Http头 Range、Content-Range【断点续传】

HTTP头中一般断点下载时才用到Range和Content-Range实体头，
Range用户请求头中，指定第一个字节的位置和最后一个字节的位置，如（Range：200-300）
Content-Range用于响应头

请求下载整个文件: 
***********************************
GET  /test.rar  HTTP/1.1 
Connection:  close 
Host:  116.1.219.219 
Range:  bytes=0-100 
***********************************
Range头域可以请求实体的一个或者多个子范围，Range的值为0表示第一个字节，也就是Range计算字节数是从0开始的
表示头500个字节：bytes=0-499
表示第二个500字节：bytes=500-999
表示最后500个字节：bytes=-500
表示500字节以后的范围：bytes=500-
第一个和最后一个字节：bytes=0-0,-1
同时指定几个范围：bytes=500-600,601-999


一般正常回应 
***********************************
HTTP/1.1 206 OK 
Content-Length:  801      
Content-Type:  application/octet-stream  
Content-Location: http://www.onlinedown.net/hj_index.htm
Content-Range:  bytes  0-100/2350 //2350:文件总大小 
Last-Modified: Mon, 16 Feb 2009 16:10:12 GMT
Accept-Ranges: bytes
ETag: "d67a4bc5190c91:512"
Server: Microsoft-IIS/6.0
Date: Wed, 18 Feb 2009 07:55:26 GMT
***********************************

