Java 多线程断点下载文件_详解

基本原理：利用URLConnection获取要下载文件的长度、头部等相关信息，并设置响应的头部信息。并且通过URLConnection获取输入流，将文件分成指定的块，每一块单独开辟一个线程完成数据的读取、写入。通过输入流读取下载文件的信息，然后将读取的信息用RandomAccessFile随机写入到本地文件中。同时，每个线程写入的数据都文件指针也就是写入数据的长度，需要保存在一个临时文件中。这样当本次下载没有完成的时候，下次下载的时候就从这个文件中读取上一次下载的文件长度，然后继续接着上一次的位置开始下载。并且将本次下载的长度写入到这个文件中。

个人博客：

http://hoojo.cnblogs.com

http://blog.csdn.net/IBM_hoojo

email: hoojo_@126.com

 

一、下载文件信息类、实体

封装即将下载资源的信息

[java] view plaincopyprint?

  1. package com.hoo.entity; 
  2.  
  3. /**
  4. * <b>function:</b> 下载文件信息类
  5. * @author hoojo
  6. * @createDate 2011-9-21 下午05:14:58
  7. * @file DownloadInfo.java
  8. * @package com.hoo.entity
  9. * @project MultiThreadDownLoad
  10. * @blog http://blog.csdn.net/IBM_hoojo
  11. * @email hoojo_@126.com
  12. * @version 1.0
  13. */ 
  14. public class DownloadInfo { 
  15.     //下载文件url 
  16.     private String url; 
  17.     //下载文件名称 
  18.     private String fileName; 
  19.     //下载文件路径 
  20.     private String filePath; 
  21.     //分成多少段下载， 每一段用一个线程完成下载 
  22.     private int splitter; 
  23.      
  24.     //下载文件默认保存路径 
  25.     private final
    static String FILE_PATH = "C:/temp"; 
  26.     //默认分块数、线程数 
  27.     private final
    static int SPLITTER_NUM =
    5; 
  28.      
  29.     public DownloadInfo() { 
  30.         super(); 
  31.     } 
  32.      
  33.     /**
  34.      * @param url 下载地址
  35.      */ 
  36.     public DownloadInfo(String url) { 
  37.         this(url,
    null, null, SPLITTER_NUM); 
  38.     } 
  39.      
  40.     /**
  41.      * @param url 下载地址url
  42.      * @param splitter 分成多少段或是多少个线程下载
  43.      */ 
  44.     public DownloadInfo(String url,
    int splitter) { 
  45.         this(url,
    null, null, splitter); 
  46.     } 
  47.      
  48.     /***
  49.      * @param url 下载地址
  50.      * @param fileName 文件名称
  51.      * @param filePath 文件保存路径
  52.      * @param splitter 分成多少段或是多少个线程下载
  53.      */ 
  54.     public DownloadInfo(String url, String fileName, String filePath,
    int splitter) { 
  55.         super(); 
  56.         if (url == null ||
    "".equals(url)) { 
  57.             throw
    new RuntimeException("url is not null!"); 
  58.         } 
  59.         this.url =  url; 
  60.         this.fileName = (fileName ==
    null || "".equals(fileName)) ? getFileName(url) : fileName; 
  61.         this.filePath = (filePath ==
    null || "".equals(filePath)) ? FILE_PATH : filePath; 
  62.         this.splitter = (splitter <
    1) ? SPLITTER_NUM : splitter; 
  63.     } 
  64.      
  65.     /**
  66.      * <b>function:</b> 通过url获得文件名称
  67.      * @author hoojo
  68.      * @createDate 2011-9-30 下午05:00:00
  69.      * @param url
  70.      * @return
  71.      */ 
  72.     private String getFileName(String url) { 
  73.         return url.substring(url.lastIndexOf("/") +
    1, url.length()); 
  74.     } 
  75.      
  76.     public String getUrl() { 
  77.         return url; 
  78.     } 
  79.  
  80.     public void setUrl(String url) { 
  81.         if (url ==
    null || "".equals(url)) { 
  82.             throw new RuntimeException("url is not null!"); 
  83.         } 
  84.         this.url = url; 
  85.     } 
  86.  
  87.     public String getFileName() { 
  88.         return fileName; 
  89.     } 
  90.  
  91.     public void setFileName(String fileName) { 
  92.         this.fileName = (fileName ==
    null || "".equals(fileName)) ? getFileName(url) : fileName; 
  93.     } 
  94.  
  95.     public String getFilePath() { 
  96.         return filePath; 
  97.     } 
  98.  
  99.     public void setFilePath(String filePath) { 
  100.         this.filePath = (filePath ==
    null || "".equals(filePath)) ? FILE_PATH : filePath; 
  101.     } 
  102.  
  103.     public int getSplitter() { 
  104.         return splitter; 
  105.     } 
  106.  
  107.     public void setSplitter(int splitter) { 
  108.         this.splitter = (splitter <
    1) ? SPLITTER_NUM : splitter; 
  109.     } 
  110.      
  111.     @Override 
  112.     public String toString() { 
  113.         return this.url +
    "#" + this.fileName +
    "#" + this.filePath +
    "#" + this.splitter; 
  114.     } 
  115. } 
package com.hoo.entity;

