java 编写的http下载器 源代码

package com.hoo.download; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import com.hoo.entity.DownloadInfo; import com.hoo.util.LogUtils; /** * <b>function:</b> 分批量下载文件 * @author hoojo * @createDate 2011-9-22 下午05:51:54 * @file BatchDownloadFile.java * @package com.hoo.download * @project MultiThreadDownLoad * @blog http://blog.csdn.net/IBM_hoojo * @email hoojo_@126.com * @version 1.0 */ public class BatchDownloadFile implements Runnable { //下载文件信息 private DownloadInfo downloadInfo; //一组开始下载位置 private long[] startPos; //一组结束下载位置 private long[] endPos; //休眠时间 private static final int SLEEP_SECONDS = 500; //子线程下载 private DownloadFile[] fileItem; //文件长度 private int length; //是否第一个文件 private boolean first = true; //是否停止下载 private boolean stop = false; //临时文件信息 private File tempFile; public BatchDownloadFile(DownloadInfo downloadInfo) { this.downloadInfo = downloadInfo; String tempPath = this.downloadInfo.getFilePath() + File.separator + downloadInfo.getFileName() + ".position"; tempFile = new File(tempPath); //如果存在读入点位置的文件 if (tempFile.exists()) { first = false; //就直接读取内容 try { readPosInfo(); } catch (IOException e) { e.printStackTrace(); } } else { //数组的长度就要分成多少段的数量 startPos = new long[downloadInfo.getSplitter()]; endPos = new long[downloadInfo.getSplitter()]; } } @Override public void run() { //首次下载，获取下载文件长度 if (first) { length = this.getFileSize();//获取文件长度 if (length == -1) { LogUtils.log("file length is know!"); stop = true; } else if (length == -2) { LogUtils.log("read file length is error!"); stop = true; } else if (length > 0) { /** * eg * start: 1, 3, 5, 7, 9 * end: 3, 5, 7, 9, length */ for (int i = 0, len = startPos.length; i < len; i++) { int size = i * (length / len); startPos[i] = size; //设置最后一个结束点的位置 if (i == len - 1) { endPos[i] = length; } else { size = (i + 1) * (length / len); endPos[i] = size; } LogUtils.log("start-end Position[" + i + "]: " + startPos[i] + "-" + endPos[i]); } } else { LogUtils.log("get file length is error, download is stop!"); stop = true; } } //子线程开始下载 if (!stop) { //创建单线程下载对象数组 fileItem = new DownloadFile[startPos.length];//startPos.length = downloadInfo.getSplitter() for (int i = 0; i < startPos.length; i++) { try { //创建指定个数单线程下载对象，每个线程独立完成指定块内容的下载 fileItem[i] = new DownloadFile( downloadInfo.getUrl(), this.downloadInfo.getFilePath() + File.separator + downloadInfo.getFileName(), startPos[i], endPos[i], i ); fileItem[i].start();//启动线程，开始下载 LogUtils.log("Thread: " + i + ", startPos: " + startPos[i] + ", endPos: " + endPos[i]); } catch (IOException e) { e.printStackTrace(); } } //循环写入下载文件长度信息 while (!stop) { try { writePosInfo(); LogUtils.log("downloading……"); Thread.sleep(SLEEP_SECONDS); stop = true; } catch (IOException e) { e.printStackTrace(); } catch (InterruptedException e) { e.printStackTrace(); } for (int i = 0; i < startPos.length; i++) { if (!fileItem[i].isDownloadOver()) { stop = false; break; } } } LogUtils.info("Download task is finished!"); } } /** * 将写入点数据保存在临时文件中 * @author hoojo * @createDate 2011-9-23 下午05:25:37 * @throws IOException */ private void writePosInfo() throws IOException { DataOutputStream dos = new DataOutputStream(new FileOutputStream(tempFile)); dos.writeInt(startPos.length); for (int i = 0; i < startPos.length; i++) { dos.writeLong(fileItem[i].getStartPos()); dos.writeLong(fileItem[i].getEndPos()); //LogUtils.info("[" + fileItem[i].getStartPos() + "#" + fileItem[i].getEndPos() + "]"); } dos.close(); } /** * <b>function:</b>读取写入点的位置信息 * @author hoojo * @createDate 2011-9-23 下午05:30:29 * @throws IOException */ private void readPosInfo() throws IOException { DataInputStream dis = new DataInputStream(new FileInputStream(tempFile)); int startPosLength = dis.readInt(); startPos = new long[startPosLength]; endPos = new long[startPosLength]; for (int i = 0; i < startPosLength; i++) { startPos[i] = dis.readLong(); endPos[i] = dis.readLong(); } dis.close(); } /** * <b>function:</b> 获取下载文件的长度 * @author hoojo * @createDate 2011-9-26 下午12:15:08 * @return */ private int getFileSize() { int fileLength = -1; try { URL url = new URL(this.downloadInfo.getUrl()); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); DownloadFile.setHeader(conn); int stateCode = conn.getResponseCode(); //判断http status是否为HTTP/1.1 206 Partial Content或者200 OK if (stateCode != HttpURLConnection.HTTP_OK && stateCode != HttpURLConnection.HTTP_PARTIAL) { LogUtils.log("Error Code: " + stateCode); return -2; } else if (stateCode >= 400) { LogUtils.log("Error Code: " + stateCode); return -2; } else { //获取长度 fileLength = conn.getContentLength(); LogUtils.log("FileLength: " + fileLength); } //读取文件长度 /*for (int i = 1; ; i++) { String header = conn.getHeaderFieldKey(i); if (header != null) { if ("Content-Length".equals(header)) { fileLength = Integer.parseInt(conn.getHeaderField(i)); break; } } else { break; } } */ DownloadFile.printHeader(conn); } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return fileLength; } }