin="8dp"
                android:onClick="@{viewModel::onTitleClick}"
                app:imageUrl="@{viewModel.repoImageUrl}"
                tools:src="@android:drawable/sym_def_app_icon"/>

            <TextView
                android:id="@+id/fullname"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentLeft="true"
                android:layout_below="@id/owner_image"
                android:layout_marginBottom="32dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:layout_marginTop="8dp"
                android:layout_toLeftOf="@+id/repo_star_image"
                android:onClick="@{viewModel::onTitleClick}"
                android:text="@{viewModel.repoFullName}"
                android:textAppearance="@android:style/TextAppearance.Large"
                tools:text="owner/reponame"/>

            <TextView
                android:id="@+id/detail"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@id/fullname"
                android:layout_margin="8dp"
                android:text="@{viewModel.repoDetail}"
                android:textAppearance="@android:style/TextAppearance"
                tools:text="this is detail text. aaaaaaaaaaaaaaaaaaaaaaaaa"/>

            <TextView
                android:id="@+id/repo_star"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentRight="true"
                android:layout_below="@id/owner_image"
                android:layout_margin="8dp"
                android:text="@{viewModel.repoStar}"
                android:textAppearance="@android:style/TextAppearance"
                tools:text="contents"/>

            <ImageView
                android:id="@id/repo_star_image"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@id/owner_image"
                android:layout_marginBottom="4dp"
                android:layout_marginLeft="4dp"
                android:layout_marginTop="8dp"
                android:layout_toLeftOf="@id/repo_star"
                android:src="@drawable/ic_star_black_18dp"/>


            <TextView
                android:id="@+id/repo_fork"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentRight="true"
                android:layout_below="@id/repo_star"
                android:layout_margin="8dp"
                android:text="@{viewModel.repoFork}"
                android:textAppearance="@android:style/TextAppearance"
                tools:text="contents"/>

            <ImageView
                android:id="@+id/repo_fork_image"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_below="@id/repo_star"
                android:layout_marginBottom="4dp"
                android:layout_marginLeft="4dp"
                android:layout_marginTop="8dp"
                android:layout_toLeftOf="@id/repo_star"
                android:src="@drawable/ic_call_split_black_18dp"/>


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

public class DetailViewModel {
  final DetailViewContract detailView;
  private final GitHubService gitHubService;
  public ObservableField<String> repoFullName = new ObservableField<>();
  public ObservableField<String> repoDetail = new ObservableField<>();
  public ObservableField<String> repoStar = new ObservableField<>();
  public ObservableField<String> repoFork = new ObservableField<>();
  public ObservableField<String> repoImageUrl = new ObservableField<>();
  private GitHubService.RepositoryItem repositoryItem;

  public DetailViewModel(DetailViewContract detailView, GitHubService gitHubService) {
    this.detailView = detailView;
    this.gitHubService = gitHubService;
  }

  public void prepare() {
    loadRepositories();
  }

  /**
   * 하나의 리포지터리에 대한 정보를 가져온다 
   * 기본적으로 API 액세스 방법에 대해서는 RepositoryListActivity#loadRepositories(String)와 같다
   */
  public void loadRepositories() {
    String fullRepoName = detailView.getFullRepositoryName();
    // 리포지터리 이름을 /로 나눈다
    final String[] repoData = fullRepoName.split("/");
    final String owner = repoData[0];
    final String repoName = repoData[1];
    gitHubService
        .detailRepo(owner, repoName)
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(new Subscriber<GitHubService.RepositoryItem>() {
          @Override
          public void onCompleted() {
            // 아무것도 하지 않는다 
          }

          @Override
          public void onError(Throwable e) {
            detailView.showError("error。");
          }

          @Override
          public void onNext(GitHubService.RepositoryItem repositoryItem) {
            loadRepositoryItem(repositoryItem);
          }
        });
  }

  private void loadRepositoryItem(GitHubService.RepositoryItem repositoryItem) {
    this.repositoryItem = repositoryItem;
    repoFullName.set(repositoryItem.full_name);
    repoDetail.set(repositoryItem.description);
    repoStar.set(repositoryItem.stargazers_count);
    repoFork.set(repositoryItem.forks_count);
    repoImageUrl.set(repositoryItem.owner.avatar_url);
  }


  public void onTitleClick(View v) {
    try {
      detailView.startBrowser(repositoryItem.html_url);
    } catch (Exception e) {
      detailView.showError("링크를 열 수 없습니다.");
    }
  }
}

/**
 * 상세 화면의 뷰가 가진 Contract(계약)을 정의해 두는 인터페이스
 * <p>
 * ViewModel이 직접 Activity를 참조하지 않도록 인터페이스로 명확히 나눈다
 */
public interface DetailViewContract {

  String getFullRepositoryName();

  void startBrowser(String url);

  void showError(String message);
}

public class BindingAdapters {

  @BindingAdapter({"imageUrl"})
  public static void loadImage(final ImageView imageView, final String imageUrl) {
    // 이미지는 Glide라는 라이브러리를 사용해 데이터를 설정한다
    Glide.with(imageView.getContext())
         .load(imageUrl)
         .asBitmap().centerCrop().into(new BitmapImageViewTarget(imageView) {
      @Override
      protected void setResource(Bitmap resource) {
        // 이미지를 동그랗게 오려낸다
        RoundedBitmapDrawable circularBitmapDrawable = RoundedBitmapDrawableFactory.create(imageView.getResources(), resource);
        circularBitmapDrawable.setCircular(true);
        imageView.setImageDrawable(circularBitmapDrawable);
      }
    });
  }
}