java网络编程之http多线程下载

/** *Author: Jiangtao He; Email: [email protected] *File Name: DownloadThread.java *Date: 2012-1-18 *Copyright: All right reserved by author - Jiangtao He *Version: MyJavaExpert v1.0 */ package com.ross.httpdownload; import java.io.*; import java.net.*; import java.text.*; import java.util.Date; import com.ross.httpdownload.util.*; /** * Author: Jiangtao He; Email: [email protected] * Date: 2012-1-18 * Since: MyJavaExpert v1.0 * Description: download thread implementation. */ public class DownloadThread implements Runnable { private String sFileURL; private long lStartIndex; private long lEndIndex; private int iThreadId; private String sFullFileName; private HttpProcess oHttpProcess; /** * Description: default constructor, it is used for initializing the fields. */ public DownloadThread() { oHttpProcess = new HttpProcess(); } /** * Author: Jiangtao He; Email: [email protected] * Description: it will implement the download logic */ public void run() { System.out.println("The download thread " + this.iThreadId + " is started at " + (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")) .format(new Date())); System.out.println("The download index of " + this.iThreadId + " is " + this.lStartIndex + " to " + this.lEndIndex); // content length long lContentlen = 0; // used to store the new url connection URLConnection oURLCon = null; // used to store the input stream of the response BufferedInputStream oBIn = null; // used to store the output writer RandomAccessFile oRAFile = null; // create the buffer byte[] bBuffer = new byte[SysValue.Buffer_Size]; // get URL connection try { // create a link for each thread oURLCon = oHttpProcess.getURLConnection(this.sFileURL); // allow the user interaction, for example: a verify pop window oURLCon.setAllowUserInteraction(true); // set the resource range oURLCon.setRequestProperty("Range", "bytes=" + this.lStartIndex + "-" + this.lEndIndex); // get the url connection input stream oBIn = new BufferedInputStream(oURLCon.getInputStream()); // initialize the random access file object oRAFile = new RandomAccessFile(this.sFullFileName, "rw"); oRAFile.seek(this.lStartIndex); // read the stream from http connection int iLen = 0; int iActualLen = 0; while (iActualLen < (this.lEndIndex - this.lStartIndex + 1)) { iLen = oBIn.read(bBuffer, 0, SysValue.Buffer_Size); if (-1 == iLen) { break; } // write the read data to file oRAFile.write(bBuffer, 0, iLen); // move the position mark iActualLen = iActualLen + iLen; } System.out.println("Thread " + this.iThreadId + " download is finished, totaly: " + iActualLen); } catch (IOException e) { System.out.println("download the file failed, IO Exception" + e.getMessage()); e.printStackTrace(); } finally { if (null != oRAFile) { try { oRAFile.close(); } catch (IOException e) { System.out .println("close object of RandomAccessFile failed, IO Exception" + e.getStackTrace()); } } if (null != oBIn) { try { oBIn.close(); } catch (IOException e) { System.out .println("close input stream of http connection failed, IO Exception" + e.getStackTrace()); } } } System.out.println("The download thread " + this.iThreadId + " is ended at " + (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")) .format(new Date())); } public String getSFileURL() { return sFileURL; } public void setSFileURL(String fileURL) { sFileURL = fileURL; } public long getLStartIndex() { return lStartIndex; } public void setLStartIndex(long startIndex) { lStartIndex = startIndex; } public long getLEndIndex() { return lEndIndex; } public void setLEndIndex(long endIndex) { lEndIndex = endIndex; } public int getIThreadId() { return iThreadId; } public void setIThreadId(int threadId) { iThreadId = threadId; } public String getSFullFileName() { return sFullFileName; } public void setSFullFileName(String fullFileName) { sFullFileName = fullFileName; } }