android 下载 代码 断点续传

package cn.itcast.net.download; import java.io.File; import java.io.RandomAccessFile; import java.net.HttpURLConnection; import java.net.URL; import java.util.LinkedHashMap; import java.util.Map; import java.util.UUID; import java.util.concurrent.ConcurrentHashMap; import java.util.regex.Matcher; import java.util.regex.Pattern; import cn.itcast.service.FileService; import android.content.Context; import android.util.Log; /** * 文件下载器 * @author lihuoming@sohu.com */ public class FileDownloader { private static final String TAG = "FileDownloader"; private Context context; private FileService fileService; /* 已下载文件长度 */ private int downloadSize = 0; /* 原始文件长度 */ private int fileSize = 0; /* 线程数 */ private DownloadThread[] threads; /* 本地保存文件 */ private File saveFile; /* 缓存各线程下载的长度*/ private Map<Integer, Integer> data = new ConcurrentHashMap<Integer, Integer>(); /* 每条线程下载的长度 */ private int block; /* 下载路径 */ private String downloadUrl; /** * 获取线程数 */ public int getThreadSize() { return threads.length; } /** * 获取文件大小 * @return */ public int getFileSize() { return fileSize; } /** * 累计已下载大小 * @param size */ protected synchronized void append(int size) { downloadSize += size; } /** * 更新指定线程最后下载的位置 * @param threadId 线程id * @param pos 最后下载的位置 */ protected void update(int threadId, int pos) { this.data.put(threadId, pos); } /** * 保存记录文件 */ protected synchronized void saveLogFile() { this.fileService.update(this.downloadUrl, this.data); } /** * 构建文件下载器 * @param downloadUrl 下载路径 * @param fileSaveDir 文件保存目录 * @param threadNum 下载线程数 */ public FileDownloader(Context context, String downloadUrl, File fileSaveDir, int threadNum) { try { this.context = context; this.downloadUrl = downloadUrl; fileService = new FileService(this.context); URL url = new URL(this.downloadUrl); if(!fileSaveDir.exists()) fileSaveDir.mkdirs(); this.threads = new DownloadThread[threadNum]; HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setConnectTimeout(5*1000); conn.setRequestMethod("GET"); 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", downloadUrl); conn.setRequestProperty("Charset", "UTF-8"); 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(); printResponseHeader(conn); if (conn.getResponseCode()==200) { this.fileSize = conn.getContentLength();//根据响应获取文件大小 if (this.fileSize <= 0) throw new RuntimeException("Unkown file size "); String filename = getFileName(conn); this.saveFile = new File(fileSaveDir, filename);/* 保存文件 */ Map<Integer, Integer> logdata = fileService.getData(downloadUrl); if(logdata.size()>0){ for(Map.Entry<Integer, Integer> entry : logdata.entrySet()) data.put(entry.getKey(), entry.getValue()); } this.block = (this.fileSize % this.threads.length)==0? this.fileSize / this.threads.length : this.fileSize / this.threads.length + 1; if(this.data.size()==this.threads.length){ for (int i = 0; i < this.threads.length; i++) { this.downloadSize += this.data.get(i+1); } print("已经下载的长度"+ this.downloadSize); } }else{ throw new RuntimeException("server no response "); } } catch (Exception e) { print(e.toString()); throw new RuntimeException("don't connection this url"); } } /** * 获取文件名 */ private String getFileName(HttpURLConnection conn) { String filename = this.downloadUrl.substring(this.downloadUrl.lastIndexOf('/') + 1); if(filename==null || "".equals(filename.trim())){//如果获取不到文件名称 for (int i = 0;; i++) { String mine = conn.getHeaderField(i); if (mine == null) break; if("content-disposition".equals(conn.getHeaderFieldKey(i).toLowerCase())){ Matcher m = Pattern.compile(".*filename=(.*)").matcher(mine.toLowerCase()); if(m.find()) return m.group(1); } } filename = UUID.randomUUID()+ ".tmp";//默认取一个文件名 } return filename; } /** * 开始下载文件 * @param listener 监听下载数量的变化,如果不需要了解实时下载的数量,可以设置为null * @return 已下载文件大小 * @throws Exception */ public int download(DownloadProgressListener listener) throws Exception{ try { RandomAccessFile randOut = new RandomAccessFile(this.saveFile, "rw"); if(this.fileSize>0) randOut.setLength(this.fileSize); randOut.close(); URL url = new URL(this.downloadUrl); if(this.data.size() != this.threads.length){ this.data.clear(); for (int i = 0; i < this.threads.length; i++) { this.data.put(i+1, 0); } } for (int i = 0; i < this.threads.length; i++) { int downLength = this.data.get(i+1); if(downLength < this.block && this.downloadSize<this.fileSize){ //该线程未完成下载时,继续下载 this.threads[i] = new DownloadThread(this, url, this.saveFile, this.block, this.data.get(i+1), i+1); this.threads[i].setPriority(7); this.threads[i].start(); }else{ this.threads[i] = null; } } this.fileService.save(this.downloadUrl, this.data); boolean notFinish = true;//下载未完成 while (notFinish) {// 循环判断是否下载完毕 Thread.sleep(900); notFinish = false;//假定下载完成 for (int i = 0; i < this.threads.length; i++){ if (this.threads[i] != null && !this.threads[i].isFinish()) { notFinish = true;//下载没有完成 if(this.threads[i].getDownLength() == -1){//如果下载失败,再重新下载 this.threads[i] = new DownloadThread(this, url, this.saveFile, this.block, this.data.get(i+1), i+1); this.threads[i].setPriority(7); this.threads[i].start(); } } } if(listener!=null) listener.onDownloadSize(this.downloadSize); } fileService.delete(this.downloadUrl); } catch (Exception e) { print(e.toString()); throw new Exception("file download fail"); } return this.downloadSize; } /** * 获取Http响应头字段 * @param http * @return */ public static Map<String, String> getHttpResponseHeader(HttpURLConnection http) { Map<String, String> header = new LinkedHashMap<String, String>(); for (int i = 0;; i++) { String mine = http.getHeaderField(i); if (mine == null) break; header.put(http.getHeaderFieldKey(i), mine); } return header; } /** * 打印Http头字段 * @param http */ public static void printResponseHeader(HttpURLConnection http){ Map<String, String> header = getHttpResponseHeader(http); for(Map.Entry<String, String> entry : header.entrySet()){ String key = entry.getKey()!=null ? entry.getKey()+ ":" : ""; print(key+ entry.getValue()); } } private static void print(String msg){ Log.i(TAG, msg); } public static void main(String[] args) { /* FileDownloader loader = new FileDownloader(context, "http://browse.babasport.com/ejb3/ActivePort.exe", new File("D:\\androidsoft\\test"), 2); loader.getFileSize();//得到文件总大小 try { loader.download(new DownloadProgressListener(){ public void onDownloadSize(int size) { print("已经下载："+ size); } }