Retrofit使用教程(三) : Retrofit與RxJava初相逢

上一篇文章講述了Retrofit的基本使用,包括GET,POST等請求.今天的文章中Retrofit要與RxJava配合使用.

瞭解RxJava

RxJava有種種好處,我不在這裏一一講述.這裏我只給出一個使用RxJava的例子.若是想更深刻地瞭解RxJava,能夠參考如下文章:

給Android開發者的RxJava詳解
RxJava Essentials 中文翻譯版

接下來的文章,我也會寫RxJava的進一步使用的.

案例說明

該例子是獲取手機上安裝的APP,而後列表顯示包括名稱,圖標,安裝時間等信息.

上代碼

下面是自定義的AppInfo類,包含名稱,圖標,安裝時間,版本號,版本名稱等屬性.

public class AppInfo {

    private String name;

    private String installTime;

    private int versionCode;

    private String versionName;

    private Drawable icon;

    public String getName() {
        return name;
    }

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

    public String getInstallTime() {
        return installTime;
    }

    public void setInstallTime(String installTime) {
        this.installTime = installTime;
    }

    public int getVersionCode() {
        return versionCode;
    }

    public void setVersionCode(int versionCode) {
        this.versionCode = versionCode;
    }

    public String getVersionName() {
        return versionName;
    }

    public void setVersionName(String versionName) {
        this.versionName = versionName;
    }

    public Drawable getIcon() {
        return icon;
    }

    public void setIcon(Drawable icon) {
        this.icon = icon;
    }

    @Override
    public String toString() {
        return "AppInfo{" +
                "name='" + name + '\'' +
                ", installTime='" + installTime + '\'' +
                ", versionCode='" + versionCode + '\'' +
                ", versionName='" + versionName + '\'' +
                ", icon=" + icon +
                '}';
    }
}

下面是獲取AppLie表的代碼,封裝爲工具類使用:

public class AppUtil {

    /**
     * 獲取已安裝的APP的列表
     * @param context 上下文
     * @return AppInfo列表
     */
    public static List<AppInfo> getAppList(Context context){
        List<AppInfo> appInfoList = new ArrayList<>();
        List<PackageInfo> packages = context.getPackageManager()
                .getInstalledPackages(PackageManager.GET_ACTIVITIES);
        for (PackageInfo packageInfo : packages) {
            AppInfo appInfo = new AppInfo();
            appInfo.setName(packageInfo.applicationInfo
                    .loadLabel(context.getPackageManager())
                    .toString());
            appInfo.setIcon(packageInfo.applicationInfo
                    .loadIcon(context.getPackageManager()));
            appInfo.setInstallTime(getFormatTime(packageInfo.firstInstallTime));
            appInfo.setVersionCode(packageInfo.versionCode);
            appInfo.setVersionName(packageInfo.versionName);
            appInfoList.add(appInfo);
        }
        return appInfoList;
    }

    public static String getFormatTime(long time){
        if (time <= 0){
            return "";
        }
        return SimpleDateFormat.getDateInstance(DateFormat.FULL).format(new Date(time));
    }
}

不使用RxJava怎麼作?

咱們在不適用RxJava時怎麼作?一般新建一個子線程去執行任務,而後回調更新界面,對不對?

private void getByNormal() {
        refreshLayout.setRefreshing(true);
        infoList.clear();
        appAdapter.notifyDataSetChanged();
        new AsyncTask<Void, Void, List<AppInfo>>(){

            @Override
            protected List<AppInfo> doInBackground(Void... params) {
                return AppHelper.getHelper().getListByNormal(MainActivity.this);
            }

            @Override
            protected void onPostExecute(List<AppInfo> appInfos) {
                infoList.addAll(appInfos);
                appAdapter.notifyDataSetChanged();
                refreshLayout.setRefreshing(false);
            }
        };
    }

使用RxJava

使用RxJava是這樣來寫代碼的:

