这篇文章主要为大家展示了“Retrofit+Rxjava下载文件进度的示例分析”，内容简而易懂，条理清晰，希望能够帮助大家解决疑惑，下面让小编带领大家一起研究并学习一下“Retrofit+Rxjava下载文件进度的示例分析”这篇文章吧。
准备工作
本文采用Dagger2，Retrofit，RxJava。
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'//dagger2compile'com.google.dagger:dagger:2.6'apt'com.google.dagger:dagger-compiler:2.6'//RxJavacompile'io.reactivex:rxandroid:1.2.0'compile'io.reactivex:rxjava:1.1.5'compile'com.jakewharton.rxbinding:rxbinding:0.4.0'改造ResponseBody
okHttp3默认的ResponseBody因为不知道进度的相关信息，所以需要对其进行改造。可以使用接口监听进度信息。这里采用的是RxBus发送FileLoadEvent对象实现对下载进度的实时更新。这里先讲改造的ProgressResponseBody。
public class ProgressResponseBody extends ResponseBody { private ResponseBody responseBody; private BufferedSource bufferedSource; public ProgressResponseBody(ResponseBody responseBody) { this.responseBody = responseBody; } @Override public MediaType contentType() { return responseBody.contentType(); } @Override public long contentLength() { return responseBody.contentLength(); } @Override public BufferedSource source() { if (bufferedSource == null) { bufferedSource = Okio.buffer(source(responseBody.source())); } return bufferedSource; } private Source source(Source source) { return new ForwardingSource(source) { long bytesReaded = 0; @Override public long read(Buffer sink, long byteCount) throws IOException { long bytesRead = super.read(sink, byteCount); bytesReaded += bytesRead == -1 ? 0 : bytesRead; //实时发送当前已读取的字节和总字节 RxBus.getInstance().post(new FileLoadEvent(contentLength(), bytesReaded)); return bytesRead; } }; }}呃，OKIO相关知识我也正在学，这个是从官方Demo中copy的代码，只不过中间使用了RxBus实时发送FileLoadEvent对象。
FileLoadEvent
FileLoadEvent很简单，包含了当前已加载进度和文件总大小。
public class FileLoadEvent { long total; long bytesLoaded; public long getBytesLoaded() { return bytesLoaded; } public long getTotal() { return total; } public FileLoadEvent(long total, long bytesLoaded) { this.total = total; this.bytesLoaded = bytesLoaded; }}RxBus
RxBus 名字看起来像一个库，但它并不是一个库，而是一种模式，它的思想是使用 RxJava 来实现了 EventBus ，而让你不再需要使用OTTO或者 EventBus。点我查看详情。
public class RxBus { private static volatile RxBus mInstance; private SerializedSubject<Object, Object> mSubject; private HashMap<String, CompositeSubscription> mSubscriptionMap; private RxBus() { mSubject = new SerializedSubject<>(PublishSubject.create()); } public static RxBus getInstance() { if (mInstance == null) { synchronized (RxBus.class) { if (mInstance == null) { mInstance = new RxBus(); } } } return mInstance; } public void post(Object o) { mSubject.onNext(o); } public <T> Observable<T> tObservable(final Class<T> type) { //ofType操作符只发射指定类型的数据，其内部就是filter+cast return mSubject.ofType(type); } public <T> Subscription doSubscribe(Class<T> type, Action1<T> next, Action1<Throwable> error) { return tObservable(type) .onBackpressureBuffer() .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(next, error); } public void addSubscription(Object o, Subscription subscription) { if (mSubscriptionMap == null) { mSubscriptionMap = new HashMap<>(); } String key = o.getClass().getName(); if (mSubscriptionMap.get(key) != null) { mSubscriptionMap.get(key).add(subscription); } else { CompositeSubscription compositeSubscription = new CompositeSubscription(); compositeSubscription.add(subscription); mSubscriptionMap.put(key, compositeSubscription); // Log.e("air", "addSubscription:订阅成功 " ); } } public void unSubscribe(Object o) { if (mSubscriptionMap == null) { return; } String key = o.getClass().getName(); if (!mSubscriptionMap.containsKey(key)) { return; } if (mSubscriptionMap.get(key) != null) { mSubscriptionMap.get(key).unsubscribe(); } mSubscriptionMap.remove(key); //Log.e("air", "unSubscribe: 取消订阅" ); }}FileCallBack
那么，重点来了。代码其实有5个方法需要重写，好吧，其实这些方法可以精简一下。其中progress()方法有两个参数，progress和total,分别表示文件已下载的大小和总大小，我们将这两个参数不断更新到UI上就行了。