/**
 * <b>function:</b> 下载文件信息类
 * @author hoojo
 * @createDate 2011-9-21 下午05:14:58
 * @file DownloadInfo.java
 * @package com.hoo.entity
 * @project MultiThreadDownLoad
 * @blog http://blog.csdn.net/IBM_hoojo
 * @email hoojo_@126.com
 * @version 1.0
 */
public class DownloadInfo {
	//下载文件url
	private String url;
	//下载文件名称
	private String fileName;
	//下载文件路径
	private String filePath;
	//分成多少段下载， 每一段用一个线程完成下载
	private int splitter;

	//下载文件默认保存路径
	private final static String FILE_PATH = "C:/temp";
	//默认分块数、线程数
	private final static int SPLITTER_NUM = 5;

	public DownloadInfo() {
		super();
	}

	/**
	 * @param url 下载地址
	 */
	public DownloadInfo(String url) {
		this(url, null, null, SPLITTER_NUM);
	}

	/**
	 * @param url 下载地址url
	 * @param splitter 分成多少段或是多少个线程下载
	 */
	public DownloadInfo(String url, int splitter) {
		this(url, null, null, splitter);
	}

	/***
	 * @param url 下载地址
	 * @param fileName 文件名称
	 * @param filePath 文件保存路径
	 * @param splitter 分成多少段或是多少个线程下载
	 */
	public DownloadInfo(String url, String fileName, String filePath, int splitter) {
		super();
		if (url == null || "".equals(url)) {
			throw new RuntimeException("url is not null!");
		}
		this.url =  url;
		this.fileName = (fileName == null || "".equals(fileName)) ? getFileName(url) : fileName;
		this.filePath = (filePath == null || "".equals(filePath)) ? FILE_PATH : filePath;
		this.splitter = (splitter < 1) ? SPLITTER_NUM : splitter;
	}

	/**
	 * <b>function:</b> 通过url获得文件名称
	 * @author hoojo
	 * @createDate 2011-9-30 下午05:00:00
	 * @param url
	 * @return
	 */
	private String getFileName(String url) {
		return url.substring(url.lastIndexOf("/") + 1, url.length());
	}

	public String getUrl() {
		return url;
	}

	public void setUrl(String url) {
		if (url == null || "".equals(url)) {
			throw new RuntimeException("url is not null!");
		}
		this.url = url;
	}

	public String getFileName() {
		return fileName;
	}

	public void setFileName(String fileName) {
		this.fileName = (fileName == null || "".equals(fileName)) ? getFileName(url) : fileName;
	}

	public String getFilePath() {
		return filePath;
	}

	public void setFilePath(String filePath) {
		this.filePath = (filePath == null || "".equals(filePath)) ? FILE_PATH : filePath;
	}

	public int getSplitter() {
		return splitter;
	}

	public void setSplitter(int splitter) {
		this.splitter = (splitter < 1) ? SPLITTER_NUM : splitter;
	}

	@Override
	public String toString() {
		return this.url + "#" + this.fileName + "#" + this.filePath + "#" + this.splitter;
	}
}

 

二、随机写入一段文件

[java] view plaincopyprint?

  1. package com.hoo.download; 
  2.  
  3. import java.io.IOException; 
  4. import java.io.RandomAccessFile; 
  5.  
  6. /**
  7. * <b>function:</b> 写入文件、保存文件
  8. * @author hoojo
  9. * @createDate 2011-9-21 下午05:44:02
  10. * @file SaveItemFile.java
  11. * @package com.hoo.download
  12. * @project MultiThreadDownLoad
  13. * @blog http://blog.csdn.net/IBM_hoojo
  14. * @email hoojo_@126.com
  15. * @version 1.0
  16. */ 
  17. public class SaveItemFile { 
  18.     //存储文件 
  19.     private RandomAccessFile itemFile; 
  20.      
  21.     public SaveItemFile()
    throws IOException { 
  22.         this("",
    0); 
  23.     } 
  24.      
  25.     /**
  26.      * @param name 文件路径、名称
  27.      * @param pos 写入点位置 position
  28.      * @throws IOException
  29.      */ 
  30.     public SaveItemFile(String name,
    long pos) throws IOException { 
  31.         itemFile = new RandomAccessFile(name,
    "rw"); 
  32.         //在指定的pos位置开始写入数据 
  33.         itemFile.seek(pos); 
  34.     } 
  35.      
  36.     /**
  37.      * <b>function:</b> 同步方法写入文件
  38.      * @author hoojo
  39.      * @createDate 2011-9-26 下午12:21:22
  40.      * @param buff 缓冲数组
  41.      * @param start 起始位置
  42.      * @param length 长度
  43.      * @return
  44.      */ 
  45.     public synchronized
    int write(byte[] buff,
    int start, int length) { 
  46.         int i = -1; 
  47.         try { 
  48.             itemFile.write(buff, start, length); 
  49.             i = length; 
  50.         } catch (IOException e) { 
  51.             e.printStackTrace(); 
  52.         } 
  53.         return i; 
  54.     } 
  55.      
  56.     public void close()
    throws IOException { 
  57.         if (itemFile !=
    null) { 
  58.             itemFile.close(); 
  59.         } 
  60.     } 
  61. } 
package com.hoo.download;

import java.io.IOException;
import java.io.RandomAccessFile;