1.建立Observable

public Observable<List<AppInfo>> getListByRxJava(final Context context){
        Observable<List<AppInfo>> observer = Observable.create(
                new Observable.OnSubscribe<List<AppInfo>>() {
                    @Override
                    public void call(Subscriber<? super List<AppInfo>> subscriber) {
                        List<AppInfo> infoList = AppUtil.getAppList(context);
                        subscriber.onNext(infoList);
                        subscriber.onCompleted();
                    }
        });
        return observer;
    }

2.在界面出調用

private void getByRxJava() {
        refreshLayout.setRefreshing(true);
        infoList.clear();
        appAdapter.notifyDataSetChanged();
        AppHelper.getHelper().getListByRxJava(this)
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(new Subscriber<List<AppInfo>>() {
                    @Override
                    public void onCompleted() {
                        appAdapter.notifyDataSetChanged();
                        refreshLayout.setRefreshing(false);
                    }

                    @Override
                    public void onError(Throwable e) {

                    }

                    @Override
                    public void onNext(List<AppInfo> list) {
                        infoList.addAll(list);
                    }
                });
    }

看結果

這個Demo的源碼在此:RxJavaDemo

在Retrofit中使用RxJava

上次咱們獲取手機的歸屬地時的PhoneService中是這樣寫的:

@GET("/apistore/mobilenumber/mobilenumber")
    Call<PhoneResult> getResult(@Header("apikey") String apikey,
                                @Query("phone") String phone);

返回了一個Call對象,使用RxJava咱們則返回一個可被觀測的PhoneResult:Observable<PhoneResult>,以下:

@GET("/apistore/mobilenumber/mobilenumber")
    Observable<PhoneResult> getPhoneResult(@Header("apikey") String apikey,
                                           @Query("phone") String phone);

爲了能返回此對象,咱們須要在建立Retrofit對象時添加一個RxJava對象的Adapter來自動完成:

Retrofit retrofit = new Retrofit.Builder()
        .baseUrl(BASE_URL)
        .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
        .addConverterFactory(GsonConverterFactory.create())
        .build();

爲此,還封裝了一個單例模式的PhoneApi類:

/**
 * 手機號相關的API
 * Created by Asia on 2016/3/24 0024.
 */
public class PhoneApi {

    /**
     * HOST地址
     */
    public static final String BASE_URL = "http://apis.baidu.com";
    /**
     * 開發者Key
     */
    public static final String API_KEY = "8e13586b86e4b7f3758ba3bd6c9c9135";

    /**
     * 獲取PhoneApi實例
     * @return
     */
    public static PhoneApi getApi(){
        return ApiHolder.phoneApi;
    }

    static class ApiHolder{
        private static PhoneApi phoneApi = new PhoneApi();
    }

    private PhoneService service;

    private PhoneApi(){
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(BASE_URL)
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .addConverterFactory(GsonConverterFactory.create())
                .build();
        service = retrofit.create(PhoneService.class);
    }

    /**
     * 獲取PhoneService實例
     * @return
     */
    public PhoneService getService(){
        return service;
    }
}

下面就是使用去獲取手機的歸屬地啦:

phoneService.getPhoneResult(PhoneApi.API_KEY, number)
        .subscribeOn(Schedulers.newThread())    //子線程訪問網絡
        .observeOn(AndroidSchedulers.mainThread())  //回調到主線程
        .subscribe(new Observer<PhoneResult>() {
            @Override
            public void onCompleted() {}

            @Override
            public void onError(Throwable e) {}

            @Override
            public void onNext(PhoneResult result) {
                if (result != null && result.getErrNum() == 0) {
                    PhoneResult.RetDataEntity entity = result.getRetData();
                    resultView.append("地址：" + entity.getCity());
                }
            }
        });
}

運行一下吧,結果是一樣的哈.

項目地址在此:Dev-Wiki/RetrofitDemo

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