android多线程断点续传下载

jopen 3年前

最近在研究下载文件的断点续传,主要是能够记录下载位置,退出应用下次再进来的时候也能从当前的位置开始下载,代码为多线程+数据库,代码能够正常运行,但是我在开发的过程中遇到了几个问题,有的没找到解决方案,分享出来,希望有的大神能够指点一下:

  1. 使用HttpURLConnection 获取文件大小的时候,速度在4.x手机上非常慢,但是找了许多中文网站上的代码基本都没有解决,后来google一下,发现添加conn.setRequestMethod(“HEAD”)就可以了,获取包头就可以了,这样conn.disconnect()关闭连接就能够快很多了
  2. 同样的使用HttpURLConnection下载,用户暂停下载或者下载完成conn.disconnect()的调用有时候会花费十几秒的时间,这个找了很久,4.X的bug,解决方法有,但是挺麻烦的,google一下就能找到,我也去参考了其他软件的断点续传,发现也有这问题,不知道有没有方便一点的解决方法,望大神解答
  3. RandomAccessFile的多线程低效率问题,看网上说在低配置手机上RandomAccessFile的效率低,网络支持3M/s的下载,但是读写速度最多只有1M/s,那么不管网速多快,下载速度就是1M/s,不知道能不能找到一个代替的方案
  4. 非常偶现的情况,下载一个超过100M的文件,有时候会莫名其妙的下载到90多M,下载线程HttpURLConnection就自动关闭了链接,但是我只是偶现了一两次,不知道是不是我代码的问题,估计是吧
  5. 在下载过程中,由于网络不稳定或者服务器错误,可能会下载不到数据,所以在线程中检测,如果3s之内没有下载到任何数据,就检测网络是否连接,如果没有链接,就直接抛出网络错误状态,要不然就抛出服务器错误状态
  6. 有一个台湾朋友,提出来的,非常感谢他,服务器状态错误,read函数会阻塞,无法返回,这个时候,我最先使用的是futureTask,非常强暴的将下载线程cancel,防止一直阻塞,虽然说可以成功,但是毕竟不好,他提出来使用setReadTimeout函数,将read函数设置为阻塞5s,在5s之内如果得不到数据,就会抛出SocketTimeoutException,下载线程就会成功关闭,这个方法非常好。

代码我贴出来吧,主体就是一个类,附加一个数据库类,主要是线程之间的交互吧,有一个开始线程,主要功能是当数据库中没有该下载文件信息的时候去创建,如果有,就去数据库中获取,并且开始数个下载线程开始下载文件;当用户暂停的时候会启动停止线程去结束开始线程(如果没有执行完成)和下载线程,这时候第2个问题就会出现,关闭下载线程时,4.x的手机关闭http连接的速度慢的惊人。

FileDownloadManager类

public class FileDownloadManager {        /** 开启线程 */      private static final int STATE_START_THREADS = -1;      /** 更新状态 */      private static final int STATE_UPDATE_PROGRESS = 0;      /** 下载状态,正在获取文件大小 */      public static final int STATE_GETSIZE = 1;      /** 下载状态,开始下载 */      public static final int STATE_STARTING = 2;      /** 下载状态,正在停止 */      public static final int STATE_STOPING = 3;      /** 下载状态,停止成功 */      public static final int STATE_STOPED = 4;      /** 下载状态,下载完成 */      public static final int STATE_FINISH = 5;      /** 下载状态,正在删除 */      public static final int STATE_DELETING = 6;      /** 下载状态,删除成功 */      public static final int STATE_DELETE = 7;      /** 下载状态,网络错误 */      public static final int STATE_NET_ERROR = 8;      /** 下载状态,服务器错误 */      public static final int STATE_SERVER_ERROR = 9;        /** 当前文件的下载状态,默认为停止成功,即为下载完成,且随时可以开始下载 */      private int currentState = STATE_STOPED;        /** 下载一个文件所开启的线程数量 */      private final int THREAD_NUM = 4;      /** 下载一个文件的所有线程信息 */      private ArrayList<DownloadInfo> infos;      /** 开始下载线程 */      private Thread startDownloadThread;      /** 结束下载线程 */      private Thread stopDownloadThread;      /** 删除下载线程 */      private Thread deleteDownloadThread;        /** 下载一个文件的线程队列 */      private ArrayList<DownloadThread> threads;        /** 更新下载信息,更新界面线程 */      private UpdateThread updateThread;      /** 数据库操作对象 */      private DownloadDBHelper helper;      /** 该文件下载名 */      private String fileName;      /** 该文件下载的url */      private String url;      /** 该文件下载路径,默认为SD卡file目录 */      private String path = FileUtils.getExternalStorageFilePath();      /** 该文件下载的文件大小 */      private long fileSize = 0;      /** 该文件下载的完成度 */      private long completeSize = 0;      /** 通知更新进度handler */      private ProgressChangeHandler progressChangeHandler;      /** 文件下载进度更新 */      private IDownloadProgressChangedListener listener;      /** 文件的下载状态,true表示正在下载 */      private boolean downloadState = false;      /** 文件是否下载完成 */      private boolean isDownloadFinish = false;      /** 下载线程是否结束标识 */      private CountDownLatch countDownLatch;        /**       * @param url 文件下载url       * @param fileName 文件名,默认将会下载到sd卡file目录下       */      public FileDownloadManager(String url, String fileName){          this(url, fileName, null);      }        /**       * @param url 文件下载url       * @param fileName 文件名       * @param path 文件下载路径,不需要带文件名       */      public FileDownloadManager(String url, String fileName, String path){          this.url = url;          if (path != null)              this.path = path;          if (!this.path.substring(this.path.length()-1).equals("/")){              this.path += "/";          }            //保存该文件原路径          this.fileName = this.path + fileName;            //将文件名字先进行md5,最后等文件下载完成之后再更改文件名字          String md5 = CommonUtils.md5(fileName);          this.path += md5;            helper = new DownloadDBHelper();          infos = new ArrayList<>();          threads = new ArrayList<>();          progressChangeHandler = new ProgressChangeHandler(this);          checkFileFinish();      }        /**       * 检测该文件是否已经下载完成       */      private boolean checkFileFinish(){          if (isDownloadFinish || isFileDownloadFinish(helper.getInfo(url))){              isDownloadFinish = true;              progressChangeHandler.sendEmptyMessage(STATE_FINISH);              return true;          }          return false;      }        /**       * 开启下载       */      public void start(){          if (!CommonUtils.isNetworkAvailable()){              progressChangeHandler.sendEmptyMessage(STATE_NET_ERROR);              T.getInstance().showShort("网络错误");              return;          }            if (checkFileFinish()){              T.getInstance().showShort("文件已下载完成");              return;          }            if (downloadState){              T.getInstance().showShort("已经启动下载");              return;          }            if (currentState == STATE_STOPING){              T.getInstance().showShort("文件还未停止成功");              return;          }            if (currentState == STATE_DELETING){              T.getInstance().showShort("文件正在删除");              return;          }            if (currentState == STATE_DELETE){              T.getInstance().showShort("文件已删除");              return;          }            downloadState = true;            //开启下载任务          startDownload(helper.getInfo(url));      }        /**       * 停止下载       */      public void stop(){          downloadState = false;          //停止更新界面线程,一定要保证最多只有一个更新线程在执行          if (updateThread != null && updateThread.isAlive())              updateThread.canRun = false;            if (checkFileFinish()){              T.getInstance().showShort("文件已下载完成");              return;          }            if (currentState == STATE_STOPING){              T.getInstance().showShort("正在停止,稍后...");              return;          }            if (currentState == STATE_STOPED){              T.getInstance().showShort("已停止");              return;          }            if (currentState == STATE_DELETING){              T.getInstance().showShort("文件正在删除");              return;          }            if (currentState == STATE_DELETE){              T.getInstance().showShort("文件已删除");              return;          }            stopDownload();      }        /**       * 删除该文件下载的相关所有信息,成功之后,该对象将自动置为null       */      public void delete(){          //停止下载线程          downloadState = false;          //停止更新界面线程,一定要保证最多只有一个更新线程在执行          if (updateThread != null && updateThread.isAlive())              updateThread.canRun = false;            if (currentState == STATE_DELETING){              T.getInstance().showShort("正在删除,稍后...");              return;          }            if (currentState == STATE_DELETE){              T.getInstance().showShort("已删除");              return;          }            if (currentState == STATE_STOPING){              T.getInstance().showShort("正在停止,稍后...");              return;          }          deleteDownload();      }        private void startDownload(final ArrayList<HashMap<String, String>> maps){          startDownloadThread = new Thread(new Runnable() {              @Override              public void run() {                  if (stopDownloadThread!=null && stopDownloadThread.isAlive()){                      Looper.prepare();                      T.getInstance().showShort("正在停止,稍后...");                      Looper.loop();                      Looper.myLooper().quit();                      return;                  }                    if (deleteDownloadThread!=null && deleteDownloadThread.isAlive()){                      Looper.prepare();                      T.getInstance().showShort("文件正在删除");                      Looper.loop();                      Looper.myLooper().quit();                      return;                  }                    //如果没有下载信息,则需要创建                  if (infos==null || infos.size()==0) {                      if (maps == null || maps.size() == 0) {                          createDownloadInfos();                      } else {                          revertDownloadInfos(maps);                      }                  }                    //更新文件状态为正在下载                  progressChangeHandler.sendEmptyMessage(STATE_STARTING);                    //上次的线程完成之后才能开启新的下载线程开始下载                  threads.clear();                  for (DownloadInfo info : infos){                      DownloadThread thread = new DownloadThread(info);                      threads.add(thread);                  }                  L.i("准备开启下载线程");                  //初始化多线程标识                  countDownLatch = new CountDownLatch(THREAD_NUM);                    progressChangeHandler.sendEmptyMessage(STATE_START_THREADS);              }          });          startDownloadThread.start();      }        private void stopDownload(){          stopDownloadThread = new Thread(new Runnable() {              @Override              public void run() {                  if (deleteDownloadThread!