/**
 * <b>function:</b> 写入文件、保存文件
 * @author hoojo
 * @createDate 2011-9-21 下午05:44:02
 * @file SaveItemFile.java
 * @package com.hoo.download
 * @project MultiThreadDownLoad
 * @blog http://blog.csdn.net/IBM_hoojo
 * @email hoojo_@126.com
 * @version 1.0
 */
public class SaveItemFile {
	//存储文件
	private RandomAccessFile itemFile;

	public SaveItemFile() throws IOException {
		this("", 0);
	}

	/**
	 * @param name 文件路径、名称
	 * @param pos 写入点位置 position
	 * @throws IOException
	 */
	public SaveItemFile(String name, long pos) throws IOException {
		itemFile = new RandomAccessFile(name, "rw");
		//在指定的pos位置开始写入数据
		itemFile.seek(pos);
	}

	/**
	 * <b>function:</b> 同步方法写入文件
	 * @author hoojo
	 * @createDate 2011-9-26 下午12:21:22
	 * @param buff 缓冲数组
	 * @param start 起始位置
	 * @param length 长度
	 * @return
	 */
	public synchronized int write(byte[] buff, int start, int length) {
		int i = -1;
		try {
			itemFile.write(buff, start, length);
			i = length;
		} catch (IOException e) {
			e.printStackTrace();
		}
		return i;
	}

	public void close() throws IOException {
		if (itemFile != null) {
			itemFile.close();
		}
	}
}

这个类主要是完成向本地的指定文件指针出开始写入文件，并返回当前写入文件的长度（文件指针）。这个类将被线程调用，文件被分成对应的块后，将被线程调用。每个线程都将会调用这个类完成文件的随机写入。

三、单个线程下载文件

[java] view plaincopyprint?

  1. package com.hoo.download; 
  2.  
  3. import java.io.IOException; 
  4. import java.io.InputStream; 
  5. import java.net.HttpURLConnection; 
  6. import java.net.MalformedURLException; 
  7. import java.net.URL; 
  8. import java.net.URLConnection; 
  9. import com.hoo.util.LogUtils; 
  10.  
  11. /**
  12. * <b>function:</b> 单线程下载文件
  13. * @author hoojo
  14. * @createDate 2011-9-22 下午02:55:10
  15. * @file DownloadFile.java
  16. * @package com.hoo.download
  17. * @project MultiThreadDownLoad
  18. * @blog http://blog.csdn.net/IBM_hoojo
  19. * @email hoojo_@126.com
  20. * @version 1.0
  21. */ 
  22. public class DownloadFile
    extends Thread { 
  23.      
  24.     //下载文件url 
  25.     private String url; 
  26.     //下载文件起始位置   
  27.     private long startPos; 
  28.     //下载文件结束位置 
  29.     private long endPos; 
  30.     //线程id 
  31.     private int threadId; 
  32.      
  33.     //下载是否完成 
  34.     private boolean isDownloadOver =
    false; 
  35.  
  36.     private SaveItemFile itemFile; 
  37.      
  38.     private static
    final int BUFF_LENGTH =
    1024 * 8; 
  39.      
  40.     /**
  41.      * @param url 下载文件url
  42.      * @param name 文件名称
  43.      * @param startPos 下载文件起点
  44.      * @param endPos 下载文件结束点
  45.      * @param threadId 线程id
  46.      * @throws IOException
  47.      */ 
  48.     public DownloadFile(String url, String name,
    long startPos, long endPos,
    int threadId) throws IOException { 
  49.         super(); 
  50.         this.url = url; 
  51.         this.startPos = startPos; 
  52.         this.endPos = endPos; 
  53.         this.threadId = threadId; 
  54.         //分块下载写入文件内容 
  55.         this.itemFile =
    new SaveItemFile(name, startPos); 
  56.     } 
  57.  
  58.      
  59.     @Override 
  60.     public void run() { 
  61.         while (endPos > startPos && !isDownloadOver) { 
  62.             try { 
  63.                 URL url = new URL(this.url); 
  64.                 HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
  65.                  
  66.                 // 设置连接超时时间为10000ms 
  67.                 conn.setConnectTimeout(10000); 
  68.                 // 设置读取数据超时时间为10000ms 
  69.                 conn.setReadTimeout(10000); 
  70.                  
  71.                 setHeader(conn); 
  72.                  
  73.                 String property = "bytes=" + startPos +
    "-"; 
  74.                 conn.setRequestProperty("RANGE", property); 
  75.                  
  76.                 //输出log信息 
  77.                 LogUtils.log("开始 " + threadId +
    "：" + property + endPos); 
  78.                 //printHeader(conn); 
  79.                  
  80.                 //获取文件输入流，读取文件内容 
  81.                 InputStream is = conn.getInputStream(); 
  82.                  
  83.                 byte[] buff =
    new byte[BUFF_LENGTH]; 
  84.                 int length = -1; 
  85.                 LogUtils.log("#start#Thread: " + threadId +
    ", startPos: " + startPos + ", endPos: " + endPos); 
  86.                 while ((length = is.read(buff)) >
    0 && startPos < endPos && !isDownloadOver) { 
  87.                     //写入文件内容，返回最后写入的长度 
  88.                     startPos += itemFile.write(buff,
    0, length); 
  89.                 } 
  90.                 LogUtils.log("#over#Thread: " + threadId +
    ", startPos: " + startPos + ", endPos: " + endPos); 
  91.                 LogUtils.log("Thread " + threadId +
    " is execute over!"); 
  92.                 this.isDownloadOver =
    true; 
  93.             } catch (MalformedURLException e) { 
  94.                 e.printStackTrace(); 
  95.             } catch (IOException e) { 
  96.                 e.printStackTrace(); 
  97.             } finally { 
  98.                 try { 
  99.                     if (itemFile !=
    null) { 
  100.                         itemFile.close(); 
  101.                     } 
  102.                 } catch (IOException e) { 
  103.                     e.printStackTrace(); 
  104.                 } 
  105.             } 
  106.         } 
  107.         if (endPos < startPos && !isDownloadOver) { 
  108.             LogUtils.log("Thread " + threadId  +
    " startPos > endPos, not need download file !"); 
  109.             this.isDownloadOver =
    true; 
  110.         } 
  111.         if (endPos == startPos && !isDownloadOver) { 
  112.             LogUtils.log("Thread " + threadId  +
    " startPos = endPos, not need download file !"); 
  113.             this.isDownloadOver =
    true; 
  114.         } 
  115.     } 
  116.      
  117.     /**
  118.      * <b>function:</b> 打印下载文件头部信息
  119.      * @author hoojo
  120.      * @createDate 2011-9-22 下午05:44:35
  121.      * @param conn HttpURLConnection
  122.      */ 
  123.     public static
    void printHeader(URLConnection conn) { 
  124.         int i = 1; 
  125.         while (true) { 
  126.             String header = conn.getHeaderFieldKey(i); 
  127.             i++; 
  128.             if (header != null) { 
  129.                 LogUtils.info(header +
    ":" + conn.getHeaderField(i)); 
  130.             } else { 
  131.                 break; 
  132.             } 
  133.         } 
  134.     } 
  135.      
  136.     /**
  137.      * <b>function:</b> 设置URLConnection的头部信息，伪装请求信息
  138.      * @author hoojo
  139.      * @createDate 2011-9-28 下午05:29:43
  140.      * @param con
  141.      */ 
  142.     public static
    void setHeader(URLConnection conn) { 
  143.         conn.setRequestProperty("User-Agent",
    "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.3) Gecko/2008092510 Ubuntu/8.04 (hardy) Firefox/3.0.3"); 
  144.         conn.setRequestProperty("Accept-Language",
    "en-us,en;q=0.7,zh-cn;q=0.3"); 
  145.         conn.setRequestProperty("Accept-Encoding",
    "utf-8"); 
  146.         conn.setRequestProperty("Accept-Charset",
    "ISO-8859-1,utf-8;q=0.7,*;q=0.7"); 
  147.         conn.setRequestProperty("Keep-Alive",
    "300"); 
  148.         conn.setRequestProperty("connnection",
    "keep-alive"); 
  149.         conn.setRequestProperty("If-Modified-Since",
    "Fri, 02 Jan 2009 17:00:05 GMT"); 
  150.         conn.setRequestProperty("If-None-Match",
    "\"1261d8-4290-df64d224\""); 
  151.         conn.setRequestProperty("Cache-conntrol",
    "max-age=0"); 
  152.         conn.setRequestProperty("Referer",
    "http://www.baidu.com"); 
  153.     } 
  154.      
  155.     public boolean isDownloadOver() { 
  156.         return isDownloadOver; 
  157.     } 
  158.      
  159.     public long getStartPos() { 
  160.         return startPos; 
  161.     } 
  162.  
  163.     public long getEndPos() { 
  164.         return endPos; 
  165.     } 
  166. } 
package com.hoo.download;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import com.hoo.util.LogUtils;

