/** * Created by Administrator on 2017/3/6 0006. */public class DownLoadDBHelper extends SQLiteOpenHelper {  /**   * DownLoadDBHelper用于創建數據庫，如果不會使用原生的建庫的話   *   * 跟隨小司機我的腳步來一起練一練   * 建兩個表：   * download_info表存儲下載信息   * localdownload_info表存儲本地下載信息   * 之后對比兩個表進行繼續下載等等   */  public static String DATABASE_NAME = "downloadFILES.db";  public static String TABLE_DOWNLOAD_INFO = "download_info";  public static String TABLE_LOCALDOWNLOAD_INFO = "localdownload_info";  private static int version = 1;  public DownLoadDBHelper(Context context) {    super(context, DATABASE_NAME, null, version);  }  @Override  public void onCreate(SQLiteDatabase db) {    /*在此進行創建數據庫和表格,來一起動手寫一遍,就是兩個sqlite語句*/    db.execSQL("create table " + TABLE_DOWNLOAD_INFO + "(" + "id integer PRIMARY KEY AUTOINCREMENT," +        "thread_id integer," + "start_position integer," + "end_position integer," + " completed_size integer," + "url varchar(100))");    db.execSQL("create table " + TABLE_LOCALDOWNLOAD_INFO + "(" + "id integer PRIMARY KEY AUTOINCREMENT," + "name varchar(50)," +        "url varchar(100)," + "completedSize integer," + "fileSize integer," + "status integer)");  }  @Override  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {    /*數據庫更新升級，檢測到版本的變化，發現版本號不一樣，就會自動調用onUpgrade函數    * 新版本號和老版本號都會作為onUpgrade函數的參數傳進來，便于開發者知道數據庫應該從哪個版本升級到哪個版本。    * */    String sql = "drop table if exists " + TABLE_DOWNLOAD_INFO + "";    String sqlOne = "drop table if exists " + TABLE_LOCALDOWNLOAD_INFO + "";    db.execSQL(sql);    db.execSQL(sqlOne);    onCreate(db);//刪除數據庫，重新創建。這里只是簡單的，并沒有添加或者減少數據庫中的其他字段  }}

/** * Created by ShanCanCan on 2017/3/6 0006. */public class Dao {  /*  * DAO層主要是做數據持久層的工作，負責與數據庫進行聯絡的一些任務都封裝在此。  * DAO層所定義的接口里的方法都大同小異，這是由我們在DAO層對數據庫訪問的操作來決定的，  * 對數據庫的操作，我們基本要用到的就是新增，更新，刪除，查詢等方法。  * 因而DAO層里面基本上都應該要涵蓋這些方法對應的操作。  * */  private static Dao dao;  private static DownLoadDBHelper dbHelper;  public static final byte[] Lock = new byte[0]; //新建兩個字節作為對象鎖  public static final byte[] file_Lock = new byte[0];  public Dao() {//空構造方法，  }  public static synchronized Dao getInstance(Context context) {//本demo用單例模式中的懶漢模式+線程不安全 線程安全的代價是效率變低    if (dao == null) {      dao = new Dao();      dbHelper = new DownLoadDBHelper(context);    }    return dao;  }  /* public static synchronized Dao getInstance(Context context) {//本demo用單例模式中的懶漢模式+線程安全 線程安全的代價是效率變低，99%情況下不需要同步    if (dao == null) { //你可以在這兩個方法中隨便選擇一個      dao = new Dao();      dbHelper = new DownLoadDBHelper(context);    }    return dao;  }*/  /***************************************  下方Dao層中對數據庫的增、刪、改、查  *********************************************************/  /**   * 檢查本地下載記錄，是否下載過   *   * @param url   * @return   */  public boolean isExist(String url) {    SQLiteDatabase database = dbHelper.getReadableDatabase(); //獲取本app所創建的數據庫    String sql = "select count(*) from " + TABLE_LOCALDOWNLOAD_INFO + " where url=?"; //查詢語句,查詢總共有多少條的語句    Cursor cursor = database.rawQuery(sql, new String[]{url});    /**     *     * @Cursor     * Cursor 是每行的集合。     * 使用 moveToFirst() 定位第一行。     * 你必須知道每一列的名稱。     * 你必須知道每一列的數據類型。     * Cursor 是一個隨機的數據源。     * 所有的數據都是通過下標取得。     * Cursor按照我的理解就是一個箭頭，指到哪一行就是那一行的集合     * 比較重要的方法有：close(),moveToFirst(),moveToNext(),moveToLast(),moveToPrevious(),getColumnCount()等。     *     * @rawQuery     * rawQuery是直接使用SQL語句進行查詢的，也就是第一個參數字符串，     * 在字符串內的“？”會被后面的String[]數組逐一對換掉     * cursor用完之后要關閉，cursor用完之后要關閉，cursor用完之后要關閉。重要的事情說三遍！！！     *     * */    cursor.moveToFirst();    int count = cursor.getInt(0);    cursor.close();    return count > 0;  }  /**   * 是否為首次下載   *   * @param url   * @return   */  public boolean isFirstDownload(String url) {    SQLiteDatabase database = dbHelper.getReadableDatabase();    String sql = "select count(*) from " + TABLE_DOWNLOAD_INFO + " where url=?";    Cursor cursor = database.rawQuery(sql, new String[]{url});    cursor.moveToFirst();    int count = cursor.getInt(0);    cursor.close();    return count == 0;  }  /**   * 保存下載的具體信息 保存所下載的list集合中的數據   *   * @param infos   * @param context   */  public void saveInfos(List<DownLoadInfo> infos, Context context) {    /**     * 事務（Transaction）是并發控制的單位，是用戶定義的一個操作序列。     * 這些操作要么都做，要么都不做，是一個不可分割的工作單位。     * 通過事務，SQL Server能將邏輯相關的一組操作綁定在一起，     * 以便保持數據的完整性。     *     * 事務具有四個特征：原子性（ Atomicity ）、一致性（ Consistency ）、     * 隔離性（ Isolation ）和持續性（ Durability ）。這四個特性簡稱為 ACID 特性。     *     * */    synchronized (Lock) {      SQLiteDatabase database = dbHelper.getWritableDatabase();      database.beginTransaction();//開啟事務      try {//如果有異常，在這里捕獲        for (DownLoadInfo info : infos) {//for循環將數據存入數據庫          String sql = "insert into " + TABLE_DOWNLOAD_INFO + "(thread_id,start_position, end_position, completed_size, url) values (?,?,?,?,?)";          Object[] bindArgs = {info.getThreadId(), info.getStartPosition(), info.getEndPosition(), info.getCompletedSize(), info.getUrl()};          database.execSQL(sql, bindArgs);        }        database.setTransactionSuccessful();//結束事務      } catch (SQLException e) {        e.printStackTrace();      } finally {        database.endTransaction();//關閉事務      }    }  }  /**   * 得到下載具體信息   *   * @param urlstr   * @return List<DownloadInfo> 一個下載器信息集合器,里面存放了每條線程的下載信息   */  public List<DownLoadInfo> getInfos(String urlstr) {    List<DownLoadInfo> list = new ArrayList<DownLoadInfo>();    SQLiteDatabase database = dbHelper.getReadableDatabase();    String sql = "select thread_id, start_position, end_position, completed_size, url from " + TABLE_DOWNLOAD_INFO + " where url=?";    Cursor cursor = database.rawQuery(sql, new String[]{urlstr});    while (cursor.moveToNext()) {//通過cursor取到下載器信息，循環遍歷，得到下載器集合      DownLoadInfo info = new DownLoadInfo(cursor.getInt(0), cursor.getInt(1), cursor.getInt(2), cursor.getInt(3), cursor.getString(4));      list.add(info);    }    cursor.close();    return list;  }  /**   * 本地下載列表添加記錄,添加本地數據庫信息，完成度等等   *   * @param fileStatus   **/  public void insertFileStatus(FileStatus fileStatus) {    synchronized (file_Lock) {//異步加開啟事務，保證數據的完整性      SQLiteDatabase database = dbHelper.getWritableDatabase();      database.beginTransaction();      try {        String sql = "insert into " + TABLE_LOCALDOWNLOAD_INFO + " (name,url,completedSize,fileSize,status) values(?,?,?,?,?)";        Object[] bindArgs = {fileStatus.getName(), fileStatus.getUrl(), fileStatus.getCompletedSize(), fileStatus.getFileSize(), fileStatus.getStatus()};        database.execSQL(sql, bindArgs);        database.setTransactionSuccessful();      } catch (SQLException e) {        e.printStackTrace();      } finally {        database.endTransaction();      }    }  }  /**   * @param context   * @param compeletedSize   * @param threadId   * @param urlstr     這里是更新數據庫，建議在保存一個表格的時候就對另一個表格數據庫進行更新   */  public void updataInfos(int threadId, int compeletedSize, String urlstr, Context context) {    synchronized (Lock) {      String sql = "update " + TABLE_DOWNLOAD_INFO + "set completed_size = ? where thread_id =? and url=?";      String localSql = "update " + TABLE_LOCALDOWNLOAD_INFO + "set completedSize = (select sum(completed_size) from " +          TABLE_DOWNLOAD_INFO + "where url=? group by url ) where url=?";      Object[] bindArgs = {compeletedSize, threadId, urlstr};      Object[] localArgs = {urlstr, urlstr};      SQLiteDatabase database = dbHelper.getWritableDatabase();      database.beginTransaction();      try {        database.execSQL(sql, bindArgs);        database.execSQL(localSql, localArgs);        database.setTransactionSuccessful();      } catch (SQLException e) {        e.printStackTrace();      } finally {        database.endTransaction();      }    }  }  /**   * @param url 更新文件的狀態，0為正在下載，1為已經下載完成,2為下載出錯   **/  public void updateFileStatus(String url) {    synchronized (file_Lock) {      String sql = "update " + TABLE_LOCALDOWNLOAD_INFO + " set status = ? where url = ?";      Object[] bindArgs = {1, url};      SQLiteDatabase database = dbHelper.getWritableDatabase();      database.beginTransaction();      try {        database.execSQL(sql, bindArgs);        database.setTransactionSuccessful();      } catch (SQLException e) {        e.printStackTrace();      } finally {        database.endTransaction();      }    }  }  /**   * @return List<FileStatus>   * 取出本地下載列表數據，如在重新進入應用時，要重新把進度之類的設置好   **/  public List<FileStatus> getFileStatus() {    List<FileStatus> list = new ArrayList<FileStatus>();    SQLiteDatabase database = dbHelper.getReadableDatabase();    //String sql = "slect * from " + TABLE_LOCALDOWNLOAD_INFO + ""; //不能用，需要哪些條件就在語句中寫出哪些條件    String sql = "select name, url, status, completedSize, fileSize from " + TABLE_LOCALDOWNLOAD_INFO + "";    Cursor cursor = database.rawQuery(sql, null);    while (cursor.moveToNext()) {      FileStatus fileState = new FileStatus(cursor.getString(0), cursor.getString(1), cursor.getInt(2), cursor.getInt(3), cursor.getInt(4));      list.add(fileState);    }    cursor.close();    return list;  }  /**   * @param url   * @param completeSize   * @param status    更新文件的下載狀態   **/  public void updateFileDownStatus(int completeSize, int status, String url) {    synchronized (file_Lock) {      String sql = "update " + TABLE_LOCALDOWNLOAD_INFO + " set completedSize = ?,status = ? where url = ?";      SQLiteDatabase database = dbHelper.getWritableDatabase();      database.beginTransaction();      try {        Object[] bindArgs = {completeSize, status, url};        database.execSQL(sql, bindArgs);        database.delete(TABLE_DOWNLOAD_INFO, "url = ?", new String[]{url});        database.setTransactionSuccessful();      } catch (SQLException e) {        e.printStackTrace();      } finally {        database.endTransaction();      }    }  }  /**   * @param url 獲取文件名稱   **/  public String getFileName(String url) {    String result = "";    String sql = "select name from " + TABLE_LOCALDOWNLOAD_INFO + " where url = ?";    SQLiteDatabase database = dbHelper.getReadableDatabase();    Cursor cursor = database.rawQuery(sql, new String[]{url});    if (cursor.moveToNext()) {      result = cursor.getString(0);    }    cursor.close();    return result;  }  /**   * 刪除文件之后，要刪除下載的數據，一個是用戶可以重新下載   * 另一個是表再次添加一條數據的時候不出現錯誤   *   * @param url   */  public void deleteFile(String url) {    SQLiteDatabase database = dbHelper.getWritableDatabase();    database.beginTransaction();    try {      database.delete(TABLE_DOWNLOAD_INFO, " url = ?", new String[]{url});      database.delete(TABLE_LOCALDOWNLOAD_INFO, " url = ?", new String[]{url});      database.setTransactionSuccessful();    } catch (Exception e) {      e.printStackTrace();    } finally {      database.endTransaction();    }  }  /**   * 關閉數據庫   *   * @close   */  public void closeDB() {    dbHelper.close();  }}