=null && deleteDownloadThread.isAlive()){                      Looper.prepare();                      T.getInstance().showShort("文件正在删除");                      Looper.loop();                      return;                  }                    stopStartThread(STATE_STOPING);                  stopDownloadThread(STATE_STOPING);                    //确保开始线程和下载线程都已经执行完成之后才能将状态修改为停止成功                  progressChangeHandler.sendEmptyMessage(STATE_STOPED);              }          });          stopDownloadThread.start();      }        private void deleteDownload(){          deleteDownloadThread = new Thread(new Runnable() {              @Override              public void run() {                  if (stopDownloadThread!=null && stopDownloadThread.isAlive()){                      Looper.prepare();                      T.getInstance().showShort("正在停止,稍后...");                      Looper.loop();                      Looper.myLooper().quit();                      return;                  }                    stopStartThread(STATE_DELETING);                  stopDownloadThread(STATE_DELETING);                    //确保开始线程,停止线程和下载线程都已经执行完成之后才能开始删除下载的相关信息                  helper.deleteInfos(url);                  File file = new File(path);                  if (file.exists()){                      file.delete();                  }else{                      L.w("FileDownloadManager deleteDownload file not exist");                  }                  progressChangeHandler.sendEmptyMessage(STATE_DELETE);              }          });          deleteDownloadThread.start();      }        /**       * 停止开始线程       */      private void stopStartThread(int sendState){          boolean state;          do {              //如果开始线程还未停止,比如用户摁完开始下载之后快速摁停止下载或删除,              // 这时需要更新状态,直到开始线程完成              state = (startDownloadThread!=null&&startDownloadThread.isAlive());              L.i("开始线程还未结束");              try {                  Thread.sleep(100);              } catch (InterruptedException e) {                  e.printStackTrace();              }              progressChangeHandler.sendEmptyMessage(sendState);          }while (state);      }        /**       * 停止下载线程       */      private void stopDownloadThread(int sendState){          boolean state;            //检测下载线程,确保下载线程要全部执行完成          state = threads.size()>0;          while(state){              state = countDownLatch.getCount()>0;              try {                  Thread.sleep(100);              } catch (InterruptedException e) {                  e.printStackTrace();              }              //还有线程在执行,所以状态还需要相应变更              progressChangeHandler.sendEmptyMessage(sendState);          }      }        /**       * 第一次下载文件,无下载记录,重新创建       */      private void createDownloadInfos(){          try {              //更新状态为正在获取文件大小              progressChangeHandler.sendEmptyMessage(STATE_GETSIZE);              URL url = new URL(FileDownloadManager.this.url);              HttpURLConnection conn = (HttpURLConnection) url.openConnection();              conn.setConnectTimeout(5 * 1000);              conn.setRequestMethod("GET");              //添加这句话,要不然disconnect()会花费很多时间              conn.setRequestMethod("HEAD");              conn.setAllowUserInteraction(true);              conn.connect();              if (conn.getResponseCode()==200) {                  fileSize = conn.getContentLength();                  File file = FileUtils.checkAndCreateFile(path);                  // 本地访问文件                  RandomAccessFile accessFile = new RandomAccessFile(file, "rwd");                  accessFile.setLength(fileSize);                  accessFile.close();              }              conn.disconnect();          } catch (Exception e) {              e.printStackTrace();              L.e("获取文件长度发生错误", e);              return;          }            //开始计算每个线程下载的字节范围          long startPos = 0;          //最后一个线程所下载的字节数一定要小于等于前面的线程保证文件完整性          long perSize = (long) Math.ceil((fileSize*1.0) / (THREAD_NUM*1.0));          for (int i=0; i<THREAD_NUM; i++){              DownloadInfo info = new DownloadInfo();              info.id = i;              info.startPos = startPos;              startPos += perSize;              startPos -= 1;              if (startPos >= fileSize)                  startPos = fileSize-1;              info.endPos = startPos;              info.completeSize = 0;              //下一个任务的开始位置要+1              startPos ++;              infos.add(info);          }          helper.insertInfos(url, infos);      }        /**       * 恢复以前的下载信息       */      private void revertDownloadInfos(ArrayList<HashMap<String, String>> maps){          ArrayList<String> columns = DownloadDB.TABLES.DOWNLOAD.getTableColumns();          for (HashMap<String, String> map : maps){              DownloadInfo info = new DownloadInfo();              info.id = Integer.parseInt(map.get(columns.get(0)));              info.startPos = Long.parseLong(map.get(columns.get(2)));              