/**
 * <b>function:</b> 单线程下载文件
 * @author hoojo
 * @createDate 2011-9-22 下午02:55:10
 * @file DownloadFile.java
 * @package com.hoo.download
 * @project MultiThreadDownLoad
 * @blog http://blog.csdn.net/IBM_hoojo
 * @email hoojo_@126.com
 * @version 1.0
 */
public class DownloadFile extends Thread {

	//下载文件url
	private String url;
	//下载文件起始位置
	private long startPos;
	//下载文件结束位置
	private long endPos;
	//线程id
	private int threadId;

	//下载是否完成
	private boolean isDownloadOver = false;

	private SaveItemFile itemFile;

	private static final int BUFF_LENGTH = 1024 * 8;

	/**
	 * @param url 下载文件url
	 * @param name 文件名称
	 * @param startPos 下载文件起点
	 * @param endPos 下载文件结束点
	 * @param threadId 线程id
	 * @throws IOException
	 */
	public DownloadFile(String url, String name, long startPos, long endPos, int threadId) throws IOException {
		super();
		this.url = url;
		this.startPos = startPos;
		this.endPos = endPos;
		this.threadId = threadId;
		//分块下载写入文件内容
		this.itemFile = new SaveItemFile(name, startPos);
	}

	@Override
	public void run() {
		while (endPos > startPos && !isDownloadOver) {
			try {
				URL url = new URL(this.url);
				HttpURLConnection conn = (HttpURLConnection) url.openConnection();

				// 设置连接超时时间为10000ms
				conn.setConnectTimeout(10000);
				// 设置读取数据超时时间为10000ms
				conn.setReadTimeout(10000);

				setHeader(conn);

				String property = "bytes=" + startPos + "-";
				conn.setRequestProperty("RANGE", property);

				//输出log信息
				LogUtils.log("开始 " + threadId + "：" + property + endPos);
				//printHeader(conn);