@SuppressLint("HandlerLeak")public class DownloadService extends Service{ public IBinder binder = new MyBinder(); public class MyBinder extends Binder { public DownloadService getService() {  return DownloadService.this; } } @Override public IBinder onBind(Intent intent) { return binder; } public static int number = 0; // 文件保存地址 public final String savePath = "/mnt/sdcard/MultiFileDownload/"; // 存放下載列表的引用 public static List<FileStatus> list = new ArrayList<FileStatus>(); public static Map<String, String> localDownList = new HashMap<String, String>(); // 保存每個文件下載的下載器 public static Map<String, Downloader> downloaders = new HashMap<String, Downloader>(); // 每個下載文件完成的長度 private Map<String, Integer> completeSizes = new HashMap<String, Integer>(); // 每個下載文件的總長度 private Map<String, Integer> fileSizes = new HashMap<String, Integer>(); private Downloader downloader; private int threadCount = 5; private Dao dao; private DownLoadCallback loadCallback;  private FileStatus mFileStatus = null; private Handler handler = new Handler() { @Override public void handleMessage(Message msg) {  super.handleMessage(msg);  if (msg.what == 1)  {  String url = (String) msg.obj;  int length = msg.arg1;  int completeSize = completeSizes.get(url);  int fileSize = fileSizes.get(url);  completeSize += length;  completeSizes.put(url, completeSize);  synchronized (list)  {   for (int i = 0; i < list.size(); i++)   {   FileStatus fileStatus = list.get(i);   if (fileStatus.getUrl().equals(url))   {    if (completeSize == fileStatus.getFileSize())    {    System.out.println("-----------下載完成:"+fileStatus.getName()+":"+completeSize+"-----"+fileStatus.getFileSize());    list.set(i, new FileStatus(fileStatus.getName(), fileStatus.getUrl(), 1, completeSize, fileStatus.getFileSize()));    dao.updateFileDownStatus(completeSize, 1, url);    }    else    {    list.set(i, new FileStatus(fileStatus.getName(), fileStatus.getUrl(), 0, completeSize, fileStatus.getFileSize()));    }    mFileStatus = list.get(i);   }   }      this.postDelayed(new Runnable()   {   @Override   public void run()   {    if (loadCallback != null && mFileStatus != null)    {    loadCallback.refreshUI(mFileStatus);    }   }   }, 1000);  }    } } }; @Override public void onCreate() { super.onCreate(); dao = Dao.getInstance(this); list = dao.getFileStatus(); for (FileStatus fileStatus : list) {  localDownList.put(fileStatus.getUrl(), fileStatus.getUrl()); }  Timer timer = new Timer(); timer.schedule(new TimerTask() {  @Override  public void run()  {  number++;  } }, 0, 1000); } public void download(final Button button, final String url, final String name, final Handler mHandler) { if (dao.isExist(url)) {  Toast.makeText(this, "別點了，已經在下載了", Toast.LENGTH_SHORT).show();  return; } final String fileName = name + url.substring(url.lastIndexOf(".")); new Thread(new Runnable() {  @Override  public void run()  {  downloader = downloaders.get(url);  if (downloader == null)  {   downloader = new Downloader(url, savePath, fileName, threadCount, DownloadService.this, handler);   downloaders.put(url, downloader);  }  if (downloader.isDownloading())   return;    LoadInfo loadInfo = downloader.getDownloaderInfors();    if(loadInfo != null)  {   FileStatus fileStatus = new FileStatus(fileName, url, 0, loadInfo.getComplete(), loadInfo.getFileSize());   dao.insertFileStatus(fileStatus);   completeSizes.put(url, loadInfo.getComplete());   fileSizes.put(url, fileStatus.getFileSize());   list.add(fileStatus);   localDownList.put(url, url);   downloader.download();   Message msg = new Message();   msg.what = 1;   msg.obj = button;   mHandler.sendMessage(msg);  }  else  {   Message msg = new