基于Ok+Rxjava+retrofit實現(xiàn)斷點續(xù)傳下載

更新時間：2019年06月22日 16:27:28 作者：Super_Ks

這篇文章主要為大家詳細介紹了基于Ok+Rxjava+retrofit實現(xiàn)斷點續(xù)傳下載，具有一定的參考價值，感興趣的小伙伴們可以參考一下

本文為大家分享了實現(xiàn)斷點續(xù)傳下載的具體代碼，供大家參考，具體內(nèi)容如下

1、基于Ok+Rxjava實現(xiàn)斷點續(xù)傳下載

2、基于Ok+Rxjava+Retrofit實現(xiàn)斷點續(xù)傳下載

上一篇博客中介紹了基于Ok+Rxjava實現(xiàn)斷點續(xù)傳下載，這一篇給大家介紹下基于Ok+Rxjava+Retrofit實現(xiàn)斷點續(xù)傳下載，demo下載地址，效果圖跟上一篇圖片一樣，哈哈

說下我的大致思路吧（跟上一篇略有不同）:根據(jù)文件下載url按照自己定義的規(guī)則生成文件名，判斷本地同路徑下是否存在此文件，如果存在，文件大小與服務(wù)器上獲取的文件大小一致的情況下，則覆蓋本地文件重新下載；如果文件比服務(wù)器獲取的文件大小小，則執(zhí)行斷點下載，從本地文件長度處開始下載。如果文件不存在，則從0字節(jié)開始下載。

還有的不同是，這里需要重新ResponseBody的source()方法，在這里監(jiān)聽文件下載的進度，然后通過我么自定義的Downloadinterceptor把我們重新的DownloadResponseBody給設(shè)置進去，從而完成我們的進度監(jiān)聽工作。

下面還是上主要代碼：

首先重寫ResponseBody

public class DownloadResponseBody extends ResponseBody {
 private ResponseBody responseBody;
 
 //進度回調(diào)接口
 private DownFileCallback downFileCallback;
 
 private BufferedSource bufferedSource;
 private String downUrl;
 
 
 public DownloadResponseBody(ResponseBody responseBody, DownFileCallback downFileCallback, String downUrl) {
 this.responseBody = responseBody;
 this.downFileCallback = downFileCallback;
 this.downUrl = downUrl;
 }
 
 @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 totalBytesRead = 0L;
 File file = new File(DownloadManager.getInstance().getTemporaryName(downUrl));
 
 @Override
 public long read(Buffer sink, long byteCount) throws IOException {
 long bytesRead = super.read(sink, byteCount);
 totalBytesRead += bytesRead != -1 ? bytesRead : 0;
 if (null != downFileCallback) {
 if (bytesRead != -1) {
 long loacalSize = file.length();//本地已下載的長度
 long trueTotal = loacalSize + responseBody.contentLength() - totalBytesRead;//文件真實長度
 downFileCallback.onProgress(trueTotal,loacalSize);
 } else {
 
 }
 
 }
 return bytesRead;
 }
 };
 
 }
}

重寫Interceptor

public class Downloadinterceptor implements Interceptor {
 
 private DownFileCallback downFileCallback;
 
 private String downUrl;
 
 public Downloadinterceptor(DownFileCallback listener,String downUrl) {
 this.downFileCallback = listener;
 this.downUrl = downUrl;
 }
 
 @Override
 public Response intercept(Chain chain) throws IOException {
 Response response = chain.proceed(chain.request());
 
 return response.newBuilder()
 .body(new DownloadResponseBody(response.body(), downFileCallback,downUrl))
 .build();
 }
}

然后我們的service

public interface HttpService {
 
 /*大文件需要加入Streaming這個判斷，防止下載過程中寫入到內(nèi)存中,造成oom*/
 @Streaming
 @GET
 Observable<ResponseBody> download(@Header("range") String start, @Url String url);
}

接下來我們的DownloadManager中download方法

 /**
 * 開始下載
 * @param url 下載地址
 * @param downFileCallback 進度回調(diào)接口
 */
 public void download(final String url, final DownFileCallback downFileCallback) {
 /*正在下載不處理*/
 if (url == null || submap.get(url) != null) {
 return;
 }
 
 Downloadinterceptor interceptor = new Downloadinterceptor(downFileCallback, url);
 okHttpClient = new OkHttpClient.Builder()
 .addInterceptor(interceptor)
 .build();
 Retrofit retrofit = new Retrofit.Builder()
 .client(okHttpClient)
 .baseUrl("http://imtt.dd.qq.com")
 .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
 .build();
 final HttpService httpservice = retrofit.create(HttpService.class);
 