				//获取文件输入流，读取文件内容
				InputStream is = conn.getInputStream();

				byte[] buff = new byte[BUFF_LENGTH];
				int length = -1;
				LogUtils.log("#start#Thread: " + threadId + ", startPos: " + startPos + ", endPos: " + endPos);
				while ((length = is.read(buff)) > 0 && startPos < endPos && !isDownloadOver) {
					//写入文件内容，返回最后写入的长度
					startPos += itemFile.write(buff, 0, length);
				}
				LogUtils.log("#over#Thread: " + threadId + ", startPos: " + startPos + ", endPos: " + endPos);
				LogUtils.log("Thread " + threadId + " is execute over!");
				this.isDownloadOver = true;
			} catch (MalformedURLException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			} finally {
				try {
					if (itemFile != null) {
						itemFile.close();
					}
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
		if (endPos < startPos && !isDownloadOver) {
			LogUtils.log("Thread " + threadId  + " startPos > endPos, not need download file !");
			this.isDownloadOver = true;
		}
		if (endPos == startPos && !isDownloadOver) {
			LogUtils.log("Thread " + threadId  + " startPos = endPos, not need download file !");
			this.isDownloadOver = true;
		}
	}

	/**
	 * <b>function:</b> 打印下载文件头部信息
	 * @author hoojo
	 * @createDate 2011-9-22 下午05:44:35
	 * @param conn HttpURLConnection
	 */
	public static void printHeader(URLConnection conn) {
		int i = 1;
		while (true) {
			String header = conn.getHeaderFieldKey(i);
			i++;
			if (header != null) {
				LogUtils.info(header + ":" + conn.getHeaderField(i));
			} else {
				break;
			}
		}
	}

	/**
	 * <b>function:</b> 设置URLConnection的头部信息，伪装请求信息
	 * @author hoojo
	 * @createDate 2011-9-28 下午05:29:43
	 * @param con
	 */
	public static void setHeader(URLConnection conn) {
		conn.setRequestProperty("User-Agent", "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.3) Gecko/2008092510 Ubuntu/8.04 (hardy) Firefox/3.0.3");
		conn.setRequestProperty("Accept-Language", "en-us,en;q=0.7,zh-cn;q=0.3");
		conn.setRequestProperty("Accept-Encoding", "utf-8");
		conn.setRequestProperty("Accept-Charset", "ISO-8859-1,utf-8;q=0.7,*;q=0.7");
		conn.setRequestProperty("Keep-Alive", "300");
		conn.setRequestProperty("connnection", "keep-alive");
		conn.setRequestProperty("If-Modified-Since", "Fri, 02 Jan 2009 17:00:05 GMT");
		conn.setRequestProperty("If-None-Match", "\"1261d8-4290-df64d224\"");
		conn.setRequestProperty("Cache-conntrol", "max-age=0");
		conn.setRequestProperty("Referer", "http://www.baidu.com");
	}

	public boolean isDownloadOver() {
		return isDownloadOver;
	}

	public long getStartPos() {
		return startPos;
	}

	public long getEndPos() {
		return endPos;
	}
}

这个类主要是完成单个线程的文件下载，将通过URLConnection读取指定url的资源信息。然后用InputStream读取文件内容，然后调用调用SaveItemFile类，向本地写入当前要读取的块的内容。

 

四、分段多线程写入文件内容

[java] view plaincopyprint?

