MVP+retrofit+rxjava基本使用实例

一个简易的APP，借助豆瓣图书API，根据isbn号查询书籍的信息。重要代码如下

需要在gradle里添加的依赖：

    compile 'io.reactivex:rxjava:x.y.z'
    compile 'io.reactivex:rxandroid:1.0.1'
    compile 'com.squareup.retrofit2:retrofit:2.0.2'
    compile 'com.squareup.retrofit2:converter-gson:2.0.2'
    compile 'com.squareup.retrofit2:adapter-rxjava:2.0.2'

bean:

网络请求返回结果的一个实体类，可由android studio的gsonformat插件自动生成，retrofit结合gson可以将返回的json转换为一个这样的实体对象

public class Detail {
    private RatingBean rating;
    private String pubdate;
    private String title;

    public RatingBean getRating() {
        return rating;
    }
    public void setRating(RatingBean rating) {
        this.rating = rating;
    }
    public String getPubdate() {
        return pubdate;
    }
    public void setPubdate(String pubdate) {
        this.pubdate = pubdate;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public static class RatingBean {
        private String average;
        public String getAverage() {
            return average;
        }
        public void setAverage(String average) {
            this.average = average;
        }
    }
}

service:

应用retrofit框架所需设置的一个接口，用于设置网络请求的url与参数。

public interface DetailService {
    @GET("isbn/{isbn}")
    Observable<Detail> getDetail(@Path("isbn") String isbn);
}

utils:

工具类RetrofitHelper，借助单例模式完成对retrofit的一次性配置

public class RetrofitHelper {
    private static Retrofit sInstance = null;

    public static Retrofit getInstance(){
        if (sInstance == null){
            synchronized (RetrofitHelper.class){
                if (sInstance == null){
                    sInstance = new Retrofit.Builder()
                            .baseUrl("https://api.douban.com/v2/book/")
                            .addCallAdapterFactory(RxJavaCallAdapterFactory.create())  //retrofit与rxjava结合必须添加一行
                            .addConverterFactory(GsonConverterFactory.create())  //添加这个方法后，retrofit就能自动将网络请求的返回结果转化为需要的bean对象
                            .build();
                }
                    
            }
        }
        return sInstance;
    }
}

view:

MVP模式中，View层包含一个接口，由Activity实现，并提供给Prestener调用

//DetailView.java
public interface DetailView {
    void updateData(Detail detail);
}

//DetailActivity:
public class DetailActivity extends BaseActivity implements DetailView{

    TextView tv_title;
    TextView tv_points;
    TextView tv_date;

    //用于测试的数据
    String isbn = "9787208094123";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        initView();

        //Activity中主动调用presenter的方法，实现V向M的交互
        new DetailPresenter(this).loadData(isbn);
    }

    private void initView(){
        tv_title = findViewById(R.id.textView1);
        tv_date = findViewById(R.id.textView2);
        tv_points = findViewById(R.id.textView3);
    }

    @Override
    public void updateData(Detail detail) {
        if (detail != null){
            tv_title.setText(detail.getTitle());
            tv_points.setText(detail.getRating().getAverage());
            tv_date.setText(detail.getPubdate());
        }
    }
}

listener:

设置一个回调接口，由presenter实现，提供给Model调用。Model在处理完数据后主动回调，从而在presenter里调用view的方法，实现M向V的交互

public interface OnLoginListener {
    void loginSuccess(User user);
    void loginFailed();
}

presenter:

presenter负责作为view和model之间的桥梁，两者只向其提供接口，从而实现view和Model的完全解耦。

public class DetailPresenter implements OnDetailListener {

    DetailView mDetailView;
    DetailModel mDetailModel;

    public DetailPresenter(DetailView detailView) {
        mDetailView = detailView;
        mDetailModel = new DetailModelImp();
    }

    public void loadData(String isbn){
        mDetailModel.get(isbn,this);
    }

    @Override
    public void getDetailSuccess(Detail detail) {
        mDetailView.updateData(detail);
    }

    @Override
    public void getDetailFailed() {
    }
}

model:

model层包含一个接口和实现该接口的具体类。接口提供给presenter调用。具体类中实现了操作数据的逻辑（即网络请求是在该层进行并解析、存储结果的）。当数据操作结束后，model需要通过一个回调接口通知presenter更新view层内容。这个接口就是由presenter实现的OnDetailListener。

public interface DetailModel {
    void get(String isbn, OnDetailListener detailListener);
}

public class DetailModelImp implements DetailModel{

    @Override
    public void get(String isbn, final OnDetailListener detailListener) {
       
        Retrofit retrofit = RetrofitHelper.getInstance();
        DetailService detailService = retrofit.create(DetailService.class);

        detailService.getDetail(isbn)
                .observeOn(AndroidSchedulers.mainThread()) //回调方法（即下面的onNext等）将在UI线程执行
                .subscribeOn(Schedulers.newThread())  //网络请求将在新线程里执行
                .subscribe(new Observer<Detail>() {
                    @Override
                    public void onCompleted() {
                        Log.d("-------","Completed");
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d("-------","Error");
                        e.printStackTrace();
                        detailListener.getDetailFailed();
                    }

                    @Override
                    public void onNext(Detail detail) {  //这里的detail是执行完网络请求后，得到的请求结果示例
                        Log.d("-------","Next");
                        detailListener.getDetailSuccess(detail);
                    }
                });
    }
}