 ProgressDownSubscriber subscriber =
 Observable.just(url)
 .flatMap(new Function<String, ObservableSource<DownloadInfo>>() {
 @Override
 public ObservableSource<DownloadInfo> apply(String s) throws Exception {
 return Observable.just(createDownInfo(s));
 }
 })
 .map(new Function<DownloadInfo, DownloadInfo>() {
 @Override
 public DownloadInfo apply(DownloadInfo s) throws Exception {
 return getRealFileName(s);
 }
 })
 .flatMap(new Function<DownloadInfo, Observable<ResponseBody>>() {
 @Override
 public Observable<ResponseBody> apply(DownloadInfo downInfo) throws Exception {
 return httpservice.download("bytes=" + downInfo.getProgress() + "-", downInfo.getUrl());
 }
 })//下載
 .map(new Function<ResponseBody, DownloadInfo>() {
 @Override
 public DownloadInfo apply(ResponseBody responsebody) {
 try {
 return writecache(responsebody, url);
 } catch (IOException e) {
 //*失敗拋出異常*//
 e.printStackTrace();
 }
 return null;
 }
 })
 .observeOn(AndroidSchedulers.mainThread())//在主線程回調(diào)
 .subscribeOn(Schedulers.io())//在子線程執(zhí)行
 .subscribeWith(new ProgressDownSubscriber<DownloadInfo>() {
 @Override
 public void onNext(DownloadInfo downInfo) {
 downFileCallback.onSuccess(downInfo);
 submap.remove(downInfo.getUrl());
 }
 
 @Override
 public void onError(Throwable t) {
 downFileCallback.onFail(t.getMessage());
 submap.remove(url);
 }
 });
 
 
 submap.put(url, subscriber);
 }

然后暫停操作：

 /**
 * 暫停下載
 */
 public void stop(String url) {
 if (url == null) return;
 if (submap.containsKey(url)) {
 ProgressDownSubscriber subscriber = submap.get(url);
 subscriber.dispose();
 submap.remove(url);
 }
 }

從服務(wù)器獲取文件長度

/**
 * 從服務(wù)器獲取文件長度
 *
 * @param downloadUrl
 * @return
 */
 private long getContentLength(String downloadUrl) {
 Request request = new Request.Builder()
 .url(downloadUrl)
 .build();
 try {
 Response response = mClient.newCall(request).execute();
 if (response != null && response.isSuccessful()) {
 long contentLength = response.body().contentLength();
 response.close();
 return contentLength == 0 ? DownloadInfo.TOTAL_ERROR : contentLength;
 }
 } catch (IOException e) {
 e.printStackTrace();
 }
 return DownloadInfo.TOTAL_ERROR;
 }

從服務(wù)器獲取文件長度的時候注意一下，Android P之后，也就是api 28以上禁止明文網(wǎng)絡(luò)傳輸。需要在你的AndroidManifest中的application標簽中聲明"android:usesCleartextTraffic="true",允許應(yīng)用進行明文傳輸。

使用方法：首先要獲取sd卡權(quán)限

DownloadManager.getInstance().downloadPath(本地存放地址).download(url1, new DownFileCallback() {
 @Override
 public void onSuccess(DownloadInfo info) {
 
 Toast.makeText(MainActivity.this, url1 + "下載完成", Toast.LENGTH_SHORT).show();
 }
 
 @Override
 public void onFail(String msg) {
 Toast.makeText(MainActivity.this, url1 + "下載失敗", Toast.LENGTH_SHORT).show();
 }
 
 @Override
 public void onProgress(final long totalSize, final long downSize) {
 // 需要注意的是，如果文件總大小為50M，已下載的大小為10M，
 // 再次下載時onProgress返回的totalSize是文件總長度
 // 減去 已下載大小 10M， 即40M，downSize為本次下載的已下載量
 // 好消息是，我已經(jīng)在內(nèi)部做過處理，放心使用吧，但是這個問題大家還是要知道的
 
 runOnUiThread(new Runnable() {
 @Override
 public void run() {
 int progress = (int) (downSize * 100 / totalSize);
 progress1.setProgress(progress);
 }
 });
 }
 });

好了今天就到這里，希望能幫到大家，這對我來說也是一種加深印象的筆記。

demo下載地址

github地址：DownManager 歡迎star

以上就是本文的全部內(nèi)容，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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