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本文為大家分享了實現斷點續傳下載的具體代碼，供大家參考，具體內容如下
1、基于Ok+Rxjava實現斷點續傳下載
2、基于Ok+Rxjava+Retrofit實現斷點續傳下載
上一篇博客中介紹了基于Ok+Rxjava實現斷點續傳下載，這一篇給大家介紹下基于Ok+Rxjava+Retrofit實現斷點續傳下載，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）:根據文件下載url按照自己定義的規則生成文件名，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；如果文件比服務器獲取的文件大小小，則執行斷點下載，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給設置進去，從而完成我們的進度監聽工作。
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
.subscribeOn(Schedulers.io())//在子線程執行
.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);
}
}
從服務器獲取文件長度
/**
* 從服務器獲取文件長度
*
* @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以上禁止明文網絡傳輸。需要在你的AndroidManifest中的application標簽中聲明"android:usesCleartextTraffic="true",允許應用進行明文傳輸。
使用方法：首先要獲取sd卡權限
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，我已經在內部做過處理，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容，希望對大家的學習有所幫助，也希望大家多多支持億速云。
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