/**
 * 開始下載
 * @param url 下載請求的網(wǎng)址
 * @param downFileCallback 用來回調(diào)的接口
 */
 public void download(final String url, final DownFileCallback downFileCallback) {
 if (url == null || downCalls.get(url) != null) {
 return;
 }
 Observable.just(url)
 .filter(new Predicate<String>() {
  @Override
  public boolean test(String s) throws Exception {
  //過濾條件 若map中存在，則這次不下載
  return !downCalls.containsKey(s);
  }
 })
 .flatMap(new Function<String, ObservableSource<DownloadInfo>>() {
  @Override
  public ObservableSource<DownloadInfo> apply(String s) throws Exception {
  //創(chuàng)建下載實體類
  return Observable.just(createDownInfo(s));
  }
 })
 .map(new Function<DownloadInfo, DownloadInfo>() {
  @Override
  public DownloadInfo apply(DownloadInfo s) throws Exception {
  //根據(jù)本地是否存在此文件，來設(shè)置文件名及文件初始下載大小
  return getRealFileName(s);
  }
 })
 .flatMap(new Function<DownloadInfo, ObservableSource<DownloadInfo>>() {
  @Override
  public ObservableSource<DownloadInfo> apply(DownloadInfo downloadInfo) throws Exception {
  //創(chuàng)建被觀察者
  return Observable.create(new DownloadSubscribe(downloadInfo));
  }
 })//下載
 .observeOn(AndroidSchedulers.mainThread())//在主線程回調(diào)
 .subscribeOn(Schedulers.io())//在子線程執(zhí)行
 .subscribe(new DownLoadObserver() {//添加觀察者
  @Override
  public void onNext(DownloadInfo downloadInfo) {
  super.onNext(downloadInfo);
  downFileCallback.onProgress(downloadInfo.getTotal(), downloadInfo.getProgress());
  }
 
  @Override
  public void onError(Throwable e) {
  super.onError(e);
  if (!(e instanceof SocketException)) {
  downFileCallback.onFail(e.getMessage());
  }
 
  }
 
  @Override
  public void onComplete() {
  downFileCallback.onSuccess(url);
  }
 
 });
 }

/**
 * 根據(jù)url暫停下載操作
 * @param url
 */
 public void cancel(String url) {
 Call call = downCalls.get(url);
 if (call != null) {
 call.cancel();//取消
 }
 downCalls.remove(url);
 }

 /**
 * 創(chuàng)建被觀察者DownloadSubscribe
 */
 private class DownloadSubscribe implements ObservableOnSubscribe<DownloadInfo> {
 private DownloadInfo downloadInfo;
 
 public DownloadSubscribe(DownloadInfo downloadInfo) {
 this.downloadInfo = downloadInfo;
 }
 
 @Override
 public void subscribe(ObservableEmitter<DownloadInfo> e) throws Exception {
 String url = downloadInfo.getUrl();
 long downloadLength = downloadInfo.getProgress();//已經(jīng)下載好的長度
 long contentLength = downloadInfo.getTotal();//文件的總長度
 //初始進度信息
 e.onNext(downloadInfo);
 
 Request request = new Request.Builder()
  //斷點續(xù)傳的核心
  .addHeader("RANGE", "bytes=" + downloadLength + "-" + contentLength)
  .url(url)
  .build();
 Call call = mClient.newCall(request);
 //根據(jù)下載url，把call存放在map中，取消的時候就可以通過call.cancle()來實現(xiàn)
 downCalls.put(url, call);
 Response response = call.execute();
 
 File file = new File(getTemporaryPath(), downloadInfo.getFileName());
 InputStream is = null;
 FileOutputStream fileOutputStream = null;
 try {
 is = response.body().byteStream();
 fileOutputStream = new FileOutputStream(file, true);
 byte[] buffer = new byte[2048];//緩沖數(shù)組2kB
 int len;
 while ((len = is.read(buffer)) != -1) {
  fileOutputStream.write(buffer, 0, len);
  downloadLength += len;
  downloadInfo.setProgress(downloadLength);
  e.onNext(downloadInfo);
 }
 fileOutputStream.flush();
 downCalls.remove(url);
 } finally {
 //關(guān)閉IO流
 IOUtil.closeAll(is, fileOutputStream);
 
 }
 e.onComplete();//完成
 }
 }

/**
 * 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;
 }

DownloadManager.getInstance().downloadPath(本地存在地址).download(url1, new DownFileCallback() {
  @Override
  public void onProgress(long totalSize, long downSize) {
  progress1.setMax((int) totalSize);
  progress1.setProgress((int) downSize);
  }
 
  @Override
  public void onSuccess(String url) {
  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();
  }
 });