BatchDownloadFile.java

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;
	}
}