info.endPos = Long.parseLong(map.get(columns.get(3)));              info.completeSize = Long.parseLong(map.get(columns.get(4)));              completeSize += info.completeSize;              fileSize = fileSize>info.endPos ? fileSize:info.endPos;              infos.add(info);          }      }        /**       * 获取该文件的总下载字节数       */      private long getCompleteSize(){          completeSize = 0;          for (DownloadThread thread : threads)              completeSize += thread.getCompleteSize();          return completeSize;      }        /**       * 检测该文件是否下载完成       */      private boolean isFileDownloadFinish(ArrayList<HashMap<String, String>> maps){          boolean result = true;          if (maps==null || maps.size() == 0){              return false;          }          ArrayList<String> columns = DownloadDB.TABLES.DOWNLOAD.getTableColumns();          for (HashMap<String, String> map : maps){              //如果完成字节数不足end-start,代表该线程未完成,所以需要继续下载              if (Long.parseLong(map.get(columns.get(4))) <                      (Long.parseLong(map.get(columns.get(3)))- Long.parseLong(map.get(columns.get(2))))){                  result = false;                  break;              }          }          return result;      }        public void setListener(IDownloadProgressChangedListener listener){          this.listener = listener;      }        /**       * 下载进度更新接口       */      public interface IDownloadProgressChangedListener{          void onProgressChanged(long completeSize, long totalSize);          void onStateChanged(int state);      }        /**       * 开启更新界面线程和开启下载线程       */      private void startThreads(){          //准备开启线程          updateThread = new UpdateThread();          updateThread.start();          for (Thread thread : threads)              thread.start();      }        /**       * 下载完成之后的处理工作       */      private void finishDownload(){          downloadState = false;          isDownloadFinish = true;          progressChangeHandler.sendEmptyMessage(STATE_FINISH);          if (updateThread!=null && updateThread.isAlive())              updateThread.canRun = false;            File file = new File(path);          File newFile = new File(fileName);          if (file.exists()){              file.renameTo(newFile);          }          helper.deleteInfos(url);      }        private static class ProgressChangeHandler extends Handler{          private WeakReference<FileDownloadManager> activityWeakReference;            public ProgressChangeHandler(FileDownloadManager manager){              activityWeakReference = new WeakReference<>(manager);          }            @Override          public void handleMessage(Message msg) {              if (msg.what == STATE_START_THREADS){                  L.i("开启线程");                  activityWeakReference.get().currentState = STATE_START_THREADS;                  activityWeakReference.get().startThreads();              }              //下载进度更新              else if (msg.what == STATE_UPDATE_PROGRESS) {                  if (activityWeakReference.get().getCompleteSize() >= activityWeakReference.get().fileSize) {                      activityWeakReference.get().finishDownload();                      T.getInstance().showShort("下载完成");                  }                  if (activityWeakReference.get().listener != null)                      activityWeakReference.get().listener.onProgressChanged                              (activityWeakReference.get().getCompleteSize(), activityWeakReference.get().fileSize);              }              //下载状态更新              else {                  L.i("state"+msg.what);                  if (activityWeakReference.get().currentState != msg.what){                      //如果在下载过程中网络发生错误,或者服务器发生错误,就不再更新后面的停止状态                      if ((activityWeakReference.get().currentState == STATE_NET_ERROR                              || activityWeakReference.get().currentState == STATE_SERVER_ERROR)                              && (msg.what==STATE_STOPING || msg.what==STATE_STOPED)){                          return;                      }                      activityWeakReference.get().currentState = msg.what;                      if (activityWeakReference.get().listener != null){                          activityWeakReference.get().listener.onStateChanged(activityWeakReference.get().currentState);                      }                  }              }          }      }        /**       * 单独一个线程下载的信息       */      public class DownloadInfo {          public int id;          public long startPos;          public long endPos;          public volatile long completeSize;      }        /**       * 下载线程       */      private class DownloadThread extends Thread{          private