注意：如果用户的请求中含有range ，则服务器的相应代码为206。

206 - Partial Content 客户发送了一个带有Range头的GET请求，服务器完成了它（HTTP 1.1新）。 

public class MyFileDownloader extends Thread{private static final String TAG = "FileDownloader";public static final int BUFFER_SIZE = 1024;//512public static final String DEFAULT_USER_AGENT = "MotoneMarket";///////////////////////////////////////////////////////////////////////** Error Code *//** 没有找到文件，请求URL有误 */public static final int E_URL_INVALID = -1;/** HTTP protocol 无效 */public static final int E_PROTOCOL_INVALID = 0;/** network I/O error*/public static final int E_IO_EXP = 1;/** 创建下载文件失败*/public static final int E_FILE_NOTFOUND = 2; /** 文件安全权限错误*/public static final int E_FILE_SECURITY = 3; /** request 状态异常*/public static final int E_ILLEGAL_STATE = 4; /** 追加验证符 错误*/public static final int E_APPEND_VER_ERROR = 5;/** 下载不完成*/public static final int E_DOWN_NOT_COMPLETE = 6;/** 断点续传，服务断点返回错误*/public static final int E_RANGE_WRANG = 7; /** 断点续传，服务断点返回错误*/public static final int E_CONNECT_TIMEOUT = 8; /** 存储空间不足，无法创建文件 或 写入文件 */public static final int E_NO_SPACE = 9; ///////////////////////////////////////////////////////////////////////** 同步锁 */private final Object mLock = new Object();/** 暂停标志：默认false,开启运行*/private boolean m_isPause = false;/** 停止标志：默认true停止未开始true，false：运行中*/private boolean m_isStop = true;/** 取消标志: 默认false未取消，true:取消 || false:未取消*/private boolean m_isCancel = false;/** 退出完成标志: 默认false未开始，未完成，true：完成 || false:未完成*/private boolean m_isExit = false;///////////////////////////////////////////////////////////////////////** 该下载对象的 ID*/private int mId; /** 该下载目标 URL*/private String mUrl;/** 文件全名*/private String mFile; /** 临时文件名*/private String mTFile; /** 文件的验证字符串*/private String mVerifyString = null;/** 文件下载监听器*/private OnDownloadListener mDownListener;//////////////////////////////////////////////////////////////////////private HttpURLConnection httpClient;/** 写入文件的位置，文件的append位置*/private long mPos = 0 ; /** 文件总长度*/private long mLength = -1; /** HTTP getInput*/private InputStream streamEntry = null;/** File Stream*/private FileOutputStream stream = null;//////////////////////////////////////////////////////////////////////public MyFileDownloader(int id, String url, String file, String verStr){this.mId = id;this.mUrl = url;this.mFile = file;this.mTFile = file + ".info";this.mVerifyString = verStr;}/** 设置下载监听器 */public synchronized void setOnDownloadListener(OnDownloadListener listener){this.mDownListener = listener;}/** 下载监听器 */public interface OnDownloadListener{void onFinish(int id);void onProgress(int id, int percent);void onError(int id, int errorCode);}/** 获取该任务ID*/public int getID(){return mId;}/** 清理资源*/public void deleteFile(){File f = new File(mFile);if (f.exists()){f.delete();}}/** 清理临时文件*/public void deleteTFile(){File f = new File(mTFile);if (f.exists()){f.delete();}}///////////////////////////////////////////////////////////////////////** 线程操作*//** 开启线程*/public synchronized void start(){super.start();Log.i(TAG, "###_start get url = " + mUrl);}/** 工作循环*/public void run(){this.setPriority(MIN_PRIORITY);// 开始运行中...m_isStop = false;/** 获取本地文件的已下载长度*/mPos = getLocalFileSize();/** 初始化网络，并获取网络文件长度*/mLength = initHttp();if (mLength < 0){close();return;}/** 开始下载文件*/boolean r = true;byte buf[] = new byte[BUFFER_SIZE];int numread = 0;int prePrec = 0;int CurPrec = 0;if (mPos < mLength){/** 输入 输出 对接*/try{/** 获取网路输入流 */streamEntry = httpClient.getInputStream();/** 装饰到 FileOutputStream*/File file = new File(mFile);if (!file.exists()){file.createNewFile();}stream = new FileOutputStream(file, true);} catch (IllegalStateException e){e.printStackTrace();doError(E_ILLEGAL_STATE);r = false;} catch (SecurityException e){e.printStackTrace();doError(E_FILE_SECURITY);r = false;} catch (FileNotFoundException e){e.printStackTrace();doError(E_FILE_NOTFOUND);r = false;} catch (IOException e){e.printStackTrace();doError(E_NO_SPACE);r = false;}if (!r){return;}/** 循环写入缓存文件*/if (streamEntry != null && stream != null){while (true && !m_isStop){/** 等待*/_wait();/** 工作*/try{/** 读取到 缓存 buf*/numread = streamEntry.read(buf);}catch (IOException e){e.printStackTrace();doError(E_IO_EXP);r = false;return;} // 休眠50ms// try// {// Thread.sleep(50);// } catch (InterruptedException e1)// {// e1.printStackTrace();// }/** the number of bytes actually read or -1 if the end of the stream has been reached.