Message();   msg.what = 2;   msg.obj = button;   mHandler.sendMessage(msg);  }  } }).start(); }  //暫停下載 public void Pause(Downloader downloader) { downloader.pause(); }  //繼續下載 public void reDownload(final Button button, final String url, final String name, final Handler mHandler) { new Thread(new Runnable() {  @Override  public void run()  {  String fileName = dao.getFileName(url);    downloader = downloaders.get(url);  if (downloader == null)  {   downloader = new Downloader(url, savePath, fileName, threadCount, DownloadService.this, handler);   downloaders.put(url, downloader);  }  if (downloader.isDownloading())   return;    LoadInfo loadInfo = downloader.getDownloaderInfors();    if(loadInfo != null && !fileName.equals(""))  {   if(!completeSizes.containsKey(url))   {   completeSizes.put(url, loadInfo.getComplete());   }   if(!fileSizes.containsKey(url))   {   fileSizes.put(url, loadInfo.getFileSize());   }   downloader.download();   Message msg = new Message();   msg.what = 1;   msg.obj = button;   mHandler.sendMessage(msg);  }  else  {   Message msg = new Message();   msg.what = 2;   msg.obj = button;   mHandler.sendMessage(msg);  }  } }).start(); }  public void delete(final String url) { Downloader down = downloaders.get(url); if(down != null) {  down.pause(); }  handler.postDelayed(new Runnable() {  @Override  public void run()  {  dao.deleteFile(url);    for (int i = 0; i < list.size(); i++)  {   FileStatus fileStatus = list.get(i);   if (fileStatus.getUrl().equals(url))   {   list.remove(i);   }  }    localDownList.remove(url);  downloaders.remove(url);  completeSizes.remove(url);  fileSizes.remove(url);    if(loadCallback != null)  {   loadCallback.deleteFile(url);  }  } }, 1000); } public interface DownLoadCallback { public void refreshUI(FileStatus fileStatus);  public void deleteFile(String url); } public void setLoadCallback(DownLoadCallback loadCallback) { this.loadCallback = loadCallback; }}

/** * Created by ShanCanCan on 2017/3/7 0007. */public class DownLoadUtil {  /**   * 此類的主要功能   * 1、檢查是否下載   * 2、下載文件,文件的下載采用httpurlconnection   */  private String downPath;// 下載路徑  private String savePath;// 保存路徑  private String fileName;// 文件名稱  private int threadCount;// 線程數  private Handler mHandler;  private Dao dao;  private Context context;  private int fileSize;// 文件大小  private int range;  private List<DownLoadInfo> infos;// 存放下載信息類的集合  private int state = INIT;  private static final int INIT = 1;// 定義三種下載的狀態：初始化狀態，正在下載狀態，暫停狀態  private static final int DOWNLOADING = 2;  private static final int PAUSE = 3;  /**   * 構造方法，獲取dao的對象   *   * @param downPath   * @param savePath   * @param fileName   * @param threadCount   * @param context   * @param mHandler   */  public DownLoadUtil(String downPath, String savePath, String fileName, int threadCount, Handler mHandler, Context context) {    this.downPath = downPath;    this.savePath = savePath;    this.fileName = fileName;    this.threadCount = threadCount;    this.mHandler = mHandler;    this.context = context;    dao = Dao.getInstance(context);  }  /**   * 判斷是否PAUSE   **/  public boolean isPause() {    return state == PAUSE;  }  /**   * 判斷是否DOWNLOADING   */  public boolean isDownloading() {    return state == DOWNLOADING;  }  /**   * @param url 判斷是否是第一次下載，利用dao查詢數據庫中是否有下載這個地址的記錄   */  private boolean isFirst(String url) {    return dao.isFirstDownload(url);  }  /**   * 獲取要下載的東西   */  public LoadItemInfo getDownloadInfos() {    if (isFirst(downPath)) {      if (initFirst()) {//如果是第一次下載的話，要進行初始化,1.獲得下載文件的長度 2.