public abstract class FileCallBack<T> { private String destFileDir; private String destFileName; public FileCallBack(String destFileDir, String destFileName) { this.destFileDir = destFileDir; this.destFileName = destFileName; subscribeLoadProgress(); } public abstract void onSuccess(T t); public abstract void progress(long progress, long total); public abstract void onStart(); public abstract void onCompleted(); public abstract void onError(Throwable e); public void saveFile(ResponseBody body) { InputStream is = null; byte[] buf = new byte[2048]; int len; FileOutputStream fos = null; try { is = body.byteStream(); File dir = new File(destFileDir); if (!dir.exists()) { dir.mkdirs(); } File file = new File(dir, destFileName); fos = new FileOutputStream(file); while ((len = is.read(buf)) != -1) { fos.write(buf, 0, len); } fos.flush(); unsubscribe(); //onCompleted(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { if (is != null) is.close(); if (fos != null) fos.close(); } catch (IOException e) { Log.e("saveFile", e.getMessage()); } } } public void subscribeLoadProgress() { Subscription subscription = RxBus.getInstance().doSubscribe(FileLoadEvent.class, new Action1<FileLoadEvent>() { @Override public void call(FileLoadEvent fileLoadEvent) { progress(fileLoadEvent.getBytesLoaded(),fileLoadEvent.getTotal()); } }, new Action1<Throwable>() { @Override public void call(Throwable throwable) { //TODO 对异常的处理 } }); RxBus.getInstance().addSubscription(this, subscription); } public void unsubscribe() { RxBus.getInstance().unSubscribe(this); }}开始下载
使用自己的ProgressResponseBody
通过OkHttpClient的拦截器去拦截Response，并将我们的ProgressReponseBody设置进去监听进度。
public class ProgressInterceptor implements Interceptor { @Override public Response intercept(Chain chain) throws IOException { Response originalResponse = chain.proceed(chain.request()); return originalResponse.newBuilder() .body(new ProgressResponseBody(originalResponse.body())) .build(); }}构建Retrofit
@Modulepublic class ApiModule { @Provides @Singleton public OkHttpClient provideClient() { OkHttpClient client = new OkHttpClient.Builder() .addInterceptor(new ProgressInterceptor()) .build(); return client; } @Provides @Singleton public Retrofit provideRetrofit(OkHttpClient client){ Retrofit retrofit = new Retrofit.Builder() .client(client) .baseUrl(Constant.HOST) .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) .addConverterFactory(GsonConverterFactory.create()) .build(); return retrofit; } @Provides @Singleton public ApiInfo provideApiInfo(Retrofit retrofit){ return retrofit.create(ApiInfo.class); } @Provides @Singleton public ApiManager provideApiManager(Application application, ApiInfo apiInfo){ return new ApiManager(application,apiInfo); }}请求接口
public interface ApiInfo { @Streaming @GET Observable<ResponseBody> download(@Url String url);}执行请求
public void load(String url, final FileCallBack<ResponseBody> callBack){ apiInfo.download(url) .subscribeOn(Schedulers.io())//请求网络 在调度者的io线程 .observeOn(Schedulers.io()) //指定线程保存文件 .doOnNext(new Action1<ResponseBody>() { @Override public void call(ResponseBody body) { callBack.saveFile(body); } }) .observeOn(AndroidSchedulers.mainThread()) //在主线程中更新ui .subscribe(new FileSubscriber<ResponseBody>(application,callBack)); }在presenter层中执行网络请求。
通过V层依赖注入的presenter对象调用请求网络，请求网络后调用V层更新UI的操作。
public void load(String url){ String fileName = "app.apk"; String fileStoreDir = Environment.getExternalStorageDirectory().getAbsolutePath(); Log.e(TAG, "load: "+fileStoreDir.toString() ); FileCallBack<ResponseBody> callBack = new FileCallBack<ResponseBody>(fileStoreDir,fileName) { @Override public void onSuccess(final ResponseBody responseBody) { Toast.makeText(App.getInstance(),"下载文件成功",Toast.LENGTH_SHORT).show(); } @Override public void progress(long progress, long total) { iHomeView.update(total,progress); } @Override public void onStart() { iHomeView.showLoading(); } @Override public void onCompleted() { iHomeView.hideLoading(); } @Override public void onError(Throwable e) { //TODO: 对异常的一些处理 e.printStackTrace(); } }; apiManager.load(url, callBack); }以上是“Retrofit+Rxjava下载文件进度的示例分析”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注编程网行业资讯频道！