  1. package com.hoo.download; 
  2.  
  3. import java.io.DataInputStream; 
  4. import java.io.DataOutputStream; 
  5. import java.io.File; 
  6. import java.io.FileInputStream; 
  7. import java.io.FileOutputStream; 
  8. import java.io.IOException; 
  9. import java.net.HttpURLConnection; 
  10. import java.net.MalformedURLException; 
  11. import java.net.URL; 
  12. import com.hoo.entity.DownloadInfo; 
  13. import com.hoo.util.LogUtils; 
  14.  
  15. /**
  16. * <b>function:</b> 分批量下载文件
  17. * @author hoojo
  18. * @createDate 2011-9-22 下午05:51:54
  19. * @file BatchDownloadFile.java
  20. * @package com.hoo.download
  21. * @project MultiThreadDownLoad
  22. * @blog http://blog.csdn.net/IBM_hoojo
  23. * @email hoojo_@126.com
  24. * @version 1.0
  25. */ 
  26. public class BatchDownloadFile
    implements Runnable { 
  27.     //下载文件信息  
  28.     private DownloadInfo downloadInfo; 
  29.     //一组开始下载位置 
  30.     private long[] startPos; 
  31.     //一组结束下载位置 
  32.     private long[] endPos; 
  33.     //休眠时间 
  34.     private static
    final int SLEEP_SECONDS =
    500; 
  35.     //子线程下载 
  36.     private DownloadFile[] fileItem; 
  37.     //文件长度 
  38.     private int length; 
  39.     //是否第一个文件 
  40.     private boolean first =
    true; 
  41.     //是否停止下载 
  42.     private boolean stop =
    false; 
  43.     //临时文件信息 
  44.     private File tempFile; 
  45.      
  46.     public BatchDownloadFile(DownloadInfo downloadInfo) { 
  47.         this.downloadInfo = downloadInfo; 
  48.         String tempPath = this.downloadInfo.getFilePath() + File.separator + downloadInfo.getFileName() +
    ".position"; 
  49.         tempFile = new File(tempPath); 
  50.         //如果存在读入点位置的文件 
  51.         if (tempFile.exists()) { 
  52.             first = false; 
  53.             //就直接读取内容 
  54.             try { 
  55.                 readPosInfo(); 
  56.             } catch (IOException e) { 
  57.                 e.printStackTrace(); 
  58.             } 
  59.         } else { 
  60.             //数组的长度就要分成多少段的数量 
  61.             startPos = new
    long[downloadInfo.getSplitter()]; 
  62.             endPos = new long[downloadInfo.getSplitter()]; 
  63.         } 
  64.     } 
  65.      
  66.     @Override 
  67.     public void run() { 
  68.         //首次下载，获取下载文件长度 
  69.         if (first) { 
  70.             length = this.getFileSize();//获取文件长度 
  71.             if (length == -1) { 
  72.                 LogUtils.log("file length is know!"); 
  73.                 stop = true; 
  74.             } else if (length == -2) { 
  75.                 LogUtils.log("read file length is error!"); 
  76.                 stop = true; 
  77.             } else
    if (length > 0) { 
  78.                 /**
  79.                  * eg
  80.                  * start: 1, 3, 5, 7, 9
  81.                  * end: 3, 5, 7, 9, length
  82.                  */ 
  83.                 for (int i =
    0, len = startPos.length; i < len; i++) { 
  84.                     int size = i * (length / len); 
  85.                     startPos[i] = size; 
  86.                      
  87.                     //设置最后一个结束点的位置 
  88.                     if (i == len -
    1) { 
  89.                         endPos[i] = length; 
  90.                     } else { 
  91.                         size = (i + 1) * (length / len); 
  92.                         endPos[i] = size; 
  93.                     } 
  94.                     LogUtils.log("start-end Position[" + i +
    "]: " + startPos[i] + "-" + endPos[i]); 
  95.                 } 
  96.             } else { 
  97.                 LogUtils.log("get file length is error, download is stop!"); 
  98.                 stop = true; 
  99.             } 
  100.         } 
  101.          
  102.         //子线程开始下载 
  103.         if (!stop) { 
  104.             //创建单线程下载对象数组 
  105.             fileItem = new DownloadFile[startPos.length];//startPos.length = downloadInfo.getSplitter() 
  106.             for (int i =
    0; i < startPos.length; i++) { 
  107.                 try { 
  108.                     //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 
  109.                     fileItem[i] = new DownloadFile( 
  110.                         downloadInfo.getUrl(),  
  111.                         this.downloadInfo.getFilePath() + File.separator + downloadInfo.getFileName(),  
  112.                         startPos[i], endPos[i], i 
  113.                     ); 
  114.                     fileItem[i].start();//启动线程，开始下载 
  115.                     LogUtils.log("Thread: " + i +
    ", startPos: " + startPos[i] + ", endPos: " + endPos[i]); 
  116.                 } catch (IOException e) { 
  117.                     e.printStackTrace(); 
  118.                 } 
  119.             } 
  120.              
  121.             //循环写入下载文件长度信息 
  122.             while (!stop) { 
  123.                 try { 
  124.                     writePosInfo(); 
  125.                     LogUtils.log("downloading……"); 
  126.                     Thread.sleep(SLEEP_SECONDS); 
  127.                     stop = true; 
  128.                 } catch (IOException e) { 
  129.                     e.printStackTrace(); 
  130.                 } catch (InterruptedException e) { 
  131.                     e.printStackTrace(); 
  132.                 } 
  133.                 for (int i =
    0; i < startPos.length; i++) { 
  134.                     if (!fileItem[i].isDownloadOver()) { 
  135.                         stop = false; 
  136.                         break; 
  137.                     } 
  138.                 } 
  139.             } 
  140.             LogUtils.info("Download task is finished!"); 
  141.         } 
  142.     } 
  143.      
  144.     /**
  145.      * 将写入点数据保存在临时文件中
  146.      * @author hoojo
  147.      * @createDate 2011-9-23 下午05:25:37
  148.      * @throws IOException
  149.      */ 
  150.     private void writePosInfo()
    throws IOException { 
  151.         DataOutputStream dos = new DataOutputStream(new FileOutputStream(tempFile)); 
  152.         dos.writeInt(startPos.length); 
  153.         for (int i =
    0; i < startPos.length; i++) { 
  154.             dos.writeLong(fileItem[i].getStartPos()); 
  155.             dos.writeLong(fileItem[i].getEndPos()); 
  156.             //LogUtils.info("[" + fileItem[i].getStartPos() + "#" + fileItem[i].getEndPos() + "]"); 
  157.         } 
  158.         dos.close(); 
  159.     } 
  160.      
  161.     /**
  162.      * <b>function:</b>读取写入点的位置信息
  163.      * @author hoojo
  164.      * @createDate 2011-9-23 下午05:30:29
  165.      * @throws IOException
  166.      */ 
  167.     private void readPosInfo()
    throws IOException { 
  168.         DataInputStream dis = new DataInputStream(new FileInputStream(tempFile)); 
  169.         int startPosLength = dis.readInt(); 
  170.         startPos = new long[startPosLength]; 
  171.         endPos = new
    long[startPosLength]; 
  172.         for (int i =
    0; i < startPosLength; i++) { 
  173.             startPos[i] = dis.readLong(); 
  174.             endPos[i] = dis.readLong(); 
  175.         } 
  176.         dis.close(); 
  177.     } 
  178.      
  179.     /**
  180.      * <b>function:</b> 获取下载文件的长度
  181.      * @author hoojo
  182.      * @createDate 2011-9-26 下午12:15:08
  183.      * @return
  184.      */ 
  185.     private int getFileSize() { 
  186.         int fileLength = -1; 
  187.         try { 
  188.             URL url = new URL(this.downloadInfo.getUrl()); 
  189.             HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
  190.              
  191.             DownloadFile.setHeader(conn); 
  192.  
  193.             int stateCode = conn.getResponseCode(); 
  194.             //判断http status是否为HTTP/1.1 206 Partial Content或者200 OK 
  195.             if (stateCode != HttpURLConnection.HTTP_OK && stateCode != HttpURLConnection.HTTP_PARTIAL) { 
  196.                 LogUtils.log("Error Code: " + stateCode); 
  197.                 return -2; 
  198.             } else if (stateCode >=
    400) { 
  199.                 LogUtils.log("Error Code: " + stateCode); 
  200.                 return -2; 
  201.             } else { 
  202.                 //获取长度 
  203.                 fileLength = conn.getContentLength(); 
  204.                 LogUtils.log("FileLength: " + fileLength); 
  205.             } 
  206.              
  207.             //读取文件长度 
  208.             /*for (int i = 1; ; i++) {
  209.                 String header = conn.getHeaderFieldKey(i);
  210.                 if (header != null) {
  211.                     if ("Content-Length".equals(header)) {
  212.                         fileLength = Integer.parseInt(conn.getHeaderField(i));
  213.                         break;
  214.                     }
  215.                 } else {
  216.                     break;
  217.                 }
  218.             }
  219.             */ 
  220.              
  221.             DownloadFile.printHeader(conn); 
  222.         } catch (MalformedURLException e) { 
  223.             e.printStackTrace(); 
  224.         } catch (IOException e) { 
  225.             e.printStackTrace(); 
  226.         } 
  227.         return fileLength; 
  228.     } 
  229. } 
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;
	}
}