創建文件,設置文件的大小        range = this.fileSize / this.threadCount;        infos = new ArrayList<DownLoadInfo>();        //這里就是啟動多線程下載，看出來了嗎？配合RandomAccessFile。每一個DownLoadInfo就是RandomAccessFile文件的一部分        for (int i = 0; i < this.threadCount - 1; i++) {          DownLoadInfo info = new DownLoadInfo(i, i * range, (i + 1) * range - 1, 0, downPath);          infos.add(info);        }        DownLoadInfo info = new DownLoadInfo(this.threadCount - 1, (this.threadCount - 1) * range, this.fileSize, 0, downPath);        infos.add(info);        dao.saveInfos(infos, this.context);        //(String urlDownload, int completePercent, int fileSize)        LoadItemInfo loadInfo = new LoadItemInfo(this.downPath, 0, this.fileSize);        return loadInfo;      } else {        return null;      }    } else {      //不是第一次下載，我們應該怎么做呢？從數據庫里面取回來      infos = dao.getInfos(this.downPath);      if (infos != null && infos.size() > 0) {        int size = 0;        int completeSize = 0;        for (DownLoadInfo info : infos) {          completeSize += info.getCompletedSize();          size += info.getEndPosition() - info.getStartPosition() + this.threadCount - 1;        }        LoadItemInfo loadInfo = new LoadItemInfo(this.downPath, completeSize, size);        return loadInfo;      } else {        return null;      }    }  }  // 設置暫停  public void pause() {    state = PAUSE;  }  // 重置下載狀態,將下載狀態設置為init初始化狀態  public void reset() {    state = INIT;  }  /**   * 基本上，RandomAccessFile的工作方式是，把DataInputStream和DataOutputStream結合起來，再加上它自己的一些方法，   * 比如定位用的getFilePointer( )，在文件里移動用的seek( )，以及判斷文件大小的length( )、skipBytes()跳過多少字節數。   * 此外，它的構造函數還要一個表示以只讀方式("r")，還是以讀寫方式("rw")打開文件的參數 (和C的fopen( )一模一樣)。它不支持只寫文件。   */  private boolean initFirst() {    boolean result = true;    HttpURLConnection conn = null;    RandomAccessFile randomFile = null;    URL url = null;    try {      url = new URL(downPath);      conn = (HttpURLConnection) url.openConnection();      conn.setConnectTimeout(5 * 1000);      conn.setRequestMethod("GET");      // 如果http返回的代碼是200或者206則為連接成功      if (conn.getResponseCode() == 200 || conn.getResponseCode() == 206) //狀態碼(206)，表示服務器已經執行完部分對資源的GET請求      {        fileSize = conn.getContentLength();// 得到文件的大小        if (fileSize <= 0) {          //("網絡故障,無法獲取文件大小");          return false;        }        File dir = new File(savePath);        // 如果文件目錄不存在,則創建        if (!dir.exists()) {          if (dir.mkdirs()) {            //("mkdirs success.");          }        }        File file = new File(this.savePath, this.fileName);        randomFile = new RandomAccessFile(file, "rwd");        randomFile.setLength(fileSize);// 設置保存文件的大小        randomFile.close();        conn.disconnect();      }    } catch (Exception e) {      e.printStackTrace();      result = false;    } finally {      if (randomFile != null) {        try {          randomFile.close();        } catch (IOException e) {          e.printStackTrace();        }      }      if (conn != null) {        conn.disconnect();      }    }    return result;  }  /**   * 下面的這個方法就是開啟多線程進行下載了數據了   */  public void downLoad() {    if (infos != null) {      if (state == DOWNLOADING) {        return;      }      state = DOWNLOADING;// 把狀態設置為正在下載      for (DownLoadInfo info : infos) {//為什么說我們是多線程呢？