DownloadInfo info;          HttpURLConnection connection = null;          RandomAccessFile randomAccessFile = null;          InputStream is = null;            public DownloadThread(DownloadInfo info){              this.info = info;          }            public long getCompleteSize(){              return info.completeSize;          }            public void initConnection() throws Exception{              URL url = new URL(FileDownloadManager.this.url);              connection = (HttpURLConnection) url.openConnection();              connection.setConnectTimeout(2000);              connection.setReadTimeout(5000);              connection.setRequestMethod("GET");              connection.setAllowUserInteraction(true);                // 设置范围,格式为Range:bytes x-y;              connection.setRequestProperty("Range", "bytes=" + (info.startPos + info.completeSize) + "-" + info.endPos);          }            @Override          public void run() {              try {                  initConnection();                  randomAccessFile = new RandomAccessFile(path, "rwd");                  // 将要下载的字节写到上次写的末尾                  randomAccessFile.seek(info.startPos + info.completeSize);                  //偶尔发现,下载的资源有时候403 FileNotFoundException,这种情况重新连接一次,不成功就Log出错误日志                  try {                      is = connection.getInputStream();                  }catch (Exception e){                      //重新连接                      initConnection();                      try {                          is = connection.getInputStream();                      }catch (Exception ee){                          L.e("无法连接"+info.startPos+"~"+info.endPos+"处资源", ee);                          return;                      }                  }                  byte[] buffer = new byte[1024 * 8];                  int length;                  while (((length = is.read(buffer)) != -1) && downloadState) {                      randomAccessFile.write(buffer, 0, length);                      info.completeSize += length;                  }                  L.i("结束下载线程");              } catch (Exception e) {                  e.printStackTrace();              } finally {                  countDownLatch.countDown();                  try {                      //android 4.x disconnect或者close会耗费很长的时间,解决了很长时间,暂未找到方法,有的联系我                      is.close();                      randomAccessFile.close();                      connection.disconnect();                  } catch (Exception e) {                      e.printStackTrace();                  }              }          }      }        /**       * 更新数据库和界面线程       */      private class UpdateThread extends Thread{            public boolean canRun = true;          private long lastCompleteSize = 0;          /** 重试时间3s */          private final int RETRYCOUNT = 3;          private int retry;            @Override          public void run() {              retry = RETRYCOUNT;              try {                  while (canRun) {                      // 更新数据库中的下载信息                      helper.updateInfos(url, infos);                        L.i("lastCompleteSize  " + lastCompleteSize);                      L.i("更新界面  " + getCompleteSize() + "   fileSize" + fileSize);                      //由于网络不稳定,或者是服务器不稳定导致的无法返回数据                      if (lastCompleteSize == getCompleteSize()){                          retry--;                          if (retry <= 0){                              //停止下载线程,并提示用户重试                              FileDownloadManager.this.stop();                              //有网络的情况下为服务器错误                              if (CommonUtils.isNetworkAvailable()){                                  L.e("服务器错误,请重试");                                  progressChangeHandler.sendEmptyMessage(STATE_SERVER_ERROR);                              }else{                                  L.e("网络错误,请连接网络后重试");                                  progressChangeHandler.sendEmptyMessage(STATE_NET_ERROR);                              }                          }                      }else{                          retry = RETRYCOUNT;                      }                        lastCompleteSize = getCompleteSize();                      //更新界面                      progressChangeHandler.sendEmptyMessage(STATE_UPDATE_PROGRESS);                      //每隔1秒操作数据库和更新界面,防止频繁的更新                      try {                          Thread.sleep(1000);                      } catch (InterruptedException e) {                          e.printStackTrace();                      }                  }              }catch (Exception e){                  e.printStackTrace();              }          }      }  }

github地址,随时更新,随时优化

来自: http://blog.csdn.net/self_study/article/details/50505865