这个类主要是完成读取指定url资源的内容，获取该资源的长度。然后将该资源分成指定的块数，将每块的起始下载位置、结束下载位置，分别保存在一个数组中。每块都单独开辟一个独立线程开始下载。在开始下载之前，需要创建一个临时文件，写入当前下载线程的开始下载指针位置和结束下载指针位置。

 

五、工具类、测试类

日志工具类

[java] view plaincopyprint?

  1. package com.hoo.util; 
  2.  
  3. /**
  4. * <b>function:</b> 日志工具类
  5. * @author hoojo
  6. * @createDate 2011-9-21 下午05:21:27
  7. * @file LogUtils.java
  8. * @package com.hoo.util
  9. * @project MultiThreadDownLoad
  10. * @blog http://blog.csdn.net/IBM_hoojo
  11. * @email hoojo_@126.com
  12. * @version 1.0
  13. */ 
  14. public abstract
    class LogUtils { 
  15.      
  16.     public static
    void log(Object message) { 
  17.         System.err.println(message); 
  18.     } 
  19.      
  20.     public static
    void log(String message) { 
  21.         System.err.println(message); 
  22.     } 
  23.      
  24.     public static
    void log(int message) { 
  25.         System.err.println(message); 
  26.     } 
  27.      
  28.     public static
    void info(Object message) { 
  29.         System.out.println(message); 
  30.     } 
  31.      
  32.     public static
    void info(String message) { 
  33.         System.out.println(message); 
  34.     } 
  35.      
  36.     public static
    void info(int message) { 
  37.         System.out.println(message); 
  38.     } 
  39. } 
package com.hoo.util;

/**
 * <b>function:</b> 日志工具类
 * @author hoojo
 * @createDate 2011-9-21 下午05:21:27
 * @file LogUtils.java
 * @package com.hoo.util
 * @project MultiThreadDownLoad
 * @blog http://blog.csdn.net/IBM_hoojo
 * @email hoojo_@126.com
 * @version 1.0
 */
public abstract class LogUtils {

	public static void log(Object message) {
		System.err.println(message);
	}

	public static void log(String message) {
		System.err.println(message);
	}

	public static void log(int message) {
		System.err.println(message);
	}

	public static void info(Object message) {
		System.out.println(message);
	}

	public static void info(String message) {
		System.out.println(message);
	}

	public static void info(int message) {
		System.out.println(message);
	}
}

下载工具类

[java] view plaincopyprint?

  1. package com.hoo.util; 
  2.  
  3. import com.hoo.download.BatchDownloadFile; 
  4. import com.hoo.entity.DownloadInfo; 
  5.  
  6. /**
  7. * <b>function:</b> 分块多线程下载工具类
  8. * @author hoojo
  9. * @createDate 2011-9-28 下午05:22:18
  10. * @file DownloadUtils.java
  11. * @package com.hoo.util
  12. * @project MultiThreadDownLoad
  13. * @blog http://blog.csdn.net/IBM_hoojo
  14. * @email hoojo_@126.com
  15. * @version 1.0
  16. */ 
  17. public abstract
    class DownloadUtils { 
  18.  
  19.     public static
    void download(String url) { 
  20.         DownloadInfo bean = new DownloadInfo(url); 
  21.         LogUtils.info(bean); 
  22.         BatchDownloadFile down = new BatchDownloadFile(bean); 
  23.         new Thread(down).start(); 
  24.     } 
  25.      
  26.     public static
    void download(String url, int threadNum) { 
  27.         DownloadInfo bean = new DownloadInfo(url, threadNum); 
  28.         LogUtils.info(bean); 
  29.         BatchDownloadFile down = new BatchDownloadFile(bean); 
  30.         new Thread(down).start(); 
  31.     } 
  32.      
  33.     public static
    void download(String url, String fileName, String filePath,
    int threadNum) { 
  34.         DownloadInfo bean = new DownloadInfo(url, fileName, filePath, threadNum); 
  35.         LogUtils.info(bean); 
  36.         BatchDownloadFile down = new BatchDownloadFile(bean); 
  37.         new Thread(down).start(); 
  38.     } 
  39. } 
package com.hoo.util;