*/if (numread < 0 || mPos == mLength){break;}/** 写入 文件*/try{stream.write(buf, 0, numread);}catch (IOException e){e.printStackTrace();doError(E_NO_SPACE);r = false;return;} /** 增加记录*/mPos += numread;/** 报告监听器*/if (mDownListener != null){CurPrec = (int) ((float) mPos / mLength * 100);if (CurPrec > prePrec){try{mDownListener.onProgress(mId, CurPrec);}catch(Exception e){e.printStackTrace();Log.e(TAG, "---> unable exception occor! <----");}prePrec = CurPrec;}}}}}/** 检验完整性*/if (mPos == mLength){/** 追加验证字符串*/boolean verable = true;if (mVerifyString != null){byte[] bytes = mVerifyString.getBytes();try{if(stream != null){stream.write(bytes, 0, bytes.length);}deleteTFile();Log.i(TAG, "---> add verstring at apk : " + mVerifyString);} catch (IOException e){e.printStackTrace();doError(E_NO_SPACE);verable = false;return;}}/** 下载完成*/if (verable && mDownListener != null){try{mDownListener.onFinish(mId);}catch(Exception e){e.printStackTrace();Log.e(TAG, "---> unable exception occor! <----");}}}else{/** 下载不完成*/if (!m_isStop){doError(E_DOWN_NOT_COMPLETE);deleteTFile();}else/** 中途暂停*/{/** do nothing*/}}/** 关闭资源*/close();return;}//////////////////////////////////////////////////////////////////////////////////////** 获取网络文件长度 */private long initHttp(){/** 创建URI*/URL url = null;try{url = new URL(mUrl);} catch (MalformedURLException e) {/** 无效的URL*/Log.e(TAG, "url = " + mUrl);doError(E_URL_INVALID);e.printStackTrace();return -1;}try{httpClient = (HttpURLConnection) url.openConnection();String property = "bytes=" + mPos + "-";httpClient.setRequestProperty("RANGE", property);/** 连接超时和读取超时都是5秒*/httpClient.setConnectTimeout(5000);httpClient.setReadTimeout(5000);httpClient.connect();int code = httpClient.getResponseCode();/** code == 200 || code == 206*/if (code < 400){String header = null;/** 获取 content-length */for ( int i = 1 ; ; i++ ){header = httpClient.getHeaderFieldKey(i);if (header != null){if (header.toLowerCase().equals("content-length")){mLength = Integer.parseInt(httpClient.getHeaderField(header));break;}}else{break;}}/** 获取 range*/for ( int j = 1 ; ; j++ ){header = httpClient.getHeaderFieldKey(j);if (header != null){if (header.toLowerCase().equals("content-range")){String range = httpClient.getHeaderField(header);int i = "bytes ".length();if(i > range.length()) {// content-range 返回不合法时,或者 不支持断点续传， 为0 跳出break;}String str = null;try{str = range.substring(i, range.length());}catch(IndexOutOfBoundsException e){// content-range 返回不合法时,或者 不支持断点续传， 为0 跳出e.printStackTrace();break;}String[] split = str.split("-");if (split != null && split.length == 2){try{long start = Long.parseLong(split[0].trim());String[] len = split[1].split("/");mLength = Long.parseLong(len[1].trim());if (start == mPos){/** 断点设置 OK*/}else{/** 断点设置 Fail*/doError(E_RANGE_WRANG);return -1;}}catch(Exception e){// content-range 返回不合法时,或者 不支持断点续传， 为0 跳出e.printStackTrace();doError(E_RANGE_WRANG);break;}}break;}}else{break;}}/** 返回网络文件长度*/return mLength;}else/** 请求的 Range 范围不合法*/if (code == 416){doError(E_RANGE_WRANG);}else{/** 请求失败*/doError(E_URL_INVALID);}}catch (SocketTimeoutException e){e.printStackTrace();doError(E_CONNECT_TIMEOUT);} catch (IOException e){e.printStackTrace();doError(E_IO_EXP);} catch(Exception e){e.printStackTrace();doError(E_IO_EXP);}return -1;}/** 获取本地文件长度*/private long getLocalFileSize(){File f = new File(mFile);if (f.exists()){return f.length();}else{File tf = new File(mTFile);try{tf.createNewFile();} catch (IOException e){e.printStackTrace();}return 0;}}/** 报告错误代码，并close*/private void doError(int errorCode){if (mDownListener != null){try{mDownListener.onError(mId, errorCode);}catch(Exception e){e.printStackTrace();Log.e(TAG, "---> unable exception occor! <----");}}close();return;}/** 关闭资源*/private void close(){/** 关闭输入流*/if (streamEntry != null){try{streamEntry.close();streamEntry = null;} catch (IOException e){e.printStackTrace();}}/** 关闭输出流*/if (stream != null){try{stream.flush();stream.getFD().sync();stream.close();stream = null;} catch (IOException e){e.printStackTrace();}}/** 关闭 HTTP Client*/if (httpClient != null){httpClient.disconnect();httpClient = null;}/** 清理资源*/if (m_isCancel){deleteFile();deleteTFile();}// 设置完成时 状态// 重新设置为未开始m_isStop = true;// 标志线程结束m_isExit = true;}///////////////////////////////////////////////////////////////////////** 线程等待*/private void _wait(){/** 睡眠50ms*/try{Thread.sleep(20);//200} catch (InterruptedException e1){e1.printStackTrace();}/** 等待 锁*/synchronized (mLock){while (m_isPause){try{mLock.wait();} catch (InterruptedException e){e.printStackTrace();}}}}/** 暂停线程*/public synchronized void _pause(){m_isPause = true;Log.i(TAG, "###_pause---->");}/** 恢复线程*/public synchronized void _resume(){m_isPause = false;synchronized (mLock){mLock.notifyAll();}Log.i(TAG, "###_resume---->");}/** 停止线程*/public synchronized void _stop(){m_isStop = true;_resume();Log.i(TAG, "###_stop---->");}/** 取消线程*/public void _cancel(){if (!m_isStop){// 运行中..._stop();m_isCancel = true;}else{// 未开始或者运行结束deleteFile();deleteTFile();}}/** 线程是否完成*/public synchronized boolean isFinished(){return m_isExit;}}