因為我們分別用新線程去下載剛才分割好的一個RandomAccessFile文件        new DownLoadThread(info.getThreadId(), info.getStartPosition(), info.getEndPosition(), info.getCompletedSize(), info.getUrl(), this.context).start();      }    }  }  /**   * 現在要創建線程用來下載了，這里采用內部類   */  public class DownLoadThread extends Thread {    private int threadId;    private int startPostion;    private int endPostion;    private int compeletedSize;    private String url;    private Context context;    public static final int PROGRESS = 1;    public DownLoadThread(int threadId, int startPostion, int endPostion, int compeletedSize, String url, Context context) {//構造方法，傳入特定的參數      this.threadId = threadId;      this.startPostion = startPostion;      this.endPostion = endPostion;      this.compeletedSize = compeletedSize;      this.url = url;      this.context = context;    }    //開始下載    @Override    public void run() {      HttpURLConnection conn = null;      RandomAccessFile randomAccessFile = null;      InputStream inStream = null;      File file = new File(savePath, fileName);      URL url = null;      try {        url = new URL(this.url);        conn = (HttpURLConnection) url.openConnection();        constructConnection(conn);        if (conn.getResponseCode() == 200 || conn.getResponseCode() == 206) {          randomAccessFile = new RandomAccessFile(file, "rwd");          randomAccessFile.seek(this.startPostion + this.compeletedSize);//RandomAccessFile移動指針，到需要下載的塊          inStream = conn.getInputStream();          byte buffer[] = new byte[4096];//這個4096為么子呢？我也不知道，就是看阿里的人下載apk的時候都用4096，我也用          int length = 0;          while ((length = inStream.read(buffer, 0, buffer.length)) != -1) {            randomAccessFile.write(buffer, 0, length);            compeletedSize += length;            // 更新數據庫中的下載信息            dao.updataInfos(threadId, compeletedSize, this.url, this.context);            // 用消息將下載信息傳給進度條，對進度條進行更新            Message message = Message.obtain();            message.what = PROGRESS;            message.obj = this.url;            message.arg1 = length;            mHandler.sendMessage(message);// 給DownloadService發送消息            if (state == PAUSE) {              //("-----pause-----");              return;            }          }          // ("------------線程:" + this.threadId + "下載完成");        }      } catch (IOException e) {        e.printStackTrace();        //("-----下載異常-----"); 這里下載異常我就不處理了，你可以發一條重新下載的消息      } finally {//用完只后流要關閉，不然容易造成資源搶占，內存泄漏        try {          if (inStream != null) {            inStream.close();          }          if (randomAccessFile != null) {            randomAccessFile.close();          }          if (conn != null) {            conn.disconnect();          }        } catch (IOException e) {          e.printStackTrace();        }      }    }    /**     * 構建請求連接時的參數 返回開始下載的位置     *     * @param conn     */    private void constructConnection(HttpURLConnection conn) throws IOException {      conn.setConnectTimeout(5 * 1000);// 設置連接超時5秒      conn.setRequestMethod("GET");// GET方式提交，如果你是用post請求必須添加 conn.setDoOutput(true); conn.setDoInput(true);      conn.setRequestProperty(          "Accept",          "image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, application/xaml+xml, application/vnd.ms-xpsdocument, application/x-ms-xbap, application/x-ms-application, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*");      conn.setRequestProperty("Accept-Language", "zh-CN");      conn.setRequestProperty("Referer", this.url);      conn.setRequestProperty("Charset", "UTF-8");      int startPositionNew = this.startPostion + this.compeletedSize;      // 設置獲取實體數據的范圍      conn.setRequestProperty("Range", "bytes=" + startPositionNew + "-" + this.endPostion);      conn.setRequestProperty(          "User-Agent",          "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.2; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)");      conn.setRequestProperty("Connection", "Keep-Alive");      conn.connect();    }  }}