import com.hoo.download.BatchDownloadFile;
import com.hoo.entity.DownloadInfo;

/**
 * <b>function:</b> 分块多线程下载工具类
 * @author hoojo
 * @createDate 2011-9-28 下午05:22:18
 * @file DownloadUtils.java
 * @package com.hoo.util
 * @project MultiThreadDownLoad
 * @blog http://blog.csdn.net/IBM_hoojo
 * @email hoojo_@126.com
 * @version 1.0
 */
public abstract class DownloadUtils {

	public static void download(String url) {
		DownloadInfo bean = new DownloadInfo(url);
		LogUtils.info(bean);
		BatchDownloadFile down = new BatchDownloadFile(bean);
		new Thread(down).start();
	}

	public static void download(String url, int threadNum) {
		DownloadInfo bean = new DownloadInfo(url, threadNum);
		LogUtils.info(bean);
		BatchDownloadFile down = new BatchDownloadFile(bean);
		new Thread(down).start();
	}

	public static void download(String url, String fileName, String filePath, int threadNum) {
		DownloadInfo bean = new DownloadInfo(url, fileName, filePath, threadNum);
		LogUtils.info(bean);
		BatchDownloadFile down = new BatchDownloadFile(bean);
		new Thread(down).start();
	}
}

下载测试类

[java] view plaincopyprint?

  1. package com.hoo.test; 
  2.  
  3. import com.hoo.util.DownloadUtils; 
  4.  
  5. /**
  6. * <b>function:</b> 下载测试
  7. * @author hoojo
  8. * @createDate 2011-9-23 下午05:49:46
  9. * @file TestDownloadMain.java
  10. * @package com.hoo.download
  11. * @project MultiThreadDownLoad
  12. * @blog http://blog.csdn.net/IBM_hoojo
  13. * @email hoojo_@126.com
  14. * @version 1.0
  15. */ 
  16. public class TestDownloadMain { 
  17.  
  18.     public static
    void main(String[] args) { 
  19.         /*DownloadInfo bean = new DownloadInfo("http://i7.meishichina.com/Health/UploadFiles/201109/2011092116224363.jpg");
  20.         System.out.println(bean);
  21.         BatchDownloadFile down = new BatchDownloadFile(bean);
  22.         new Thread(down).start();*/ 
  23.          
  24.         //DownloadUtils.download("http://i7.meishichina.com/Health/UploadFiles/201109/2011092116224363.jpg"); 
  25.         DownloadUtils.download("http://mp3.baidu.com/j?j=2&url=http%3A%2F%2Fzhangmenshiting2.baidu.com%2Fdata%2Fmusic%2F1669425%2F%25E9%2599%25B7%25E5%2585%25A5%25E7%2588%25B1%25E9%2587%258C%25E9%259D%25A2.mp3%3Fxcode%3D2ff36fb70737c816553396c56deab3f1",
    "aa.mp3", "c:/temp",
    5); 
  26.     } 
  27. } 
package com.hoo.test;

import com.hoo.util.DownloadUtils;

/**
 * <b>function:</b> 下载测试
 * @author hoojo
 * @createDate 2011-9-23 下午05:49:46
 * @file TestDownloadMain.java
 * @package com.hoo.download
 * @project MultiThreadDownLoad
 * @blog http://blog.csdn.net/IBM_hoojo
 * @email hoojo_@126.com
 * @version 1.0
 */
public class TestDownloadMain {

	public static void main(String[] args) {
		/*DownloadInfo bean = new DownloadInfo("http://i7.meishichina.com/Health/UploadFiles/201109/2011092116224363.jpg");
		System.out.println(bean);
		BatchDownloadFile down = new BatchDownloadFile(bean);
		new Thread(down).start();*/

		//DownloadUtils.download("http://i7.meishichina.com/Health/UploadFiles/201109/2011092116224363.jpg");
		DownloadUtils.download("http://mp3.baidu.com/j?j=2&url=http%3A%2F%2Fzhangmenshiting2.baidu.com%2Fdata%2Fmusic%2F1669425%2F%25E9%2599%25B7%25E5%2585%25A5%25E7%2588%25B1%25E9%2587%258C%25E9%259D%25A2.mp3%3Fxcode%3D2ff36fb70737c816553396c56deab3f1", "aa.mp3", "c:/temp", 5);
	}
}

多线程下载主要在第三部和第四部，其他的地方还是很好理解。源码中提供相应的注释了，便于理解。

本文转载于：http://blog.csdn.net/ibm_hoojo/article/details/6838222

时间： 2024-10-31 15:01:24

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